Gene flow and population structure in the Mexican blind cavefish complex (Astyanax mexicanus)
| Autor: | Richard Borowsky, Francisco J. García de León, Sarai Esquivel-Bobadilla, Peter Beerli, Martina Bradic |
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| Rok vydání: | 2012 |
| Předmět: |
Gene Flow
0106 biological sciences Evolution Cavefish Zoology Biology Eye 010603 evolutionary biology 01 natural sciences 03 medical and health sciences Gene Frequency Effective population size Cave QH359-425 Animals 14. Life underwater 10. No inequality Ecology Evolution Behavior and Systematics 030304 developmental biology Population Density 0303 health sciences geography Genetic diversity geography.geographical_feature_category Pigmentation Genetic Variation Mexican tetra social sciences musculoskeletal system biology.organism_classification Biological Evolution humanities Genetic divergence Characidae Caves Cypriniformes Genetics Population Evolutionary biology Genetic structure Animal Migration Microsatellite Repeats Research Article |
| Zdroj: | BMC Evolutionary Biology BMC Evolutionary Biology, Vol 12, Iss 1, p 9 (2012) |
| ISSN: | 1471-2148 |
| DOI: | 10.1186/1471-2148-12-9 |
| Popis: | Background Cave 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. Results To 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. Conclusions Cave 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. |
| Databáze: | OpenAIRE |
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