Genetic management of the red squirrel, Sciurus vulgaris: a practical approach to regional conservation

Abstract

The progressive decline in red squirrel (Sciurus vulgaris) numbers in Wales has led to conservation and reintroduction projects being established on the island of Anglesey. The recovery of the island's remnant wild population was initially successful, however concern remained over potential loss of genetic diversity resulting from an observed demographic bottleneck. We used mitochondrial DNA (mtDNA) control region sequences and six microsatellite loci to assess current levels of genetic variation in the population. Samples were monomorphic for control region sequences and a historic specimen from the same area carrying a different haplotype demonstrated a loss of mtDNA diversity during the last 20 years. Inclusion of other Welsh haplotypes indicated phylogeographic structure in the region, in contrast to previous UK studies. Genotyping results showed allelic diversity and heterozygosity to be less than 50% of that recorded in other UK populations, with strong evidence for a recent genetic bottleneck. A parallel reintroduction programme on Anglesey included genetic analysis of individuals during the selection of captive breeding pairs. We present analysis of sequence and microsatellite data, and subsequent management decisions taken to maximise diversity in the founder and F1 generations. Population and Habitat Viability Analysis applied to both populations modelled future levels of heterozygosity and allelic diversity. Supplementation of the remnant and reintroduced populations with translocated squirrels was simulated as a potential management tool; results support use of this strategy to reduce loss of diversity and increase survival. The limitations of applying conservation genetic theory within small-scale management projects are discussed.

Origin of, and conservation units in, the Irish red squirrel (Sciurus vulgaris) population

“…In addressing the first aim of this study; to determine whether the Irish population is distinct from that found in Britain, these results found, as described in previous genetic studies of red squirrels (Barratt et al 1999;Hale et al 2004;Ogden et al 2005), no clear geographic partitioning of haplotypes (Fig. 2), meaning that the Irish red squirrel population is not an ESU (Moritz 1994).…”

“…Sequences were then aligned with published red squirrel sequence data (AY178452-AY178479, Hale et al 2004) in CLUSTAL_X (Thompson et al 1997), and novel haplotypes identified with the MS EXCEL SEQUENCE TOOLKIT (Stephen Park, UCD). These haplotypes were further compared to other published data (AF1110001-AF111027, Barratt et al 1999; AY372270-AY534120, AY534120-AY534121, Ogden et al 2005) which overlapped with our sequences by 175 bp, to ensure that the haplotypes were indeed novel along this area of overlap, Fig. 1 Locations of collection sites of samples used in this study; the three regions to which the contemporary samples were assigned are also shown.…”

Dwindling genetic diversity in European ground squirrels?

“…Compared to our study, only one island population of S. vulgaris in Pentraeth, Anglesey, U.K. (Ogden et al 2005), the endangered Delmarva fox squirrel (S. niger cinereus, see Lance et al 2003), and the endangered Vancouver Island marmot (M. vancouverensis, Kruckenhauser et al 2009) had similar or even lower levels of genetic diversity.…”

Genetic assessment of the Arabian oryx founder population in the Emirate of Abu Dhabi, UAE: an example of evaluating unmanaged captive stocks for reintroduction

“…Nowhere is this more evident than in reintroduction projects, where typically fewer than 100 individuals and sometimes less than 20 individuals, are released to found new populations (e.g. Greth and Schwede 1993;Ogden et al 2005). Arabian oryx represent an extreme case in which the numbers of founders for both private collections and the world herd stock were remarkably low.…”