| 1. |
- Abbey-Lee, Robin, et al.
(författare)
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Experimental manipulation of monoamine levels alters personality in crickets
- 2018
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Animal personality has been described in a range of species with ecological and evolutionary consequences. Factors shaping and maintaining variation in personality are not fully understood, but monoaminergic systems are consistently linked to personality variation. We experimentally explored how personality was influenced by alterations in two key monoamine systems: dopamine and serotonin. This was done using ropinirole and fluoxetine, two common human pharmaceuticals. Using the Mediterranean field cricket (Gryllus bimaculatus), we focused on the personality traits activity, exploration, and aggression, with confirmed repeatability in our study. Dopamine manipulations explained little variation in the personality traits investigated, while serotonin manipulation reduced both activity and aggression. Due to limited previous research, we created a dose-response curve for ropinirole, ranging from concentrations measured in surface waters to human therapeutic doses. No ropinirole dose level strongly influenced cricket personality, suggesting our results did not come from a dose mismatch. Our results indicate that the serotonergic system explains more variation in personality than manipulations of the dopaminergic system. Additionally, they suggest that monoamine systems differ across taxa, and confirm the importance of the mode of action of pharmaceuticals in determining their effects on behaviour.
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| 2. |
- Abbey-Lee, Robin N., et al.
(författare)
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The Influence of Rearing on Behavior, Brain Monoamines, and Gene Expression in Three-Spined Sticklebacks
- 2018
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Ingår i: Brain, behavior, and evolution. - Basel : S. Karger AG. - 0006-8977 .- 1421-9743. ; 91:4, s. 201-213
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Tidskriftsartikel (refereegranskat)abstract
- The causes of individual variation in behavior are often not well understood, and potential underlying mechanisms include both intrinsic and extrinsic factors, such as early environmental, physiological, and genetic differences. In an exploratory laboratory study, we raised three-spined sticklebacks (Gasterosteus aculeatus) under 4 different environmental conditions (simulated predator environment, complex environment, variable social environment, and control). We investigated how these manipulations related to behavior, brain physiology, and gene expression later in life, with focus on brain dopamine and serotonin levels, turnover rates, and gene expression. The different rearing environments influenced behavior and gene expression, but did not alter monoamine levels or metabolites. Specifically, compared to control fish, fish exposed to a simulated predator environment tended to be less aggressive, more exploratory, and more neophobic; and fish raised in both complex and variable social environments tended to be less neophobic. Exposure to a simulated predator environment tended to lower expression of dopamine receptor DRD4A, a complex environment increased expression of dopamine receptor DRD1B, while a variable social environment tended to increase serotonin receptor 5-HTR2B and serotonin transporter SLC6A4A expression. Despite both behavior and gene expression varying with early environment, there was no evidence that gene expression mediated the relationship between early environment and behavior. Our results confirm that environmental conditions early in life can affect phenotypic variation. However, the mechanistic pathway of the monoaminergic systems translating early environmental variation into observed behavioral responses was not detected.
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| 3. |
- Friesen, Christopher R., et al.
(författare)
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Correlated evolution of sexually selected traits: interspecific variation in ejaculates, sperm morphology, copulatory mate guarding, and body size in two sympatric species of garter snakes
- 2017
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Ingår i: Behavioral Ecology and Sociobiology. - : SPRINGER. - 0340-5443 .- 1432-0762. ; 71:12
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Tidskriftsartikel (refereegranskat)abstract
- Male reproductive success is dependent on a correlated suite of traits related to a species ecology and mating system dynamics. Closely related species differing in their mating systems and ecology, such as the garter snakes (Thamnophis), are ideal for studying the correlated evolution of sexually selected traits. Here, we compare the degree of sexual size dimorphism (SSD), copulatory behavior, copulatory plug size, and traits associated with sperm competition between two sympatric and closely related Thamnophis species, T. sirtalis and T. radix with divergent mating aggregation size and density. Our findings indicate that T. sirtalis has greater female-biased SSD, shorter copulations, and larger, more strongly adhering copulatory plugs than T. radix. Our finding that T. sirtalis have longer sperm and higher numbers of sperm per ejaculate is further evidence of more intense sperm competition in this species than in T. radix. However, this reduced number of sperm in the ejaculate means that T. radix males are likely capable of more matings per season than T. sirtalis. This result may reflect differences in feeding during the breeding season (obligate aphagy in T. sirtalis) and the potential for sperm loss in T. radix during prolonged copulations that are prevented in T. sirtlais by their substantial copulatory plugs. Our findings demonstrate that ecological and mating system dynamics have the capacity to strongly influence correlated selection of pre- and postcopulatory traits.
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| 4. |
- Rollings, N., et al.
(författare)
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Age-related sex differences in body condition and telomere dynamics of red-sided garter snakes
- 2017
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Ingår i: Proceedings of the Royal Society B-Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 284:1852
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Tidskriftsartikel (refereegranskat)abstract
- Life-history strategies vary dramatically between the sexes, which may drive divergence in sex-specific senescence and mortality rates. Telomeres are tandem nucleotide repeats that protect the ends of chromosomes from erosion during cell division. Telomeres have been implicated in senescence and mortality because they tend to shorten with stress, growth and age. We investigated age-specific telomere length in female and male red-sided garter snakes, Thamnophis sirtalis parietalis. We hypothesized that age-specific telomere length would differ between males and females given their divergent reproductive strategies. Male garter snakes emerge from hibernation with high levels of corticosterone, which facilitates energy mobilization to fuel mate-searching, courtship and mating behaviours during a two to four week aphagous breeding period at the den site. Conversely, females remain at the dens for only about 4 days and seem to invest more energy in growth and cellular maintenance, as they usually reproduce biennially. As male investment in reproduction involves a yearly bout of physiologically stressful activities, while females prioritize self-maintenance, we predicted male snakes would experience more age-specific telomere loss than females. We investigated this prediction using skeletochronology to determine the ages of individuals and qPCR to determine telomere length in a cross-sectional study. For both sexes, telomere length was positively related to body condition. Telomere length decreased with age in male garter snakes, but remained stable in female snakes. There was no correlation between telomere length and growth in either sex, suggesting that our results are a consequence of divergent selection on life histories of males and females. Different selection on the sexes may be the physiological consequence of the sexual dimorphism and mating system dynamics displayed by this species.
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