Amazon butterfly evolved from hybrids

In a new study published in Nature, an international team of researchers, led by researchers in OEB, found that hybrids between two Heliconius species of butterflies produced a new species genetically distinct from both parent species and their earlier forebears.

The team, led by co-authors, Associate Neil Rosser, Postdoc Fernando Seixas, and Professor James Mallet, used whole-genome sequencing to show that a hybridization event, that occurred approximately 180,000 years ago, between Heliconius melpomene and the ancestor of today's Heliconius pardalinus produced a third hybrid species, Heliconius elevatus. Historically, hybridization has been thought to inhibit the creation of new species. But the authors say that the genomic data have shown that hybridization among species is actually worldwide. And these findings may alter how we view species going forward.

In a statement to the Harvard Gazette, Rosser said “A lot of species are not intact units. They’re quite leaky, and they’re exchanging genetic material.” 

Hybridization has long been thought to inhibit the creation of new species. However, the researchers say that, in this case, hybridization is driving the evolution of the species. Evolving species constantly exchanging genes can actually trigger new lineages. The study provides steps to understanding how hybridization and speciation work, and can also help with the current biodiversity crisis.

Image: James Mallet displays a Heliconius elevatus specimen. Photo by Kris Snibbe/Harvard Staff Photographer