Biology subjects

Ramnarine, I. W.

Publications and source records attributed to Ramnarine, I. W..

6 recordsLinked to original sources

bioRxiv2022

Ephemeral Resource Availability Makes Wild Guppies More Social

Sociality can facilitate the discovery of novel resources, yet it can also entail costs, including increased competition, aggression, sexual harassment and disease transmission. Selection should therefore favour social flexibility as a response to changes in resource conditions, allowing individuals to adjust their social associations optimally. Quantifying these social adjustments and how they allow individuals to benefit in dynamically changing resource environments can provide insight into the adaptive capacity of wild animal populations. We experimentally studied social flexibility in wild guppies (Poecilia reticulata) by examining their fission-fusion dynamics. Using mixed-sex sets of individually marked fish, we manipulated recent foraging experience by presenting them with unpredictable, ephemeral food patches or control patches in the wild. Guppies exposed to ephemeral food patches significantly increased their sociality, doubling the proportion of time spent social compared to controls. This shift was driven by an increase in the probability of starting social contact and a decrease in the probability of ending social contact. Stronger increases in sociality were associated with individuals more often locating ephemeral food patches, mediated by foraging motivation. Importantly, increased sociality was not merely the result of local aggregation, as exposure to ephemeral food patches increased, rather than reduced, spatial activity. And stronger spatial activity did not result in more time spent social. In a second experiment, fish were briefly presented with food patches they could see and smell but not actually consume. Again, fish increased their level of sociality compared to control, indicating that the observed social response was not merely driven by satiation-related changes in activity budgets. Together, our results highlight the adaptive and dynamic nature of fission-fusion social systems and support the view that wild animals adaptively shape their social environment in response to fluctuations in resource variability.

animal behavior and cognition↗

bioRxiv2021

Social partner cooperativeness influences brain oxytocin transcription in Trinidadian guppies (Poecilia reticulata)

For non-kin cooperation to be maintained, individuals need to respond adaptively to the cooperative behaviour of their social partners. Currently, however, little is known about the biological responses of individuals to experiencing cooperation. Here, we quantify the neuroregulatory response of Trinidadian guppies (Poecilia reticulata) experiencing cooperation or defection by examining the transcriptional response of the oxytocin gene (oxt; also known as isotocin), which has been implicated in cooperative decision-making. We exposed wild-caught females to social environments where partners either cooperated or defected during predator inspection, or to a control (non-predator inspection) context, and quantified the relative transcription of the oxt gene. We tested an experimental group, originating from a site where individuals are under high predation threat and have previous experience of large aquatic predators (HP), and a control group, where individuals are under low predation threat and naive to large aquatic predators (LP). In HP, but not LP, fish brain mid-section oxt relative transcription varied depending on social partner behaviour. HP fish experiencing cooperation during predator inspection had lower oxt transcription than those experiencing defection. This effect was not present in the control population or in the control context, where the behaviour of social partners did not affect oxt transcription. Our findings provide insight into the neuromodulation underpinning behavioural responses to social experiences, and ultimately to the proximate mechanisms underlying social decision-making.

animal behavior and cognition↗

bioRxiv2020

Causal evidence for the adaptive benefits of social foraging in the wild

Sociality is a fundamental organizing principle across taxa, thought to come with a suite of adaptive benefits. However, making causal inferences about these adaptive benefits requires experimental manipulation of the social environment, which is rarely feasible in the field. Here we manipulated the number of conspecifics in Trinidadian guppies (Poecilia reticulata) in the wild, and quantified how this affected a key benefit of sociality, social foraging, by investigating several components of foraging success. As adaptive benefits of social foraging may differ between sexes, we studied males and females separately, expecting females, the more social and risk-averse sex, to benefit more from conspecifics than males. Conducting over 1,600 foraging trials, we found that in both sexes, increasing the number of conspecifics led to faster detection of novel food patches and a higher probability of feeding following detection of the patch, resulting in greater individual resource consumption. The slope of the latter relationship differed between the sexes, with males unexpectedly exhibiting a stronger social benefit. Our study provides rare causal evidence for the adaptive benefits of social foraging in the wild, and highlights that sex differences in sociality do not necessarily imply an unequal ability to profit from the presence of others.

animal behavior and cognition↗

bioRxiv2020

Predatory behaviour as a personality trait in a wild fish population

Consistent inter-individual differences in behaviour (i.e. animal personality variation) can influence a range of ecological and evolutionary processes, including predation. Variation between individual predators in commonly measured personality traits, such as boldness and activity, has previously been linked to encounter rates with their prey. Given the strong selection on predators to respond to prey, individual predators may also vary consistently in their response to prey in a manner that is specific to the context of predation. By studying wild piscivorous fish (pike cichlids, Crenicichla frenata) in their natural environment using experimental presentations of prey and control stimuli, we show that individual predators differ consistently in the amount of time spent near prey. Crucially, these differences were not explained by the behaviour of the same individuals in control presentations (the same apparatus lacking prey), suggesting that variation in the response to prey reflects a ‘predator personality trait’ which is independent from other individual traits (body size, boldness and/or neophobia) and environmental factors. Pike cichlids which spent more time near prey also attacked prey at a higher rate. These findings imply that the risk posed by individual predators cannot always be adequately predicted from typically studied axes of personality variation.Competing Interest StatementThe authors have declared no competing interest.View Full Text

animal behavior and cognition↗

bioRxiv2018

Females facilitate male patch discovery in a wild fish population

When individuals are more socially responsive to one sex than the other, the benefits they get from foraging socially are likely to depend on the sex composition of the social environment. We tested this hypothesis by performing experimental manipulations of guppy, Poecilia reticulata, sex compositions in the wild. Males found fewer novel food patches in the absence of females than in mixed-sex compositions, while female patch discovery did not differ between compositions. We argue that these results were driven by sex-dependent mechanisms of social association: Markov chain-based fission-fusion modeling revealed that males reduced sociality when females were absent, while less social individuals found fewer patches. Females were similarly social with or without males. Finally, males, but not females, preferred to join females over males at patches. Our findings reveal the relevance of considering how individual and population-level traits interact in shaping the adaptive value of social living in the wild.

animal behavior and cognition↗

bioRxiv2018

Individual- and population-level drivers of consistent foraging success across environments

Individual foraging is under strong natural selection. Yet, whether individuals differ consistently in their foraging success across environments, and which individual and population-level traits might drive such differences, is largely unknown. We addressed this question in a field experiment, conducting over 1,100 foraging trials with nine subpopulations of guppies, Poecilia reticulata, translocating them across environments in the wild. A-priori, we determined the individual social phenotypes. We show that individuals consistently differed in reaching food, but not control, patches across environments. Social individuals reached more food patches than less social ones and males reached more food patches than females. Overall, individuals were, however, more likely to join females at patches than males, which explains why individuals in subpopulations with relatively more females reached, on average, more food patches. Our results provide rare evidence for individual differences in foraging success across environments, driven by individual and population level (sex ratio) traits.

animal behavior and cognition↗