Demographic history of wood stork (Mycteria americana) Brazilian Pantanal colonies revealed by mitochondrial DNA analysis

Iara Freitas Lopes,Reinaldo Alves De Brito,Flávio Henrique-Silva,Silvia Nassif Del Lama

doi:10.1590/s1415-47572006000200008

Iara Freitas Lopes, Reinaldo Alves De Brito + Show 2 more

Open Access

https://doi.org/10.1590/s1415-47572006000200008

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Abstract

We used mitochondrial DNA (mtDNA) sequences to investigate the demographic history of the wood stork (Mycteria americana) populations in the Brazilian Pantanal. Sequences of 390/460 bp fragment of the mtDNA control region were analyzed in 62 wood stork specimens from 8 colonies using neutrality tests, phylogeographic, and coalescent analyses. Population expansion was supported by the significantly negative values of Tajima’s (D = -2.071) and Fu’s (Fs = -14.544) statistics and the unimodal pattern of mismatch distribution. Nested clade analyses indicated a historic range expansion event and recurrent gene flow that was restricted by isolation by distance as explanations for the haplotype distribution among the sampled colonies. High genetic diversity and the strictly unidirectional gene flow pattern emphasized the conservation importance of preserving the southern Pantanal colonies. Coalescence analyses suggested that northern and southern colonies diverged approximately 6,250 years before the present (YBP), and that their most recent common ancestor was approximately 18,900 YBP. Our results suggest that the contemporary wood stork Pantanal population originated from a more geographically limited founder population. Potential source populations may have occurred in the southern Pantanal or ancestry may reside in populations inhabiting the Brazilian central plateau or areas closer to the equatorial region.

Highlights

Combinations of historical and contemporary processes determine the genetic structure and geographical distribution of genetic diversity among populations (Templeton et al, 1995)
The observed heteroplasmic pattern was explained by an insertion/deletion of a 70 bp repeat that results in simultaneous amplification of 390 and 460 bp fragments in the same individual
Intra-individual sequence length variation in the mitochondrial DNA (mtDNA) control region has been described in several bird families, including Laridae (Berg et al, 1995; Kidd and Friesen, 1998; Crochet and Desmarais, 2000), Scolopacidae (Berg et al, 1995) and Paridae (Kvist et al, 2003)

Summary

Introduction

Combinations of historical and contemporary processes determine the genetic structure and geographical distribution of genetic diversity among populations (Templeton et al, 1995). Genetic markers can be used to track population demographic responses to climatic shifts and other historical processes (Lessa et al, 2003; Templeton et al, 1995) while phylogeographic studies allow inferences to be made about the history of population divergence based on associations between the geographical distribution of mitochondrial DNA haplotypes and their genealogical relationships (Avise, 2000). The wood stork (Mycteria americana, Ciconiidae, Ciconiiformes) is a colonial nesting wading bird adapted to the fluctuating water levels found in wetlands. Like other species in the family Ciconiidae that are threatened by habitat loss, the wood stork US population is endangered because of its sensitivity to environmental disturbances such as anthropogenic water level manipulations (Coulter et al, 1999; Wetlands International, 2002). The species occurs in the Brazilian Pantanal, a region characterized by wet/dry cycles which result in large fluctuations in the availability of prey that limits the presence of wood stork during the dry season

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