Speciation without gene flow in the Golden-fronted – Red-bellied Woodpecker species complex

Project authors: Matthew Miller and Phil Lavretsky (UTEP)
Project github repository

For over half a century, ornithologists have debated how to interpret phenotypic variation in the Golden-fronted – Red-bellied Woodpecker species complex and closely related parapatric allies (Melanerpes) from North and Central America. This includes Velasquez’s Woodpecker (M. santacruzi), which some authorities have treated as conspecific with the Golden-fronted Woodpecker (M. aurifrons).

We have generated genome-wide ddRAD-seq loci to reconstruct historical demography and to estimate historical and contemporary patterns of gene flow in this group. Our data indicate a sister-species relationship between Red-bellied and Golden-fronted Woodpeckers.The common ancestor of these two species is sister to Velasquez’s Woodpecker, which should be considered a separate species from Golden-fronted Woodpecker.

Admixture between the species in this group is non-existent, despite the fact that hybrids are often reported. We did find evidence for two hybrids between Red-bellied and Golden-fronted Woodpeckers.

Analysis of birds collected in the Red-bellied/Golden-fronted Woodpecker contact zone in SW Oklahoma and NW Texas show that hybridization is rare, and limited to F1 hybrids. This suggests that reproductive isolation has evolved extremely rapidly in this group.