Evolution

Sparrow Speciation

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Science  30 Sep 2011:
Vol. 333, Issue 6051, pp. 1802
DOI: 10.1126/science.333.6051.1802-c

Homoploid hybrid speciation creates new species that arise from interbreeding between two species without a chromosomal doubling. Although long thought to be a rare mode of speciation in animals, a growing number of examples have been reported. Hermansen et al. have now identified a likely homoploid hybrid, the Italian sparrow, which is intermediate in phenotype between Spanish sparrows and house sparrows. Microsatellite loci and mitochondrial DNA sequences of sampled sparrows showed that Italian sparrows are genetically intermediate between the other two species. Italian and Spanish sparrows behave like distinct species in an area of geographical overlap; however, Italian and house sparrows do form hybrid zones. A genetic analysis of these species by Elgvin et al. found evidence that the Italian sparrow is genetically intermediate between its putative progenitors. Furthermore, they found that the sex (Z) chromosome has probably played an important role in this case of speciation.

Mol. Ecol. 20, 3812; 3823 (2011).

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