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  • 51.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Hagman, Mattias
    Association of coloration mode with population declines and endangerment in Australian frogs2009In: Conservation Biology, ISSN 0888-8892, E-ISSN 1523-1739, Vol. 23, no 6, p. 1535-1543Article in journal (Refereed)
    Abstract [en]

    Successful protection of biodiversity requires increased understanding of the ecological characteristics that predispose some species to endangerment. Theory posits that species with polymorphic or variable coloration should have larger distributions, use more diverse resources, and be less vulnerable to population declines and extinctions, compared with taxa that do not vary in color. We used information from literature on 194 species of Australian frogs to search for associations of coloration mode with ecological variables. In general, species with variable or polymorphic color patterns had larger ranges, used more habitats, were less prone to have a negative population trend, and were estimated as less vulnerable to extinction compared with nonvariable species. An association of variable coloration with lower endangerment was also evident when we controlled statistically for the effects of range size. Nonvariable coloration was not a strong predictor of endangerment, and information on several characteristics is needed to reliably identify and protect species that are prone to decline and may become threatened by extinction in the near future. Analyses based on phylogenetic-independent contrasts did not support the hypothesis that evolutionary transitions between nonvariable and variable or polymorphic coloration have been accompanied by changes in the ecological variables we examined. Irrefutable demonstration of a role of color pattern variation in amphibian decline and in the dynamics and persistence of populations in general will require a manipulative experimental approach.

  • 52.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Hagman, Mattias
    Calling is an honest indicator of paternal genetic quality in poison frogs2006In: Evolution, Vol. 60, no 10, p. 2148-2157Article in journal (Refereed)
  • 53.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Hagman, Mattias
    Correlated evolution of conspicuous coloration and body size in poison frogs (Dendrobatidae).2003In: Evolution 57: 2904-2910Article in journal (Refereed)
  • 54.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Herrström, Joakim
    Asymmetry in size, shape and colour impairs the protective value of conspicuous colour patterns.2004In: Behavioral Ecology, Vol. 15:141-147Article in journal (Refereed)
  • 55.
    Forsman, Anders
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karlsson, Magnus
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Wennersten, Lena
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Johansson, Jenny
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karpestam, Einat
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rapid evolution of fire melanism in replicated populations of pygmy grasshoppers2011In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 65, no 9, p. 2530-2540Article in journal (Refereed)
    Abstract [en]

    Evolutionary theory predicts an interactive process whereby spatiotemporal environmental heterogeneity will maintain genetic variation, while genetic and phenotypic diversity will buffer populations against stress and allow for fast adaptive evolution in rapidly changing environments. Here, we study color polymorphism patterns in pygmy grasshoppers (Tetrix subulata) and show that the frequency of the melanistic (black) color variant was higher in areas that had been ravaged by fires the previous year than in nonburned habitats, that, in burned areas, the frequency of melanistic grasshoppers dropped from ca. 50% one year after a fire to 30% after four years, and that the variation in frequencies of melanistic individuals among and within populations was genetically based on and represented evolutionary modifications. Dark coloration may confer a selective benefit mediated by enhanced camouflage in recently fire-ravaged areas characterized by blackened visual backgrounds before vegetation has recovered. These findings provide rare evidence for unusually large, extremely rapid adaptive contemporary evolution in replicated natural populations in response to divergent and fluctuating selection associated with spatiotemporal environmental changes.

  • 56.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Lindell, L E
    Resource dependent growth and body condition dynamics in juvenile snakes: an experiment1996In: Oecologia, Vol. 108, p. 669-675Article in journal (Refereed)
  • 57.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Lindell, L E
    Responses of a predator to variation in prey abundance: survival and emigration of adders in relation to vole density1997In: Canadian Journal of Zoology, Vol. 75, p. 1099-1108Article in journal (Refereed)
  • 58.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Lindell, L E
    The advantage of a big head: swallowing performance in adders, Vipera berus (L.)1993In: Functional Ecology, Vol. 7, p. 183-189Article in journal (Refereed)
  • 59.
    Forsman, Anders
    et al.
    Department of Zoology, Uppsala University.
    Lindell, L E
    Trade-off between growth and energy storage in male Vipera berus (L.) under different prey densities1991In: Functional Ecology, Vol. 5, p. 717-723Article in journal (Refereed)
    Abstract [en]

    There are constraints on the rate of energy intake of foraging animals, and allocation of energy, for example, to growth therefore must be at the expense of allocation to other purposes, such as energy storage. Moreover, the relative amount of energy allocated to different kinds of activities is likely to depend upon food availability. We have compared the patterns of energy allocation between adders, Vipera berus (L.), in populations inhabiting two different island groups in the Baltic Sea. These adders primarily feed on field voles, Microtus agrestis (L.), which undergo great population density fluctuations. In order to survive periods of low food supply adders allocate some energy to storage, and they can be expected to increase the proportion of energy devoted to storage when food levels and rate of energy intake decrease. Individuals allocating much energy to storage have less energy available for growth, reproduction and maintenance, and one can expect a trade-off between growth and energy storage, especially during resource shortage. Since the size of energy reserves influences fasting endurance, while body size influences future reproductive success, the pattern of energy allo- cation between growth and storage might have important fitness consequences for these animals. We compared the size of energy reserves (body mass in relation to body length) and the growth rates of individual male adders from two localities with different densities of field voles. Relative body mass was similar to both adder populations, but individuals grew faster where vole density was higher. This suggests that the pattern of energy allocation changed with resource availability. We also investigated the relationships between rela- tive growth rate and relative mass within the two adder populations. We found a significant nega- tive relationship where prey density was low, and a negative but non-significant relationship where prey density was high, indicating a trade-off between growth and energy storage in male adders that changes with food availability. 

  • 60.
    Forsman, Anders
    et al.
    Department of Zoology, University of Uppsala.
    Malmquist, M G
    Evidence for echolocation in the common shrew, Sorex araneus L1988In: Journal of Zoology, ISSN 0952-8369, E-ISSN 1469-7998, Vol. 216, p. 655-662Article in journal (Refereed)
    Abstract [en]

    In this laboratory experiment it is shown that, like four North American soricid shrew species, the European common shrew Sorex araneus L. is able to use echolocation to identify open and closed tubes at a distance of 200 mm.Three common shrews captured in Sweden were used for the experiments, which were carried out in darkness and within a sound-proof box. The experimental set-up eliminated orientation using sight, sound or scent from outside the experimental cage. Echolocation calls consisted of broadband ultrasonic clicks at low sound pressure. These were recorded using an ultrasound detector.The ecological significance of echolocation in shrews is discussed. It is proposed that common shrews use echolocation to locate protective cover, thus minimizing the risk to be taken by, e.g. owls.Echolocation may also be used for detecting obstacles in subterranean tunnels. Hence, echolocation could be of certain importance when abandoned burrows in the periphery of the tunnel system are restored during periods of increasing population densities. Since density peaks in most populations occur regularly each summer, and may reach extreme magnitudes in cyclic populations, the ecological significance of echolocation in shrews may be considerable. 

  • 61.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Merilaita, Sami
    Fearful symmetry? Intra-individual comparisons of asymmetry in signalling versus cryptic colour patterns in butterflies.2003In: Evolutionary Ecology 17: 491-507.Article in journal (Refereed)
  • 62.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Merilaita, Sami
    Fearful symmetry: pattern size and asymmetry affects aposematic signal efficacy1999In: Evolutionary Ecology, Vol. 13, p. 131-140Article in journal (Refereed)
  • 63.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Merilä, J
    Lindell, L E
    Do scale anomalies cause differential survival in Vipera berus?1994In: Journal of Herpetology, Vol. 28, p. 435-440Article in journal (Refereed)
  • 64.
    Forsman, Anders
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Merilä, Juha
    University of Helsinki.
    Ebenhard, Torbjörn
    Swedish Biodiversity Centre.
    Phenotypic evolution of dispersal-enhancing traits in insular voles2011In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 278, no 1703, p. 225-232Article in journal (Refereed)
    Abstract [en]

    Evolutionary theory predicts that in metapopulations subject to rapid extinction-recolonization dynamics, natural selection should favour evolution of traits that enhance dispersal and recolonization ability. Metapopulations of field voles (Microtus agrestis) on islands in the Stockholm archipelago, Sweden, are characterized by frequent local extinction and recolonization of subpopulations. Here, we show that voles on the islands were larger and had longer feet than expected for their body size, compared with voles from the mainland; that body size and size-specific foot length increased with increasing geographical isolation and distance from mainland; and that the differences in body size and size-specific foot length were genetically based. These findings provide rare evidence for relatively recent (less than 1000 years) and rapid (corresponding to 100-250 darwins) evolution of traits facilitating dispersal and recolonization in island metapopulations.

  • 65.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Ringblom, K
    Civantos, E
    Ahnesjö, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Coevolution of color pattern and thermoregulatory behavior in polymorphic pygmy grasshoppers, Tetrix undulata2002In: Evolution, Vol. 56, p. 349-360Article in journal (Refereed)
  • 66.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Shine, R
    Parallel geographic variation in body shape and reproductive life history within the Australian scincid lizard Lampropholis delicata1995In: Functional Ecology, Vol. 9, p. 818-828Article in journal (Refereed)
  • 67.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Shine, R
    Rejection of non-adaptive hypotheses for intraspecific variation in trophic morphology in gape-limited predators1997In: Biological Journal of the Linnean Society, Vol. 62, p. 209-223Article in journal (Refereed)
  • 68.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Shine, R
    Sexual size dimorphism in relation to frequency of reproduction in turtles (Testidunes: Emydidae)1995In: Copeia, Vol. 1995, p. 727-729Article in journal (Refereed)
  • 69.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Shine, R
    The adaptive significance of colour pattern polymorphism in the Australian scincid lizard Lampropholis delicata1995In: Biological Journal of the Linnean Society, Vol. 55, p. 273-291Article in journal (Refereed)
  • 70.
    Forsman, Anders
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tibblin, Petter
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Berggren, Hanna
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Nordahl, Oscar
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Koch-Schmidt, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Pike Esox lucius as an emerging model organism for studies in ecology and evolutionary biology: a review.2015In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 87, no 2, p. 472-479Article, review/survey (Refereed)
    Abstract [en]

    The pikeEsox luciusis a large, long-lived, iteroparous, top- predator fish species with a circumpolardistribution that occupies a broad range of aquatic environments. This study reports on a literaturesearch and demonstrates that the publication rate ofE. luciusresearch increases both in absolute termsand relative to total scientific output, and that the focus of investigation has changed over time frombeing dominated by studies on physiology and disease to being gradually replaced by studies on ecol-ogy and evolution.Esox luciuscan be exploited as a model in future research for identifying causes andconsequences of phenotypic and genetic variation at the levels of individuals, populations and speciesas well as for investigating community processes.

  • 71.
    Forsman, Anders
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Wennersten, Lena
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Inter-individual variation promotes ecological success of populations and species: evidence from experimental and comparative studies2016In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 39, no 7, p. 630-648Article, review/survey (Refereed)
    Abstract [en]

    Biological diversity is threatened by exploitation, fragmentation of natural habitats, pollution, climatechange, and anthropogenic spread of species. The question of how among-individual variation influencesthe performance of populations and species is a poorly explored but currently growing field of research.Here, we review 31 experimental and 14 comparative studies and first investigate whether there is empiricalsupport for the propositions that higher levels of among-individual phenotypic and genetic variationpromote the ecological and evolutionary success of populations and species in the face of environmentalchange. Next, we examine whether and how the effect of diversity depends on environmental conditions.Finally, we explore whether the relationship linking population fitness to diversity is typically linear,asymptotic, or whether the benefits peak at intermediate diversity. The reviewed studies provide strong,almost invariable, evidence that more variable populations are less vulnerable to environmental changes,show decreased fluctuations in population size, have superior establishment success, larger distributionranges, and are less extinction prone, compared with less variable populations or species. Given theoverwhelming evidence that variation promotes population performance, it is important to identifyconditions when increased variation does not have the theoretically expected effect, a question ofconsiderable importance in biodiversity management, where there are many other practical constraints. Wefind that experimental outcomes generally support the notion that genetic and phenotypic variation is ofgreater importance under more stressful than under benign conditions. Finally, population performanceincreased linearly with increasing diversity in the majority (10 of 12) of manipulation studies that includedfour or more diversity levels; only two experiments detected curvilinear relationships.

  • 72.
    Forsman, Anders
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Wennersten, Lena
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karlsson, Magnus
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Caesar, Sofia
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Variation in founder groups promotes establishment success in the wild2012In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 279, no 1739, p. 2800-2806Article in journal (Refereed)
    Abstract [en]

    Environmental changes currently pose severe threats to biodiversity, and reintroductions and translocations are increasingly used to protect declining populations and species from extinction. Theory predicts that establishment success should be higher for more variable groups of dissimilar individuals. To test this ‘diversity promotes establishment’ hypothesis, we introduced colour polymorphic pygmy grasshoppers (Tetrix subulata) to different sites in the wild. The number of descendants found at the release sites the subsequent year increased with increasing number of colour morphs in the founder group, and variation in founder groups also positively affected colour morph diversity in the established populations. Since colour morphs differ in morphology, physiology, behaviour, reproductive life history and types of niche used, these findings demonstrate that variation among individuals in functionally important traits promotes establishment success under natural conditions, and further indicate that founder diversity may contribute to evolutionary rescue and increased population persistence.

  • 73.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Åberg, Viktor
    Associations of variable coloration with niche breadth and conservation status among Australian reptiles2008In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 89, p. 1201-1207Article in journal (Refereed)
  • 74.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Åberg, Viktor
    Variable coloration is associated with more northerly geographic range limits and larger range sizes in North American lizards and snakes2008In: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 10, p. 1025-1036Article in journal (Refereed)
  • 75.
    Forsman, Anders
    et al.
    Dept of Zoology, Univ. of Uppsala.
    Ås, S
    Dept of Zoology, Univ. of Uppsala.
    Maintenance of colour polymorphism in adder populations, Vipera berus L.: a test of a popular hypothesis1987In: Oikos, Vol. 50, p. 13-16Article in journal (Refereed)
    Abstract [en]

    Accordingt o a currenth ypothesis,t he colourp olymorphismin populationso f the adder,Vipera berus L., is maintained by a thermal superiority of melanistic snakes,which enables them to grow more quickly than normally coloured ones. Since largermales are superior in sexual combats, and larger females get more offspring, thisclearly should favour the melanistic trait. On the other hand, melanistic individualsare believed to suffer a higher predation pressure due to their more conspicuous appearance.T he predictionf rom this hypothesisi s that melanistici ndividualso n averageshould be largert han normali ndividualsi n mixed populations.T his predictionwas tested on adders captured on several small islands in the Stockholm archipelago(N 59°20';E 19°20').N o significantd ifferencew as found in weight, lengtho r weight/length ratio between melanistic and normally coloured male adders. Neither slopenor elevation of the regression lines of length on weight differed. Thus, the hypothesiswas not supported by our data. 

  • 76.
    Franzén, Markus
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Forsman, Anders
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Betzholtz, Per-Eric
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Variable color patterns influence continental range size and species-area relationships on islands2019In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 10, no 1, article id e02577Article in journal (Refereed)
    Abstract [en]

    It has been hypothesized that species with more variable color patterns should have higher establishment success and be less sensitive to environmental changes and local extinction compared with species that do not vary in color. This difference in colonization/extinction balance should manifest as larger continental range distributions and modulate the species-area relationship on true islands. We evaluated these predictions using data for 1216 species of butterflies and moths that differed with regard to inter-individual variation in color pattern. We show that species with more variable color patterns have larger continental range sizes in Europe compared with non-variable species. We also provide rare evidence that the slope of the species-area relationship on islands is steeper for species having non-variable color patterns, suggesting that to preserve 60% of non-variable species would require an area twice as large compared to what would be needed to preserve 60% of variable species. Our findings suggest that combining information on ecological characteristics with presence/absence data from small and medium sized islands can help identify traits that drive species range patterns at the continental scale, and that individual variation in color pattern can be used as a proxy for ecological generalization and the ability to cope with environmental change.

  • 77. Hovmark, A
    et al.
    Jaensson, T G T
    Åsbrink, E
    Forsman, Anders
    Section of Animal Ecology, Department of Zoology, Uppsala University.
    Jansson, E
    First isolations of Borrelia burgdorferi from rodents collected in Northern Europe1988In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 96, p. 917-920Article in journal (Refereed)
    Abstract [en]

    Spirochetes were found in 13% of Ixodes ricinus collected from an island, near Stockholm where human borreliosis is endemic. Borrelia burgdorferi was cultivated from the kidney and/or spleen of wild rodents (Clethrionomys glareolus and Apodemus flavicollis) from the same island. Spirochetes were identified as Borrelia burgdorferi by indirect immunofluorescence assays using species and genus specific monoclonal antibodies. In these tests the spirochetes could not be differentiated from strains previously cultured from Swedish patients with Ixodes-borne borreliosis. The results show that small rodents in Europe may harbour borreliae and indicate that C. glareolus and A. flavicollis may be important reservoirs for the spirochetes causing Ixodes-borne borreliosis in humans and domestic animals in Europe. 

  • 78. Jaensson, Thomas
    et al.
    Meijlon, Hans
    Hovmark, Anders
    Åsbrink, Eva
    Forsman, Anders
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Den fästingöverförda Borreliainfektionen i Sverige1989In: Fauna och flora : populär tidskrift för biologi, ISSN 0014-8903, Vol. 84, p. 124-129Article in journal (Other (popular science, discussion, etc.))
  • 79.
    Johansson, Jenny
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Caesar, Sofia
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Forsman, Anders
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Multiple paternity increases phenotypic diversity in Tetrix subulata pygmy grasshoppers2013In: Journal of Orthoptera Research, ISSN 1082-6467, Vol. 22, no 2, p. 79-85Article in journal (Refereed)
    Abstract [en]

    Multiple paternity within clutches has been recorded among a variety of organisms. The degree of genetic similarity between parents may influence the number and viability of offspring. Females may therefore mate with several males as an insurance against sterile, low quality or genetically incompatible mates, but also to obtain half sibling offspring that are genetically and phenotypically more diverse. We examine the links between polyandry, multiple paternity and offspring phenotypic diversity in the color polymorphic pygmy grasshopper Tetrix subulata. By experimentally mating virgin females and genotyping the resulting offspring using microsatellite markers, we demonstrate that polyandrous females can produce offspring sired by different males. Analyses of microsatellite data and color patterns of captive reared families produced by wild caught females that were not mated in the laboratory, confirmed that multiple paternity occurs in the wild, and that it may increase color morph diversity among half-siblings. Polyandrous mating behavior may thus influence the evolutionary dynamics and maintenance of color polymorphism in this species.

  • 80.
    Karlsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Caesar, Sofia
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Forsman, Anders
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Ahnesjö, Jonas
    University of Kalmar, eHealth Institute, School of Human Sciences, University of Kalmar,.
    Dynamics of colour polymorphism in a changing environment: Fire melanism and then what?2008In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 154, no 4, p. 715-724Article in journal (Refereed)
  • 81.
    Karlsson, Magnus
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Forsman, Anders
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Is melanism in pygmy grasshoppers induced by crowding?2010In: Evolutionary Ecology, ISSN 0269-7653, E-ISSN 1573-8477, Vol. 24, no 5, p. 975-983Article in journal (Refereed)
    Abstract [en]

    Color polymorphisms in animals may result from plasticity of the developmental system in response to genetic cues in the form of allelic variation at polymorphic loci, environmental cues, or a combination of genetic and environmental cues. An increased understanding of the evolution of color polymorphisms requires better knowledge of when we should expect genetic and environmental cues respectively to influence phenotype determination. Theory posits that the developmental systems of organisms should evolve sensitivity to such cues that most accurately predict coming selective conditions. Pygmy grasshoppers (Orthoptera, Tetrigidae) vary in color pattern within and among populations and show fire melanism, i.e., an increased frequency of black and dark colored phenotypes in high density populations inhabiting fire-ravaged areas. We examined if the population density experienced by individuals during development influenced the phenotypic expression of color pattern in Tetrix subulata. Individuals were experimentally reared either in solitude, at intermediate density or under crowded conditions. We found that color patterns of experimental individuals were independent of rearing density but strongly influenced by maternal color pattern. High population density and crowding may not constitute reliable predictors of the selective regime that characterizes post-fire environments.

  • 82.
    Karlsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Johansson, Jenny
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Caesar, Sofia
    University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar.
    Forsman, Anders
    University of Kalmar, School of Pure and Applied Natural Sciences.
    No evidence for developmental plasticity of colour patterns in response to rearing substrate in pygmy grasshoppers2009In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 87, no 11, p. 1044-1051Article in journal (Refereed)
    Abstract [en]

    Color polymorphisms in animals may result from genetic polymorphisms, developmental plasticity, or a combination where some phenotypic components are under strong genetic control and other aspects are influenced by developmental plasticity. Understanding how color polymorphisms evolve demands knowledge of how genetic and epigenetic environmental cues influence the development and phenotypic expression of organisms. Pygmy grasshoppers (Orthoptera, Tetrigidae) vary in color pattern within and among populations. Color morphs differ in morphology, behavior, and life history, suggesting that they represent alternative ecological strategies. Pygmy grasshoppers also show fire melanism, a rapid increase in the frequency of black and dark-colored phenotypes in populations inhabiting fire-ravaged areas. We examined the influence of plasticity on color polymorphism in the pygmy grasshopper Tetrix subulata (L., 1761) using a split-brood design. Individuals were experimentally raised in solitude on either crushed charcoal or white aquarium gravel. Our analyses uncovered no plasticity of either color pattern or overall darkness of coloration in response to rearing substrate. Instead, we find a strong resemblance between maternal and offspring color patterns. We conclude that pygmy grasshopper color morphs are strongly influenced by genetic cues or maternal effects, and that there is no evidence for developmental plasticity of coloration in response to rearing conditions in these insects.

  • 83.
    Karlsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Wennersten, Lena
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Johansson, Jenny
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Caesar, Sofia
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Lapid, Einat
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Forsman, Anders
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Rapid parallel evolution of fire melanism in pygmy grasshoppers.Manuscript (preprint) (Other academic)
  • 84.
    Karpestam, Einat
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Forsman, Anders
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Dietary differences among colour morphs of pygmy grasshoppers revealed by behavioural experiments and stable isotopes.2011In: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 13, p. 461-477Article in journal (Refereed)
  • 85.
    Karpestam, Einat
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Forsman, Anders
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Stable isotopes reveal dietary divergence between dispersal phenotypes in Tetrix subulata pygmy grasshoppers (Orthoptera: Tetrigidae)2013In: European Journal of Entomology, ISSN 1210-5759, E-ISSN 1802-8829, Vol. 110, no 1, p. 65-70Article in journal (Refereed)
    Abstract [en]

    In some species of insects, individuals with fully developed wings and capable of flying coexist with flightless individuals that lack functional wings. Their diets may differ if long-winged individuals are more mobile and therefore likely to be better at finding and utilizing high quality food resources, or if they have different food preferences or physiological requirements. Despite its potential importance, differences in the diet of dispersal phenotypes have not been unequivocally demonstrated under natural conditions. To test for dietary divergence, we compared natural abundances of carbon and nitrogen stable isotope ratios (d13C and d15N) in long- and short-winged free ranging Tetrix subulata pygmy grasshoppers collected as adults from two natural populations. Overall, this comparison of stable isotopes indicated long-term differences in the diet of the two wing morphs in both populations, but not between males and females of the same morph. We conclude that it is likely that the dietary niches of the long winged and flightless individuals differ under natural conditions. This may reduce intra-specific competition, offset the expected trade-off between flight capacity and reproduction and promote ecological speciation.

  • 86.
    Karpestam, Einat
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Merilaita, Sami
    Åbo Akademi University, Finland.
    Forsman, Anders
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Body size influences differently the detectabilities of colour morphs of cryptic prey2014In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 113, no 1, p. 112-122Article in journal (Refereed)
    Abstract [en]

    Body size and coloration may contribute to variation in performance and fitness among individuals, for instance by influencing vulnerability to predators. Yet, the combined effect of size and colour pattern on susceptibility to visual predators has received little attention, particularly in camouflaged prey. In the colour polymorphic pygmy grasshopper Tetrix subulata (Linnaeus, 1758) females are larger than males although there is a size overlap between sexes. We investigated how body size and colour morph influenced detection of these grasshoppers, and whether differences in protective value among morphs change with size. We conducted a computer-based experiment and compared how human ‘predators’ detected images of large, intermediate or small grasshoppers belonging to black, grey or striped colour morphs when embedded in photographs of natural grasshopper habitats. We found that time to detection increased with decreasing size, that differences in time to detection of the black, grey and striped morphs depended differently on body size, and that no single morph provided superior or inferior protection in all three size classes. By comparing morph frequencies in samples of male and female grasshoppers from natural populations we also examined whether the joint effects of size and colour morph on detection could explain evolutionary dynamics in the wild. Morph frequency differences between sexes were largely in accordance with expectations from the results of the detection experiment. Our results demonstrate that body size and colour morph can interactively influence detection of camouflaged prey. This may contribute to the morph frequency differences between male and female pygmy grasshoppers in the wild. Such interactive effects may also influence the dynamics of colour polymorphisms, and contribute to the evolution of ontogenetic colour change and sexual dichromatism.

  • 87.
    Karpestam, Einat
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Merilaita, Sami
    Åbo Akademi University, Finland.
    Forsman, Anders
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Colour polymorphism protects prey individuals and populations against predation2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 22122Article in journal (Refereed)
    Abstract [en]

    Colour pattern polymorphism in animals can influence and be influenced by interactions between predators and prey. However, few studies have examined whether polymorphism is adaptive, and there is no evidence that the co-occurrence of two or more natural prey colour variants can increase survival of populations. Here we show that visual predators that exploit polymorphic prey suffer from reduced performance, and further provide rare evidence in support of the hypothesis that prey colour polymorphism may afford protection against predators for both individuals and populations. This protective effect provides a probable explanation for the longstanding, evolutionary puzzle of the existence of colour polymorphisms. We also propose that this protective effect can provide an adaptive explanation for search image formation in predators rather than search image formation explaining polymorphism.

  • 88.
    Karpestam, Einat
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Merilaita, Sami
    Department of Biosciences, Åbo Akademi University, Turku 780 FI-20520, Finland..
    Forsman, Anders
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Detection experiments with humans implicate visual predation as a driver of colour polymorphism dynamics in pygmy grasshoppers2013In: BMC Ecology, ISSN 1472-6785, E-ISSN 1472-6785, Vol. 13, p. Article number 17-Article in journal (Refereed)
    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.

  • 89.
    Karpestam, Einat
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Merilaita, Sami
    Åbo Akademi University, Finland.
    Forsman, Anders
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Natural levels of colour polymorphism reduce performance of visual predators searching for camouflaged prey2014In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 112, no 3, p. 546-555Article in journal (Refereed)
    Abstract [en]

    Polymorphism, the coexistence of two or more variants within a population, has served as a classic model system to address questions about the evolution and maintenance of intra-specific variation. It has been hypothesized that natural level of colour polymorphism may impair the search efficiency of visually oriented predators. To test this polymorphism protects hypothesis, we asked human participants to search for images of natural black, striped or grey Tetrix subulata grasshopper colour morphs presented against photographs of their natural habitat on computer screens. Fewer grasshoppers were detected when morphs were presented in mixed than in uniform sequences. All three morphs benefitted to comparable degrees, in terms of reduced detection, from being presented in polymorphic sequences. Our findings demonstrate that natural levels of polymorphic variation can impede the efficiency of visually oriented predators and increase survival of prey. This protective effect supports the limited attention hypothesis, explains why predators develop ‘search images’, may account for the spread and establishment of novel colour variants, and contribute to maintenance of polymorphisms.

  • 90.
    Karpestam, Einat
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Merilaita, Sami
    Åbo Akademi University, Finland.
    Forsman, Anders
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Reduced predation risk for melanistic pygmy grasshoppers in post-fire environments2012In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 2, no 9, p. 2204-2212Article in journal (Refereed)
    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.

  • 91.
    Karpestam, Einat
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Merilaita, Sami
    Åbo Akad Univ, Finland;Univ Turku, Finland.
    Forsman, Anders
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Size variability effects on visual detection are influenced by colour pattern and perceived size2018In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 143, p. 131-138Article in journal (Refereed)
    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.

  • 92.
    Karpestam, Einat
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Wennersten, Lena
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Forsman, Anders
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Matching habitat choice by experimentally mismatched phenotypes2012In: Evolutionary Ecology, ISSN 0269-7653, E-ISSN 1573-8477, Vol. 26, no 4, p. 893-907Article in journal (Refereed)
    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.

  • 93.
    Larsson, Per
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tibblin, Petter
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Koch-Schmidt, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Engstedt, Olof
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Nilsson, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Nordahl, Oscar
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Forsman, Anders
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Ecology, evolution, and management strategies of northern pike populations in the Baltic Sea2015In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 44, no Supplement 3, p. S451-S461Article, review/survey (Refereed)
    Abstract [en]

    Baltic Sea populations of the northern pike (Esox lucius) have declined since the 1990s, and they face additional challenges due to ongoing climate change. Pike in the Baltic Sea spawn either in coastal bays or in freshwater streams and wetlands. Pike recruited in freshwater have been found to make up about 50 % of coastal pike stocks and to show natal homing, thus limiting gene flow among closely located spawning sites. Due to natal homing, sub-populations appear to be locally adapted to their freshwater recruitment environments. Management actions should therefore not involve mixing of individuals originating from different sub-populations. We offer two suggestions complying with this advice: (i) productivity of extant freshwater spawning populations can be boosted by modifying wetlands such that they promote spawning and recruitment; and (ii) new sub-populations that spawn in brackish water can potentially be created by transferring fry and imprinting them on seemingly suitable spawning environments.

  • 94. Lindell, L E
    et al.
    Forsman, Anders
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Density effects and snake predation: prey limitation and reduced growth rate of adders at high density of conspecifics1996In: Canadian Journal of Zoology, Vol. 74, p. 1000-1007Article in journal (Refereed)
  • 95. Lindell, L E
    et al.
    Forsman, Anders
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Sexual dichromatism in snakes: support for the flicker-fusion hypothesis1996In: Canadian Journal of Zoology, Vol. 74, p. 2254-2256Article in journal (Refereed)
  • 96. Lindell, L E
    et al.
    Forsman, Anders
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Merilä, J
    Variation in number of ventral scales in snakes: effects on body size, growth rate and survival in the adder, Vipera berus1993In: Journal of Zoology, Vol. 230, p. 101-115Article in journal (Refereed)
  • 97. Martin, J
    et al.
    Forsman, Anders
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Social costs and development of nuptial coloration in male Psammodromus algirus lizards: an experiment1999In: Behavioral Ecology, Vol. 10, p. 396-400Article in journal (Refereed)
  • 98. Merilä, J
    et al.
    Forsman, Anders
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Lindell, L E
    High frequency of ventral scute anomalies in Vipera berus populations.1992In: Copeia, ISSN 0045-8511, E-ISSN 1938-5110, Vol. 1992, no 4, p. 1127-1130Article in journal (Refereed)
  • 99. Nilsson, M
    et al.
    Forsman, Anders
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Evolution of conspicuous colouration, body size and gregariousness: a comparative analysis of lepidopteran larvae2003In: Evolutionary Ecology, Vol. 17, p. 51-66Article in journal (Refereed)
  • 100.
    Nordahl, Oscar
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Koch-Schmidt, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Sunde, Johanna
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Yildirim, Yeserin
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tibblin, Petter
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Forsman, Anders
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Larsson, Per
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Genetic differentiation between and within ecotypes of pike (Esox lucius) in the Baltic Sea2019In: Aquatic conservation, ISSN 1052-7613, E-ISSN 1099-0755, Vol. 29, no 11, p. 1923-1935Article in journal (Refereed)
    Abstract [en]

    Aquatic systems often lack physical boundaries for gene flow, but ecological and behavioural barriers can form surprisingly fine spatial scale genetic patterns that challenge traditional, large scale management. To detect fine spatial scale structures, understand sources of intraspecific diversity, and design appropriate management plans requires identification of reproductively isolated units. This study reports on genetic differentiation in pike (Esox lucius) within a coastal area stretching 55 km from south to north in the central Baltic Sea. Pike is here an economically and ecologically important top predator that has declined in abundance. However, population structures have mostly been studied on large spatial scales, and without considering the potential for genetic divergence between the sympatric anadromous fresh water and the resident brackish water spawning ecotypes. To this end, 487 individuals from the east coast of Sweden and the island of oland, representing sympatric anadromous and resident spawning individuals, categorized to ecotype based on spawning location or otolith microchemistry, were genotyped for 10 microsatellites and used to test for divergence between ecotypes. Furthermore, divergence between regions (island/mainland), neighbouring spawning locations (n = 13) and isolation by distance within and between regions were evaluated for the anadromous ecotype. The results revealed strong genetic differences between regions, between spawning locations separated by as little as 5 km and the first evidence of genetic differentiation between resident and anadromous ecotypes; despite a high dispersal capacity of pike and a high connectivity within the study area. The signatures of isolation by distance indicated that connectivity among populations differed between regions, probably reflecting availability of spawning habitats. To safeguard against the challenges and uncertainties associated with environmental change, adaptive conservation management should aim to promote high intra-population functional genetic diversity without compromising the continued integrity and coexistence of the different ecotypes and of locally adapted sub-populations.

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