| dc.description.abstract | The Bechstein’s bat, Myotis bechsteinii, is known as one of Britain’s most
elusive mammals. Critical information on the species is lacking, hindering
evidence-based conservation and management in a human-dominated
landscape. In this thesis, I used a combination of molecular and landscape
approaches to assess the genetic health and population genetic structure of M.
bechsteinii and understand how the British landscape affects the species
habitat and its connectivity. I also aimed to develop new molecular tools, such
as non-invasive genetic sampling and molecular ageing, which could then be
used to better monitor the species.
Data from nuclear markers (microsatellites) showed high levels of genetic
diversity and little inbreeding across the species range, though genetic diversity
was slightly lower in Britain than in mainland Europe. Bayesian and spatial
Principal Components (sPCA) analysis showed a clear separation between
British and European populations. This analysis also revealed that in Europe
the Italian population south of the Alps was found to constitute a different group
from other sites. In Britain, there was genetic structuring between the northern
and southern part of the species range. Despite there being little genetic
divergence in mitochondrial DNA (mtDNA) sequences throughout most of
Europe, the mtDNA patterns in Britain confirmed this separation of northern and
southern populations. Such genetic structuring within Britain — in the absence
of any obvious physical barriers — suggested that other features such as landuse
may limit gene-flow. To better understand how the species interacts with
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the British landscape, I used a landscape genetic approach, habitat suitability
modelling using presence-only data and a landscape connectivity analysis. The
negative association of M. bechsteinii presence with distance from woodland
was identified as the main variable determining habitat suitability, while the
landscape genetics results highlighted the importance of woodlands for gene
flow. M. bechsteinii habitat was highly fragmented and only showed good
connectivity if the species was able to disperse over 5,000 m. These results
subsequently highlight the importance of woodlands not only for providing
suitable habitat, but also in maintaining genetic connectivity between
populations.
Then, I investigated the use of non-invasive capture-mark-recapture (CMR) and
demographic history models to estimate the population size and changes of M.
bechsteinii. Bat droppings were collected below roosting sites of a single
colony. After species identification, the 123 droppings belonging to M.
bechsteinii were genotyped at nine DNA microsatellite loci in order to
differentiate all individuals. All microsatellites showed very low amplification
rates indicating low quality samples. However, at a larger scale, the use of
population demographic models to assess effective population size variation
using a dataset of 260 bats of the British population gave an estimate of the
effective population size of 6,569 (CI: 5,307-8,006) and suggested that the
British population of Myotis bechsteinii is stable and possibly expanding. Finally,
I developed an epigenetic assay to estimate the age of individual bats. For this,
I measured DNA methylation on bats of known age at seven CpG sites from
three genes. All CpG sites from the tested genes showed a significant
relationship between DNA methylation and age and provided reliable age
estimates.
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The findings presented in this thesis show that despite exhibiting high levels of
genetic diversity throughout its range, the genetic structure, habitat and
connectivity of M. bechsteinii populations is highly influenced by woodlands. It
also offers a novel method to monitor the species by developing an assay which
can provide information on the age structure of an entire colony from a single
sampling session. Such approaches are much needed in the field of
conservation and could in the future help preserve a wider range of species. | en_GB |
