Hybridization between divergent taxa can provide insight into the breakdown of characters used in mate choice, as well as reproductive compatibility across deep evolutionary timescales. Hybridization can also occur more frequently in declining populations, as there is a smaller pool of conspecific mates from which to choose. Here, we report an unusual combination of factors that has resulted in a rare, three-species hybridization event among two genera of warblers, one of which is experiencing significant population declines. We use bioacoustic, morphometric and genetic data, to demonstrate that an early generation female hybrid between a golden-winged warbler (
Vermivora chrysoptera
) and a blue-winged warbler (
V. cyanoptera
) went on to mate and successfully reproduce with a chestnut-sided warbler (
Setophaga pensylvanica
)
.
We studied the product of this event—a putative
chrysoptera
×
cyanoptera
×
pensylvanica
hybrid—and show that this male offspring sang songs like
S. pensylvanica
, but had morphometric traits similar to
Vermivora
warblers. The hybrid's maternal parent had
V. chrysoptera
mitochondrial DNA and
,
with six plumage-associated loci, we predicted the maternal parent's phenotype to show that it was likely an early generation
Vermivora
hybrid
.
That this hybridization event occurred within a population of
Vermivora
warblers in significant decline suggests that females may be making the best of a bad situation, and that wood-warblers in general have remained genetically compatible long after they evolved major phenotypic differences.
Genomic and transcriptomic alterations following intergeneric hybridization and polyploidization in the Chrysanthemum nankingense×Tanacetum vulgare hybrid and allopolyploid (Asteraceae)
