From “Appalachian Tiger Swallowtail Butterfly Is a Hybrid of Two Other Swallowtails, Scientists Find” (ScienceDaily, Sep. 12, 2011), we learn of an interesting case of two very closely related butterfly species producing a hybrid that seldom mates with parent species:
They discovered that the Appalachian tiger swallowtail, Papilio appalachiensis, evolved from mixing between the Eastern tiger swallowtail, P. glaucus, and the Canadian tiger swallowtail, P. canadensis. The Appalachian tiger swallowtail rarely reproduces with its parental species and is a unique mixture of the two in both its outward traits and inward genetic makeup.
Hybridization is common among plants but thought to be rare in animals.
The Appalachian tiger exhibits a mix of those traits. It shares an affinity for cooler habitats with the Canadian tiger, while sharing the ability to mimic the black Pipevine swallowtail with the Eastern tiger.
Digging into the butterflies’ genomes, the scientists found that the Appalachian tiger inherited genes associated with cold habitats from males of the Canadian tiger, and inherited a gene for mimicry from Eastern tiger females.
Tiger swallowtails are found as far north as the Yukon.
The study authors think the Appalachians set up on their own about 100,000 years ago, which – they point out – is not a long time. No, but the changes are not spectacular either. The swallowtails (so called because a hind wing extension produces a gliding flight) are not the only butterfly group that hybridizes. Danaus species (including the Admiral) also do it.
Hybridization seems to a limited but durable method of producing a new species under favorable conditions.
See also: See also: Scientists discover supergene that controls a butterfly’s mimicry patterns.