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Dr. Larisa DeSantis, Vanderbilt University – Mammal Survival and Deep Time

In today’s Academic Minute, Dr. Larisa DeSantis of Vanderbilt University explains the evolutionary strategy that allowed mammals to survive multiple shifts in the Earth’s climate.

Larisa DeSantis is an Assistant Professor in the Department of Earth and Environmental Sciences at Vanderbilt University.  Her research focuses on revealing the ecology and biology of ancient mammals, with a focus on assessing past responses to climate change.  She earned her Ph.D. in Zoology at the University of Florida.

About Dr. DeSantis

Dr. Larisa DeSantis – Mammal Survival and Deep Time

Climate change and habitat loss are occurring at unprecedented rates around the globe.  While it can be difficult to predict how plants and animals will respond to such changes in the future, we can learn important lessons from the past. 

In collaboration with graduate students at Vanderbilt University, we examined how mammalian families were distributed over space and time in the continental US.  Using a database of fossil occurrences and GIS we determined relative range areas for families of mammals – allowing us to better understand what made some mammals more successful than others.

In short, diversity is critical to determining which families are most widely distributed at any given interval of time.  Families containing a greater diversity of species were able to occupy greater land areas, and this has held true during all geologic epochs since the evolution of most modern mammalian families, approximately 56 million years ago.  As no two species can do exactly the same thing, having more species may allow a family a greater chance of success by investing in different lifestyles. This is analogous to “hedging one’s bets” in a game of roulette by placing chips on more numbers, as opposed to just one.   

Mammals also maintain similar range sizes through time, relative to one another.  However, the mid-point of family ranges moves southeast over time and may be in response to a general pattern of climatic cooling since roughly 50 million years ago.  Collectively, we reveal the potential adaptability of mammalian families with a diversity of lifestyles to maintain dominance even in the face of dramatic environmental change. 

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