| Summary: | The water vole (<i>Arvicola terrestris</i>) is a microtine that occurs naturally in highly fragmented populations, which persist as metapopulations. Here, I investigate two metapopulations consisting of 183 habitat patches in two areas. The aim of this thesis is to investigate the factors that determine the dispersal decisions of individuals. Specifically, I examined 1) the ecological characteristics of the natal patch that underlie the emigration decision of an individual, 2) the characteristics of intermediate patches encountered during dispersal that affect dispersal distance; 3) differences in fitness between dispersing and philopatric individuals. Findings were: 1) Dispersal rate was high with no sex bias. The probability of a female dispersing was influenced by the presence of other females. There was a greater probability of males immigrating into larger patches with less related individuals thus leading to inbreeding avoidance. 2) Individuals settle at different distances from the natal patch. There was a negative relationship between dispersal distance and number of patches with opposite sex conspecifics. There was a higher probability of males immigrating into a patch if there were other adult females. For females, the probability of dispersing into a patch was proportional to the number of adults present in that patch. The results suggest that individuals sample patches before settling. 3) There were no differences in fitness between immigrating and philopatric individuals. These results suggest that individuals distribute themselves in the metapopulation according to the patch carrying capacity to maximize their own fitness. These findings are discussed in relation to the dynamics and persistence of metapopulations and consequences for fragmented populations in general.
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