Beginning with Emlen (1966) and MacArthur and Pianka (1966) and extending through the last ten years, several authors have sought to predict the foraging behavior of animals by means of mathematical models. These models are very similar,in that they all assume that the fitness of a foraging animal is a function of the efficiency of foraging measured in terms of some "currency" (Schoener, 1971) -usually energy- and that natural selection has resulted in animals that forage so as to maximize this fitness. As a result of these similarities, the models have become known as "optimal foraging models"; and the theory that embodies them, "optimal foraging theory." The situations to which optimal foraging theory has been applied, with the exception of a few recent studies, can be divided into the following four categories: (1) choice by an animal of which food types to eat (i.e., optimal diet); (2) choice of which patch type to feed in (i.e., optimal patch choice); (3) optimal allocation of time to different patches; and (4) optimal patterns and speed of movements. In this review we discuss each of these categories separately, dealing with both the theoretical developments and the data that permit tests of the predictions. The review is selective in the sense that we emphasize studies that either develop testable predictions or that attempt to test predictions in a precise quantitative manner. We also discuss what we see to be some of the future developments in the area of optimal foraging theory and how this theory can be related to other areas of biology. Our general conclusion is that the simple models so far formulated are supported are supported reasonably well by available data and that we are optimistic about the value both now and in the future of optimal foraging theory. We argue, however, that these simple models will requre much modification, espicially to deal with situations that either cannot easily be put into one or another of the above four categories or entail currencies more complicated that just energy.

Citation classic - optimal foraging - a selective review of theory and tests

Coloration mediates the relationship between an organism and its environment in important ways, including social signaling, antipredator defenses, parasitic exploitation, thermoregulation, and protection from ultraviolet light, microbes, and abrasion. Methodological breakthroughs are accelerating knowledge of the processes underlying both the production of animal coloration and its perception, experiments are advancing understanding of mechanism and function, and measurements of color collected noninvasively and at a global scale are opening windows to evolutionary dynamics more generally. Here we provide a roadmap of these advances and identify hitherto unrecognized challenges for this multi- and interdisciplinary field.

https://eprints.ncl.ac.uk/file_store/production/250158/C9F83EB1-F60A-4757-B527-1A7E855E8109.pdf

The biology of color

Across a range of disciplines, researchers are becoming increasingly interested in studying the variation in cognitive abilities found within populations. Behavioral ecology is no exception: the pursuit to understand the evolution of cognition has lead to a rapidly expanding literature that uses various tasks to measure individuals’ cognitive abilities. While this is an exciting time, we are concerned that without being clearer as to the cognitive abilities under test it will be difficult to design appropriate experiments and the interpretation of the data may be unsound. The aim of this review is 3-fold: 1) to highlight problems with designing tasks for measuring individual variation in cognitive abilities and interpreting their outcomes; 2) to increase awareness that noncognitive factors can cause variation in performance among individuals; and 3) to question the theoretical basis for thinking that performance in any cognitive task should necessarily correlate with a measure of fitness. Our take-home message is that variability in performance in cognitive tasks does not necessarily demonstrate individual variation in cognitive ability, and that we need to both design more stringent cognitive tests and be more cautious in their interpretation.

/pdf/measuring-variation-in-cognition-335gru3v9m.pdf

Measuring variation in cognition

Though it has long been known that animal communication is complex, recent years have seen growing interest in understanding the extent to which animals give multicomponent signals in multiple modalities, and how the different types of information extracted by receivers are interpreted and integrated in animal decision-making. This interest has culminated in the production of the present special issue on multimodal communication, which features both theoretical and empirical studies from leading researchers in the field. Reviews, comparative analyses, and species-specific empirical studies include manuscripts on taxa as diverse as spiders, primates, birds, lizards, frogs, and humans. The present manuscript serves as both an introduction to this special issue, as well as an introduction to multimodal communication more generally. We discuss the history of the study of complexity in animal communication, issues relating to defining and classifying multimodal signals, and particular issues to consider with multimodal (as opposed to multicomponent unimodal) communication. We go on to discuss the current state of the field, and outline the contributions contained within the issue. We finish by discussing future avenues for research, in particular emphasizing that ‘multimodal’ is more than just ‘bimodal’, and that more integrative frameworks are needed that incorporate more elements of efficacy, such as receiver sensory ecology and the environment.

An introduction to multimodal communication

Glucocorticoids exert a wide variety of physiological and pathological responses, most of which are mediated by the ubiquitously expressed glucocorticoid receptor (GR). The glucocorticoid response varies among individuals, as well as within tissues from the same individual, and this phenomenon can be partially explained through understanding the process of generating bioavailable ligand and the molecular heterogeneity of GR. This review focuses on the recent advances in our understanding of prereceptor ligand metabolism, GR subtypes and GR polymorphisms. Furthermore, we evaluate the impact of tissue- and individual-specific diversity in the glucocorticoid pathway on human health and disease.

/pdf/tissue-specific-glucocorticoid-action-a-family-affair-1gpk7vwa82.pdf

Tissue-specific glucocorticoid action: a family affair

Avian Cognition and the Evolution of Warning Signals

/pdf/what-do-predators-do-a-response-to-comments-on-skelhorn-et-3dhsoojo5l.pdf

What do predators do? A response to comments on Skelhorn et al.


 Animal warning signals show remarkable diversity, yet subjectively appear to share visual features that make defended prey stand out and look different from more cryptic palatable species. Here we develop and apply a computational model that emulates avian visual processing of pattern and colour to Lepidopteran wing patterns to show that warning signals have specific neural signatures that set them apart not only from the patterns of undefended species but also from natural scenes. For the first time, we offer an objective and quantitative neural-level definition of warning signals based on how the pattern generates neural activity in the brain of the receiver. This opens new perspectives for understanding and testing how warning signals function and evolve, and, more generally, how sensory systems constrain general principles for signal design.

/pdf/understanding-the-design-of-warning-signals-a-predator-s-ufxup5yjqe.pdf

Christina G. Halpin

Papers

Avian Cognition and the Evolution of Warning Signals

What do predators do? A response to comments on Skelhorn et al.

Understanding the design of warning signals: a predator’s view