Spatio-temporal processes drive fine-scale genetic structure in an otherwise panmictic seabird population

Lucy J H Garrett,John K Colbourne,S James Reynolds,Sam B Weber,Helen Hipperson,Roger C Dickey,Julia P Myatt,Jon P Sadler,Deborah A Dawson

doi:10.1038/s41598-020-77517-w

Abstract

When and where animals breed can shape the genetic structure and diversity of animal populations. The importance of drivers of genetic diversity is amplified in island populations that tend to have more delineated gene pools compared to continental populations. Studies of relatedness as a function of the spatial distribution of individuals have demonstrated the importance of spatial organisation for individual fitness with outcomes that are conditional on the overall genetic diversity of the population. However, few studies have investigated the impact of breeding timing on genetic structure. We characterise the fine-scale genetic structure of a geographically-isolated population of seabirds. Microsatellite markers provide evidence for largely transient within-breeding season temporal processes and limited spatial processes, affecting genetic structure in an otherwise panmictic population of sooty terns Onychoprion fuscatus. Earliest breeders had significantly different genetic structure from the latest breeders. Limited evidence was found for localised spatial structure, with a small number of individuals being more related to their nearest neighbours than the rest of the population. Therefore, population genetic structure is shaped by heterogeneities in collective movement in time and to a lesser extent space, that result in low levels of spatio-temporal genetic structure and the maintenance of genetic diversity.

Highlights

When and where animals breed can shape the genetic structure and diversity of animal populations
Mainland populations of Kentish plovers Charadrius alexandrinus have high levels of gene flow and genetic panmixia, whereas those breeding on islands have lower genetic diversity, and genetic differentiation from the mainland populations increases with increasing distance from the mainland[7]
Our findings provide evidence for genetic temporal partitioning and less support for fine-scale spatial genetic structure in an otherwise panmictic seabird population

Summary

Introduction

When and where animals breed can shape the genetic structure and diversity of animal populations. Isolation over time may result in heterogeneity in genetic structure[15], whereby temporal barriers impede gene flow[16], giving rise to differentiation within a species occupying the same spatial location. For such a scenario to influence a population’s genetic structure, variation in individual breeding timing must have some heritable basis[17]. Their study did not consider temporal effects, they provided evidence for the importance of fine-scale spatial genetic heterogeneity, driven by variations in habitat quality in a panmictic king penguin Aptenodytes patagonicus colony in the Crozet Archipelago in the Southern Indian Ocean

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