These large insects are generally recognized by yellow wings with black stripes and small "tails" on their hind wings.
Of the three species, Eastern tiger swallowtails prefer warmer climes and lower elevations, and the females come in two different forms.
They are either striped--yellow and black--or almost entirely black, the latter mimicking a poisonous butterfly called the Pipevine swallowtail, Battus philenor.
Canadian tigers are only striped yellow and black, and found in cooler habitats at higher latitudes and elevations.
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.
They also found that the Appalachian tiger's genome has become distinct from the genomes of its two parental species, even though the butterflies come into contact with each other in the wild.
"Hybrid speciation is a controversial phenomenon, and this is especially true in animals, where clear-cut examples are exceedingly rare," says Marcus Kronforst of Harvard University, also a co-author of the paper.
The Appalachian tiger's range nudges against the Canadian tiger in the northern Appalachian Mountains, and against the Eastern tiger in the lower elevations surrounding the mountains.
The conventional view of speciation is that one species splits into two over time. With time, the species become more and more reproductively isolated from each other.
In the case of hybrid speciation, new species are formed when two s
|Contact: Cheryl Dybas|
National Science Foundation