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Mayr, Dobzhansky, and Bush and the complexities of sympatric speciation in Rhagoletis
Journal article   Open access   Peer reviewed

Mayr, Dobzhansky, and Bush and the complexities of sympatric speciation in Rhagoletis

Jeffrey L Feder, Xianfa Xie, Juan Rull, Sebastian Velez, Andrew Forbes, Brian Leung, Hattie Dambroski, Kenneth E Filchak and Martin Aluja
Proceedings of the National Academy of Sciences - PNAS, Vol.102(Suppl 1), pp.6573-6580
Colloquium Paper
05/03/2005
DOI: 10.1073/pnas.0502099102
PMCID: PMC1131876
PMID: 15851672
url
https://doi.org/10.1073/pnas.0502099102View
Published (Version of record) Open Access

Abstract

The Rhagoletis pomonella sibling species complex is a model for sympatric speciation by means of host plant shifting. However, genetic variation aiding the sympatric radiation of the group in the United States may have geographic roots. Inversions on chromosomes 1-3 affecting diapause traits adapting flies to differences in host fruiting phenology appear to exist in the United States because of a series of secondary introgression events from Mexico. Here, we investigate whether these inverted regions of the genome may have subsequently evolved to become more recalcitrant to introgression relative to collinear regions, consistent with new models for chromosomal speciation. As predicted by the models, gene trees for six nuclear loci mapping to chromosomes other than 1-3 tended to have shallower node depths separating Mexican and U.S. haplotypes relative to an outgroup sequence than nine genes residing on chromosomes 1-3. We discuss the implications of secondary contact and differential introgression with respect to sympatric host race formation and speciation in Rhagoletis , reconciling some of the seemingly dichotomous views of Mayr, Dobzhansky, and Bush concerning modes of divergence.

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