Behavioural Phenotypes: Associated Life-History Traits and Environmental Effects on Development

It is widely documented that non-human organisms express individual differences in behavioural patterns. For example individuals can be categorised as bold or shy and when these individual behavioural differences are consistent through time, they are termed behavioural types (BTs). In recent years research has identified that BTs often correlate across contexts/situations and these correlations are referred to as behavioural syndromes. Behavioural types and syndromes (i.e. personality) have also been implicated as major factors shaping population dynamics and the ability to buffer environmental disturbance. Recent theoretical predictions have proposed that BT variation may be underpinned by life-history strategies; however, these predictions have been little studied to date. Moreover, little research has focused upon environmental influences and the ontogeny of personality. In this thesis I use the Mangrove killifish (Kryptolebias marmoratus), a naturally occurring clonal vertebrate, as a model organism. This species presents a powerful tool providing the ability to replicate within and between isogenic genotypes in a controlled manner. Moreover the natural clonality expressed by this species permits environmental effects upon BT plasticity and BT-life-history interactions to be investigated within a developmental framework. In chapter 2, I present microsatellite genotyping results which show that the founding individuals used to propagate a laboratory population at The University of Exeter represent 20 genetically distinct homozygous genotypes. I additionally address five research questions exploring genotypic, environmental, and developmental effects upon three commonly studied BTs (exploration, boldness and aggression): Firstly; I ask do adult hermaphrodite and secondary males exhibit personality i.e. repeatable BT expression? In chapter 3, I present results showing that both of the sexes express short term personality. Moreover, I show that that genotype is an important factor influencing BTs expressed, regardless of sex, indicating underlying genetic control. Secondly I ask; does genotype level life-history variation underpin personality trait variation during ontogeny? In chapter 4, I show considerable developmental plasticity in behavioural expression between genotypes but not life-history and I find limited behaviour-life-history relationships during development. Thirdly I ask; does the rearing environment influence life-history and behavioural plasticity? In chapter 5, I show that in comparison to a control treatment, the presence of conspecifics during ontogeny results in an average reduction in behavioural scores; however, life-history was unaffected. In addition, I show that development in a low food environment lowered average exploration and growth rate but had no effect on boldness or aggression. Furthermore, fish exposed to a predation risk simulation during ontogeny exhibited similar behavioural scores as the control, yet this treatment generated BTs i.e. personality. My fourth question asks; does the parental rearing environment (utilised in chapter 5) influence behavioural expression in the next generation? In chapter 6, I show that transgeneratonal effects of each parental rearing environment influenced life-history but had a minimal effect upon behaviour in the next generation. Finally I ask; does kin or familiarity influence plasticity in associations and aggression? In chapter 7, I show that genotypes have the ability to discriminate kin and familiars and modulate aggression and association accordingly. These results support the concept that developmental and environmental induced plasticity may be more important than life-history in shaping behaviour. Furthermore, although adults exhibit personality and genotypic effects appear important, genotype interacts with environmental/experiential influences to differentially shape behavioural plasticity during ontogeny. I suggest that theoretical predictions regarding life-history may be insufficient to explain the complexity of animal personality in this species. I discuss these results within developmental and epigenetic frameworks with reference to the ecological significance of these patterns within this species and the animal kingdom as a whole.Fisheries Society of the British Isles (FSBI

Evolution of non-kin cooperation: social assortment by cooperative phenotype in guppies

This is the final version. Available from The Royal Society via the DOI in this record.Data accessibility: The data used in this study are available at the Dryad Digital Repository: doi:10.5061/dryad.js446q8Cooperation among non-kin constitutes a conundrum for evolutionary biology. Theory suggests that non-kin cooperation can evolve if individuals differ consistently in their cooperative phenotypes and assort socially by these, such that cooperative individuals interact predominantly with one another. However, our knowledge of the role of cooperative phenotypes in the social structuring of real-world animal populations is minimal. In this study, we investigated cooperative phenotypes and their link to social structure in wild Trinidadian guppies (Poecilia reticulata). We first investigated whether wild guppies are repeatable in their individual levels of cooperativeness (i.e. have cooperative phenotypes) and found evidence for this in seven out of eight populations, a result which was mostly driven by females. We then examined the social network structure of one of these populations where the expected fitness impact of cooperative contexts is relatively high, and found assortment by cooperativeness, but not genetic relatedness. In contrast, in accordance with our expectations we did not find assortment by cooperativeness in a population where the expected fitness impact of cooperative contexts is lower. Our results provide empirical support for current theory and suggest that assortment by cooperativeness is important for the evolution and persistence of non-kin cooperation in real-world populations.Leverhulme TrustDanish Council for Independent Researc

Evolution of non-kin cooperation:social assortment by cooperative phenotype in guppies

© 2019 The Authors. Cooperation among non-kin constitutes a conundrum for evolutionary biology. Theory suggests that non-kin cooperation can evolve if individuals differ consistently in their cooperative phenotypes and assort socially by these, such that cooperative individuals interact predominantly with one another. However, our knowledge of the role of cooperative phenotypes in the social structuring of real-world animal populations is minimal. In this study, we investigated cooperative phenotypes and their link to social structure in wild Trinidadian guppies (Poecilia reticulata). We first investigated whether wild guppies are repeatable in their individual levels of cooperativeness (i.e. have cooperative phenotypes) and found evidence for this in seven out of eight populations, a result which was mostly driven by females. We then examined the social network structure of one of these populations where the expected fitness impact of cooperative contexts is relatively high, and found assortment by cooperativeness, but not by genetic relatedness. By contrast, and in accordance with our expectations, we did not find assortment by cooperativeness in a population where the expected fitness impact of cooperative contexts is lower. Our results provide empirical support for current theory and suggest that assortment by cooperativeness is important for the evolution and persistence of non-kin cooperation in real-world populations

Early environmental conditions shape personality types in a jumping spider

Individuals of many species across the animal kingdom are found to be less plastic than expected, even in behavioral traits. The existence of consistent behavioral differences between individuals, termed personality differences, is puzzling, since plastic behavior is considered ideal to enable animals to adaptively respond to changes in environmental conditions. In order to elucidate which mechanisms are important for the evolution of personality differences, it is crucial to understand which aspects of the environment are important for the development of personality differences. Here, we tested whether physical or social aspects of the environment during development influence individual differentiation (mean level of behavior) using the jumping spider Marpissa muscosa. Furthermore, we assessed whether those behaviors were repeatable, i.e. whether personalities existed. We applied a split-brood design and raised spider siblings in three different environments: a deprived environment with no enrichment, a socially and a physically enriched environment. We focused on exploratory behavior and repeatedly assessed individual behavior in a novel environment and a novel object test. Results show that the environment during development influenced spiders’ exploratory tendencies: spiders raised in enriched environments tended to be more exploratory. Most investigated behaviors were repeatable (i.e. personalities existed) across all individuals tested, whereas only few behaviors were also repeatable across individuals that had experienced the same environmental condition. Taken together, our results indicate that external stimuli can influence the development of one aspect of personality, the inter-individual variation (mean level of behavior), in a jumping spider. We also found family by environment interactions on behavioral traits potentially suggesting genetic variation in developmental plasticity

No behavioural response to kin competition in a lekking species

The processes of kin selection and competition may occur simultaneously if limited individual dispersal i.e. population viscosity, is the only cause of the interactions between kin. Therefore, the net indirect benefits of a specific behaviour may largely depend on the existence of mechanisms dampening the fitness costs of competing with kin. In lekking species, males may increase the mating success of their close relatives (and hence gain indirect fitness benefits) because female prefer large leks. At the same time, kin selection may also lead to the evolution of mechanisms that dampen the costs of kin competition. As this mechanism has largely been ignored to date, we used detailed behavioural and genetic data collected in the black grouse Lyrurus tetrix to test whether males mitigate the costs of kin competition through the modulation of their fighting behaviours according to kinship and the avoidance of close relatives when establishing a lek territory. We found that neighbouring males’ fighting behaviour was unrelated to kinship and males did not avoid settling down with close relatives on leks. As males’ current and future mating success are strongly related to their behaviour on the lek (including fighting behaviour and territory position), the costs of kin competition may be negligible relative to the direct benefits of successful male-male contests. As we previously showed that the indirect fitness benefits of group membership were very limited in this black grouse population, these behavioural data support the idea that direct fitness benefits gained by successful male-male encounters likely outbalance any indirect fitness benefits

†Kenyaichthyidae fam. nov and †Kenyaichthys gen. nov - First Record of a Fossil Aplocheiloid Killifish (Teleostei, Cyprinodontiformes)

The extant Cyprinodontiformes (killifishes) with their two suborders Cyprinodontoidei and Aplocheiloidei represent a diverse and well-studied group of fishes. However, their fossil record is comparatively sparse and has so far yielded members of the Cyprinodontoidei only. Here we report on cyprinodontiform fossils from the upper Miocene Lukeino Formation in the Tugen Hills of the Central Rift Valley of Kenya, which represent the first fossil record of an aplocheiloid killifish. A total of 169 specimens - mostly extraordinarily well preserved and a sample of ten extant cyprinodontiform species were studied on the basis of morphometrics, meristics and osteology. A phylogenetic analysis using PAUP was also conducted for the fossils. Both the osteological data and the phylogenetic analysis provide strong evidence for the assignment of the fossils to the Aplocheiloidei, and justify the definition of the new family dagger Kenyaichthyidae, the new genus dagger Kenyaichthys and the new species dagger K. kipkechi sp. nov. The phylogenetic analysis unexpectedly places dagger Kenyaichthys gen. nov. in a sister relationship to the Rivulidae (a purely Neotropical group),a probable explanation might be lack of available synapomorphies for the Rivulidae, Nothobranchiidae and Aplocheilidae. The specimens of dagger K. kipkechi sp. nov. show several polymorphic characters and large overlap in meristic traits, which justifies their interpretation as a species flock in statu nascendi. Patterns of variation in neural and haemal spine dimensions in the caudal vertebrae of dagger Kenyaichthys gen. nov. and the extant species studied indicate that some previously suggested synapomorphies of the Cyprinodontoidei and Aplocheiloidei need to be revised

Social networks in elasmobranchs and teleost fishes

Over the last decade, there has been an exponential increase in studies using social network analysis to describe the structure of animal societies. In this synthesis, we examine the contribution of social network analysis towards developing our understanding of the social organization of elasmobranchs and teleost fishes. We review and discuss the current state of knowledge of the mechanisms and functions underpinning social network structure in fishes with particular emphasis on cooperation, familiarity, site fidelity, population structure and the welfare of captive populations. We also discuss important methodological issues (e.g. how to identify and mark fish) and highlight new developments in this area of research and their implications for the study of fish behaviour. Finally, we outline promising future research areas for the application of social network analysis to teleost fishes and elasmobranchs

Behavioural phenotypes : associated life-history traits and environmental effects on development

It is widely documented that non-human organisms express individual differences in behavioural patterns. For example individuals can be categorised as bold or shy and when these individual behavioural differences are consistent through time, they are termed behavioural types (BTs). In recent years research has identified that BTs often correlate across contexts/situations and these correlations are referred to as behavioural syndromes. Behavioural types and syndromes (i.e. personality) have also been implicated as major factors shaping population dynamics and the ability to buffer environmental disturbance. Recent theoretical predictions have proposed that BT variation may be underpinned by life-history strategies; however, these predictions have been little studied to date. Moreover, little research has focused upon environmental influences and the ontogeny of personality. In this thesis I use the Mangrove killifish (Kryptolebias marmoratus), a naturally occurring clonal vertebrate, as a model organism. This species presents a powerful tool providing the ability to replicate within and between isogenic genotypes in a controlled manner. Moreover the natural clonality expressed by this species permits environmental effects upon BT plasticity and BT-life-history interactions to be investigated within a developmental framework. In chapter 2, I present microsatellite genotyping results which show that the founding individuals used to propagate a laboratory population at The University of Exeter represent 20 genetically distinct homozygous genotypes. I additionally address five research questions exploring genotypic, environmental, and developmental effects upon three commonly studied BTs (exploration, boldness and aggression): Firstly; I ask do adult hermaphrodite and secondary males exhibit personality i.e. repeatable BT expression? In chapter 3, I present results showing that both of the sexes express short term personality. Moreover, I show that that genotype is an important factor influencing BTs expressed, regardless of sex, indicating underlying genetic control. Secondly I ask; does genotype level life-history variation underpin personality trait variation during ontogeny? In chapter 4, I show considerable developmental plasticity in behavioural expression between genotypes but not life-history and I find limited behaviour-life-history relationships during development. Thirdly I ask; does the rearing environment influence life-history and behavioural plasticity? In chapter 5, I show that in comparison to a control treatment, the presence of conspecifics during ontogeny results in an average reduction in behavioural scores; however, life-history was unaffected. In addition, I show that development in a low food environment lowered average exploration and growth rate but had no effect on boldness or aggression. Furthermore, fish exposed to a predation risk simulation during ontogeny exhibited similar behavioural scores as the control, yet this treatment generated BTs i.e. personality. My fourth question asks; does the parental rearing environment (utilised in chapter 5) influence behavioural expression in the next generation? In chapter 6, I show that transgeneratonal effects of each parental rearing environment influenced life-history but had a minimal effect upon behaviour in the next generation. Finally I ask; does kin or familiarity influence plasticity in associations and aggression? In chapter 7, I show that genotypes have the ability to discriminate kin and familiars and modulate aggression and association accordingly. These results support the concept that developmental and environmental induced plasticity may be more important than life-history in shaping behaviour. Furthermore, although adults exhibit personality and genotypic effects appear important, genotype interacts with environmental/experiential influences to differentially shape behavioural plasticity during ontogeny. I suggest that theoretical predictions regarding life-history may be insufficient to explain the complexity of animal personality in this species. I discuss these results within developmental and epigenetic frameworks with reference to the ecological significance of these patterns within this species and the animal kingdom as a whole.EThOS - Electronic Theses Online ServiceFisheries Society of the British Isles (FSBI)GBUnited Kingdo