Genetic erosion in a stenotopic heathland ground beetle (Coleoptera: Carabidae): a matter of habitat size?

Abstract

Two centuries ago large areas of north-west Europe were covered by coherent heathlands which hosted numerous specialized species. Changes in land use made heathlands fragmented and rare, consequently, they are in the focus of nature conservation efforts today. But how large should remaining heathland patches be in order to secure the survival of populations of specialized species? We investigated the genetic diversity at five allozyme loci of Poecilus lepidus, a flightless and stenotopic heathland ground beetle. 29 populations from differently sized heathland patches in north-west Germany were analyzed. Results show a weak but significant genetic differentiation and no evidence for isolation by distance or other patterns of spatial autocorrelation. Linear regression analysis revealed significant relationships between patch size, allelic richness, number of alleles and expected heterozygosity. These findings are explained by severe habitat fragmentation together with strong fluctuations in population size which have been reported for this species in the past. To conserve the vast majority of the species' genetic diversity for a period of 100 years we suggest to maintain heathland patches of at least 50 ha in size.

Genetic erosion in habitat specialist shows need to protect large peat bogs

“…Taking into account the known population size fluctuations in this species (Den Boer and Van Dijk 1994), however, the observed significant reduction in allelic richness becomes explainable. A very similar situation was described for another stenotopic ground beetle species (Drees et al 2011).…”

“…Basic population genetic tests were run as described in Drees et al (2011). Allelic richness was calculated by extrapolating to 50 individuals ('AR 50') using the R package ARES (100 bootstraps, each, Van Loon et al 2007).…”

Losing uniqueness – shifts in carabid species composition during dry grassland and heathland succession

“…Many rare and dry‐loving (xerophilic) arthropods depend on early and dynamic successional stages and are negatively affected by the development of dense vegetation and an increasing soil stabilization (De Vries, den Boer & van Dijk, ; Price, ; Buchholz, ; Drees et al ., ; Schirmel & Buchholz, ). The conservation of these habitats and their dynamics is therefore most urgently needed (Steven, ; Buchholz, ).…”

Loss of genetic diversity and increased genetic structuring in response to forest area reduction in a ground dwelling insect: a case study of the flightless carabid beetle Carabus problematicus (Coleoptera, Carabidae)

“…For example, unique alleles were almost only found in the larger forest fragments. A comparable result was found for other ground beetles, albeit in other habitat types (Desender, ; Drees et al ., ) and for other insects (Knutsen et al ., ; Williams et al ., ; Keyghobadi et al ., ) Whether or not this loss of genetic diversity effectively decreases the adaptive potential of these smaller populations remains, however, elusive as the use of neutral genetic markers only gives an indirect estimate of the genetic variation at loci under selection.…”