Biology ETDs

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An important component of evaluating the consequences of climate change is to understand not only how climate trends, such as warming, affect species abundance but also how increasing climate variability will change population abundances. Studies on species' sensitivities to interannual variability are rare because they require long-term data collected either over naturally variable climate conditions or within direct manipulations of year-to-year variability. Physiology, functional traits, and diet composition related to resource acquisition or reproduction may be valuable predictors of species sensitivities to changes in both climate mean and variability. We predicted that species with certain physiologies, such as large body mass, and functional traits such as caching, would be less sensitive to aridification in mean climate while strategies, and large litter sizes and flexibility in storage of reserves as fat, would facilitate benefits from increases in the variance of aridity by enabling populations to boom in ‘good’ years. We integrated new and published physiological, trait, and diet data with 30 years of small mammal abundance data over highly variable natural climate conditions to test this hypothesis for two common dryland ecosystem types in the southwestern US. Our results revealed we revealed that species with certain physiologies (larger mass and larger variation in mass) were less sensitive to aridification in mean climate, and that species with certain physiologies, traits, and diet composition (smaller mass, smaller variation in mass, larger variation in percentage body fat in the spring, less litters per year, and higher percentage of annual plants in diet) benefited from increases in the variance of aridity. In sum, this study demonstrates that the life history and functional traits as well as foraging strategies of small mammals can provide a generalizable framework to predict the sensitivities of population abundance to both non-stationary components of climate change: the mean and the variance.

Document Type


Degree Name


Level of Degree


Department Name

UNM Biology Department

First Committee Member (Chair)

Dr. Seth Newsome

Second Committee Member

Dr. Jennifer Rudgers

Third Committee Member

Dr. Joseph Cook

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Biology Commons