Metapopulation ecology has developed to explain the population dynamics that occur in spatially structured landscapes. In this study, I combined an empirical laboratory approach, using metapopulation microcosms of Callosobruchus maculatus and its endospecific parasitoid Anisopteromalus calandrae, with mathematical population models in order to investigate several fundamental metapopulation processes. Population dynamics in these systems can be studied at two scales; the local patch-wise scale and the regional metapopulation scale. Here I demonstrate that in both homogeneous and heterogeneous landscapes knowledge of local scale demographic processes is necessary in order to understand regional metapopulation dynamics. The differences in the rate and net direction of dispersal between patches as a result of the permeability of the matrix in homogeneous systems and density-dependent dispersal in heterogeneous systems were also explored. Metapopulation dynamics rely on a balance between local extinctions and recolonisations. Therefore, increasing local mortality rates is likely to be detrimental to the persistence of the system. Here, the impact of several common harvesting strategies on the persistence of a host-parasitoid metapopulation was examined. Contrary to expectation I discovered that harvesting in these systems increased both local and regional population sizes. The increased population size as a result of increased mortality was explained in terms of a hydra effect, where harvesting relaxed density-dependence acting on local host populations. The results presented in this thesis are relevant for the monitoring, management and conservation of natural metapopulations and the development of sustainable harvesting strategies in structured landscapes.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:531791 |
| Date | January 2010 |
| Creators | Strevens, Chloë |
| Contributors | Bonsall, M. B. |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://ora.ox.ac.uk/objects/uuid:3e6c30d1-6c88-42d0-92d8-83c59f4269d2 |
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