A recent study published in the Journal of Paleontology has been making international headlines with the discovery of the fossils of four new families of insects whose extinction may offer insight into how some animals respond to climate change and its effect on biodiversity.
Dr. Bruce Archibald and Dr. Rolf Mathewes, both faculty members at SFU, co-authored the study along with Dr. David Greenwood of Brandon University, Manitoba. The three have worked together as a team in the past, looking at the larger question of communities that existed long ago in what is British Columbia and northern Washington state today.
Archibald explained, “We each bring a different perspective to these things, and the greater project is to look at communities about 50 million years ago here in British Columbia and northern Washington, and how they relate to climate, how climate affected these communities, the diversity, where they lived by geography, those sorts of issues.”
When he first came to inspect the newly discovered fossils near Cache Creek, BC and Republic, Washington, Archibald immediately realized there was something exciting and new to be learned here. The fossils are of extinct scorpionflies that belong to a previously unknown families.
What interested Archibald about the fossils was the story of a family of instincts that popped up at that time, and then abruptly went extinct, a rare story in the narrative of insect evolution in the Cenozoic, the last 66 millions years since the extinction of the dinosaurs.
“In what you could call our modern era, that’s the general pattern, accumulation,” said Archibald. “There are some losses, some extinctions, but they’re kind of scattered throughout insects, they don’t really follow a pattern. But here we see with this one a very closely related family, a cluster of four family extinctions, all very closely related.”
At the time, there were six groups of closely related scorpionflies. By the end of the Eocene, an early portion of the Ceonzoic, only two remained. When it came to answering the question of why these four families didn’t make it through the era, Archibald, Mathewes, and Greenwood came up with what they believe are two strong theories: ants and climate change.
Scorpionflies are scavenging insects that feed on the remains of other insects. The research team suggests that the rise and diversification of the ant, another scavenger, may have proved too much competition for the scorpionfly families. Archibald believes it was a combination of this competition for resources as well as a change in climate that may have led to the insects’ demise.
Archibald describes southern British Columbia of 50 million years ago as a very different environment than we see today. In a world that was very warm at the time, BC and northern Washington was a cooler upland, with little variation in temperature from the hottest summer months to the coldest winter days.
“In the winter we may have seen few frost days, and that allowed organisms that today are restricted to the tropics to range right up into this region,” explained Archibald. “So, organisms which don’t necessarily require heat but can’t stand cold winters. And that’s really the big deal.”
In a previous study by Archibald and Greenwood on the biodiversity of the region during the Eocene, they found diversity comparable to a tropical rainforest in Central America, according to Archibald. “It was quite shocking to see in a cool, mid-latitude upland.”
When the global climates eventually cooled, insects there were forced to adapt, relocate to warmer climates, or go extinct. In the case of the scorpionfly, Archibald suggested that the latter may have been the fate of those four families. “Either you can adapt to where you are, or move and adapt to that, or you’re toast,” he said.
The modern variation of the scorpionfly persists in cold areas, suggesting that those families managed to adapt to the colder climates, which in turn leads to the theory that those families that went extinct just couldn’t make that leap.
Arbichald likens the extinction of the scorpionfly families to the rise of the pine beetle that has been seen in British Columbia in recent years, in terms of the effect of climate change on their populations. While the extinct scorpionflies show researchers what happens to populations when a period of global warming comes to an end, the pine beetle illustrates a community thriving due to climate change. Warmer winters and less frost in recent years have lead the pine beetle to destroy 18 million hectares of lodgepole pine in BC.
Concluded Archibald, “It helps us understand how organisms and communities change when climate does.”
