Chihuahuan Desert kangaroo rats: nonlinear effects of population dynamics, competition, and rainfall

Using long-term data on two kangaroo rats in the Chihuahuan Desert of North America, we fitted logistic models including the exogenous effects of seasonal rainfall patterns. Our aim was to test the effects of intraspecific interactions and seasonal rainfall in explaining and predicting the numerical...

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Bibliographic Details
Published in:	Ecology (Durham) 2008-09, Vol.89 (9), p.2594-2603
Main Authors:	Lima, Mauricio, Ernest, S.K. Morgan, Brown, James H, Belgrano, Andrea, Stenseth, Nils Chr
Format:	Article
Language:	eng
Subjects:	Animal and plant ecology Animal populations Animal, plant and microbial ecology Animals Biological and medical sciences Chihuahuan Desert Climate models Demecology Desert Climate desert rodents Deserts Dipodomys Dipodomys - classification Dipodomys - physiology Dipodomys merriami Dipodomys ordii Dipodomys spectabilis Ecological modeling Ecology Ecosystem Fundamental and applied biological sciences. Psychology General aspects interspecific competition intraspecific competition kangaroo rat Kangaroos limiting factors Modeling Models, Biological Models, Statistical Nonlinear Dynamics nonlinear models Population Dynamics population growth population processes Rain Rats Rodents seasons seeds Species Specificity Summer summer rainfall theoretical models Time Factors winter
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Summary:	Using long-term data on two kangaroo rats in the Chihuahuan Desert of North America, we fitted logistic models including the exogenous effects of seasonal rainfall patterns. Our aim was to test the effects of intraspecific interactions and seasonal rainfall in explaining and predicting the numerical fluctuations of these two kangaroo rats. We found that logistic models fit both data sets quite well; Dipodomys merriami showed lower maximum per capita growth rates than Dipodomys ordii, and in both cases logistic models were nonlinear. Summer rainfall appears to be the most important exogenous effect for both rodent populations; models including this variable were able to predict independent data better than models including winter rainfall. D. merriami was also negatively affected by another kangaroo rat (Dipodomys spectabilis), consistent with previous experimental evidence. We hypothesized that summer rainfall influences the carrying capacity of the environment by affecting seed availability and the intensity of intraspecific competition.
ISSN:	0012-9658 1939-9170