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Rapid Evolution of Assortative Fertilization between Recently Allopatric Species of Drosophila
Journal article   Open access   Peer reviewed

Rapid Evolution of Assortative Fertilization between Recently Allopatric Species of Drosophila

Yasir Ahmed-Braimah and Bryant McAllister
International Journal of Evolutionary Biology, Vol.2012, pp.1-9
2012
DOI: 10.1155/2012/285468
PMCID: PMC3270401
PMID: 22315696
url
https://doi.org/10.1155/2012/285468View
Published (Version of record) Open Access

Abstract

The virilis group of Drosophila represents a relatively unexplored but potentially useful model to investigate the genetics of speciation. Good resolution of phylogenetic relationships and the ability to obtain fertile hybrid offspring make the group especially promising for analysis of genetic changes underlying reproductive isolation separate from hybrid sterility and inviability. Phylogenetic analyses reveal a close relationship between the sister species, Drosophila americana and D. novamexicana, yet excepting their contemporary allopatric distributions, factors that contribute to reproductive isolation between this species pair remain uncharacterized. A previous report has shown reduced progeny numbers in laboratory crosses between the two species, especially when female D. novamexicana are crossed with male D. americana. We show that the hatch rate of eggs produced from heterospecific matings is reduced relative to conspecific matings. Failure of eggs to hatch, and consequent reduction in hybrid progeny number, is caused by low fertilization success of heterospecific sperm, thus representing a postmating, prezygotic incompatibility. Following insemination, storage and motility of heterospecific sperm is visibly compromised in female D. novamexicana. Our results provide evidence for a mechanism of reproductive isolation that is seldom reported for Drosophila species, and indicate the rapid evolution of postmating, prezygotic reproductive barriers in allopatry.

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