Sex-biased breeding dispersal is predicted by social environment in birds.

Zsolt Végvári,Robert P Freckleton,Jean‐Michel Gaillard,Tamás Székely,Gergely Katona,Balázs Vági,András Liker

doi:10.1002/ece3.4095

Abstract

Sex‐biased dispersal is common in vertebrates, although the ecological and evolutionary causes of sex differences in dispersal are debated. Here, we investigate sex differences in both natal and breeding dispersal distances using a large dataset on birds including 86 species from 41 families. Using phylogenetic comparative analyses, we investigate whether sex‐biased natal and breeding dispersal are associated with sexual selection, parental sex roles, adult sex ratio (ASR), or adult mortality. We show that neither the intensity of sexual selection, nor the extent of sex bias in parental care was associated with sex‐biased natal or breeding dispersal. However, breeding dispersal was related to the social environment since male‐biased ASRs were associated with female‐biased breeding dispersal. Male‐biased ASRs were associated with female‐biased breeding dispersal. Sex bias in adult mortality was not consistently related to sex‐biased breeding dispersal. These results may indicate that the rare sex has a stronger tendency to disperse in order to find new mating opportunities. Alternatively, higher mortality of the more dispersive sex could account for biased ASRs, although our results do not give a strong support to this explanation. Whichever is the case, our findings improve our understanding of the causes and consequences of sex‐biased dispersal. Since the direction of causality is not yet known, we call for future studies to identify the causal relationships linking mortality, dispersal, and ASR.

Highlights

Dispersal is an essential part of life history in many organisms that has knock-on consequences for demography, ecology, and behavior.By moving from one area to another, dispersal influences metapopulation dynamics and gene flow and has implications for diversification rates and responses of animals to environmental changes by shifting their geographic ranges
Our comparative ana yses using the argest dataset of sex biased dispersal distances in birds ever compiled, produced two new major findings First whi e we found support for previous resu ts that both natal and breeding dispersal are female-biased
This imp ies that sex differences in these two types of dispersa may be driven by different biological mechanisms: the primary function of natal dispersal is to establish home ranges for all activity types and resources, whereas breeding dispersal occurs at substantially shorter time scales and focus predominantly on mating opportunities For examp e whi e ASR is re ated to breeding dispersa we did not find evidence for a similar association with natal dispersal see be ow A though further studies are needed to exp ore why sex differences in these two types of dispersal behavior are decoupled from each other an important imp ication is that ana yses of sex specific dispersal should distinguish between natal and breeding dispersal

Summary

| INTRODUCTION

Dispersal is an essential part of life history in many organisms that has knock-on consequences for demography, ecology, and behavior. We aim to fill this knowledge gap by testing whether the magnitude and the direction of sex biased nata and breeding dispersa in birds are positive y associated with the intensity of sexua selection

| MATERIALS AND METHODS

A PGLS ana yses were run with R

| RESULTS

| DISCUSSION

Findings

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