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Density, climate and varying return points: an analysis of long-term population fluctuations in the threatened
Jérôme Pellet1, Benedikt R Schmidt, Fabien Fivaz
1Laboratory for Conservation Biology, Department of Ecology and Evolution, University of Lausanne, Biology Building, 1015, Dorigny, Switzerland. jerome.pellet@amaibach.ch
Abstract:
Experimental research has identified many putative agents of amphibian decline, yet the population-level consequences of these agents remain unknown, owing to lack of information on compensatory density dependence in natural populations. Here, we investigate the relative importance of intrinsic (density-dependent) and extrinsic (climatic) factors impacting the dynamics of a tree frog (Hyla arborea) population over 22 years. A combination of log-linear density dependence and rainfall (with a 2-year time lag corresponding to development time) explain 75% of the variance in the rate of increase. Such fluctuations around a variable return point might be responsible for the seemingly erratic demography and disequilibrium dynamics of many amphibian populations.
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