Evol Ecol Res 1: 21-48 (1999)     Full PDF if your library subscribes.

Cohesion and survivorship of a rodent community during the past 4 million years in southwestern Kansas

R.A. Martin1* and K.B. Fairbanks2

1Department of Biological Sciences and 2Department of Mathematics and Statistics, Murray State University, Murray, KY KY 42071, USA

Author to whom all correspondence should be addressed.
e-mail: robert.martin@murraystate.edu


Preliminary studies of rodent community evolution in the Meade Basin of southwestern Kansas do not support the hypothesis that all organismal communities are tightly bound, highly co-evolved units. With the Jaccard Index as a measure of similarity, rodent community composition appears to change continually through the 4.2 million year study period, thus supporting the classic ‘open’ community concept of Gleason (1926) and Whittaker (1975). This also logically suggests that many predator–prey systems are opportunistic, although larger predators and prey may co-exist for longer periods if their species lifespans are longer. Survivorship analyses show that extinction rates are statistically similar for much of late Pliocene time, but escalate rapidly during the middle Pleistocene. Survivorship data are best fit by a linear model, providing empirical support for the idea that rodent community structure is determined primarily by the interplay of stochastic climatic and biotic influences. An exponential distribution (straight line) on a semi-log survivorship plot in real time may indicate either a dynamic (Red Queen) or stable (evolutionarily stable strategy) equilibrium. The ‘smoking gun’ for Red Queen competitive co-evolution in a study system will be data demonstrating that species in a community evolve in the presence of guild associates, combined with independent climatic data identifying a pacemaker for continual, albeit stochastic, environmental change during the study period. Preliminary data from the Meade Basin rodent community support a ‘weak’ version (Ridley, 1993) of the Red Queen hypothesis.

Keywords: carnivore, community similarity, extinction, immigration, Pleistocene, Pliocene, Quaternary, Red Queen, survivorship.

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        © 1999 Robert. A. Martin. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

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