Hybridization in the Recent Past

The question we address in this article is how hybridization in the recent past can be detected in recently evolved species. Such species may not have evolved genetic incompatibilities and may hybridize with little or no fitness loss. Hybridization can be recognized by relatively small genetic diffe...

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Bibliographic Details
Published in:The American naturalist 2005-07, Vol.166 (1), p.56-67
Main Authors: Grant, Peter R., Grant, B. Rosemary, Petren, K.
Format: Article
Language:English
Subjects:
Allopatric species
Animals
Biological Evolution
Camarhynchus
Comparative studies
Ecuador
Evolutionary biology
Evolutionary genetics
Finches
Finches - genetics
Genetic hybridization
Genetic Speciation
Genetics
Geospiza
Hybridity
Hybridization
Hybridization, Genetic
Microsatellite Repeats
Population genetics
Radiation genetics
Speciation
Sympatric species
Sympatry
Time Factors
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Summary:The question we address in this article is how hybridization in the recent past can be detected in recently evolved species. Such species may not have evolved genetic incompatibilities and may hybridize with little or no fitness loss. Hybridization can be recognized by relatively small genetic differences between sympatric populations because sympatric populations have the opportunity to interbreed whereas allopatric populations do not. Using microsatellite DNA data from Darwin’s finches in the Galápagos archipelago, we compare sympatric and allopatric genetic distances in pairs ofGeo spizaandCamarhynchusspecies. In agreement with the hybridization hypothesis, we found a statistically strong tendency for a species to be more similar genetically to a sympatric relative than to allopatric populations of that relative. Hybridization has been studied directly on two islands, but it is evidently more widespread in the archipelago. We argue that introgressive hybridization may have been a persistent feature of the adaptive radiation through most of its history, facilitating evolutionary diversification and occasionally affecting both the speed and direction of evolution.
ISSN:0003-0147
1537-5323
DOI:10.1086/430331