The Dynamics of Animal Distribution: An Evolutionary/Ecological Model (Ph.D. Dissertation)
Investigators have sometimes assumed that the factors underlying animal distribution are too complex to lend themselves to normative modelling. In this work, a model of environment and community interaction is constructed which lends itself to the latter kind of interpretation. It is posed that spatially-varying rates and magnitudes of availability of moisture at given locations act as stresses on the nature of community infrastructure, and secondarily on the rates at which new populations may become integrated into these. Populations are thereby viewed as tending to change range in common directions, though at overall rates remaining peculiar to each. This interpretation is shown to lend itself to a synthesis of ecological and evolutionary approaches to distributional controls, and to suggest some novel viewpoints on the nature of evolutionary change and ecological interaction in general. The model is tested through a series of empirical studies of distribution patterns of all mammal and herptile species inhabiting the middle one-half of the United States. The results of the tests are in general consistent with expectations; for example, highly stressed community structures are shown to be correlated with smaller range sizes, greater variation in range sizes, and direction of dispersal. Spatial variation in stress magnitude is also shown to influence rates of faunal interaction between locations. The study concludes with a discussion of means whereby ecological modes of analysis can be extended to the study of evolutionary change over longer periods of time through the present model.
Charles H. Smith. The Dynamics of Animal Distribution: An Evolutionary/Ecological Model (Ph.D. Dissertation). Champaign-Urbana, IL: Department of Geography, University of Illinois, 1984.