Determinants and Consequences of Dispersal in Vertebrates with Complex Life Cycles: A Review of Pond-Breeding Amphibians

Abstract

Dispersal is a central process in ecology and evolution. It strongly influences the dynamics of spatially structured populations and affects evolutionary processes by shaping patterns of gene flow. For these reasons, dispersal has received considerable attention from ecologists, evolutionary biologists, and conservationists. Although it has been studied extensively in taxa such as birds and mammals, much less is known about 2 dispersal in vertebrates with complex life cycles such as pond-breeding amphibians. Over the past two decades, researchers have taken an ever-increasing interest in amphibian dispersal and initiated both basic and applied studies, using a broad range of experimental and observational approaches. This body of research reveals complex dispersal patterns, causations, and syndromes, with dramatic consequences for the demography and genetics of amphibian populations. In this review, our goals are to: redefine and clarify the concept of amphibian dispersal; review current knowledge about the effects of individual (i.e., condition-dependent dispersal) and environmental (i.e., context-dependent dispersal) factors during the three stages of dispersal (i.e., emigration, transience, and immigration); identify the demographic and genetic consequences of dispersal in spatially structured amphibian populations; and propose new research avenues to extend our understanding of amphibian dispersal.

Anthropogenic disturbance drives dispersal syndromes, demography, and gene flow in amphibian populations

“…Adopting the most realistic lifecycle for the yellow‐bellied toad (see Results: Simulating the effect of patch turnover and dispersal on logging SSP dynamics and long‐term persistence ) determined in previous studies (e.g., Cayuela et al. , , b, ), we used a three age‐class (juveniles, subadults, and adults), female‐dominant, prebreeding Leslie matrix (Caswell ) (see Results: Simulating the effect of patch turnover and dispersal on logging SSP dynamics and long‐term persistence ). We used the demographic parameters of a riverine SSP (R1; see Cayuela et al.…”

“…As in Cayuela et al. (, b, , ), we made the assumption that survival loss was similar across life stages (i.e., juvenile, subadult, and adult).…”

“…To be as realistic as possible, we used demographic stochasticity (fecundity was thus randomly sampled from a Poisson distribution, and survival from a binomial distribution), as in Cayuela et al. (, b, , ). For patches that disappeared, we applied the same procedure, but using the survival probability (affected or not by dispersal cost, depending on the scenario) for individuals occupying patches that subsequently disappeared.…”

“…In this study, our first step was to quantify dispersal probability and distance throughout an individual's lifetime, as natal dispersal was lacking in previous studies and a review of recent literature suggested that natal and breeding dispersal patterns can strongly differ in amphibians (Cayuela et al. ). We expected that (1) both natal and breeding dispersal rates and distances would be higher in logging than in riverine SSPs.…”

“…We expected (3) toadlets from logging SSPs to have behavioral traits (i.e., high exploration propensity and boldness) and morphological traits (i.e., long hind limbs) that generally facilitate dispersal in amphibians (reviewed in Cayuela et al. ). In a fourth step, we examined how human‐driven variation in patch turnover, by affecting neutral genetic diversity and gene flow, leads to contrasting genetic footprints over the longer term in riverine and logging SSPs.…”