Synergistic Interaction Between Temperature and Algal Abundance on a Size-Structured Daphnia Population

Wang, Xueqi
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University of Guelph

Reductions in body size has been suggested as a universal response to global warming for many species. Here, I investigate the population level consequence of changes in body size and size-dependent life history characteristics using size-structured matrix projection models. Analyzing experimental data from 412 isolated Daphnia magna individuals raised under varying temperature and food levels, I show that temperature and food availability interact in a complex fashion in shaping Daphnia population size structure and the asymptotic population growth rate. I find food abundance determines the direction of population growth and temperature affects the magnitude of demographic variability, mediated through simultaneous limitation on size-dependent growth, survival and reproduction. Given the evidence for the synergistic interaction between temperature and food abundance on Daphnia individual fitness and population demography, I argue that accounting for the variation in food availability is crucial in understanding how populations might respond to rapid climate change.

global warming, body size, food abundance, life history characteristics, matrix projection model, population dynamics, vital rates