The structural complexity of a habitat dictates the availability of shelter, and shelter may affect population and community structure in many systems. I test a specific hypothesis of the effects of habitat structure, the demographic bottleneck hypothesis, which proposes that shelter limitation can control population size structure and recruitment density by acting strongly on only one size class. To test this hypothesis, I first experimentally manipulated the size-specific availability of shelter for stone crabs in St. Joseph Bay, Florida, and I found evidence for a bottleneck that affects the growth and fecundity of large stone crabs. / These results provide support for the demographic bottleneck hypothesis, but they do not address its generality. It is a common problem in ecology that we rely on singular tests of hypotheses and the scientific generalization of these results. To address this problem, I suggest that we repeat experiments and use random factors more often in experimental designs. The use of random factors can lead to an unbiased estimate of the generality of patterns and to an understanding of the mechanisms that underlie these patterns. / To address these concerns, I repeat the shelter supplementation experiments in St. Joseph Bay and in three additional haphazardly-selected bays in the northeast Gulf of Mexico in a mixed-model experimental design. In addition to the shelter manipulations, which test the bottleneck hypothesis at the individual level, I use observational and experimental techniques to examine five biotic factors (habitat structure, food, predation, settlement, and competition) that may contribute to population-level differences among bays. / I find differences among bays in the natural population-level parameters of stone crab size structure and density and in crab responses to shelter supplementation. The demographic bottleneck hypothesis best accounts for these differences. I show that there are demographic consequences of shelter limitation on stone crab growth and fecundity at the individual level, and that these effects appear to explain population-level differences among bays. However, the demographic bottleneck hypothesis does not explain all the differences in crab populations. The bottleneck effects are mediated by differences in food, competition, and settlement among bays. / Source: Dissertation Abstracts International, Volume: 56-11, Section: B, page: 5894. / Major Professor: Daniel S. Simberloff. / Thesis (Ph.D.)--The Florida State University, 1995.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_77605 |
| Contributors | Beck, Michael William., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 155 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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