Fine-scale population genetic structure and sex-biased dispersal in the smooth snake (Coronella austriaca) in southern England

Abstract

Human-induced alteration of natural habitats has the potential to impact on the genetic structuring of remnant populations at multiple spatial scales. Species from higher trophic levels, such as snakes, are expected to be particularly susceptible to land-use changes. We examined fine-scale population structure and looked for evidence of sex-biased dispersal in smooth snakes (Coronella austriaca), sampled from 10 heathland localities situated within a managed coniferous forest in Dorset, United Kingdom. Despite the limited distances between heathland areas (maximum o6 km), there was a small but significant structuring of populations based on eight microsatellite loci. This followed an isolation-bydistance model using both straight line and 'biological' distances between sampling sites, suggesting C. austriaca's low vagility as the causal factor, rather than closed canopy conifer forest exerting an effect as a barrier to dispersal. Within population comparisons of male and female snakes showed evidence for sex-biased dispersal, with three of four analyses finding significantly higher dispersal in males than in females. We suggest that the fine-scale spatial genetic structuring and sex-biased dispersal have important implications for the conservation of C. austriaca, and highlight the value of heathland areas within commercial conifer plantations with regards to their future management.

Phylogeography of the smooth snakeCoronella austriaca(Serpentes: Colubridae): evidence for a reduced gene pool and a genetic discontinuity in Central Europe

“…Based on biparentally inherited microsatellite loci, Pernetta et al . () suggested sex‐biased dispersal in the species. Taking the results of their study into consideration, we chose to determine the genetic structure of the species on the basis of both biparentally and uniparentally (maternally) inherited markers.…”

“…This is not attributed to a lack of interest in the species but, instead, to the fact that C. austriaca is not easy to study as a result of its secretive mode of life and low densities in a number of areas within its geographical distribution (Sewell et al ., ). To date, only two studies based on molecular markers have been conducted for the species: one based on microsatellite markers that evaluated the fine‐scale population differentiation in one locality in Great Britain (Pernetta et al ., ) and the other using mitochondrial cytochrome b sequences to elucidate the phylogeography of the species, mostly focusing on the south‐western edge of its range (Santos et al ., ), where two subspecies have been distinguished: Coronella austriaca acutirostris in the north of Iberian Peninsula, and Coronella austriaca fitzingeri in southern Italy and Sicily (Arnold & Ovenden, ).…”

Phenotypic variation contrasts with genetic homogeneity across scattered sea snake colonies

“…To our knowledge, this contrasted pattern was not previously observed in marine tetrapods or in any snake species. Instead, strong phenotypic and genetic structuring effects caused by local factors have previously been documented in snakes (Kuriyama et al ., ; Pernetta et al ., ). Sea kraits are major colonial predators that are widely distributed in the western Pacific.…”

“…Besides, previous genetic investigations suggested spatially oriented sex‐biased dispersal among six colonies of yellow and blue sea kraits ( L. saintgironsi and L. laticaudata ) sampled in New Caledonia; indicating possible geographical genetic structure (Lane & Shine, ). Further, SGS was documented in other marine and terrestrial snake species (Pernetta et al ., ; Lukoschek & Shine, ).…”

Post-birth separation affects the affiliative behaviour of kin in a pitviper with maternal attendance

“…This might be expected if cottonmouths exhibit male‐biased juvenile dispersal and avoid related males during this time to reduce kin competition and inbreeding (Johnson & Gaines, ), as well as the potential for cannibalizing siblings. While cannibalism in cottonmouths has been documented (reviewed by Campbell & Lamar, ), information on dispersal patterns of this species is not available; however, recent genetic studies have found evidence for male‐biased dispersal in several snake species (Rivera, Gardenal & Chiaraviglio, ; Keogh, Web & Shine, ; Clark et al ., ; Dubey et al ., ; Pernetta et al ., ).…”