First instance of an observed speciation event in the wild: researchers watched as an individual non-native bird arrived, mated with one of the native species, and produced viable hybrids that have now gone on to form a separate breeding population of their own—they are also ecologically isolated by having a beak length that is different from both parent species.
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 >100km from Daphne. From the second generation onwards 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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