Indar Ramnarine

Indar Ramnarine
University of the West Indies, St. Augustine | UWI · Department of Life Sciences

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140
Publications
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Introduction
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Publications

Publications (140)
Article
Full-text available
Animals can reduce their uncertainty of predation risk by gathering new information via exploration behaviour. However, a decision to explore may also be costly due to increased predator exposure. Here, we found contextual effects of predation risk on the exploratory activity of Trinidadian guppies Poecilia reticulata in a novel environment. First,...
Preprint
Resource availability and sociality are tightly coupled. Sociality facilitates resource access in a wide range of animal species. Simultaneously, resource availability may change sociality. However, experimental evidence for resource-driven social changes in the wild, beyond local aggregations at the resource, remains scarce. Moreover, it is largel...
Article
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) experiencin...
Article
When faced with uncertainty, animals can benefit from using multiple sources of information in order to make an optimal decision. However, information sources (e.g., social and personal cues) may conflict, while also varying in acquisition cost and reliability. Here, we assessed behavioral decisions of Trinidadian guppies (Poecilia reticulata), in...
Article
Full-text available
Understanding how the biodiversity of freshwater fish assemblages changes over time is an important challenge. Until recently most emphasis has been on taxonomic diversity but it is now clear that measures of functional diversity can shed new light on the mechanisms that underpin this temporal change. Fish biologists use different currencies, such...
Article
Full-text available
Parallel evolution, in which independent populations evolve along similar phenotypic trajectories, offers insights into the repeatability of adaptive evolution. Here, we revisit a classic example of parallelism, that of repeated evolution of brighter males in the Trinidadian guppy (Poecilia reticulata). In guppies, colonisation of low predation hab...
Preprint
Full-text available
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) experiencin...
Article
Making fast and accurate group decisions under uncertain and risky conditions is a fundamental problem for groups. Currently, there is little empirical evidence of how natural selection (such as environmental predation risk) has shaped the mechanisms of group decision making. We repeatedly tested individually marked guppies, Poecilia reticulata, fr...
Article
Full-text available
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 (Po...
Article
Full-text available
Consistent interindividual 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. Giv...
Preprint
Parallel evolution, in which independent populations evolve along similar phenotypic trajectories, offers insights into the repeatability of adaptive evolution. Here, we revisit a classic example of parallelism, that of repeated evolution of brighter males in the Trinidadian guppy. In guppies, colonisation of low predation habitats is associated wi...
Article
Full-text available
While larger groups tend to be better at making decisions, very few studies have explored how ecological variables, including predation pressure, shape how group size affects decision making. Our cross-population study of wild-caught guppies ( Poecilia reticulata ) shows that leading individuals from larger groups made faster decisions when decidin...
Preprint
Full-text available
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 (Po...
Article
Full-text available
The intensity of mate competition is often influenced by predation pressure. The threat-sensitive predator avoidance hypothesis predicts that prey should precisely adjust their fitness-related activities to the level of perceived acute predation risk and this effect should be stronger under high background risk. Individuals should compensate during...
Article
Full-text available
Predation fear is a unifying theme across vertebrate taxa. Here, we explored how the frequency and duration of predation risk affects post-risk fear behavior in Trinidadian guppies. We first exposed individuals to visual cues of potential predators for 3 days, either frequently (6×/day) or infrequently (1×/day). Each exposure lasted for either a re...
Article
Full-text available
Variation in predation risk can drive variation in fear intensity, the length of fear retention, and whether fear returns after waning. Using Trinidadian guppies, we assessed whether a low-level predation threat could easily re-trigger fear after waning. First, we show that background risk induced neophobia after either multiple exposures to a low-...
Article
Full-text available
There is a global lack of data concerning shark consumption trends, consumer attitudes, and public knowledge regarding sharks. This is the case in Trinidad and Tobago, where shark is a popular culinary delicacy. A Knowledge, Attitudes, and Practices (KAP) survey was conducted in Trinidad and Tobago. Six hundred and seven questionnaires were adminis...
Article
Understanding the adaptive function of conspicuous coloration has been a major focus of evolutionary biology for much of the last century. Although considerable progress has been made in explaining how conspicuous coloration can be used in functions as diverse as sexual and social signaling, startling predators, and advertising toxicity [1], there...
Article
Full-text available
Under predation threat, many species produce cues that can serve as crucial sources of information for social companions. For instance, chemical cues released when experiencing a disturbing event (i.e. ‘disturbance cues’), such as a predator chase, can lead to antipredator avoidance and increased survival for nearby individuals. These chemicals als...
Article
Full-text available
Collective decision-making is predicted to be more egalitarian in conditions where the costs of group fission are higher. Here, we ask whether Trinidadian guppies (Poecilia reticulata) living in high or low predation environments, and thereby facing differential group fission costs, make collective decisions in line with this prediction. Using a cl...
Article
Full-text available
Predation is a pervasive selection pressure, shaping morphological, physiological and behavioural phenotypes of prey species. Recent studies have begun to examine how the effects of individual experience with predation risk shapes the use of publicly-available risk assessment cues. Here, we investigated the effects of prior predation risk experienc...
Article
Full-text available
Responding to the information provided by others is an important foraging strategy in many species. Through social foraging, individuals can more efficiently find unpredictable resources and thereby increase their foraging success. When individuals are more socially responsive to particular phenotypes than others, however, the advantage they obtain...
Article
Full-text available
Neophobic predator avoidance (NPA), the fear response exhibited by prey animals exposed to novel stimuli, is a plastic trait thought to be induced by exposure to elevated chronic risk of predation. Indeed, prey experiencing low levels of background risk fail to display NPA, while those experiencing high background risk do display NPA. Recent work h...
Article
Full-text available
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...
Preprint
Full-text available
BioRxiv link to article: https://doi.org/10.1101/478537 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 co...
Article
Full-text available
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 subpopulat...
Article
Full-text available
Animal eyes are some of the most widely recognisable structures in nature. Due to their salience to predators and prey, most research has focused on how animals hide or camouflage their eyes [1]. However, across all vertebrate Classes, many species actually express brightly coloured or conspicuous eyes, suggesting they may have also evolved a signa...
Article
Full-text available
Neophobic predator avoidance allows prey to reduce the risk of predation but is costly in terms of reduced foraging or courtship opportunities if the novel cues do not represent an actual threat. Consequently, neophobic responses to novel cues should wane with repeated exposures in the absence of an actual threat. We tested the prediction that indi...
Article
Social behaviour potentially plays an important role in invasion success. New colonists, for example, may glean useful information about predators and food by interacting with native heterospecifics. The extent to which invaders benefit from such social interactions could hinge on their prior exposure to other species. Here we asked how the shoalin...
Article
The Earth's ecosystems are under unprecedented pressure, yet the nature of contemporary biodiversity change is not well understood. Growing evidence that community size is regulated highlights the need for improved understanding of community dynamics. As stability in community size could be underpinned by marked temporal turnover, a key question is...
Preprint
Full-text available
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 subpop...
Article
Full-text available
Variation in predation risk is a major driver of ecological and evolutionary change, and, in turn, of geographical variation in behaviour. While predation risk is rarely constant in natural populations, the extent to which variation in predation risk shapes individual behaviour in wild populations remains unclear. Here, we investigated individual d...
Article
Identifying mechanisms of reproductive isolation is key to understanding speciation. Among the putative mechanisms underlying reproductive isolation, sperm-female interactions (postmating-prezygotic barriers) are arguably the hardest to identify, not least because these are likely to operate at the cellular or molecular level. Yet sperm-female inte...
Article
Full-text available
Predation is thought to shape the macroscopic properties of animal groups, making moving groups more cohesive and coordinated. Precisely how predation has shaped individuals' fine-scale social interactions in natural populations, however, is unknown. Using high-resolution tracking data of shoaling fish (Poecilia reticulata) from populations differi...
Article
Heterozygosity-fitness correlations (HFCs) have been examined in a wide diversity of contexts, and the results are often used to infer the role of inbreeding in natural populations. Although population demography, reflected in population-level genetic parameters such as allelic diversity or identity disequilibrium, is expected to play a role in the...
Article
Full-text available
Unprecedented threats to natural ecosystems mean that accurate quantification of biodiversity is a priority, particularly in the tropics which are underrepresented in monitoring schemes. Data from a freshwater fish assemblage in Trinidad were used to evaluate the effectiveness of hand-seining as a survey method in tropical streams. We uncovered lar...
Article
Full-text available
Collective decisions play a major role in the benefits that animals gain from living in groups. Although the mechanisms of how groups collectively make decisions have been extensively researched, the response of within-group dynamics to ecological conditions is virtually unknown, despite adaptation to the environment being a cornerstone in biology....
Article
The social network approach has focused increasing attention on the complex web of relationships found in animal groups and populations. As such, network analysis has been used frequently to identify the role that particular individuals play in their social interactions and this approach has led to the question of whether, and in what context, indi...
Article
Models of cooperation among nonkin suggest that social assortment is important for the evolution of cooperation. Theory predicts that interacting phenotypes, whereby an individual’s behavior depends on the behavior of its social partners, can drive such social assortment. We measured repeated indirect genetic effects (IGEs) during cooperative preda...
Article
Full-text available
Both selection and phylogenetic history can influence the evolution of phenotypic traits. Here we used recently characterized variation in kin recognition mechanisms among six guppy populations to explore the phylogenetic history of this trait. Guppies can use two different kin recognition mechanisms: either phenotype matching, in which individuals...
Article
Full-text available
Social relationships can have important consequences for fitness in animals. Whilst numerous studies have shown that individuals often join larger groups in response to perceived predation risk (i.e. fear of predation), the importance of predation risk in driving the formation and stability of social relationships within groups has been relatively...
Article
Full-text available
In populations with male mate-choice copying, males may mitigate their risk of sexual competition by reducing their preference for a particular female in the presence of sexual rivals (audience). Because of the cost of missed mating opportunities from such an audience effect, males should reduce their mating preference to a greater extent in the pr...
Article
Full-text available
Threat-sensitive behavioural trade-offs allow prey animals to balance the conflicting demands of successful predator detection and avoidance and a suite of fitness related activities such as foraging, mating and territorial defence. Here, we test the hypothesis that background predation level and reproductive status interact to determine the form a...
Article
Full-text available
Understanding how animals recognize their kin has been a major challenge in biology. Most animals use one of 2 mechanisms: “familiarity” whereby kin are remembered from interactions early in life, such as in a nest, or “phenotype matching” whereby putative kin are compared with a template of what kin should look, smell, or sound like. Cross-species...
Data
Figure S2. Regression tree for reciprocal Simpson's index (cond=conductivity; lboulder=large boulders).
Data
Figure S3. Regression tree for exponential Shannon index. (lboulder=large boulders).
Data
Figure S4. Regression tree for Berger‐Parker index.
Data
Figure S1. Regression tree for community allocation (proportion of total biomass represented by guppies).
Article
Full-text available
Disturbance can impact natural communities in multiple ways. However, there has been a tendency to focus on single indicators of change when examining the effects of disturbance. This is problematic as classical diversity measures, such as Shannon and Simpson indices, do not always detect the effects of disturbance. Here, we instead take a multilev...
Article
Full-text available
Social network analysis (SNA) has become a widespread tool for the study of animal social organization. However despite this broad applicability, SNA is currently limited by both an overly strong focus on pattern analysis as well as a lack of dynamic interaction models. Here we use a dynamic modeling approach that can capture the responses of socia...
Article
Contemporary anthropogenic impacts, such as climate warming, habitat fragmentation, and pollution can pose severe challenges for natural populations (Vitousek et al. 1997; Palumbi 2001; Stockwell et al. 2003). One challenge is that environmental change renders populations poorly adapted for the new environment, which can cause population declines a...
Article
Full-text available
Recent studies have shown that prey living under conditions of elevated predation risk respond very differently to novel predators than prey living under low-risk conditions, by displaying generalized avoidance patterns to novel stimuli. This phenotypic plasticity in neophobic responses provides prey with the means to respond flexibly to uncertain...
Article
Full-text available
Turbidity, caused by suspended particles in the water column, induces light scattering and shifts in the wavelengths of light. These changes may impair the ability of fish to use physical cues and hence may modify social interactions. We experimentally investigated the social interactions of guppies, Poecilia reticulata, in clear and turbid water....