The Ups and Downs of the Mammal World: How Mammal Diversity Has Changed in the United States throughout the 20th Century

Presenter: Kendra Walters

Faculty Mentor: Edward Davis, Samantha Hopkins

Presentation Type: Oral

Primary Research Area: Science

Major: Geology, Biology

Funding Source: Presidential Undergraduate Research Scholar, Undergraduate Research Opportunity Program, $5,000

Biodiversity loss is recognized as a global crisis. Current research strives to create models that predict regions that are at high risk for a significant drop in biodiversity levels. These models must be scaled by analyses of historic changes in biodiversity. However, no study has yet to analyze the changes in mammal richness in the United States at a high enough spatial and temporal resolution to produce a predictive model of mammal diversity. Our research is a high-resolution analysis of the changes in mammal richness in the contiguous United States from 1906 to 1995. We collected mammal occurrence data from the online database VertNet and BISON and individual museum collections, divided it into ten year increments, and used scripts in R to produce sampling-standardized patterns of mammal richness for each decade. We then analyzed the geographic distribution of change in richness over the 20th century. From our results, we were able to determine which regions experienced a significant rise in diversity levels and which experienced a significant drop. We also identified regions where sampling intensities remain too low to conclusively determine how mammal diversity has changed. Regions experiencing the most severe biodiversity changes, as well as those without adequate data, should be focal areas for continued research in conservation efforts.

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