Pernetta, Angelo P.
Population ecology and conservation genetics of the smooth snake (Coronella austriaca) in a fragmented heath landscape.
University of Southampton, School of Biological Sciences,
Coronella austriaca is the United Kingdom’s rarest snake, being confined to the lowland
heathlands of Dorset, Hampshire and Surrey. As a result, it remains the least understood;
despite being listed as a key biodiversity action plan species. Substantial loss and
fragmentation of its primary UK habitat - lowland heathland - has occurred in recent
times, and yet research examining the population ecology and conservation genetics of
this species remains limited. As a result, this PhD research was developed to fill this
need. Based on three years of data collection, a combination of field studies, laboratory
experiments, mathematical modelling and genetic analyses, were employed in an attempt
to answer questions of relevance to the future conservation management of this species.
Modelling smooth snake occupancy of remnant heathland patches using an
information-theoretic approach showed patch size and the percentage of grassland in
surrounding matrix habitats to be the primary determinants of smooth snake presence.
Field-based studies based on 27 arrays of artificial refugia showed the size of trees and
prey abundance to be important in determining mean smooth snake capture rates at
Eight previously described microsatellite markers were used to complete the first
assessments of the genetic population structure of C. austriaca at two spatial scales.
Initial fine-scale analysis of structuring based on 11 sampling localities within a
heathland/coniferous forest mosaic found significant population structuring as a result of
isolation-by-distance effects, in addition to evidence of male-biased dispersal. At the
wider scale, analysis of seven distinct populations across Dorset also found small but
significant differences in genetic diversity. The observed patterns were not consistent
with isolation-by-distance effects, nor was there any evidence of them being a result of
habitat patch size or isolation. Phylogenetic analysis of the coarse-scale microsatellite
data showed some evidence of population clustering based on their geographic locality in
relation to the historical extent of Dorset’s heathland, suggesting they represent distinct
The reproductive ecology of C. austriaca was also examined using a combination
of field data and microsatellite analysis. In contrast to continental populations, there was
no relationship between female body size and litter size. However, there was a negative
relationship between relative clutch mass and female body size, suggesting that there may
be a trade-off between female survival and reproductive output. Microsatellite based
genotyping of neonates from 16 litters born in the laboratory provides the first evidence
of multiple paternity occurring in C. austriaca.
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