Red squirrels from south–east Iberia: low genetic diversity at the southernmost species distribution limit

Abstract

South–east Iberia is the southernmost limit of this species in Europe. Squirrels in the region mainly inhabit coniferous forests of Pinus. In this study, we analyzed the pattern of mitochondrial genetic variation of southern Iberian red squirrels. Fragments of two mitochondrial genes, a 350–base pair of the displacement loop (D–loop) and a 359–bp of the cytochrome b (Cytb), were sequenced using samples collected from 88 road–kill squirrels. The genetic variation was low, possibly explained by a recent bottleneck due to historical over–exploitation of forest resources. Habitat loss and fragmentation caused by deforestation and geographic isolation may explain the strong genetic subdivision between the study regions. Six new haplotypes for the D–loop and two new haplotypes for the Cytb fragments are described. A Cytb haplotype of south–east Iberia was found to be present in Albania and Japan, suggesting local extinction of this haplotype in intermediate areas. No significant clustering was found for the south–east of Spain or for the other European populations (except Calabria) in the phylogenetic analysis.

Keywords

• Sciurus vulgaris
• Mitochondrial DNA
• Genetic diversity
• Population bottleneck