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Research: Sky island mammals can travel to breed

New research hints that most mammals living on sky islands – largely isolated mountaintop ecological niches – have unoccupied lowland habitat that could be crossed for breeding.

“Mammals can actually move around between these islands and achieve intermingling,” said University of Colorado Assistant Professor Robert Guralnick, who co-authored the study.

The work corroborates findings of single-species studies, broadening the concept to show likelihood of links across several species now and during the last ice age.

Guralnick and Eric Waltari, of the Sackler Institute of Comparative Genomics at the American Museum of Natural History, used computer models to study 13 small mammal species in the Great Basin, which stretches roughly from Utah to California and from Oregon and Idaho to northern Arizona.

Almost all of the species lived at broader elevation ranges 21,000 years ago than they do now, and nearly all now have unoccupied low-elevation habitat, computer models show.

Gene pool mingling does not require a constant flow of animals, Waltari said.

“Just that one migrant every few years is enough,” he said.

Guralnick warns the study looked only at the Great Basin and only at mammals, though the “ecological niche modeling” they used could be applied in a variety of settings for various plants or animals.

The Arizona Game & Fish Department has contacted the researchers about using the technique to study sky islands here, such as the Chiricahua Mountains southeast of Tucson, Guralnick said.

“We can use the modeling techniques as a window into those areas,” he said.

Though the study shows a widespread potential for mammals to move, it does not shoot down the sky island concept, Guralnick said.

“There is certainly plenty of evidence that sky islands are definitely unique habitats.”

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