Fossils of extinct scorpionflies found in B.C.
Discovery may offer insight into effect of climate change on diversity
Ancient fossils of an extinct family of insects have been found in British Columbia and northern Washington state, and a Canadian biologist says they may hold valuable lessons about climate change and evolution.
Bruce Archibald of Simon Fraser University said researchers found fossils belonging to a previously unknown family of scorpionflies near Cache Creek, B.C., and Republic, Wash., while conducting fieldwork.
Scorpionflies are flying scavengers that feed on the remains of other insects.
The new scorpionfly family has been named Eorpidae after the age of history in which the insects lived, the Eocene epoch. A family is a fairly narrow taxonomic group that can contain multiple genuses, which in turn can contain multiple species.
Archibald said the Eorpidae scorpionflies lived about 50 million years ago. They may have gone extinct because of competition from other species or climate change.
"By looking at fossil insects and their diversity and their biogeography and all, we can try and understand broader principles about how communities work in relation to climate," he said.
"When we look out at forests today and see, for example, the mountain pine-beetle devastation, we can see that with a little bit of climate change we get all this tremendous impact, which is going to have a strong effect on us economically and socially."
The pine beetle has destroyed more than 18 million hectares of lodgepole pine in B.C. and turned vast swaths of once-green forests to an orange-red and then to black.
Scientists have argued the beetle's range was once limited by annual freezing, but the voracious insects have since spread because of climate change.
4 of 6 scorpionfly families now extinct
Archibald said the Eorpidae scorpionflies lived at a time when the global climate was much warmer. When climates outside of the tropics cooled, seasonal temperatures widened, forming patterns of freezing winters and hot summers. Scorpionflies had to migrate to the hot tropics, evolve a tolerance for colder winters or go extinct, and some families of scorpionflies met the latter fate.
Archibald noted that there are now only two families of scorpionflies left, even though there were once six.
Researchers also believe the insects could have faced increasing competition for food from ants, which had begun to diversify, Archibald said.
Ants can recruit their nest mates, cover a large territory with scouts, and clean out an area very quickly, he said, adding such a development would have made it hard for a diversity of scorpionflies to exist.
Archibald, along with David Greenwood of Brandon University in Manitoba and Rolf Mathewes, also of SFU, co-authored a research paper of their findings, published recently in the Journal of Paleontology.