Gene flow and population structure in the Mexican blind cavefish complex (Astyanax mexicanus)

BMC Evolutionary Biology

Research Article

Richard L Borowsky¹  Peter Beerli²  Martina Bradic³  Francisco J García-de León⁴  Sarai Esquivel-Bobadilla⁴ 

[1] Biology Department, New York University, 100 Washington Square East, 10003, NYC, USA;Department of Scientific Computing, Florida State University, 150-T Dirac Science Library, 32306-4120, Tallahassee, USA;Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal;Biology Department, New York University, 100 Washington Square East, 10003, NYC, USA;Laboratorio de Genética para la Conservación, Centro de Investigaciones Biologicas del Noroeste La Paz, Mar Bermejo #195, 23090, La Paz, CP, Mexico;

关键词: Gene Flow;    Migration Rate;    Effective Population Size;    Shared Allele;    Surface Population;   

DOI  :  10.1186/1471-2148-12-9

 received in 2011-06-17, accepted in 2012-01-23,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundCave animals converge evolutionarily on a suite of troglomorphic traits, the best known of which are eyelessness and depigmentation. We studied 11 cave and 10 surface populations of Astyanax mexicanus in order to better understand the evolutionary origins of the cave forms, the basic genetic structuring of both cave and surface populations, and the degree to which present day migration among them affects their genetic divergence.ResultsTo assess the genetic structure within populations and the relationships among them we genotyped individuals at 26 microsatellite loci. We found that surface populations are similar to one another, despite their relatively large geographic separation, whereas the cave populations are better differentiated. The cave populations we studied span the full range of the cave forms in three separate geographic regions and have at least five separate evolutionary origins. Cave populations had lower genetic diversity than surface populations, correlated with their smaller effective population sizes, probably the result of food and space limitations. Some of the cave populations receive migrants from the surface and exchange migrants with one another, especially when geographically close. This admixture results in significant heterozygote deficiencies at numerous loci due to Wahlund effects. Cave populations receiving migrants from the surface contain small numbers of individuals that are intermediate in both phenotype and genotype, affirming at least limited gene flow from the surface.ConclusionsCave populations of this species are derived from two different surface stocks denoted "old" and "new." The old stock colonized caves at least three times independently while the new stock colonized caves at least twice independently. Thus, the similar cave phenotypes found in these caves are the result of repeated convergences. These phenotypic convergences have occurred in spite of gene flow from surface populations suggesting either strong natural or sexual selection for alleles responsible for the cave phenotype in the cave environment.

【 授权许可】

Unknown   
© Bradic et al; licensee BioMed Central Ltd. 2012. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.