When discussing how one species evolves into two or more distinct species, scientists often surmise that the major contributing factor is the uplift of mountains, which separates populations and allows them to develop in different ways.
Not so fast, says Utah State University entomologist James Pitts.
"You might especially expect this of plants and animals in the desert, where the terrain is typically isolated by mountain ranges," he says. "But for some organisms, species variation appears to have happened much more recently and the evidence points to glaciations that occurred during the Ice Age."
An assistant professor in USU's department of biology, Pitts has found evidence that vast glaciers were responsible for isolating groups of velvet ants, leading to the formation of distinct new species.
Taking place from 2 million to as little as 10,000 years ago, the process is much more recent than the time periods when the Rocky Mountains and the Colorado Plateau arose.
Pitt's research reveals that roughly one-third of velvet ant species emerged during the Ice Age.
"You can't make a sweeping claim that mountains caused all species variation," he added.
To make this discovery, Pitts gathered velvet ants from an area near St. George.
Using molecular data collected from the current-day specimens and morphological data collected from fossils, Pitts and his students employed mathematical algorithms to assign probable dates of origin to each branch of the insect's known family tree.
This information, coupled with the fossil data, helped determine when various species emerged.
The work was published in the report "Evolution of the nocturnal Nearctic Sphaeropthalminae velvet ants (Hymenoptera: Mutillidae) driven by Neogene orogeny and Pleistocene glaciations," found in the July 2010 issue of "Molecular Phylogenetics and Evolution."
A solitary insect, velvet ants are actually wasps that pack a powerful sting, earning them the nickname "cow killers" in some parts of the country.
"Female velvet ants lack wings so they resemble ants," Pitts explained. "The ‘velvet' part of their name comes from the dense, velvety hair that covers their bodies."
A USU faculty member since 2005, Pitts is one of only a handful of researchers worldwide who study velvet ants.
The insects "are very abundant and are probably much more ecologically significant than we give them credit for," he said.