ReportsGenetics

Rapid hybrid speciation in Darwin’s finches

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Science  12 Jan 2018:
Vol. 359, Issue 6372, pp. 224-228
DOI: 10.1126/science.aao4593

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Rapid hybrid speciation in Darwin's finches

Galapagos finches have driven hypotheses of how speciation occurs. Most commonly, it is assumed that natural selection separates species originating from a single population on the basis of variation in traits that confer advantages for survival and reproduction. Lamichhaney et al. document a case where cross-species hybridization established a reproductively isolated lineage, which demonstrates a process known as homoploid hybrid speciation in action (see the Perspective by Wagner). The authors used genetic markers and phenotypic analyses to create a pedigree that revealed how a cross-island migrant bred with a native species to form a self-perpetuating hybrid population that was reproductively isolated from both parental species.

Science, this issue p. 224; see also p. 157

Abstract

Homoploid hybrid speciation in animals has been inferred frequently from patterns of variation, but few examples have withstood critical scrutiny. Here we report a directly documented example, from its origin to reproductive isolation. An immigrant Darwin’s finch to Daphne Major in the Galápagos archipelago initiated a new genetic lineage by breeding with a resident finch (Geospiza fortis). Genome sequencing of the immigrant identified it as a G. conirostris male that originated on Española >100 kilometers from Daphne Major. From the second generation onward, the lineage bred endogamously and, despite intense inbreeding, was ecologically successful and showed transgressive segregation of bill morphology. This example shows that reproductive isolation, which typically develops over hundreds of generations, can be established in only three.

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