/pdf/tadpoles-the-biology-of-anuran-larvae-1srxbfb0hr.pdf

Tadpoles: the biology of anuran larvae

Empirical studies of sexual traits continue to generate conflicting results, leading to a growing awareness that the current understanding of this topic is limited Here we argue that this is because studies of sexual traits fail to encompass three important features of evolution First, sexual traits evolve via natural selection of which sexual selection is just one part Second, selection on sexual traits fluctuates in strength, direction and form due to spatial and temporal environmental heterogeneity Third, phenotypic plasticity is ubiquitous and generates selection and responses to selection within and across generations A move from purely gene-focused theories of sexual selection towards research that explicitly integrates development, ecology and evolution is necessary to break the stasis in research on sexual traits

https://www.cell.com/trends/ecology-evolution/pdf/S0169-5347(09)00298-5.pdf

Towards an evolutionary ecology of sexual traits

Author(s): Maia, Rafael; Gruson, Hugo; Endler, John; White, Thomas | Abstract: Abstract Biological colouration presents a canvas for the study of ecological and evolutionary processes. Enduring interest in colour-based phenotypes has driven, and been driven by, improved techniques for quantifying colour patterns in ever-more relevant ways, yet the need for flexible, open frameworks for data processing and analysis persists. Here we introduce pavo 2 , the latest iteration of the R package pavo . This release represents the extensive refinement and expansion of existing methods, as well as a suite of new tools for the cohesive analysis of the spectral and (now) spatial structure of colour patterns and perception. At its core, the package retains a broad focus on (a) the organisation and processing of spectral and spatial data, and tools for the alternating (b) visualisation, and (c) analysis of data. Significantly, pavo 2 introduces image-analysis capabilities, providing a cohesive workflow for the comprehensive analysis of colour patterns. We demonstrate the utility of pavo with a brief example centred on mimicry in Heliconius butterflies. Drawing on visual modelling, adjacency, and boundary strength analyses, we show that the combined spectral (colour and luminance) and spatial (pattern element distribution and boundary salience) features of putative models and mimics are closely aligned. pavo 2 offers a flexible and reproducible environment for the analysis of colour, with renewed potential to assist researchers in answering fundamental questions in sensory ecology and evolution.

pavo 2: New tools for the spectral and spatial analysis of colour in r

The world in color presents a dazzling dimension of phenotypic variation. Biological interest in this variation has burgeoned, due to both increased means for quantifying spectral information and heightened appreciation for how animals view the world differently than humans. Effective study of color traits is challenged by how to best quantify visual perception in nonhuman species. This requires consideration of at least visual physiology but ultimately also the neural processes underlying perception. Our knowledge of color perception is founded largely on the principles gained from human psychophysics that have proven generalizable based on comparative studies in select animal models. Appreciation of these principles, their empirical foundation, and the reasonable limits to their applicability is crucial to reaching informed conclusions in color research. In this article, we seek a common intellectual basis for the study of color in nature. We first discuss the key perceptual principles, namely, retinal photoreception, sensory channels, opponent processing, color constancy, and receptor noise. We then draw on this basis to inform an analytical framework driven by the research question in relation to identifiable viewers and visual tasks of interest. Consideration of the limits to perceptual inference guides two primary decisions: first, whether a sensory-based approach is necessary and justified and, second, whether the visual task refers to perceptual distance or discriminability. We outline informed approaches in each situation and discuss key challenges for future progress, focusing particularly on how animals perceive color. Given that animal behavior serves as both the basic unit of psychophysics and the ultimate driver of color ecology/evolution, behavioral data are critical to reconciling knowledge across the schools of color research.

/pdf/an-integrative-framework-for-the-appraisal-of-coloration-in-3so15205iv.pdf

An Integrative Framework for the Appraisal of Coloration in Nature

Interactions between individual consumer and resource organisms can be modified by neighbors, e.g., when herbivory depends on the identity or diversity of neighboring plants. Effects of neighbors on consumer-resource interactions (“associational effects”) occur in many systems, including plant-herbivore interactions, predator-prey interactions (mimicry), and plant-pollinator interactions. Unfortunately, we know little about how ecologically or evolutionarily important these effects are because we lack appropriate models and data to determine how neighbor effects on individuals contribute to net interactions at population and community levels. Here we supply a general definition of associational effects, review relevant theory, and suggest strategies for future theoretical and empirical work. We find that mathematical models from a variety of fields suggest that individual-level associational effects will influence population and community dynamics when associational effects create local frequency ...

/pdf/a-conceptual-framework-for-associational-effects-when-do-yn4i9ifx33.pdf

A conceptual framework for associational effects : when do neighbors matter and how would we know?

The role of colours and colour patterns in behavioural ecology has been extensively studied in a variety of contexts and taxa, while almost overlooked in many others. For decades anurans have been the focus of research on acoustic signalling due to the prominence of vocalisations in their communication. Much less attention has been paid to the enormous diversity of colours, colour patterns, and other types of putative visual signals exhibited by frogs. With the exception of some anecdotal observations and studies, the link between colour patterns and the behavioural and evolutionary ecology of anurans had not been addressed until approximately two decades ago. Since then, there has been ever-increasing interest in studying how colouration is tied to different aspects of frog behaviour, ecology and evolution. Here I review the literature on three different contexts in which frog colouration has been recently studied: predator-prey interactions, intraspecific communication, and habitat use; and I highlight those aspects that make frogs an excellent, yet understudied, group to examine the role of colour in the evolution of anti-predation strategies and animal communication systems. Further, I argue that in addition to natural-history observations, more experiments are needed in order to elucidate the functions of anuran colouration and the selective pressures involved in its diversity. To conclude, I encourage researchers to strengthen current experimental approaches, and suggest future directions that may broaden our current understanding of the adaptive value of anuran colour pattern diversity.

/pdf/behavioural-ecological-and-evolutionary-aspects-of-diversity-4c0khmdavn.pdf

Behavioural, ecological, and evolutionary aspects of diversity in frog colour patterns

Differential detectability of polymorphic warning signals under varying light environments

Despite the predicted purifying role of stabilising selection against variation in warning signals, many aposematic species exhibit high variation in their colour patterns. The maintenance of such variation is not well understood, but it has been suggested to be the result of an interaction between sexual and natural selection. This interaction could also facilitate the evolution of sexual dichromatism. Here we analyse in detail the colour patterns of the poison frog Dendrobates tinctorius and evaluate the possible correlates of the variability in aposematic signals in a natural population. Against the theoretical predictions of aposematism, we found that there is enormous intra-populational variation in colour patterns and that these also differ between the sexes: males have a yellower dorsum and bluer limbs than females. We discuss the possible roles of natural and sexual selection in the maintenance of this sexual dimorphism in coloration and argue that parental care could work synergistically with aposematism to select for yellower males.

Sexual dimorphism and intra-populational colour pattern variation in the aposematic frog Dendrobates tinctorius

Animals have evolved different defensive strategies to survive predation, among which chemical defences are particularly widespread and diverse. Here we investigate the function of chemical defence...

https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2017.1424

How to fight multiple enemies: target-specific chemical defences in an aposematic moth.

Aposematic signal variation is a paradox: predators are better at learning and retaining the association between conspicuousness and unprofitability when signal variation is low. Movement patterns and variable colour patterns are linked in non-aposematic species: striped patterns generate illusions of altered speed and direction when moving linearly, affecting predators' tracking ability; blotched patterns benefit instead from unpredictable pauses and random movement. We tested whether the extensive colour-pattern variation in an aposematic frog is linked to movement, and found that individuals moving directionally and faster have more elongated patterns than individuals moving randomly and slowly. This may help explain the paradox of polymorphic aposematism: variable warning signals may reduce protection, but predator defence might still be effective if specific behaviours are tuned to specific signals. The interacting effects of behavioural and morphological traits may be a key to the evolution of warning signals.

https://royalsocietypublishing.org/doi/pdf/10.1098/rsbl.2014.0193

Bibiana Rojas

Papers

Behavioural, ecological, and evolutionary aspects of diversity in frog colour patterns

Differential detectability of polymorphic warning signals under varying light environments

Sexual dimorphism and intra-populational colour pattern variation in the aposematic frog Dendrobates tinctorius

How to fight multiple enemies: target-specific chemical defences in an aposematic moth.

Paradox lost: variable colour-pattern geometry is associated with differences in movement in aposematic frogs