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The Evolution of Body Size on Islands: A Computer Simulation
Richard J. Wassersug, Harold Yang, J. John Sepkoski, Jr. and David M. Raup
The American Naturalist
Vol. 114, No. 2 (Aug., 1979), pp. 287-295
Stable URL: http://www.jstor.org/stable/2460224
Page Count: 9
You can always find the topics here!Topics: Biomass, Evolution, Mammals, Dwarfism, Simulations, Body size, Species, Species extinction, Carrying capacity, Predators
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We have modified a preexisting computer model that generates phylogenetic trees by a stochastic branching process (Raup et al. 1973; Raup and Gould 1974; Gould et al. 1977) in order to examine the consequences of random evolution of size in a biomass (resource) limited universe. Evolution toward a few lineages of large average biomass increases variance on the total biomass of the system; evolution toward many lineages of small average size decreases the variance in the total biomass. This means that under strict conditions of biomass limitation, dwarfism permits tighter tracking of the carrying capacity. Evolution toward small size is not a common phenomenon except for species of large mammals isolated on small islands or in certain late and post-Pleistocene continental deposits. Our model may be comparable to situations where there is strict resource limitation, neither immigration nor emigration, and no selection favoring large size. We suggest that, for strictly statistical reasons, dwarfism is a common though not universal expectation under these conditions.
The American Naturalist © 1979 The University of Chicago Press