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  • 51.
    Karpestam, Einat
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Merilaita, Sami
    Department of Biosciences, Åbo Akademi University, Turku 780 FI-20520, Finland..
    Forsman, Anders
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Detection experiments with humans implicate visual predation as a driver of colour polymorphism dynamics in pygmy grasshoppers2013Inngår i: BMC Ecology, ISSN 1472-6785, E-ISSN 1472-6785, Vol. 13, s. Article number 17-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Animal colour patterns offer good model systems for studies of biodiversity and evolution of local adaptations. An increasingly popular approach to study the role of selection for camouflage for evolutionary trajectories of animal colour patterns is to present images of prey on paper or computer screens to human 'predators'. Yet, few attempts have been made to confirm that rates of detection by humans can predict patterns of selection and evolutionary modifications of prey colour patterns in nature. In this study, we first analyzed encounters between human 'predators' and images of natural black, grey and striped colour morphs of the polymorphic Tetrix subulata pygmy grasshoppers presented on background images of unburnt, intermediate or completely burnt natural habitats. Next, we compared detection rates with estimates of capture probabilities and survival of free-ranging grasshoppers, and with estimates of relative morph frequencies in natural populations. Results: The proportion of grasshoppers that were detected and time to detection depended on both the colour pattern of the prey and on the type of visual background. Grasshoppers were detected more often and faster on unburnt backgrounds than on 50% and 100% burnt backgrounds. Striped prey were detected less often than grey or black prey on unburnt backgrounds; grey prey were detected more often than black or striped prey on 50% burnt backgrounds; and black prey were detected less often than grey prey on 100% burnt backgrounds. Rates of detection mirrored previously reported rates of capture by humans of free-ranging grasshoppers, as well as morph specific survival in the wild. Rates of detection were also correlated with frequencies of striped, black and grey morphs in samples of T. subulata from natural populations that occupied the three habitat types used for the detection experiment. Conclusions: Our findings demonstrate that crypsis is background-dependent, and implicate visual predation as an important driver of evolutionary modifications of colour polymorphism in pygmy grasshoppers. Our study provides the clearest evidence to date that using humans as 'predators' in detection experiments may provide reliable information on the protective values of prey colour patterns and of natural selection and microevolution of camouflage in the wild.

  • 52.
    Karpestam, Einat
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Merilaita, Sami
    Åbo Akademi University, Finland.
    Forsman, Anders
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Reduced predation risk for melanistic pygmy grasshoppers in post-fire environments2012Inngår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 2, nr 9, s. 2204-2212Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The existence of melanistic (black) color forms in many species represents interesting model systems that have played important roles for our understanding of selective processes, evolution of adaptations, and the maintenance of variation. A recent study reported on rapid evolutionary shifts in frequencies of the melanistic forms in replicated populations of Tetrix subulata pygmy grasshoppers; the incidence of the melanistic form was higher in recently burned areas with backgrounds blackened by fire than in nonburned areas, and it declined over time in postfire environments. Here, we tested the hypothesis that the frequency shifts of the black color variant were driven, at least in part, by changes in the selective regime imposed by visual predators. To study detectability of the melanistic form, we presented human “predators” with images of black grasshoppers and samples of the natural habitat on computer screens. We demonstrate that the protective value of black coloration differs between burnt and nonburnt environments and gradually increases in habitats that have been more blackened by fire. These findings support the notion that a black color pattern provides improved protection from visually oriented predators against blackened backgrounds and implicate camouflage and predation as important drivers of fire melanism in pygmy grasshoppers.

  • 53.
    Karpestam, Einat
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Merilaita, Sami
    Åbo Akad Univ, Finland;Univ Turku, Finland.
    Forsman, Anders
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Size variability effects on visual detection are influenced by colour pattern and perceived size2018Inngår i: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 143, s. 131-138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Most animals including humans use vision to detect, identify, evaluate and respond to potential prey items in complex environments. Theories predict that predators' visual search performance is better when targets are similar than when targets are dissimilar and require divided attention, and this may contribute to colour pattern polymorphism in prey. Most prey also vary in size, but how size variation influences detectability and search performance of predators that utilize polymorphic prey has received little attention. To evaluate the effect of size variability on prey detection we asked human subjects to search for images of black, grey and striped pygmy grasshoppers presented on computer screens in size-variable (large, medium and small) or in size-invariable (all medium) sequences (populations) against photographs of natural grasshopper habitat. Results showed that size variability either increased or reduced detection of medium-sized targets depending on colour morph. To evaluate whether bias in perceived size varies depending on colour pattern, subjects were asked to discriminate between two grasshopper images of identical size that were presented in pairs against a monochromatic background. Subjects more often incorrectly classified one of the two identical-sized targets as being larger than the other in colour-dimorphic than in monomorphic presentations. The distinctly patterned (striped) morph elicited stronger size perception biases than the dorsally grey or black morphs, and striped grasshoppers were incorrectly classified more often as smaller than grey grasshoppers. The direction of the effect of size variability on detection changed across colour patterns as the bias in perceived size increased. Such joint effects of variation in size and colour pattern on detection and perception can impact the outcome of behavioural and evolutionary interactions between visually oriented predators and their camouflaged prey. This may have consequences for population dynamics, evolution of polymorphisms, community species composition and ecosystem functioning. (C) 2018 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

  • 54.
    Karpestam, Einat
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Wennersten, Lena
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Forsman, Anders
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Matching habitat choice by experimentally mismatched phenotypes2012Inngår i: Evolutionary Ecology, ISSN 0269-7653, E-ISSN 1573-8477, Vol. 26, nr 4, s. 893-907Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gene flow is often regarded a random process that homogenizes differencesbetween populations and constrains local adaptation. However, the matching habitat choicehypothesis posits that individuals actively choose those microhabitats that best match theirspecific phenotype to maximize fitness. Dispersal (and possibly gene flow) may thus bedirected. Many studies report associations between habitats and phenotypes, but they mayreflect selection, plasticity or adaptation rather than matching choice. Here, we test twopredictions from the matching habitat choice hypothesis by manipulating the dorsal colourof Tetrix subulata, a pygmy grasshopper. (1) Is microhabitat choice flexible such thatdifferently manipulated phenotypes distribute themselves differently in a microclimaticand solar radiation mosaic? (2) If they do, are their fitness prospects higher in the morepreferred microhabitat? We find that individuals painted white or black do distributethemselves differently, with black individuals residing in habitats with less radiation, onaverage, than white individuals, demonstrating that microhabitat choices are plastic. Furthermore,white females had more hatchlings than black ones in the increased radiationtreatment, and this was mainly due to increased mortality of black females under increasedradiation. These findings provide rare experimental evidence in line with predictions fromthe matching habitat choice hypothesis.

  • 55.
    Larsson, Kjell
    Uppsala University, Sweden.
    Genetic and environmental effects on the timing of wing moult in the barnacle goose1996Inngår i: Heredity, ISSN 0018-067X, E-ISSN 1365-2540, Vol. 76, s. 100-107Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Genetic and environmental effects on the timing of wing moult were analysed in a breeding barnacle goose (Branta leucopsis) population recently established in the Baltic area. Start of wing moult of adults was found to be correlated with number of fledged young produced and start of wing moult of their breeding partners. Date of birth and age were not significantly correlated with start of wing moult although the length of the interval between hatching date of broods and start of wing moult was correlated with age. Repeatability estimates were significantly different from zero showing individual consistency of start of wing moult between years. Offspring-parent regressions and full-sib analyses yielded significant heritability estimates for start of wing moult. No indications of maternal effects were found. An especially high degree of resemblance between one-year-old full-sibs indicated the presence of a common environment effect on start of wing moult.

  • 56.
    Larsson, Kjell
    Uppsala University, Sweden.
    Genetic and social inheritance of body and egg size in the barnacle goose (Branta leucopsis)1992Inngår i: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 46, nr 1, s. 235-244Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present heritability estimates for final size of body traits and egg size as well as phenotypic and genetic correlations between body and egg traits in a recently established population of the barnacle goose (Branta leucopsis) in the Baltic area. Body traits as well as egg size were heritable and, hence, could respond evolutionarily to phenotypic selection. Genetic correlations between body size traits were significantly positive and of similar magnitude or higher than the corresponding phenotypic correlations. Heritability estimates for tarsus length obtained from fullsib analyses were higher than those obtained from midoffspring-midparent regressions, and this indicates common environment effects on siblings. Heritabilities for tarsus length obtained from midoffspring-mother regressions were significantly higher than estimates from midoffspring-father regressions. The results suggest that this discrepancy is not caused by maternal effects through egg size, nor by extra-pair fertilizations, but by a socially inherited foraging site fidelity in females.

  • 57.
    Larsson, Kjell
    Uppsala University, Sweden.
    Inheritance of body size in the Barnacle Goose under different environmental conditions1993Inngår i: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 6, nr 2, s. 195-208Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Heritabilities, genetic variances and covariances for body size traits, i.e. tarsus length, head length and body mass, were estimated under different environmental conditions in a Barnacle Goose (Branta leucopsis) population. Under poor growth conditions, that is, when average body size of fully grown offspring in a given cohort was small, the offspring-parent regressions and full-sib analyses yielded heritability estimates not significantly different from zero. By contrast, when growth conditions were normal or good the heritability estimates were generally significantly positive. Comparisons of genetic covariance estimates indicated that they also differed across the analysed environmental conditions. This result, together with similar results obtained in studies of passerine birds, suggests that genotype-environment interactions might be frequent within the range of environments normally encountered by birds in natural populations. If general, such results might question the validity of assuming approximate constancy of additive genetic variances and covariances over time and environments in evolutionary models.

  • 58.
    Larsson, Kjell
    et al.
    Uppsala University, Sweden.
    Forslund, Pär
    Uppsala University, Sweden.
    Environmentally induced morphological variation in the Barnacle Goose, Branta leucopsis1991Inngår i: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 4, nr 4, s. 619-636Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The environmental conditions to which juvenile barnacle geese (Branta leucopsis) were exposed during growth were found to affect their body size at fledging as well as their final adult body size. Small juveniles showed compensatory growth from the time of fledging up to one year of age, but this did not fully compensate the differences in body size that were established before fledging. The variation in protein content in plants eaten during growth could probably explain the observed body size differences, sometimes of more than 10%, between different categories of adult geese. Our results imply that one cannot infer selection on morphological characters from differences between samples of adult birds from different localities or from different cohorts within a population, without first showing that environmental conditions during growth do not affect the development of the characters under study.

  • 59.
    Larsson, Kjell
    et al.
    Uppsala University, Sweden.
    Rattiste, Kalev
    Uppsala University, Sweden ; Estonian Institute of Zoology and Botany, Estonia.
    Lilleleht, Vilju
    Estonian Institute of Zoology and Botany, Estonia.
    Heritability of head size in the common gull Larus canus in relation to environmental conditions during offspring growth1997Inngår i: Heredity, ISSN 0018-067X, E-ISSN 1365-2540, Vol. 79, nr 2, s. 201-207Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We studied the heritability of head length in a common gull (Larus canus) population breeding in western Estonia. Heritability estimates obtained from offspring-parent regressions were moderate to high and significantly different from zero. Head size might hence respond evolutionarily to phenotypic selection. Offspring-mother and offspring-father regressions yielded similar heritability estimates. This indicated that size-related maternal or paternal effects were absent or weak. Heritability and additive genetic variance estimates obtained from offspring-parent regressions and full-sib analyses were higher when offspring had grown up under good environmental conditions than under poor environmental conditions. Such a pattern has previously been found in some other studies of birds. This suggests that genotype-environment interactions might be frequent within the range of conditions experienced by natural bird populations.

  • 60.
    Larsson, Kjell
    et al.
    Uppsala University, Sweden.
    van der Jeugd, Henk P
    Uppsala University, Sweden.
    van der Veen, Ineke
    Uppsala University, Sweden ; University of Groningen, The Netherlands.
    Forslund, Pär
    Swedish University of Agricultural Sciences, Sweden.
    Body size declines despite positive directional selection on heritable size traits in a barnacle goose population1998Inngår i: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 52, nr 4, s. 1169-1184Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Analyses of more than 2000 marked barnacle geese (Branta leucopsis) in the largest Baltic colony, Sweden, showed that structurally large females generally produced larger clutches and larger eggs, hatched their broods earlier in the season, and produced more and heavier young than smaller females. In males, the corresponding relationships between reproductive parameters and structural body size were weaker or nonsignificant. Because structural body size traits have previously been found to be significantly heritable and positively genetically correlated, an increase in mean structural body size of individuals as a response to selection might have been expected. By contrast, we found that the mean adult head length and mean adult tarsus length decreased significantly in the largest colony by approximately 0.7 and 0.5 standard deviations, respectively, in both males and females during the 13-year study period. Environmental factors, such as the amount of rain in different years, were found to affect the availability of high-quality food for growing geese. As a consequence of this temporal variability in the availability of high-quality food, the mean adult structural body size of different cohorts differed by up to 1.3 standard deviations. Comparisons of mean body size of cohorts born in different colonies suggest that the most likely explanation for the body-size decline in the main study colony is that a density-dependent process, which mainly was in effect during the very early phase of colony growth, negatively affected juvenile growth and final size. We conclude that large environmental effects on growth and final structural body size easily can mask microevolutionary responses to selection. Analyses of environmental causes underlying temporal and spatial body size variation should always be considered in the reconstruction and prediction of evolutionary changes in natural populations.

  • 61.
    Lehtonen, Topi K.
    et al.
    Monash University, Australia ; University of Turku, Finland.
    Svensson, P. Andreas
    Monash University, Australia ; Deakin University, Australia.
    Wong, Bob B. M.
    Monash University, Australia.
    Both male and female identity influence variation in male signalling effort2011Inngår i: BMC Evolutionary Biology, ISSN 1471-2148, E-ISSN 1471-2148, Vol. 11, artikkel-id 233Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Male sexual displays play an important role in sexual selection by affecting reproductive success. However, for such displays to be useful for female mate choice, courtship should vary more among than within individual males. In this regard, a potentially important source of within male variation is adjustment of male courtship effort in response to female traits. Accordingly, we set out to dissect sources of variation in male courtship effort in a fish, the desert goby (Chlamydogobius eremius). We did so by designing an experiment that allowed simultaneous estimation of within and between male variation in courtship, while also assessing the importance of the males and females as sources of courtship variation. Results: Although males adjusted their courtship depending on the identity of the female (a potentially important source of within-male variation), among-male differences were considerably greater. In addition, male courtship effort towards a pair of females was highly repeatable over a short time frame. Conclusion: Despite the plasticity in male courtship effort, courtship displays had the potential to reliably convey information about the male to mate-searching females. Our experiment therefore underscores the importance of addressing the different sources contributing to variation in the expression of sexually-selected traits.

  • 62.
    Lehtonen, Topi K.
    et al.
    University of Konstanz, Germany ; Monash University, Australia; University of Turku, Finland.
    Wong, Bob B. M.
    Monash University, Australia.
    Svensson, P. Andreas
    Monash University, Australia.
    Meyer, Axel
    University of Konstanz, Germany.
    Adjustment of brood care behaviour in the absence of a mate in two species of Nicaraguan crater lake cichlids2011Inngår i: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 65, nr 4, s. 613-619Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In many taxa, parental strategies can vary among individuals. This is especially true in species with biparental care, with males, more often than females, deserting their mates. While there is an abundance of theoretical predictions and empirical data on factors inducing mate abandonment by males, much less is known about what consequences this may have on female behaviour, particularly in the field and in non-avian systems. Here, we compared brood defence rate, behavioural defence types, and brood success of solitary and paired females in two species of Neotropical cichlid fish in their natural habitat. In terms of the rate of territorial aggression towards potential brood predators, solitary females were able to fully compensate in the absence of a male but, in so doing, ended up maintaining smaller territories, which appeared to compromise offspring fitness in at least one of the two species. Hence, our results suggest that even extensive quantitative compensation in parental effort by solitary females may not be enough to ensure adequate qualitative compensation for the lack of male participation, highlighting the importance of distinguishing between these two aspects of compensatory parental care.

  • 63.
    Lundin, Daniel
    et al.
    Stockholm University.
    Berggren, Gustav
    Stockholm University.
    Logan, Derek T.
    Lund University.
    Sjöberg, Britt-Marie
    Stockholm University.
    The Origin and Evolution of Ribonucleotide Reduction2015Inngår i: Life, E-ISSN 2075-1729, Vol. 5, nr 1, s. 604-636Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ribonucleotide reduction is the only pathway for de novo synthesis of deoxyribonucleotides in extant organisms. This chemically demanding reaction, which proceeds via a carbon-centered free radical, is catalyzed by ribonucleotide reductase (RNR). The mechanism has been deemed unlikely to be catalyzed by a ribozyme, creating an enigma regarding how the building blocks for DNA were synthesized at the transition from RNA- to DNA-encoded genomes. While it is entirely possible that a different pathway was later replaced with the modern mechanism, here we explore the evolutionary and biochemical limits for an origin of the mechanism in the RNA + protein world and suggest a model for a prototypical ribonucleotide reductase (protoRNR). From the protoRNR evolved the ancestor to modern RNRs, the urRNR, which diversified into the modern three classes. Since the initial radical generation differs between the three modern classes, it is difficult to establish how it was generated in the urRNR. Here we suggest a model that is similar to the B12-dependent mechanism in modern class II RNRs.

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  • 64.
    Lundin, Daniel
    et al.
    Stockholm University.
    Gribaldo, Simonetta
    Institut Pasteur, France.
    Torrents, Eduard
    Stockholm University ; Scientific Park of Barcelona, Spain.
    Sjöberg, Britt-Marie
    Stockholm University.
    Poole, Anthony M.
    Stockholm University ; University of Canterbury, New Zealand.
    Ribonucleotide reduction - horizontal transfer of a required function spans all three domains2010Inngår i: BMC Evolutionary Biology, ISSN 1471-2148, E-ISSN 1471-2148, Vol. 10, nr 1, artikkel-id 383Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ribonucleotide reduction is the only de novo pathway for synthesis of deoxyribonucleotides, the building blocks of DNA. The reaction is catalysed by ribonucleotide reductases (RNRs), an ancient enzyme family comprised of three classes. Each class has distinct operational constraints, and are broadly distributed across organisms from all three domains, though few class I RNRs have been identified in archaeal genomes, and classes II and III likewise appear rare across eukaryotes. In this study, we examine whether this distribution is best explained by presence of all three classes in the Last Universal Common Ancestor (LUCA), or by horizontal gene transfer (HGT) of RNR genes. We also examine to what extent environmental factors may have impacted the distribution of RNR classes. PMID: 21143941

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    fulltext
  • 65.
    Lundin, Daniel
    et al.
    Stockholm University;KTH Royal Institute of Technology.
    Poole, Anthony M.
    University of Canterbury, New Zealand.
    Sjöberg, Britt-Marie
    Stockholm University.
    Högbom, Martin
    Stockholm University.
    Use of Structural Phylogenetic Networks for Classification of the Ferritin-like Superfamily2012Inngår i: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 287, nr 24, s. 20565-20575Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the postgenomic era, bioinformatic analysis of sequence similarity is an immensely powerful tool to gain insight into evolution and protein function. Over long evolutionary distances, however, sequence-based methods fail as the similarities become too low for phylogenetic analysis. Macromolecular structure generally appears better conserved than sequence, but clear models for how structure evolves over time are lacking. The exponential growth of three-dimensional structural information may allow novel structure-based methods to drastically extend the evolutionary time scales amenable to phylogenetics and functional classification of proteins. To this end, we analyzed 80 structures from the functionally diverse ferritin-like superfamily. Using evolutionary networks, we demonstrate that structural comparisons can delineate and discover groups of proteins beyond the “twilight zone” where sequence similarity does not allow evolutionary analysis, suggesting that considerable and useful evolutionary signal is preserved in three-dimensional structures.

  • 66.
    Lundin, Daniel
    et al.
    Stockholm University.
    Torrents, Eduard
    Stockholm University ; Scientific Park of Barcelona, Spain.
    Poole, Anthony M.
    Stockholm University.
    Sjöberg, Britt-Marie
    Stockholm University.
    RNRdb, a curated database of the universal enzyme family ribonucleotide reductase, reveals a high level of misannotation in sequences deposited to Genbank2009Inngår i: BMC Genomics, ISSN 1471-2164, E-ISSN 1471-2164, Vol. 10, nr 1, artikkel-id 589Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ribonucleotide reductases (RNRs) catalyse the only known de novo pathway for deoxyribonucleotide synthesis, and are therefore essential to DNA-based life. While ribonucleotide reduction has a single evolutionary origin, significant differences between RNRs nevertheless exist, notably in cofactor requirements, subunit composition and allosteric regulation. These differences result in distinct operational constraints (anaerobicity, iron/oxygen dependence and cobalamin dependence), and form the basis for the classification of RNRs into three classes. PMID: 19995434

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  • 67.
    Melkikh, Alexey V.
    et al.
    Ural Federal University, Russia.
    Khrennikov, Andrei
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för matematik (MA).
    Quantum-like model of partially directed evolution2017Inngår i: Progress in Biophysics and Molecular Biology, ISSN 0079-6107, E-ISSN 1873-1732, Vol. 125, s. 36-51Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The background of this study is that models of the evolution of living systems are based mainly on the evolution of replicators and cannot explain many of the properties of biological systems such as the existence of the sexes, molecular exaptation and others. The purpose of this study is to build a complete model of the evolution of organisms based on a combination of quantum-like models and models based on partial directivity of evolution. We also used optimal control theory for evolution modeling. We found that partial directivity of evolution is necessary for the explanation of the properties of an evolving system such as the stability of evolutionary strategies, aging and death, the presence of the sexes. The proposed model represents a systems approach to the evolution of species and will facilitate the understanding of the evolution and biology as a whole.

  • 68. Mobley, K. B.
    et al.
    Amundsen, T.
    Forsgren, E.
    Svensson, P. Andreas
    School of Biological Sciences, Monash University, Melbourne, VIC 3800, Australia.
    Jones, A.G.
    Multiple mating and a low incidence of cuckoldry for nest-holding males in the two-spotted goby, Gobiusculus flavescens2009Inngår i: BMC Evolutionary Biology, ISSN 1471-2148, E-ISSN 1471-2148, Vol. 9, s. 1-10, artikkel-id 6Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: A major question in behavioural ecology concerns the relationship between genetic mating systems and the strength of sexual selection. In this study, we investigated the genetic mating system of the two-spotted goby (Gobiusculus flavescens), a useful fish model for the study of sexual selection whose genetic mating system remains uncharacterized. We developed four polymorphic microsatellite markers and used them to conduct parentage analyses on 21 nests collected during the breeding season to examine the rates of multiple mating by males and to test for evidence of alternative mating strategies. Results: Results of this study indicate that male G. flavescens mate with multiple females and enjoy confidence of paternity. We detected only one instance of sneaking, so cuckoldry contributed a very small percentage (~0.1%) of the total fertilizations in this population. Nests were nearly full and males that maintain larger nests have higher mating and reproductive success, irrespective of body size. Conclusion: Overall, our investigation shows that G. flavescens is similar to other, related gobies in that the nests of care-giving males often contain eggs from multiple females. However, G. flavescens differs from other gobies in displaying an extremely low rate of cuckoldry. The study of ecological factors responsible for this important difference between G. flavescens and related species should be a fertile area for future work.

  • 69.
    Neumann, Nadja
    et al.
    Stockholm University.
    Lundin, Daniel
    Stockholm University.
    Poole, Anthony M.
    Stockholm University ; University of Canterbury, New Zealand.
    Comparative Genomic Evidence for a Complete Nuclear Pore Complex in the Last Eukaryotic Common Ancestor2010Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 5, nr 10, artikkel-id e13241Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BackgroundThe Nuclear Pore Complex (NPC) facilitates molecular trafficking between nucleus and cytoplasm and is an integral feature of the eukaryote cell. It exhibits eight-fold rotational symmetry and is comprised of approximately 30 nucleoporins (Nups) in different stoichiometries. Nups are broadly conserved between yeast, vertebrates and plants, but few have been identified among other major eukaryotic groups.

    Methodology/Principal FindingsWe screened for Nups across 60 eukaryote genomes and report that 19 Nups (spanning all major protein subcomplexes) are found in all eukaryote supergroups represented in our study (Opisthokonts, Amoebozoa, Viridiplantae, Chromalveolates and Excavates). Based on parsimony, between 23 and 26 of 31 Nups can be placed in LECA. Notably, they include central components of the anchoring system (Ndc1 and Gp210) indicating that the anchoring system did not evolve by convergence, as has previously been suggested. These results significantly extend earlier results and, importantly, unambiguously place a fully-fledged NPC in LECA. We also test the proposal that transmembrane Pom proteins in vertebrates and yeasts may account for their variant forms of mitosis (open mitoses in vertebrates, closed among yeasts). The distribution of homologues of vertebrate Pom121 and yeast Pom152 is not consistent with this suggestion, but the distribution of fungal Pom34 fits a scenario wherein it was integral to the evolution of closed mitosis in ascomycetes. We also report an updated screen for vesicle coating complexes, which share a common evolutionary origin with Nups, and can be traced back to LECA. Surprisingly, we find only three supergroup-level differences (one gain and two losses) between the constituents of COPI, COPII and Clathrin complexes.

    Conclusions/SignificanceOur results indicate that all major protein subcomplexes in the Nuclear Pore Complex are traceable to the Last Eukaryotic Common Ancestor (LECA). In contrast to previous screens, we demonstrate that our conclusions hold regardless of the position of the root of the eukaryote tree.

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  • 70. Nilsson Sköld, H.
    et al.
    Svensson, P. Andreas
    Monash Univ, Sch Biol Sci, Clayton, Vic 3800, Australia.
    Zejlon, C.
    The capacity for internal colour change is related to body transparency in fishes2010Inngår i: Pigment Cell & Melanoma Research, ISSN 1755-1471, E-ISSN 1755-148X, Vol. 23, nr 2, s. 292-295Artikkel i tidsskrift (Fagfellevurdert)
  • 71.
    Nordahl, Oscar
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Intraspecific diversity of pike (Esox lucius) in the Baltic Sea and new insights on thermoregulation in fish2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Fish display a fascinating variation in behavior, morphology and physiology among species, among individuals within species, and within individuals over time. A central quest in ecology and evolution is to understand causes and consequences of such variation. This thesis aims to contribute to this knowledge by: (1) investigating the evolutionary processes that shape intraspecific variation among sympatric subpopulations of pike in coastal areas of the Baltic Sea; and (2) exploring whether fish can utilize sun-basking to regulate body temperature and whether this has any consequences for fitness.

    Identifying barriers that delineate populations is a first step towards evaluating the evolutionary origin of intraspecific variation. This thesis reports on genetic population structures among co-existing pike in the coastal Baltic Sea separated by homing behavior, different spawning strategies and geographic barriers. Field studies revealed that these subpopulations also show phenotypic divergence in reproductive and meristic traits. Experimental studies suggested that differentiation among subpopulations likely was a result of divergent selection and local adaptations to spawning grounds. These adaptations that may further reinforce barriers among subpopulations due to a reduced success of immigrant genotypes.

    For the second aim of the thesis, we first studied seasonal and diel patterns of activity and vertical migration among the Baltic Sea pike. The results suggested that pike exposed themselves to sunlight during spring and summer, and that body temperatures were positively correlated with sun exposure during these basking events. This was followed by experimental studies on inanimate physical models and a field study on carp which demonstrated that fish can become warmer than ambient water when exposed to sun light, a previously overlooked mechanism for fish thermoregulation, and that the heat gain was positively correlated with growth.

    This thesis contributes to our understanding of the origin and maintenance of intraspecific variation among coexisting populations with direct implications for management of pike. It also establishes sun-basking as a novel mechanism for fish to obtain body temperatures in excess of ambient water which could motivate adaptations, both evolutionary and plastic, that optimize heat gain, affect spatiotemporal distributions and biotic interaction within and among species.

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  • 72.
    Nordahl, Oscar
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Tibblin, Petter
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Koch-Schmidt, Per
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Berggren, Hanna
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Larsson, Per
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Forsman, Anders
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Sun-basking fish benefit from body temperatures that are higher than ambient water2018Inngår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 285, nr 1879, artikkel-id 20180639Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In terrestrial environments, cold-blooded animals can attain higher bodytemperatures by sun basking, and thereby potentially benefit from broaderniches, improved performance and higher fitness. The higher heat capacityand thermal conductivity of water compared with air have been universallyassumed to render heat gain from sun basking impossible for aquaticectotherms, such that their opportunities to behaviourally regulate body temperatureare largely limited to choosing warmer or colder habitats. Here wechallenge this paradigm. Using physical modelswe first showthat submergedobjects exposed to natural sunlight attain temperatures in excess of ambientwater. We next demonstrate that free-ranging carp (Cyprinus carpio) canincrease their body temperature during aquatic sun basking close to thesurface. The temperature excess gained by basking was larger in dark thanin pale individuals, increased with behavioural boldness, and was associatedwith faster growth. Overall, our results establish aquatic sun basking as a novelecologically significant mechanism for thermoregulation in fish. The discoveryof this previously overlooked process has practical implications for aquaculture,offers alternative explanations for behavioural and phenotypicadaptations, will spur future research in fish ecology, and calls for modificationsof models concerning climate change impacts on biodiversity inmarine and freshwater environments.

  • 73.
    Pauliny, Angela
    et al.
    University of Gothenburg.
    Larsson, Kjell
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Sjöfartshögskolan, SJÖ. Gotland University.
    Blomqvist, Donald
    University of Gothenburg.
    Telomere dynamics in a long-lived bird, the barnacle goose2012Inngår i: BMC Evolutionary Biology, ISSN 1471-2148, E-ISSN 1471-2148, Vol. 12, artikkel-id 257Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Theories of ageing predict a trade-off between metabolism, reproduction, and maintenance. Species with low investment in early reproduction are thus expected to be able to evolve more efficient maintenance and repair mechanisms, allowing for a longer potential life span (intrinsic longevity). The erosion of telomeres, the protective caps at the ends of linear chromosomes, plays an important role in cellular and organismal senescence, signalling the onset of age-related disease due to accumulation of unrepaired somatic damage. Using extensive longitudinal data from a long-term study of a natural population of barnacle geese Branta leucopsis, we investigated individual rates of telomere length changes over two years in 34 birds between 0 and 22 years of age, covering almost 80% of the species' lifespan. We show that telomeres in this long-lived bird are very well maintained, as theoretically expected, with an average loss rate of only 5 base pairs per year among adults. We thus found no significant relationship between change in telomere length and age. However, telomeres tended to shorten at a faster pace in juveniles compared to adults. For the first time, we demonstrate a faster telomere attrition rate in females compared to males. We found no correlation between telomere loss rate and adult survival or change in body mass. Our results add further support for a link between longevity and telomere maintenance, and highlight the complexities of telomere dynamics in natural populations.

  • 74.
    Sigurdardóttir, Sunniva Samson
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Hit and Miss: The Complexity of Admixture2014Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    With massive population declines all over the world, conservationists are faced with a serious threat of extinctions with a need to explore possibilities of translocations and interbreeding programs. While admixture, mixing of separate gene pools, can have beneficial effects, scientists have become aware of the risk of outbreeding depression. The aim of the present study was to investigate the symmetry in outcome in interbreeding population pairs and examine if there are any general patterns. A systematic review was conducted on 28 experimental studies about interbreeding and admixture in plants and animals with comparisons between purebred groups and hybrid groups. Three main types of traits were investigated, chosen to represent quantity, quality and body size of offspring. Overall, symmetrical outcomes were most frequent (62.8 ± 2.6 %), most commonly with a neutral outcome (i.e. none of the populations significantly affected by admixture) in both populations (40.6  ± 3.9 % of all outcome possibilities), which even might be an underestimate because of potential publication bias. Positive and negative outcomes were similar in frequency (11.5 and 11.2 %, respectively, in symmetrical outcomes; 18.1 and 14.4 % in asymmetrical outcomes). The results indicate that consequences of admixture differed between experiments conducted in the laboratory versus semi-natural or natural conditions, between plants and animals, and between the three types of traits. The effects of admixture depended on whether the response was measured in first, second, third generation hybrids, or backcrosses. However, there was no difference in outcome between first and second generation hybrids, which is not in agreement with theory where a more frequent and/or severe negative outcome is expected in later generations. The cause of positive or negative admixture could not be identified, although the heterogenous outcome might indicate that interactions in population pairs are unique. Accordingly, no translocation should be carried out into endangered populations before cautious investigation of possible admixture outcomes. Future research should aim to disentangle the cause and effect of admixture and, preferably, use genetic divergence as an explanatory variable.

  • 75. Sköld, H. N.
    et al.
    Amundsen, T.
    Svensson, P. Andreas
    Mayer, I.
    Bjelvenmark, J.
    Forsgren, E.
    Hormonal regulation of female nuptial coloration in a fish2008Inngår i: Hormones and Behavior, ISSN 0018-506X, E-ISSN 1095-6867, Vol. 54, nr 4, s. 549-556Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Physiological color change in camouflage and mating is widespread among fishes, but little is known about the regulation of such temporal changes in nuptial coloration and particularly concerning female coloration. To better understand regulation of nuptial coloration we investigated physiological color change in female two-spotted gobies (Gobiusculus flavescens). Females of this species develop an orange belly that acts as an ornament. The orange color is caused by the color of the gonads combined with the chromathophore based pigmentation and transparency of the skin. Often during courtship and female-female competition, a rapid increase in orange coloration, in combination with lighter sides and back that increases skin and body transparency, gives the belly an intense 'glowing' appearance. To understand how this increased orange coloration can be regulated we analysed chromatic and transparency effects of neurohumoral agents on abdominal skin biopsies in vitro. We found prolactin and alpha-melanocyte stimulating hormone (MSH) to increase orange coloration of the skin. By contrast, melatonin and noradrenaline increased skin transparency, but had a negative effect on orange coloration. However, mixtures of melatonin and MSH, or melatonin and prolactin, increased both orange coloration and transparency. This effect mimics the chromatic 'glow' effect that commonly takes place during courtship and intra sexual aggression. Notably, not only epidermal chromatophores but also internal chromatophores lining the peritoneum responded to hormone treatments. There were no chromatic effects of the sex steroids 17 beta-estradiol, testosterone or 11-ketotestosterone. We hypothesize that similar modulation of nuptial coloration by multiple hormones may be widespread in nature. (C) 2008 Elsevier Inc. All rights reserved.

  • 76.
    Stewart, Joshua D.
    et al.
    University of California, USA ; The Manta Trust, UK.
    Beale, Calvin S.
    Misool Manta Project, Indonesia.
    Fernando, Daniel
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). The Manta Trust, UK ; Blue Resources, Sri Lanka.
    Sianipar, Abraham B.
    Conservation International, Indonesia.
    Burton, Ronald S.
    University of California, USA.
    Semmens, Brice X.
    University of California, USA.
    Aburto-Oropeza, Octavio
    University of California, USA.
    Spatial ecology and conservation of Manta birostris in the Indo-Pacific2016Inngår i: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 200, s. 178-183Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Information on the movements and population connectivity of the oceanic manta ray (Manta birostris) is scarce. The species has been anecdotally classified as a highly migratory species based on the pelagic habitats it often occupies, and migratory behavior exhibited by similar species. As a result, in the absence of ecological data, population declines in oceanic manta have been addressed primarily with international-scale management and conservation efforts. Using a combination of satellite telemetry, stable isotope and genetic analyses we demonstrate that, contrary to previous assumptions, the species appears to exhibit restricted movements and fine-scale population structure. M. birostris tagged at four sites in the Indo-Pacific exhibited no long-range migratory movements and had non-overlapping geographic ranges. Using genetic and isotopic analysis, we demonstrate that the observed movements and population structure persist on multi-year and generational time scales. These data provide the first insights into the long-term movements and population structure of oceanic manta rays, and suggest that bottom-up, local or regional approaches to managing oceanic mantas could prove more effective than existing, international-scale management strategies. This case study highlights the importance of matching the scales at which management and relevant ecological processes occur to facilitate the effective conservation of threatened species.

  • 77.
    Sunde, Johanna
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Forsman, Anders
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Mate choice is not consistent with short-term effects of intraspecific admixture in the common rough woodlouse (Porcellio scaber)2016Inngår i: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 119, nr 2, s. 359-369Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Theory posits that individuals should exhibit mate preferences in part based on genetic relatedness such that fitness is maximized. Intraspecific genetic admixture can have different effects depending on the genetic characteristics and evolutionary history of the individuals and populations involved. We investigated whether female mate choice behavior in the common rough woodlouse (Porcellio scaber) matched the fitness consequences of genetic admixture. We found that most females from two populations that were in sequence introduced to one male from each population mated with both males, and further that monandrous females (females that only mated with one male) predominantly mated with males from their own population. To test for effects of genetic admixture, females from four populations were divided into two replicate pairs and assigned to mate either with a male from the same population as the female (pure) or with a male from the other population (admixed). The effect of mating treatment on the proportion of females that produced eggs and hatched young, as well as on the number and viability of offspring depended on female source population. Mating treatment had opposing effects in two of the populations, whereas there were no detectable effects in the other two populations. Contrary to what was expected, the mating patterns did not match the observed effects of genetic admixture. We discuss alternative adaptive and non-adaptive explanations for the observed patterns.

  • 78.
    Sunde, Johanna
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Tibblin, Petter
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Larsson, Per
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Forsman, Anders
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Sex-specific effects of outbreeding on offspring quality in pike (Esox lucius)2018Inngår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 8, nr 21, s. 10448-10459Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Intraspecific genetic admixture occurs when previously separated populations withina species start interbreeding, and it can have either positive, negative, or neutral effectson reproductive performance. As there currently is no reliable predictor for theoutcome of admixture, an increased knowledge about admixture effects in differentspecies and populations is important to increase the understanding about what determinesthe response to admixture. We tested for effects of admixture on F1 offspringquality in three subpopulations of pike (Esox lucius). Gametes were collected inthe field, and eggs from each female were experimentally fertilized with milt from amale from each population (one “pure” and two “admixed” treatments). Three offspringquality measures (hatching success, fry survival, and fry length) were determinedand compared between (a) pure and admixed population combinations and (b)the sex-specifictreatments within each admixed population combination (based onthe origin of the male and female, respectively). The results suggested that althoughthere were no overall effects of admixture on offspring quality, the consequences fora given population combination could be sex-specificand thus differ depending onwhich of the parents originated from one or the other population. All offspring qualitytraits were influenced by both maternal ID and paternal ID. Sex-andindividual-specificeffects can have implications for dispersal behavior and gene flow betweennatural populations, and are important to consider in conservation efforts.

  • 79.
    Sunde, Johanna
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Yildirim, Yeserin
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Tibblin, Petter
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Forsman, Anders
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Comparing the performance of microsatellites and RADseq in population genetic studies: analysis of data for pike (Esox lucius) and a synthesis of previous studies2020Inngår i: Frontiers in Genetics, ISSN 1664-8021, E-ISSN 1664-8021, Vol. 11, s. 1-17, artikkel-id 218Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Population genetic studies reveal biodiversity patterns and inform about drivers of evolutionary differentiation and adaptation, including gene flow, drift and selection. This can advance our understanding and aid decision making regarding management and conservation efforts. Microsatellites have long been used in population genetic studies. Thanks to the development of newer techniques, sequencing approaches such as restriction site associated DNA sequencing (RADseq) are on their way to replace microsatellites for some applications. However, the performance of these two marker types in population genetics have rarely been systematically compared. We utilized three neutrally and adaptively differentiated populations of anadromous pike (Esox lucius) to assess the relative performance of microsatellites and RADseq with respect to resolution and conclusiveness of estimates of population differentiation and genetic structure. To this end, the same set of individuals (N = 64) were genotyped with both RADseq and microsatellite markers. To assess effects of sample size, the same subset of 10 randomly chosen individuals from each population (N = 30 in total) were also genotyped with both methods. Comparisons of estimated genetic diversity and structure showed that both markers were able to uncover genetic structuring. The full RADseq dataset provided the clearest detection of the finer scaled genetic structuring, and the other three datasets (full and subset microsatellite, and subset RADseq) provided comparable results. A search for outlier loci performed on the full SNP dataset pointed to signs of selection potentially associated with salinity and temperature, exemplifying the utility of RADseq to inform about the importance of different environmental factors. To evaluate whether performance differences between the markers are general or context specific, the results of previous studies that have investigated population structure using both marker types were synthesized. The synthesis revealed that RADseq performed as well as, or better than microsatellites in detecting genetic structuring in the included studies. The differences in the ability to detect population structure, both in the present and the previous studies, are likely explained by the higher number of loci typically utilized in RADseq compared to microsatellite analysis, as increasing the number of markers will (regardless of the marker type) increase power and allow for clearer detection and higher resolution of genetic structure.

  • 80.
    Svensson, P. Andreas
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    A new goby research lab in the central Baltic Proper2013Konferansepaper (Annet vitenskapelig)
  • 81.
    Svensson, P. Andreas
    Högskolan i Kalmar, Naturvetenskapliga institutionen.
    Adaptations and strategies for paternal care in a desert-dwelling fish. 2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Parental care enhances offspring development and survival, but also imposes costs to the caring parent by reducing, for example, future reproduction. This is especially true in species with paternal care, that is, where the male cares for the offspring. Both anatomical and behavioural adaptations are expected to have evolved in order to economize paternal care. The Australian desert goby is a sexually dimorphic species that expresses exclusive paternal care. Males have larger pectoral fins relative to females, possibly to assist in the fanning of the eggs. Males also strategically adjust their parental effort to maximise their fitness. In laboratory experiments, we found that males with larger fins fanned at a lower frequency. The presence of ready-to-spawn females led to a reduction in paternal care effort suggesting a temporal trade-off between care of existing eggs and courtship of additional females. In addition, both the degree and type of filial cannibalism was related to the size of the clutch, and, therefore, female quality. Our results suggest that desert gobies have evolved both morphological adaptations and behavioural strategies to balance the costs and benefits of paternal care.

  • 82.
    Svensson, P. Andreas
    Högskolan i Kalmar, Naturvetenskapliga institutionen.
    Female coloration and beneficial egg carotenoids2006Konferansepaper (Fagfellevurdert)
  • 83.
    Svensson, P. Andreas
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Female coloration and beneficial egg carotenoids2007Konferansepaper (Annet vitenskapelig)
  • 84.
    Svensson, P. Andreas
    Department of Biology, NTNU, Trondheim.
    Female coloration, egg carotenoids and reproductive success: gobies as a model system2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In two-spotted gobies (Gobiusculus flavescens), females develop an orange belly as they approach sexual maturity. Toward the end of the single breeding season, males become rare and females compete for spawnings. Nest-holding males then prefer females with more colourful bellies and this trait has been suggested to act as a female ornament. I found a positive relationship between belly coloration and the coloration of the underlying gonads. This shows that belly coloration honestly reflects egg pigmentation, mainly because the transparency of the abdominal skin allows other fish to see the gonads directly. The factors contributing to variation in the nuptial coloration of female G. flavescens was examined in a series of investigations (Paper I). When gonads matured they became more colourful while the abdominal skin became more transparent. This caused an increase in nuptial coloration as females approached maturity. However, there was considerable variation in belly coloration also among fully mature females. Mature females had more colourful bellies late in the breeding season, partly due to an increase in gonad carotenoid concentration but also due to a seasonal increase in skin coloration. Analyses of gonads from wild-caught female G. flavescens showed the three main carotenoids to be astaxanthin, idoxanthin and adonixanthin (34%, 23% and 21% of the total carotenoid concentration, respectively). Compared to females of the five other gobiid species found in the same area, G. flavescens had much more colourful bellies. The unique ornamentation of G. flavescens females was achieved by the concurrent exaggeration of all signal components: gonad coloration, skin coloration and skin transparency. To understand how gonad and skin pigmentation interact in the nuptial coloration of female G. flavescens, the role of skin chromatophores was examined in detail (Paper II). Noradrenaline caused aggregation of chromatophore pigment and was used to experimentally reduce the contribution of skin chromatophores to the nuptial coloration. Interestingly, the aggregation of skin pigment weakened the positive relationship between belly and gonad coloration, despite an increase in skin transparency. The results show that female G. flavescens have a potential to use skin chromatophores to rapidly alter their nuptial coloration, thereby affecting the efficacy with which information about gonad coloration is conveyed.  

     

    Carotenoid-based ornamentation has often been suggested to signal mate quality, and species with such ornaments have frequently been used in studies of sexual selection. Carotenoids can be beneficial to animals in various ways, especially during sensitive life stages such as embryonic development. However, empirical work has so far provided equivocal evidence of beneficial effects of carotenoids in vivo. Because males invest heavily in offspring during incubation, the evolution of the male mate preference can be explained if colourful females provide males with eggs of higher quality. This hypothesis was tested by letting males spawn with naturally ‘colourful’ and ‘drab’ females, and comparing several reproductive parameters (Paper III).   

     

    Colourful females produced slightly larger clutches and eggs with significantly higher concentrations of total carotenoids than drab females, but their clutches were not of higher quality. In addition, there were no significant relationships between egg carotenoids and clutch quality. These results call into question a link between female nuptial coloration and offspring quality. In a second study, females were given two diets, differing only in carotenoid concentration (Paper IV). Females given carotenoid- rich feed attained a stronger nuptial coloration, laid more carotenoid-rich eggs and were more likely to spawn. This group also produced larvae that had a stronger phototactic response, suggesting higher offspring quality. This result suggests a direct benefit for males that choose to mate with colourful females. Other measures of reproductive success commonly reported in the literature, such as fertilization rate, hatching success and offspring susceptibility to starvation, were not affected by maternal carotenoid supply.

    In this thesis I have established a link between female ornamentation and egg carotenoid concentration, as well as a relationship between egg carotenoid concentration and offspring quality. The work constitute a uniquely detailed description of factors affecting variation in a nuptial signal and in its different components, and relate these to current theory on signal evolution.  

  • 85.
    Svensson, P. Andreas
    Norwegian University of Science and Technology.
    Female coloration, egg carotenoids and reproductive success gobies as a model system, PhD Thesis2006Doktoravhandling, med artikler (Annet vitenskapelig)
  • 86.
    Svensson, P. Andreas
    Högskolan i Kalmar, Naturvetenskapliga institutionen.
    Female two-spotted gobies display egg carotenoid status2004Konferansepaper (Annet vitenskapelig)
  • 87.
    Svensson, P. Andreas
    Högskolan i Kalmar, Naturvetenskapliga institutionen.
    Female two-spotted gobies display egg carotenoid status.2004Konferansepaper (Fagfellevurdert)
  • 88.
    Svensson, P. Andreas
    Monash University.
    Gobies and carotenoids2008Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    In the thirty years since John Endler's seminal work on guppies, carotenoid based signals have become a large and growing topic in behavioural ecology, especially in birds and fishes. Carotenoids are common pigments in animal signals,but they are also important as antioxidants and provitamins. Their dual role in ornaments and physiology make carotenoids ideally suited for answering questions about honest signalling. However, testing the theoretical predictions is not always straightforward, and properly designed experiments are a rather recent phenomenon. In many birds and fishes, females incorporate large quantities of carotenoids into eggs, but the reasons for this are only partially understood. For example, many species seem to do fine without carotenoids. I will briefly introduce carotenoids in signalling before discussing their role in gobies, based on work in nordic gobies.

  • 89. Svensson, P. Andreas
    Shoaling decisions in the two-spotted goby,Gobiusculus flavescens. MSc thesis.2000Rapport (Annet vitenskapelig)
    Abstract [en]

    Shoaling behavior of young-of-year Gobiusculus flavescens was studied in the lab and in the field outside Kristineberg Marine Research Station, in the Gullmar fjord, Sweden. Natural shoals varied in size from a few to several hundred fish, and were found to be assorted by body size. The structure of the shoals was very dynamic, and any particular group of individuals was unlikely to stay together for more than a few hours. In aquarium experiments, individual G. flavescens preferred joining a small shoal of conspecifics to being on their own. Also, larger shoals were preferred over smaller shoals. Large fish preferred the company of fish of matching body size. Small fish, however, did not show size assortative preferences. Focal fish showed no significant preference for shoaling with familiar compared to unfamiliar fish, not even under predator threat. The results are discussed in view of theories concerning the adaptive basis of shoaling behavior, such as dilution, confusion and oddity effects.

  • 90.
    Svensson, P. Andreas
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Strategic male courtship effort in a desert-dwelling fish.2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Strategic allocation of male mating effort is expected if females vary greatly in reproductive value and/or the costs of mating for males are high. Here, we conducted experiments investigating male signalling effort in the Australian desert goby, Chlamydogobius eremius. Males in this species exhibit elaborate courtship of females and exclusive parental care. In the first experiment, we offered focal males two females presented simultaneously in a dichotomous choice design. We found that males preferentially courted the larger of the two females. We found that the same was also true when, in a second experiment, males were presented with females sequentially. Intriguingly, the order of presentation appeared to be important, with males adjusting their courtship depending on the size of the female encountered previously. Our study highlights male mate choice as an important source of variation in male signalling effort.

  • 91.
    Svensson, P. Andreas
    Deakin Univeristy.
    The interval between sexual encounters affect male courtship tactics.2011Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Courtship displays can enhance male mating success, but are often costly. Thus, instead of courting all females indiscriminately, males could strategically adjust their signalling effort by directing greater courtship towards females of higher reproductive quality. However, plasticity in male courtship intensity remains a largely neglected aspect of sexual selection. Theory predicts that the expression of such plasticity should depend on both the order, and the rate, with which potential mates are encountered. We tested these predictions in a fish, the Australian desert goby, Chlamydogobius eremius. Males preferentially courted the larger of two simultaneously encountered females, probably because larger females are also more fecund. We then investigated male courtship under different sequential scenarios, that is, presenting one female at a time. We found a "previous female effect", with males adjusting their signalling output based on the size of the female they had encountered previously. However, males did not adjust their courtship in this way when the interval between female presentations was longer. Thus, both variation in mate quality, mate encounter rate and previous experiences affected male reproductive decisions. Our findings underscore the importance of considering temporal aspects of mate encounters when trying to understand how mate selection operates in nature.

  • 92.
    Svensson, P. Andreas
    Monash University.
    The interval between sexual encounters affect male courtship tactics2010Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Courtship displays can enhance male mating success, but are often costly. Thus, instead of courting all females indiscriminately, males could strategically adjust their signalling effort by directing greater courtship towards females of higher reproductive quality. However, plasticity in male courtship intensity remains a largely neglected aspect of sexual selection. Theory predicts that the expression of such plasticity should depend on both the order, and the rate, with which potential mates are encountered. We tested these predictions in a fish, the Australian desert goby, Chlamydogobius eremius. Males preferentially courted the larger of two simultaneously encountered females, probably because larger females are also more fecund. We then investigated male courtship under different sequential scenarios, that is, presenting one female at a time. We found a "previous female effect", with males adjusting their signalling output based on the size of the female they had encountered previously. However, males did not adjust their courtship in this way when the interval between female presentations was longer. Thus, both variation in mate quality, mate encounter rate and previous experiences affected male reproductive decisions. Our findings underscore the importance of considering temporal aspects of mate encounters when trying to understand how mate selection operates in nature.

  • 93.
    Svensson, P. Andreas
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Adcock, Jacqui L.
    Endler, John A.
    Quantifying ornamental carotenoids in male guppies, Poecilia reticulata2012Inngår i: 5th International Conference of Poeciliid Biologists (Trinidad and Tobago), 2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    For over 30 years, the orange spots of male guppies have been an iconic example of carotenoid-based ornamentation. The humble guppy was the first of many model species used to study carotenoids in sexual coloration and it is a favoured text book example of signal evolution. It is therefore rather surprising that few have attempted to identify and quantify the carotenoids present in guppies. With some exceptions (most notably Greg Grether's work), researchers have instead tried to infer pigment concentration from colorimetric techniques such as reflectance spectrophotometry or photography. Three major obstacles exist for accurate biochemical determination the carotenoids present in guppies. First, the small body size means that only miniscule amounts are available for analysis. Second, fish skin carotenoids are esterified and samples therefore require potentially destructive hydrolysis. Third, some of the carotenoids are structurally similar, which poses a challenge for successful separation. We have developed a method to identify and quantify the individual carotenoids in guppy skin by using mild saponifiction followed by normal phase high performance liquid chromatography (NP-HPLC). It provides effective hydrolysis of the carotenoid esters without damage to the pigments and is sensitive enough to quantify the carotenoids in a single skin spot. We also used different photographic techniques to measure coloration of both free-swimming and sedated male guppies to investigate how accurate photographic methods are in estimating carotenoid levels.

  • 94. Svensson, P. Andreas
    et al.
    Barber, I.
    Forsgren, E.
    Shoaling behaviour of the two-spotted goby2000Inngår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 56, nr 6, s. 1477-1487Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Naturally formed shoals of adult Gobiusculus flavescens in a Swedish fjord ranged in size from a few individuals to several hundred fish and were sorted by body size. Shoal composition was highly dynamic and any particular group was unlikely to remain together for more than a few hours. Shoaling tendency of juveniles in laboratory experiments was high, and consistent preferences were demonstrated for numerically larger shoals. Large test fish preferred to associate with shoals composed of large, over shoals composed of small fish, whereas small test fish associated with both size classes equally. The ecological importance of shoaling in small shallow water fish is discussed, and possible mechanisms for the observed patterns are proposed. (C) 2000 The Fisheries Society of the British Isles.

  • 95.
    Svensson, P. Andreas
    et al.
    School of Biological Sciences, Monash University 3800, Clayton,VIC, Australia.
    Blount, J. D.
    Forsgren, E.
    Amundsen, T.
    Female ornamentation and egg carotenoids of six sympatric gobies2009Inngår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 75, s. 2777–2787-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Belly colouration, gonad carotenoid concentration and skin transparency were quantified in gravid Gobiusculus flavescens, as well as in females of five sympatric gobies where belly ornamentation has not been described. Although G. flavescens females did, indeed, have far more colourful bellies than the other species, this could only in part be explained by a high concentration of total gonad carotenoids. Comparable, or occasionally higher, carotenoid levels were found in the gonads of other species. Instead, the unusual ornamentation of G. flavescens arises from a unique combination of carotenoid-rich gonads and a highly transparent abdominal skin.

  • 96.
    Svensson, P. Andreas
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Endler, John A.
    Adcock, Jacqui L.
    Experimentally induced divergence of carotenoid usage in male guppy ornaments2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Females are often believed to use male ornaments as observable indicators of non-observable male traits. However, if signal form (e.g. coloration) is highly flexible, its link to signal content (e.g. quality) should be unreliable. Therefore, it is often implicitly assumed that signals are heavily constrained and relatively stable over generations. One popular illustration of costly ornaments is carotenoid-based colour signals. Recent but indirect evidence suggest that such signals may in fact evolve rapidly, but this has not been tested experimentally. We exposed large replicated populations of guppies (Poecilia reticulata; effective population sizes >1000) to three environmental conditions in a multi-generation experiment. The treatments differed in the spectral composition of ambient light by using colour filters which affected how male colours were percieved. This, in turn, was expected to lead to male coloration divergence between treatments due to female choice. In addition, the filters affected the micro-flora and -fauna, which are dietary sources of ornamental pigments. Male skin carotenoids were analysed after 3 and 5 generations. In this short time, populations had diverged in male coloration and in the carotenoid composition of sexual ornaments. A second experiment disentangled environmental and genetic effects. Our study demonstrates evolutionary innovation in signal traits, and how dietary-driven responses to environmental change can impact sexual ornaments.

  • 97.
    Svensson, P. Andreas
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Endler, John A.
    Adcock, Jacqui L.
    Experimentally induced divergence of carotenoid usage in male guppy ornaments2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Females are often believed to use male ornaments as observable indicators of non-observable male traits. However, if signal form (e.g. coloration) is highly flexible, its link to signal content (e.g. quality) should be unreliable. Therefore, it is often implicitly assumed that signals are heavily constrained and relatively stable over generations. One popular illustration of costly ornaments is carotenoid-based colour signals. Recent but indirect evidence suggest that such signals may in fact evolve rapidly, but this has not been tested experimentally. We exposed large replicated populations of guppies (Poecilia reticulata; effective population sizes >1000) to three environmental conditions in a multi-generation experiment. The treatments differed in the spectral composition of ambient light by using colour filters which affected how male colours were percieved. This, in turn, was expected to lead to male coloration divergence between treatments due to female choice. In addition, the filters affected the micro-flora and -fauna, which are dietary sources of ornamental pigments. Male skin carotenoids were analysed after 3 and 5 generations. In this short time, populations had diverged in male coloration and in the carotenoid composition of sexual ornaments. A second experiment disentangled environmental and genetic effects. Our study demonstrates evolutionary innovation in signal traits, and how dietary-driven responses to environmental change can impact sexual ornaments.

  • 98. Svensson, P. Andreas
    et al.
    Forsgren, E.
    Amundsen, T.
    Nilsson Sköld, H.
    Chromatic interaction between egg pigmentation and skin chromatophores the nuptial coloration of female two-spotted gobies2005Inngår i: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 208, s. 4391-4397Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In two-spotted gobies (Gobiusculus flavescens Fabricius 1779), females develop an orange belly as they approach sexual maturity. Bright belly coloration is preferred by males and has been suggested to act as a female ornament. This coloration is unusual in that it originates partly from pigmentation of the abdominal skin but also from strongly pigmented gonads directly visible through the skin. In addition, females have been observed to temporarily become more colourful during courtship and competition. To understand how gonad and skin pigmentation interact in this nuptial coloration, the potential for colour modification via regulation of skin chromatophores was investigated. Noradrenaline caused aggregation of chromatophore pigment and was used to experimentally reduce the contribution of skin chromatophores to the nuptial coloration. Chromatophore pigment aggregation caused bellies to become less colourful and abdominal skin biopsies to become less colourful and more transparent. There was a strong positive relationship between belly coloration and the coloration of the underlying gonads. This shows that belly coloration honestly reflects egg pigmentation, mainly because the transparency of the abdominal skin allows other fish to see the gonads directly. Interestingly, when noradrenaline caused pigment to aggregate and thereby increased the transparency of the skin, the relationship between belly and gonad coloration weakened. We conclude that female G. flavescens have a potential to use skin chromatophores to rapidly alter their nuptial coloration, thereby affecting the efficacy with which information about gonad coloration is conveyed.

  • 99.
    Svensson, P. Andreas
    et al.
    Monash Univ, Sch Biol Sci, Clayton, Vic 3800, Australia.
    Lehtonen, T. K.
    Monash Univ, Sch Biol Sci, Clayton, Vic 3800, Australia.
    Wong, B. B. M.
    Monash Univ, Sch Biol Sci, Clayton, Vic 3800, Australia.
    The interval between sexual encounters affects male courtship tactics in a desert-dwelling fish2010Inngår i: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 64, nr 2, s. 1967-1970Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Courtship displays are often important in determining male mating success but can also be costly. Thus, instead of courting females indiscriminately, males might be expected to adjust their signalling effort strategically. Theory, however, predicts that such adjustments should depend on the rate with which males encounter females, a prediction that has been subject to very little empirical testing. Here, we investigate the effects of female encounter rate on male courtship intensity by manipulating the time interval between sequential presentations of large (high quality) and small (low quality) females in a fish, the Australian desert goby Chlamydogobius eremius. Males that were presented with a small female immediately after a large female reduced their courtship intensity significantly. However, males courted large and small females with equal intensity if the interval between the sequential presentations was longer. Our results suggest that mate encounter rate is an important factor shaping male reproductive decisions and, consequently, the evolutionary potential of sexual selection.

  • 100.
    Svensson, P. Andreas
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Lehtonen, Topi K.
    Wong, Bob B. M.
    A high aggression strategy for smaller males2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Male-male conflict is common among animals, but questions remain as to when, how and by whom aggression should be initiated. Factors that affect agonistic strategies include residency, the value of the contested resource and the fighting ability of the contestants. Game-theoretical models often assume that strategies for aggression are conditional and shaped by mutual assessment. We quantified aggression in a fish, the Australian desert goby, <i>Chlamydogobius eremius</i>, by exposing nest-holding males to male intruders. The perceived value of the resource (the nest) was manipulated by exposing half of the residents to sexually receptive females before the trial. We found resident male aggression to be unaffected by perceived mating opportunities. It was also unaffected by the size of the intruder. Instead, aggression was related the residents' own size, namely, smaller males attacked sooner and with greater intensity than larger males. Thus, contrary to theory, resident desert goby males appeared to have set strategies for initiating aggression. Rather than viewing high aggression in small males as a paradox (i.e. the Napoleon effect), we suggest that small individuals may benefit from attacking early, before an intruder has time to assess the resident and/or the resource.

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