The Effects of Food, Cover and Competition on Demography, Dispersal and Density of Voles
Lin, Yu-Teh Kirk
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Permalink
https://hdl.handle.net/2142/85405
Description
Title
The Effects of Food, Cover and Competition on Demography, Dispersal and Density of Voles
Author(s)
Lin, Yu-Teh Kirk
Issue Date
1999
Doctoral Committee Chair(s)
Batzli, George O.
Department of Study
Biology
Discipline
Biology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Zoology
Language
eng
Abstract
I investigated the demography, dispersal, and population dynamics of prairie voles (Microtus ochrogaster) and meadow voles ( Microtus pennsylvanicus) populations that occupied habitat patches that differed in availability of high quality food and amount of vegetative cover. I tested a series of a priori hypotheses regarding the effects of habitat quality on the movement of individuals between habitats. These hypotheses included the ideal-free distribution and the ideal-despotic distribution hypotheses, the source-sink and the balanced dispersal models, and the saturation presaturation dispersal hypothesis. My results had led to several conclusions. First, the amount of vegetative cover had a greater impact on vole populations than did availability of high quality food. Food was more important in habitat patches with less natural food and in late season when natural food declined. Second, unequal fitness occurred among different habitats types, however, cost of habitat selection rather than despotism may have maintained the fitness difference. Third, the patterns of dispersal generally conformed to the balanced dispersal model, although unbalanced dispersal occurred in prairie voles, probably due to a time lag in response to habitat differences. Fourth, density-dependent feedback had a major effect on in situ net recruitment in high quality habitats and on net movement in low quality habitats. Fifth, the patterns of emigration in favorable habitats appear to be neither growth-dependent nor directly density dependent for either species. Sixth, interspecific competition alone seemed unlikely to produce the habitat segregation observed in the nature. Rather, differences in habitat preference, dispersal ability, and resident effects seem likely to couple with interference competition to explain differences in habitat use. Seventh, different factors seemed to affect dispersal of each sex. Resource competition likely drove the dispersal of females, whereas competition for mates likely drove the dispersal of males. Finally, there was no overall difference in survivorship between emigrants and the background population in either species, which supported the hypothesis that dispersal and philopatry were components of a mixed evolutionary stable strategy.
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