College of Liberal Arts and Sciences

Rising Sea Levels after Last Ice Age Explain Caribbean Extinction of Bats

Date: October 23, 2012

Most extinction loss explained by loss of area caused by rising seas

deglaciation of Caribbean

Outline of Caribbean islands at Last Glacial Maximum and present.

Photo:: Liliana M. Dávalos

STONY BROOK, NY, October 23, 2012 – Global climate change is expected to have lasting impacts on populations worldwide, even driving some to extinction. The last time ecological communities experienced climate change on such a scale was at the end of the last glaciation, some 12,000 years ago. In new research published in the journal Ecology and Evolution, Liliana M. Dávalos, Assistant Professor in the Department of Ecology and Evolution at Stony Brook University, and her collaborator, Amy Russell, from Grand Valley State University, demonstrate that rising sea levels caused by deglaciation explain most of the extinction of bats in the Caribbean islands.

In the article, entitled, “Deglaciation explains bat extinction in the Caribbean,” Assistant Professor Dávalos and Amy L. Russell (Assistant Professor, Biology Department at GVSU), explain that one dramatic consequence of deglaciation was the abruptly rising sea levels that drowned vast expanses of low-lying islands. The researchers used deep sea bathymetry and GIS to model the extent to which land would have been exposed in the Caribbean at the peak of the glaciation, when sea levels were 125 meters below their current levels. Combining the record of current and fossil bats with the area for each island, they then used a simple mathematical relationship between the number of species and area of an island to estimate the number of local extinction events that could be explained by the change in area.

The high extinction rate following deglaciation in the Caribbean has been noted for decades. Rich fossil deposits in the Bahamas and the Greater Antilles attest to a fauna that no longer exists. Among mammals, most terrestrial species were wiped out around the time humans arrived, and many bat populations that persisted elsewhere went extinct on one or several islands. Some bat species went extinct altogether, including the Cuban vampire bat and the Puerto Rican flower bat. The many instances of both extinction and persistence of bats across dozens of islands made it an ideal system for investigating how climate change may shape island fauna.

Together, Professors Dávalos and Russell found that most of the species loss in the Bahamas and Greater Antilles could be explained by the loss of area caused by rising sea levels. In the Lesser Antilles the mathematical models pointed out gaps in the fossil record of most islands. The large impact of area loss on species loss held, even after excluding species that may have colonized the islands recently, and accounting for coral accretion in the Bahamas.

“There have been many explanations before as to why so many bat populations collapsed: cave drowning, the arrival of new species, lack of tolerance to the warmer and wetter climate of the Holocene are examples,” said Professor Dávalos.

“We were expecting area loss to be important in explaining extinction, but not as important as we found. This drives home the point that rising sea levels pose great risks to biodiversity today,” Professor Russell said.

This work was funded in part by the National Science Foundation.

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