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Title: An investigation on the changing processes and emergent patterns of occupancy from the core to the edge of the species range, and the consequences for onward expansion
Author: Morgan, William Hugh
ISNI:       0000 0004 7652 7001
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2018
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The geographical distributions of many species are changing in response to rapid environmental change, and lags between the emergence and colonisation of new habitat areas are common. Given many species distributions are not at equilibrium with the environment, a greater understanding of the processes that underpin range expansion is required to predict where lags might emerge. Here I explore how population processes lead to emergent patterns of occupancy from the core to the edge of the species range. Working with water voles (Arvicola amphibius) in the UK, I carry out large scale surveys of a recovering metapopulation to explore the contribution of environment and the colonisation process in limiting range extent. I then use experimental translocations of water voles to quantify drivers of colonisation and local persistence, and the spatial scale over which these processes operate. I also explore the role of sociality and conspecific attraction in driving the formation of local populations at low landscape densities, and investigate the potential for between-individual variation in a behavioural trait to influence the formation of these spatial structures. Onward expansion was limited by the spatial scale of the colonisation process, and abrupt declines in occupancy at the range edge suggest that immigration increased the chance of local persistence. Social attraction led to build up of local populations, while more distant, equally suitable habitat area remained vacant. Using an individual based modelling approach, I then test the effect of different dispersal strategies on the rate of range expansion for biologically realistic mating systems. Mating finding requirements lead to slower expansion, though avoiding high density patches and mate-searching reduced these lags. Lags may emerge from processes across a range of spatial scales, though species translocations may offer a potential tool for mitigating these lags, and prevent substantial declines in geographical distributions.
Supervisor: Lambin, Xavier Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Biogeography ; Global environmental change ; Habitat selection ; Animals ; Arvicola