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The Demographic Basis of Population Growth: A 32‐Year Transient Life Table Response Experiment
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International audience. ABSTRACT It has recently been recognised that populations are rarely in demographic equilibrium, but rather in a ‘transient’ state. To examine how transient dynamics influence our empirical understanding of the links between changes in demographic rates and population growth, we conducted a 32‐year study of Columbian ground squirrels. The population increased rapidly for 10 years, followed by a 2‐year crash, and a gradual 19‐year recovery. Transient life table response experiment (LTRE) analysis showed that demographic stochasticity accounted for approximately one‐fourth of the variation in population growth, leaving the majority to be explained by environmental influences. These relatively small rodents appeared to have a slow pace of life. But unlike the general pattern for large mammals with slow life histories, ground squirrel survival did not exhibit low variation associated with environmental ‘buffering’; instead, survival varied substantially over time and contributed substantially (78%) to changes in abundance over the long‐term study, with minor contributions from reproduction and unstable stage structure.
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