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Title: Thresholds for ecto-parasite persistence in a vertebrate metapopulation
Author: Shati, A. A. M.
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2007
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This thesis investigates how host metapopulation processes (local population size and dispersal) affect the prevalence and persistence of ectoparasites of water voles (Arvicola terrestris). Water voles have been found to persist as metapopulations in the study areas in northern Scotland (fragmented populations with frequent extinction and colonisation and linked by dispersal). The ectoparasites examined were: 1) three tick species: Ixodes trianguliceps, Ixodes ricinus and Ixodes apronophorus; 2) four flea species: Megabothris walkeri, Peromyscopsylla spectabilis, Ctenopthalmus nobilis and Histrichopsylla talpae; 3) two species of mites: Laelaps muris and Hyperlaelaps amphibia. The prevalence and persistence of these parasites were examined over three years in 155 vole sub-populations which varied in density and isolation from each other. The effect of connectivity between vole sub-populations (where the number of immigrants a patch receives can be indexed by both the size of populations in the surrounding area and distance to these populations) on the spatial population dynamics of two tick species: a specialist small mammal tick (I. trianguliceps) and the sheep tick (I. ricinus) were examined. Connectivity had positive effects on the prevalence and burden of I. trianguliceps but not on I. ricinus. The relative effect of local (vole population size/density) versus metapopulation processes (connectivity) on the burden and prevalence of fleas was investigated. Local population dynamics had a weak influence on flea burden and prevalence (no or negative effect) whereas number of infected voles in neighbouring populations increased flea burden and prevalence. Extinction thresholds, taken as connectivity or proportion of habitat loss/“disinfection” below which a parasite cannot persist, were examined and compared for all parasites. Overall, the findings of this study show that host spatial structure and distance dependent dispersal (heterogeneous mixing) are important factors that affect parasite persistence. Therefore, these factors should be considered when planning conservation and disease control programmes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available