Genetic diversity and spatial structure of the Rufous-throated Antbird (Gymnopithys rufigula), an Amazonian obligate army-ant follower.

Juliana Menger,Klaus Henle,Martin Schlegel,Antonella Soro,William E Magnusson,Martin Husemann

doi:10.1002/ece3.2880

Abstract

Amazonian understory antbirds are thought to be relatively sedentary and to have limited dispersal ability; they avoid crossing forest gaps, and even narrow roads through a forest may limit their territories. However, most evidence for sedentariness in antbirds comes from field observations and plot‐based recapture of adult individuals, which do not provide evidence for lack of genetic dispersal, as this often occurs through juveniles. In this study, we used microsatellite markers and mitochondrial control‐region sequences to investigate contemporary and infer historical patterns of genetic diversity and structure of the Rufous‐throated Antbird (Gymnopithys rufigula) within and between two large reserves in central Amazonia. Analyses based on microsatellites suggested two genetically distinct populations and asymmetrical gene flow between them. Within a population, we found a lack of genetic spatial autocorrelation, suggesting that genotypes are randomly distributed and that G. rufigula may disperse longer distances than expected for antbirds. Analyses based on mitochondrial sequences did not recover two clear genetic clusters corresponding to the two reserves and indicated the whole population of the Rufous‐throated Antbird in the region has been expanding over the last 50,000 years. Historical migration rates were low and symmetrical between the two reserves, but we found evidence for a recent unilateral increase in gene flow. Recent differentiation between individuals of the two reserves and a unilateral increase in gene flow suggest that recent urban expansion and habitat loss may be driving changes and threatening populations of Rufous‐throated Antbird in central Amazonia. As ecological traits and behavioral characteristics affect patterns of gene flow, comparative studies of other species with different behavior and ecological requirements will be necessary to better understand patterns of genetic dispersal and effects of urban expansion on Amazonian understory antbirds.

Highlights

In an increasingly human-modified environment, the ability of an organism to disperse from one place to another is essential, for its own fitness, and for population dynamics and genetic structuring
Individuals of G. rufigula in the Manaus region form two distinct genetic clusters, which are undergoing an expansion in effective population size
The star-like shape of the haplotype network indicates that both reserves shared an ancestral population whose structure cannot be distinguished from a panmictic population in expansion, the presence of haplotypes unique to each reserve suggests that the two areas have been undergoing a process of differentiation and that anthropogenic changes are likely to be driving recent changes in population dynamics

Summary

| INTRODUCTION

In an increasingly human-modified environment, the ability of an organism to disperse from one place to another is essential, for its own fitness, and for population dynamics and genetic structuring. Several studies have shown that antbirds avoid crossing forest gaps, and even narrow roads through a forest may act as barriers, limiting bird territories and movements (Develey & Stouffer, 2001; Laurance, 2004; Lees & Peres, 2009; Stouffer & Bierregaard, 1995). Such studies are based on field observations and on plot-based resighting or recapture of adult individuals, which may underestimate longer-distance dispersal occurring through juveniles, that is, natal dispersal (Woltmann, Sherry, & Kreiser, 2012). As restricted dispersal over short distances is expected to generate fine-scale spatial patterns of genetic structure, and sex-biased dispersal may lead to differences in the genetic structure of males and females (Banks & Peakall, 2012; Peakall, Ruibal, & Lindenmayer, 2003), we (5) investigated local genetic structure within a reserve and (6) sought differences in genetic structure between sexes

| METHODS

Findings

| DISCUSSION