Dynamics of large mammal range shifts and extinction : evidence from the Holocene record of Europe

Abstract

The global extent of past and present biodiversity loss is increasingly well documented, but a focus on investigating timings and correlates of final species extinctions often means that patterns and processes associated with earlier population declines are poorly understood. I used a comprehensive database of zooarchaeological records and regional last occurrence data in order to investigate dynamics of range shift, contraction, expansion and fragmentation of Europe’s large mammals over the past 11,500 years, the Holocene Epoch. As a relatively climatically stable period that also witnessed the rapid growth of human populations, it was an ideal model system for studying human impacts on biodiversity over time. Whilst there were inherent biases associated with zooarchaeological data, I was nonetheless able to identify diverse mechanisms of large mammal decline across different species. Despite low numbers of faunal records I was able to attribute the Late Holocene extinction of the European wild ass (Equus hydruntinus) to habitat fragmentation associated with postglacial climate-driven vegetation change. Using bootstrapping to control for sampling bias, I then reconstructed temporal and spatial patterns of range contraction across Europe’s temperate large mammal fauna from the Mesolithic to the Late Medieval and found that overall, large herbivores experienced significant declines prior to large carnivores. Finally, by combining data from the zooarchaeological, historical and ecological record, I was able to reconstruct through-time patterns of regional extirpation to identify major correlates of species declines as well as calculate species-specific tolerances to human population density. Overall results demonstrate an extinction filter that removed large-bodied species with low tolerance to human impacts from the European landscape from at least the Mid-Holocene onwards. The results from the thesis have relevance across a range of disciplines from palaeontology and zooarchaeology, to ecology and the current day conservation management of large mammals.