Research

I am currently a postdoctoral researcher (supported by the fund for scientific research, FWO-IV Flanders-Belgium) working with Raoul Van Damme in the Functional Morphology Laboratory at the University of Antwerp. My research concerns the interface between function and behaviour. I am particularly interested in how physiological capacities affect the evolution of reproductive strategies and associated traits. Although lizards feature prominently in my research as they are in many ways ideal organisms for addressing broad evolutionary and behavioural hypotheses, I have also used invertebrates such as beetles, spiders, crabs and grasshoppers as study organisms where appropriate. To gain a better understanding of trait evolution at multiple levels of organization I employ integrative approaches wherever possible and have used methods such as phylogenetic comparisons, demographic mark-recapture techniques, behavioural measures, kinetic analyses, morphometrics and hormone analyses, amongst others.

Sexual selection Much of my research concerns the functional components of sexual selection - for example, do male armaments signal information to rivals on functional capacities that may affect the outcomes of male fights? Do male and female performance or physiological capacities influence female mate choice? I use a combination of whole-organism performance measures (i.e. any measure of an organism conducting a dynamic, ecologically relevant task such as running or biting), behavioural methods and comparative techniques to answer these and other questions about animal mating strategies. Current research in this area includes an evolutionary analysis of performance-based fighting ability in Caribbean Anolis lizards (w/ Duncan Irschick), an investigation into the life history trade-offs between performance and condition (w/ Casper Breuker and Raoul Van Damme), and a study of performance signaling in fiddler crabs (w/ Leeann Reaney and Pat Backwell).

Anolis lineatopus from Jamaica (left), and Anolis angusticeps from South Bimini, Bahamas (right).

The evolution of performance A more mechanistic part of my research program deals with identifying and understanding factors that might promote or constrain the evolution of performance, and then examining how those factors interact or trade-off under natural conditions. Two factors that I am particularly interested in are sex and temperature. Males and females from several animal taxa differ in locomotor performance capacities such as sprinting and jumping. These performance dimorphisms may be explained at least partially by sex differences in physiology (e.g. dissimilarity in metabolic rate or relative muscularity). Given that the physiological and performance capacities of lizards and other ectotherms are limited by their thermal ecology, physiological constraints on performance capacities in one sex relative to another may cause divergence in thermal performance optima (i.e. body temperatures conducive to maximum performance) between males and females. This divergence may have important implications for male and female ecology. For example, I previously examined the relevance of sex differences in locomotor performance for escape behaviour in the flat lizard Platysaurus intermedius wilhelmi. I am currently investigating how sex differences in thermal tolerance affect thermal performance curves for locomotion in male and female lizards.

The thermal dependence of non-locomotor performance Although I have done most of my temperature work on lizard locomotion, I have recently begun exploring the thermal dependence of non-locomotor performance traits in reptiles. Temperature effects on whole-organism performance traits other than locomotion have received very little attention from functional biologists, and with few exceptions our understanding of the thermal dependence of such traits is extremely limited. Bite force is particularly interesting in this regard, as biting in lizards appears to show very little thermal dependence compared to locomotion. In collaboration with Anthony Herrel I am conducting a large comparative study of the thermal dependence of bite force in lizards. We are also investigating the effects of temperature on a variety of other performance traits in lizards and snakes.

Photographs by S. Lailvaux and D. Irschick

Moving away from the performance angle, I have also looked at the multivariate nature of female choice in lizards, factors influencing the expression of dewlap size (a male secondary sexual character in some lizards) in Anolis carolinensis and the ecomorphological correlates of polyandry in spiders.