Origins of Sparrow Speciation

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Science  21 Feb 2014:
Vol. 343, Issue 6173, pp. 817
DOI: 10.1126/science.343.6173.817-a

Homoploid hybrid speciation is the result of hybridization between two parental species without a change in chromosome number. Such speciation is relatively rare, however, because it requires the rapid establishment of reproductive isolation of the new species from that of its parents. Trier et al. examine the origins of the Italian sparrow, which originated as a result of hybridization between the house and Spanish sparrows. Transcriptome analysis of the parental sparrows identified 86 species-specific SNPs. This allowed tracing of the genetic ancestry within the Italian sparrow and identified some ongoing, but limited, gene flow between the parental species and the Italian sparrows. Mosaic ancestry of the Italian sparrow sex chromosomes was evidenced by a cline analysis framework. This identified ancestry of both house and Spanish sparrow sex chromosome–linked loci that exhibited allele frequency shifts. Mitochondrial and nuclear encoded mitochondrial genes exhibited similar divergences. These results suggest that mito–nuclear interactions may also be a factor in isolating the Italian sparrows from their parental species and that reproductive isolation may be evolving as a result of mito–sex chromosome interactions.

PLOS Genet. 10, e1004075 (2014).

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