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  • 1. Barber, I.
    et al.
    Svensson, P. A.
    Effects of experimental Schistocephalus solidus infections on growth, morphology and sexual development of female three-spined sticklebacks, Gasterosteus aculeatus2003In: Parasitology, ISSN 0031-1820, E-ISSN 1469-8161, Vol. 126, p. 359-367Article in journal (Refereed)
    Abstract [en]

    The use of naturally infected hosts in studies attempting to identify parasite-induced changes in host biology is problematical because it does not eliminate the possibility that infection may be a consequence, rather than a cause, of host trait variation. In addition, uncontrolled concomitant infections may confound results. In this study we experimentally infected individual laboratory-bred female three-spined sticklebacks Gasterosteus aculeatus L. with the pseudophyllidean cestode Schistocephalus solidus [Muller], and compared the morphology and growth patterns of infected females with sham-exposed controls over a 16-week period. Fish were fed a ration of 8% body weight per day. Non-invasive image analysis techniques allowed the growth of individual plerocercoids to be tracked in vivo throughout the course of infection, and patterns of host and parasite growth were determined. Females that developed infections diverged morphometrically from unexposed control females and exposed-uninfected females at 6 weeks post-infection, with the width of the body at the pectoral fins giving the earliest indication of infection success. When including the plerocercoid, infected females gained weight more quickly than controls, but when plerocercoid weight was removed this trend was reversed. There was no effect of infection on the increase in fish length. Plerocercoids grew at different rates in individual hosts, and exhibited measurable sustained weight increases of up to 10% per day. Final estimates of plerocercoid weight from morphometric analysis prior to autopsy were accurate to within +/-17% of actual plerocercoid weight. At autopsy, infected female sticklebacks had significantly lower perivisceral fat reserves but had developed significantly larger ovaries than controls. The results are discussed in relation to previous studies examining natural infections, and the value of utilizing experimental infections to examine ecological aspects of host-parasite interactions is discussed.

  • 2. Barber, I.
    et al.
    Svensson, P. Andreas
    Synchrony between parasite development and host behaviour change2003In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 63 Supp A, p. 246-Article in journal (Refereed)
  • 3. Barber, I.
    et al.
    Walker, P.
    Svensson, P. A.
    Behavioural responses to simulated avian predation in female three spined sticklebacks the effect of experimental Schistocephalus solidus infections2004In: Behaviour, ISSN 0005-7959, E-ISSN 1568-539X, Vol. 141, p. 1425-1440Article in journal (Refereed)
    Abstract [en]

    Plerocercoid larvae of Schistocephalus solidus are common parasites of three-spined sticklebacks that require the ingestion of stickleback hosts by birds to complete their life cycle. Amongst wild-caught sticklebacks, infection is associated with a reduction in antipredator behaviour; however, to date no study has examined the escape responses of experimentally infected sticklebacks, and thus assigning causality remains difficult. Here, we compare aspects of the antipredator behaviour of five experimentally infected female sticklebacks with shamexposed controls over a 16 post-exposure week period. During weeks 1-7 post-exposure, the escape responses of infected fish did not differ significantly from those of sham-exposed fish. However, over weeks 9-15, when infected fish had developed plerocercoids of >50 mg—the size at which they become infective to birds —a lower proportion of infected fish performed directional responses and reached cover within 2 s of the strike. Infected fish also performed a lower frequency of ‘staggered dashes’, and a higher frequency of ‘slow swims’, than shamexposed fish over weeks 9-15. Amongst sham-exposed fish, re-emergence from cover was uncommon throughout the study, but infected fish regularly left cover during weeks 9-15. Our results support those of previous studies examining behavioural change in naturally infected fish and, although other explanations remain possible, our finding that behaviour change in experimentally-infected fish is limited to hosts harbouring single infective parasites provides further evidence that the behaviour changes may be parasite adaptations.

  • 4.
    Doane, Marie
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Sarenbo, Sirkku
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    A modified combined C-BARQ and QoL for both the companion dog and its owner. An embryo to a companion dog welfare measurement?2019In: Applied Animal Behaviour Science, ISSN 0168-1591, E-ISSN 1872-9045, Vol. 213, p. 91-106Article in journal (Refereed)
    Abstract [en]

    The results of this pilot study demonstrate that it is possible to construct a reliable questionnaire from prior validated surveys. This questionnaire displays possible suitability for further development into a tool for a comprehensive dog welfare assessment. The welfare model used is assuming that canine welfare consists of three major considerations, the dogs’ behavior, the dogs’ quality of life (QoL dog) and the owner’s quality of life as pertaining to being a dog owner (QoL Owner). A questionnaire was constructed and tested. Three different parts from reliable and validated sections of previous surveys were included: 1) a modified C-BARQ, 2) QoL for the dog, and 3) QoL owner. 185 satisfactory answers were obtained from the respondents, dog owners in Sweden, Canada and USA. Principal component factor analysis rendered 13 extracted factors similar to the original questionnaires, suggesting that the construct is valid. Eleven of the thirteen factors showed moderate internal consistency of Cronbach’s alpha >0.7, the remaining two factors were relatively low with Cronbach’s alpha >0.6.

    Several significant correlations between the extracted factors were found. Quality of life as a dog owner (QoL owner) was significantly affected by stress caused by dogs displaying fear, excitability and separation anxiety. No significant correlations were found between any factors describing aggressive behaviors and the dogs QoL or QoL owner. Several significant correlations were found between the extracted factors and the demographics, for instance, the Swedes are more active with their dogs compared to Americans and Canadians. Further investigations should be commenced to validate the results in a larger population.

  • 5. Engkvist, R.
    et al.
    Malm, T.
    Svensson, A.
    Asplund, L.
    Isaeus, M.
    Kautsky, L.
    Greger, M.
    Lanberg, T.
    Makroalgsblomningar längs Ölands kuster, effekter på det lokala näringslivet och det marina ekosystemet. (English title: Macro algal blooms in the central Baltic proper, effects on the economy and the marine ecosystem.)2001Report (Refereed)
  • 6. Guevara-Fiore, P.
    et al.
    Svensson, P. Andreas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Endler, J.A.
    Sex as moderator of early life experiences: interaction between rearing environment and sexual experience in male guppies2012In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 84, no 4, p. 1023-1029Article in journal (Refereed)
    Abstract [en]

    The effects of learning have been neglected in studies of sexual selection because previous researchers have assumed, implicitly or explicitly, that sexual behaviour is genetically fixed. To understand the role of learning in sexual selection, it is important to investigate how early experience interacts with adult experience to determine the use of different mating strategies. We explored this interaction by comparing the sexual behaviour of male guppies, Poecilia reticulata, raised in different social environments before and after they gained sexual experience. Males raised with other males performed long courtship displays at first, but decreased their courtship after they had gained sexual experience. However, for males raised only with females, sexual experience did not modify courtship duration. Males raised exclusively with females exhibited high rates of forced copulation attempts in their first encounter with a female, but reduced this behaviour after sexual experience. In contrast, males raised with other males did not modify their forced copulations. Adult sexual experience appeared to mitigate the behavioural differences caused by variation in rearing environment. Sexual experience helps males to find an optimal balance between courtship displays and forced copulation attempts. We also show that more males exhibited male–male aggression after sexual experience if they had social interactions with other males early in life. This study highlights that courtship and other sexual strategies are not fixed, and that several potential sources of variation exist in the development of an animal's sexual behaviour. Importantly, juvenile and adult experiences can interact to shape sexual behaviour in males.

  • 7. Härlin, Mikael
    Humor gör oss osjälviska: Därför bör du skämta mer på jobbet2014In: Modern Psykologi, ISSN 2000-4087, no 7, p. 35-35Article in journal (Other (popular science, discussion, etc.))
  • 8.
    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 effort2011In: BMC Evolutionary Biology, ISSN 1471-2148, E-ISSN 1471-2148, Vol. 11, article id 233Article in journal (Refereed)
    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.

  • 9.
    Lehtonen, Topi K.
    et al.
    Monash Univ, Australia.
    Svensson, P. Andreas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Monash Univ, Australia.
    Wong, Bob B. M.
    Monash Univ, Australia.
    The influence of recent social experience and physical environment on courtship and male aggression2016In: BMC Evolutionary Biology, ISSN 1471-2148, E-ISSN 1471-2148, Vol. 16, article id 18Article in journal (Refereed)
    Abstract [en]

    Background: Social and environmental factors can profoundly impact an individual's investment of resources into different components of reproduction. Such allocation trade-offs are expected to be amplified under challenging environmental conditions. To test these predictions, we used a desert-dwelling fish, the desert goby, Chlamydogobius eremius, to experimentally investigate the effects of prior social experience (with either a male or a female) on male investment in courtship and aggression under physiologically benign and challenging conditions (i.e., low versus high salinity). Results: We found that males maintained a higher level of aggression towards a rival after a recent encounter with a female, compared to an encounter with a male, under low (but not high) salinity. In contrast, male investment in courtship behaviour was unaffected by either salinity or social experience. Conclusion: Together, our results suggest that male investment in aggression and courtship displays can differ in their sensitivity to environmental conditions and that not all reproductive behaviours are similarly influenced by the same environmental context.

  • 10.
    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 cichlids2011In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 65, no 4, p. 613-619Article in journal (Refereed)
    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.

  • 11. 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 flavescens2009In: BMC Evolutionary Biology, ISSN 1471-2148, E-ISSN 1471-2148, Vol. 9, p. 1-10, article id 6Article in journal (Refereed)
    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.

  • 12.
    Olsson, Karin
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Är min häst lycklig?: Indikatorer på positiv välfärd hos häst och en checklista för bedömning2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    It is now widely accepted that the concept of ”animal welfare” includes both the physical and mental wellbeing, and that providing positive experiences is equally important as avoiding and limiting negative ones. Most scientists seem to agree that horses experience positive welfare when exploring and feeding in complex environments and through friendly interactions with other members of the flock. In contrast, it is less clear in which situations they experience positive welfare when kept in captivity and their natural behaviours are restricted. We need indicators to assess if animals experience positive welfare, and the first aim of this thesis was a summary of the research on this subject presented the last decade. The indicators can be divided into signs of enjoyment and content (for example facial expression, body language and vocal and non-vocal sounds), luxury behaviours (behaviours not necessary for survival, such as play or allogrooming) and behaviours that supports the possibility to cope with challenges (such as friendly interactions or the possibility to control a situation). Since research has progressed so much the last decade, the second aim of this thesis was to create a checklist to be used when assessing the positive side of the welfare spectrum. However, it became clear that there is still need for more research before the indicators of positive welfare can be used in practice in a detailed checklist. This is partly due to the need for special equipment for analysis of some indicators and because many results were inconclusive or dependent on a specific context. The checklist is therefore limited to how to exclude that the horse experience negative welfare, how to provide more that the minimum level stated in the animal welfare legislation and how to provide daily possibilities to experience positive feelings.

  • 13.
    Sarenbo, Sirkku
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Canines seized by the Swedish Police Authority in 2015–20162019In: Forensic Science International, ISSN 0379-0738, E-ISSN 1872-6283, Vol. 296, p. 101-109Article in journal (Refereed)
    Abstract [en]

    The inspection protocols of the Swedish police, based on the Act (2007:1150) on Supervision of Dogs and Cats, were used to examine the characteristics of 101 seized dogs, their owners, and the circumstances in which the attacks occurred. Most common reasons to seize a dog was that the dog owner was not following a previous order or ban, or that the dog had attacked and caused damage to humans or animals. The most common circumstances of the attacks involved dogs that escaped from gardens, unleashed dogs on walks and attacks by dogs on a leash. Bull breeds caused the highest number of injuries, the most serious injuries, and they were most often categorized as high risk, followed by Rottweilers and German Shepherds. Affenpinscher, Chihuahua, Cocker Spaniel, Japanese Spitz, Pug, Shih Tzu, Shetland Sheepdog and Golden Retriever were identified as victim breeds. The seized dogs had caused substantial harm to humans, animals, and their environment. The largest proportion of dogs returned to owners occurred in the Stockholm region.

  • 14.
    Sarenbo, Sirkku
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Min hund är egentligen snäll: Jag vet inte varför den gjorde så här2015 (ed. 1)Book (Other academic)
    Abstract [sv]

    Min hund är egentligen snäll är i första hand riktad till den myndighet som handlägger tillsynsärenden, enligt lag om tillsyn (2007:1150) över hundar och katter. I boken redovisas bakgrunden till rasförbuden i Danmark och Norge, och demografi över hundpopulationer i Sverige av de hos grannländerna förbjudna raserna, samt en analys av 107 stycken överklagade beslut enligt tillsynslagen. I boken redovisas också de många olika brottstyper där hundar kan vara inkluderade, vilket kan vara av intresse för brottsutredare och åklagare. Boken kan vara av intresse även för andra aktörer som arbetar med djurskyddsfrågor, beslutsfattare, veterinärer, forskare, studenter m.fl.

  • 15.
    Schrödl, Sara
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Do the tufted capuchins (Cebus apella) use their animal exploration trail?: A space use study on a 360 zoo exhibit at a Swedish zoo2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Zoos have important roles in society such as conservation, but also a responsibility concerning their captive animals’ welfare. One way of improving animal welfare is by providing enrichment and one such enrichment is the innovative animal exploration trails in 360 Zoo exhibits. These are supposed to enable the animals to travel larger, continuous distances and provide enriching visual, scent, and noise stimuli in hopes that the animals will have an activity budget closer to in their wild counterparts and having a larger behaviour repertoire. These are both ways to determine if animals’ welfare is good. However, these animal trails have yet to be evaluated for their effect on animal welfare, and this study aimed to evaluate how much a group of tufted capuchins (Cebus apella) at Öland Zoo and Amusement Park in Sweden used their animal trail and to investigate if their use was affected by the weather, temperature, or by visitors being present. The results show that the capuchins used the trail to a great extent, and that their use varied significantly depending on the weather, temperature and visitors. The data sample was, however questionable for these environmental factors and no strong associations were found for their effect, which was attributed to the capuchins possibly having a preference for being outside despite aversive conditions, but also to the design of the trail. Its design was maybe not optimal as it only had one entrance, which could impede its usefulness as a result of social factors for example. The trail does, however grant the capuchins a more complex environment, which is known to be related to better animal welfare, and the trail also gives the animals choice and control of their environment, which has been found to enable animals to better cope with stress and the presence of visitors. In conclusion, the animal trail was found to be a great extent by the capuchins and the trail could potentially provide better animal welfare, but the effect would depend on its design. Further research on animal trails’ effect of animal welfare is needed before expanding the its use.

  • 16. Sköld, H. N.
    et al.
    Amundsen, T.
    Svensson, P. Andreas
    Mayer, I.
    Bjelvenmark, J.
    Forsgren, E.
    Hormonal regulation of female nuptial coloration in a fish2008In: Hormones and Behavior, ISSN 0018-506X, E-ISSN 1095-6867, Vol. 54, no 4, p. 549-556Article in journal (Refereed)
    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.

  • 17.
    Sköld, Rebecka
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Predatoriskt beteende hos hund (Canis lupus familiaris)2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Domestication of the dog has led to a number of different breeds worldwide. All these breeds were from the beginning bred for a specific purpose. However, the dogs are no longer used in the same order for their main goal. Today dogs are mainly kept for company. Although they are no longer used for the purpose they were developed, their behavior remains in the genes. With this work I want to highlight the predatory behavior that remains in the dog, and how certain breeds exhibit a greater predatory aggressiveness than others. Some breeds are more likely to show this behavior regardless if it is desired or not. Because there are genes that control the dog's behavior, we cannot avoid that some breeds are more likely to perform predatory behaviors and predatory aggression.

  • 18.
    Sopelsa Hall, Emma
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Ex situ lion conservation: Behavioural responses to playbacks of competitors with focus on sex and age differences2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Due to increasing habitat loss, human-lion conflict, poaching and other reasons, African lion (Panthera leo) populations have suffered a drastic decline. The African Lion and Environmental Research Trust (ALERT) is working to stop this pattern and is the first organization with an ex-situ conservation project for lions. Before releasing lions raised by captive-bred adults, they must first be ensured to behave properly to make sure they have the highest chance of survival. One challenge in the wild is encountering and competition with unknown conspecifics. By conducting playback of unfamiliar lion roars, the behaviours of lions under this ex-situ reintroduction program were tested and compared with observations from earlier studies of wild lions. Social interactions were also collected and a social network analysis was done to give information about the social structure in the pride. This in turn was compared with boldness scores, calculated from behavioural responses in the playback experiments. Lastly, I searched for associations between age and sex with both boldness and social interactions.

     

    The studied pride consisted of 12 lions. The lions were more vigilant when a playback consisted of numerous lions vocalizing, but playing more than three lions seemed to make them loose interest, suggesting either habituation or false information. One adult female and the alpha-male were most bold, followed by five sub-adults. Boldness did not vary according to sex or age differences, but the social network analysis showed that some social interactions were more dominated by one sex or age group. These behaviours were in agreement with comparisons of wild prides.

     

    This study showed that captive-bred lions have developed natural social behaviours. Based on the behavioural responses observed by the captive-origin lions to the playbacks of unfamiliar lions, it is unclear whether these lions would appropriately respond when encountered with unfamiliar conspecifics in the wild post-release.

  • 19.
    Svensson, P. Andreas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Adaptations and strategies for paternal care in a desert-dwelling fish. 2009Conference paper (Refereed)
    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.

  • 20.
    Svensson, P. Andreas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Female coloration and beneficial egg carotenoids2006Conference paper (Refereed)
  • 21.
    Svensson, P. Andreas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Female coloration and beneficial egg carotenoids2007Conference paper (Other academic)
  • 22.
    Svensson, P. Andreas
    Department of Biology, NTNU, Trondheim.
    Female coloration, egg carotenoids and reproductive success: gobies as a model system2007Doctoral thesis, comprehensive summary (Other academic)
    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.  

  • 23.
    Svensson, P. Andreas
    Norwegian University of Science and Technology.
    Female coloration, egg carotenoids and reproductive success gobies as a model system, PhD Thesis2006Doctoral thesis, comprehensive summary (Other academic)
  • 24.
    Svensson, P. Andreas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Female two-spotted gobies display egg carotenoid status2004Conference paper (Other academic)
  • 25.
    Svensson, P. Andreas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Female two-spotted gobies display egg carotenoid status.2004Conference paper (Refereed)
  • 26.
    Svensson, P. Andreas
    Monash University.
    Gobies and carotenoids2008Conference paper (Other academic)
    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.

  • 27.
    Svensson, P. Andreas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Gobies as biomarkers.2006Conference paper (Other academic)
  • 28. Svensson, P. Andreas
    Shoaling decisions in the two-spotted goby,Gobiusculus flavescens. MSc thesis.2000Report (Other academic)
    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.

  • 29.
    Svensson, P. Andreas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Strategic male courtship effort in a desert-dwelling fish.2008Conference paper (Refereed)
    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.

  • 30.
    Svensson, P. Andreas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Techniques for incubating and analyzing goby eggs.2006Conference paper (Other academic)
  • 31.
    Svensson, P. Andreas
    Deakin Univeristy.
    The interval between sexual encounters affect male courtship tactics.2011Conference paper (Other academic)
    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.

  • 32.
    Svensson, P. Andreas
    Monash University.
    The interval between sexual encounters affect male courtship tactics2010Conference paper (Other academic)
    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.

  • 33. Svensson, P. Andreas
    et al.
    Barber, I.
    Forsgren, E.
    Shoaling behaviour of the two-spotted goby2000In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 56, no 6, p. 1477-1487Article in journal (Refereed)
    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.

  • 34.
    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 gobies2009In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 75, p. 2777–2787-Article in journal (Refereed)
    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.

  • 35. 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 gobies2005In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 208, p. 4391-4397Article in journal (Refereed)
    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.

  • 36.
    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 fish2010In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 64, no 2, p. 1967-1970Article in journal (Refereed)
    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.

  • 37.
    Svensson, P. Andreas
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences. Monash University, Australia.
    Lehtonen, Topi K.
    Monash University, Australia ; University of Turku, Finland.
    Wong, Bob B. M.
    Monash University, Australia.
    A high aggression strategy for smaller males2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 8, article id e43121Article in journal (Refereed)
    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 two contestants. We quantified initiation of aggression in a fish, the desert goby, Chlamydogobius eremius, by exposing nest-holding males to a male intruder. The perceived value of the resource ( the nest) was manipulated by exposing half of the residents to sexually receptive females for two days before the trial. Resident male aggression, however, was unaffected by perceived mating opportunities. It was also unaffected by the absolute and relative size of the intruder. Instead resident aggression was negatively related to resident male size. In particular, smaller residents attacked sooner and with greater intensity compared to larger residents. These results suggest that resident desert goby males used set, rather than conditional, strategies for initiating aggression. If intruders are more likely to flee than retaliate, small males may benefit from attacking intruders before these have had an opportunity to assess the resident and/or the resource.

  • 38. Svensson, P. Andreas
    et al.
    Malm, T.
    Engkvist, R.
    Distribution and host plant preference of Idotea baltica (Pallas) (Crustacea Isopoda) on shallow rocky shores in the central Baltic Sea2004In: Sarsia, ISSN 0036-4827, E-ISSN 1503-1128, Vol. 89, no 1, p. 1-7Article in journal (Refereed)
    Abstract [en]

    Partially due to the mass occurrence of the isopod Idotea baltica, the perennial fucoid vegetation in the Baltic Sea has been destroyed over large areas and replaced by filamentous algae. With a combination of field investigations and laboratory experiments, we tested whether I. baltica preferred Fucus serratus to the dominant red alga Polysiphonia fucoides. In the field, the I. baltica density was higher inside F. serratus than P. fucoides patches when measured per unit area, but the situation was reversed if measured per biomass algae. Diet in the field was well correlated with the distribution of the isopods. A large proportion of the isopod faecal pellets collected in the field contained remnants of microalgae, planktonic animals, and bacteria, but the dominating material was always cells from the actual host plant. In a host plant preference experiment, I. baltica distributed evenly between the two host plant types, but the isopods grazed more heavily on F. serratus: We conclude that although F. serratus is the preferred food item in a choice situation, P. fucoides appears to have the potential to support the I. baltica population with food and shelter. A possible relationship between the weak host plant preference and the low stocks of predatory fish is discussed.

  • 39.
    Svensson, P. Andreas
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Nilsson-Sköld, Helen
    University of Gothenburg.
    Skin biopsies as tools to measure fish coloration and colour change2011In: Skin Biopsy - Perspectives / [ed] Uday Khopkar, InTech, 2011Chapter in book (Other academic)
  • 40.
    Svensson, P. Andreas
    et al.
    Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
    Pélabon, C.
    Blount, J. D.
    Forsgren, E.
    Bjerkeng, B.
    Amundsen, T.
    Temporal variability in a multicomponent trait: nuptial coloration of female two-spotted gobies2009In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 20, no 2, p. 346-353Article in journal (Refereed)
  • 41. Svensson, P. Andreas
    et al.
    Pélabon, C.
    Blount, J. D.
    Surai, P. F.
    Amundsen, T.
    Does female nuptial coloration reflect egg carotenoids and clutch quality in the two-spotted goby (Gobiusculus flavescens, Gobiidae)?2006In: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 20, p. 689-698Article in journal (Refereed)
    Abstract [en]

    1. 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. 2. FemaleGobiusculus flavescens(two-spotted goby) develop colourful orange bellies during the breeding season. Belly coloration varies among mature females, and previous work has shown nest holding males to prefer females with more colourful bellies. Since males invest heavily in offspring during incubation, the evolution of this preference can be explained if colourful females provide males with eggs of higher quality. 3. We tested this hypothesis by allowing males to spawn with 'colourful' and 'drab' females and comparing parameters including egg carotenoid concentration, clutch size, hatchability and larval viability between groups. We also investigated relationships between egg carotenoid concentration and clutch quality parameters. 4. Eggs from colourful females had higher concentrations of total carotenoids than eggs from drab females. Colourful females produced slightly larger clutches, but no measure of offspring quality differed between the two groups. Belly coloration quantified in photographs prior to spawning was a good predictor of egg carotenoid concentration, but there were no significant relationships between egg carotenoids and the measures of clutch quality. Females with high levels of egg carotenoids spawned slightly earlier, however, possibly because they were more ready to spawn or because of male mate choice. 5. We found that colourful females provided males with slightly larger clutches and eggs that contained more carotenoids, but despite this, the offspring were not of higher quality. Our results call into question the generality of a causal link between egg carotenoids and offspring quality.

  • 42.
    Svensson, P. Andreas
    et al.
    Monash University, Australia.
    Wong, B. B. M.
    Monash University, Australia.
    Carotenoid-based signals in behavioural ecology: a review2011In: Behaviour, ISSN 0005-7959, E-ISSN 1568-539X, Vol. 148, no 2, p. 131-189Article in journal (Refereed)
    Abstract [en]

    Carotenoids are among the most prevalent pigments used in animal signals and are also important for a range of physiological functions. These concomitant roles havemade carotenoidbased signals a popular topic in behavioural ecology while also causing confusion and controversy. After a thorough background, we review the many pitfalls, caveats and seemingly contradictory conclusions that can result from not fully appreciating the complex nature of carotenoid function. Current controversies may be resolved through a more careful regard of this complexity, and of the immense taxonomic variability of carotenoid metabolism. Studies investigating the physiological trade-offs between ornamental and physiological uses of carotenoids have yielded inconsistent results. However, in many studies, homeostatic regulation of immune and antioxidant systems may have obscured the effects of carotenoid supplementation. We highlight how carefully designed experiments can overcome such complications. There is also a need to investigate factors other than physiological trade-offs (such as predation risk and social interactions) as these, too, may shape the expression of carotenoidbased signals.Moreover, the processes limiting signal expression individuals are likely different from those operating over evolutionary time-scales. Future research should give greater attention to carotenoid pigmentation outside the area of sexual selection, and to taxa other than fishes and birds.

  • 43.
    Symons, N.
    et al.
    Monash Univ, Sch Biol Sci, Melbourne, Vic 3004, Australia .
    Svensson, P. Andreas
    Monash Univ, Sch Biol Sci, Melbourne, Vic 3004, Australia .
    Wong, B. B. M.
    Monash Univ, Sch Biol Sci, Melbourne, Vic 3004, Australia .
    Do Male Desert Gobies Compromise Offspring Care to Attract Additional Mating Opportunities?2011In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, no 6, p. e20576-Article in journal (Refereed)
    Abstract [en]

    Males often play a critical role in offspring care but the time and energy invested in looking after young can potentially limit their ability to seek out additional mating opportunities. Recent studies, however, suggest that a conflict between male parental effort and mating effort may not always be inevitable, especially if breeding occurs near the nest, or if parental behaviours are under sexual selection. Accordingly, we set out to experimentally investigate male care and courtship in the desert goby Chlamydogobius eremius, a nest-guarding fish with exclusive paternal care. Despite courtship occurring near the nest, we found that when egg-tending males were given the opportunity to attract additional females, they fanned their eggs less often, engaged in shorter fanning bouts, and spent more of their time outside their nests courting. Our findings highlight the importance of understanding the circumstances under which reproductive tradeoffs are expected to occur and how these, in turn, operate to influence male reproductive decisions.

  • 44. Wong, B. B. M.
    et al.
    Svensson, P. Andreas
    School of Biological Sciences, Monash University, Melbourne, VIC, 3800, Australia.
    Strategic male signalling effort in a desert-dwelling fish2009In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 63, no 4, p. 543-549Article in journal (Refereed)
    Abstract [en]

    Males often use elaborate courtship displays to attract females for mating. Much attention, in this regard, has been focused on trying to understand the causes and consequences of signal variation among males. Far less, by contrast, is known about within-individual variation in signal expression and, in particular, the extent to which males may be able to strategically adjust their signalling output to try to maximise their reproductive returns. Here, we experimentally investigated male courtship effort in a fish, the Australian desert goby, Chlamydogobius eremius. When offered a simultaneous choice between a large and a small female, male gobies spent significantly more time associating with, and courting, the former, probably because larger females are also more fecund. Male signalling patterns were also investigated under a sequential choice scenario, with females presented one at a time. When first offered a female, male courtship was not affected by female size. However, males adjusted their courtship effort towards a second female depending on the size of the female encountered previously. In particular, males that were first offered a large female significantly reduced their courtship effort when presented with a subsequent, smaller, female. Our findings suggest that males may be able to respond adaptively to differences in female quality, and strategically adjust their signalling effort accordingly.

  • 45.
    Åman, Isabelle
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Störningar i ledarhundens arbete: Orsak och konsekvenser2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Aggression is a common behavior among many species and can be signaled through both vocalization and visual signals. The behavior may be based on dominance, competition for a partner or because the individual defends a resource or a territory. Around 15 000 years ago the wolf Canis lupus was domesticated, which resulted in the subspecies dog Canis familiaris and through an extensive breeding program there are currently over 400 recognized breeds. In Sweden there are about 300 active guide dogs in service and every year around 40 new dogs are trained, that will come to work for a guide dog owner. The aim of this study was to see to which frequency and in what way guide dogs for the visually impaired are disturbed when they are on duty out in public places. In order to collect data a survey was conducted, where 18 guide dog owners described one to two typical situations of disturbance from other dogs, which occurs when the guide dog are on duty. Nearly 90 percent of the guide dog owners reported that one or more disturbance had occurred, where lunges was the most common type of disturbance followed by active play and attack. The majority of the affected guide dogs in this study were males of the breed Labrador retriever. Several of the guide dogs got mental and/or physical injuries due to the disturbance and had to be taken out of duty temporarily. The attacks may have been based on a lack of communication between the dogs. The results are based on a limited sample, therefore they may not be representative of the situation for the entire Swedish guide dog population but it is possible to sense a problem. This study is the first of its kind to be carried out in Sweden and leaves room for further research. 

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