Hybrid Speciation: When Two Species Become Three

Contrary to what many people think, two species can hybridize naturally in the wild to give rise to a third species, a finding that fundamentally alters our understanding of the evolution of species

by GrrlScientist for Forbes | @GrrlScientist

Salvin’s medium-billed prion (Pachyptila salvini), is apparently a hybrid species between the Antarctic prion (Pachyptila desolata), and the broad-billed prion (Pachyptila vittata). The Crozet Islands, where this bird was photographed, are a sub-Antarctic archipelago of small islands in the southern Indian Ocean.
(Credit: Peter Ryan.)

Ligers! Tigons! And bears! Oh my!

Not long ago, I told you about a fascinating songbird that was discovered to be the hybrid offspring of three different species (more here). This unique bird raised an intriguing question: can hybrids give rise to a perfectly valid species?

Hybrid speciation is quite rare in animals, but it does occur naturally. In this scenario, the resulting hybrid population is an independent new species that is reproductively isolated from both parental species. One such example is the Heliconius butterfly (ref). These brightly colored butterflies are widespread throughout South and Central America and are even found in parts of North America. They are remarkable for their astonishing diversity of wing patterns and for extensive mimicry within the group.

Amongst birds, probably the best-known examples of hybrid species are the Italian sparrow, Passer italiae, golden‐crowned manakin, Lepidothrix vilasboasi, and a recently identified but currently unnamed Galapagos finch that was estimated to have…