Mexico, US Southwest Desert Proves to Be Butterfly Hotspot

Butterflies are ditching the budding flowers of the east and flocking to the more arid Southwest and Mexico, a new study finds.

(CN) — Like a daydream, butterflies seem to go where they please. The arch of their flight is erratic at times, seeming to befuddle anyone who wants to snap a photo while they are in midflight.

The insects are often photographed against colorful flowers and other plant life, an often-portrayed marriage much like the cohesion of peanut butter and jelly. But a new study published Tuesday says butterflies are fluttering their way to the warmest, wettest parts of North America, including deserts in Southwest United States and throughout Mexico.

The study published in the journal iScience found that butterflies are clustering in different parts of the continent as opposed to flowering plants and the insects are especially attracted to warm deserts.

“Our results make a strong case for habitat conservation across warm deserts in particular, especially because they are not already documented biodiversity hotspots,” the study authors said.

Changes across North America from climate change have dramatically reshaped the landscape for both plant life and animals. Previous studies of plant life in eastern parts of the U.S. show older forests than in parts of the Great Plains and western parts of the country. This is due to both cooling and drought. Researchers expected to find similar groupings between plant life and butterfly biodiversity, but that was not the case. There was more biodiversity of butterflies than plants in Mexico.

Butterflies have diversified from the abundant flowering-plants in the eastern part of the U.S. Instead, what researchers found in the West was butterflies following new plant lineages forming in the region, driven by the loss of forests, a warmer climate and a more arid region. The multiple types of butterflies recorded in the study shows that the insects have adapted, but it’s still unclear if other plant-eating animals reacted the same way to the absence of vegetation.

“When you think of desert, you don’t automatically jump to butterflies, but our results showed that this area is actually a really important hotspot for butterflies, even if it isn’t for plants,” said study co-author Chandra Earl from the University of Florida in a statement that accompanied the paper. “Just because butterflies are closely tied to their host plants doesn’t mean their diversity outcomes have to be similar.”

The study gathered data from multiple biodiversity databanks including GenBank, Barcode of Life Data System and Map of Life. The study authors said they did not simply count the number of butterfly and plant species in a given area, but instead tracked phylodiversity or the different types of insects and plants.

“We wouldn’t have found the same result if we’d just counted the species like most biodiversity studies,” Earl said. “But we really wanted to step away from that, so we didn’t lose the importance of evolutionary history.”

But butterflies are not exactly lining up in front of a microphone to discuss their fondness for the American Southwest. Researchers have their theories and it’s a bit of Occam’s razor, with the simplest answer probably staring all of us in the face.

“Most butterflies are generalists that don’t utilize just one host plant. This means that there are a lot of plants with no real functional relevance to butterflies” co-author Michael Belitz, a PhD biology candidate with University of Florida said in a statement. “This makes butterflies less likely to clump into groups of tightly related species like plants do.”

The study authors said their approach to comparing groups is a young method, which provides a large-scale comparison which spans across the continent. This new approach to looking at butterflies could hopefully provide for a new avenue in preservation.

“People already know about the decline of monarch butterflies, but the entire group is under threat,” Earl said. “We need to start paying better attention to insects, and this study helps prioritize North American deserts as a new target for conservation efforts.”

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