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North American deserts are home to tremendous butterfly diversity

The deserts of the American Southwest are home to a surprisingly diverse array of evolutionarily distinct butterfly groups, according to a new study. Photo by Don DeBold/Flickr
The deserts of the American Southwest are home to a surprisingly diverse array of evolutionarily distinct butterfly groups, according to a new study. Photo by Don DeBold/Flickr

March 23 (UPI) -- The deserts of Mexico and the American Southwest are home to an array of evolutionarily distinct butterfly groups, according to a new study.

The research -- published Tuesday in the journal iScience -- highlights the importance of an ecosystem thought of as being mostly inhospitable.

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"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," co-first author Chandra Earl said in a press release.

"Just because butterflies are closely tied to their host plants doesn't mean their diversity outcomes have to be similar," said Earl, who recently earned her doctorate degree from the University of Florida.

For the new survey, scientists amalgamated butterfly records from a variety of biodiversity databases, including GenBank, Barcode of Life Data System and Map of Life.

Instead of focusing strictly on the number of butterfly and plant species in any one location, researchers homed in on habitat with the highest concentrations of phylodiversity.

To calculate phylodiversity, scientists measure the degree of evolutionary relatedness among species. Places were greater phylodiversity host a wider array of evolutionarily distinct species.

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"We wouldn't have found the same result if we'd just counted the species like most biodiversity studies." said Earl, who also works as a research assistant at the Florida Museum of Natural History. "But we really wanted to step away from that, so we didn't lose the importance of evolutionary history."

Surprisingly, researchers found butterfly diversity across the deserts of North America was much greater than plant diversity.

"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" said Michael Belitz, the study's other co-first author.

"This makes butterflies less likely to clump into groups of tightly related species like plants do," said Belitz, a doctoral candidate in biology at Florida.

Of course, butterflies are also more mobile and less explicitly constrained by resource limitations, like water scarcity, which allows butterflies to respond more immediately to climate and ecological shifts.

"These factors all add noise to the data, where you won't see as strong a relationship between plants and butterflies as you might expect," said Belitz.

The authors of the new study hope their analysis will inspire other biologists to look at phylodiversity across larger geographical scales, as well as provide insights for conservationists working to protect butterfly diversity.

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"People already know about the decline of monarch butterflies, but the entire group is under threat," said Earl. "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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