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)

Abstract

Abstract. 1. Old growth temperate broadleaved forests are characterised by a large proportion of forest specialists with low dispersal capability. Hence, species bound to this habitat are expected to be highly susceptible to the effects of decreasing patch size and increasing isolation.2. Here, we investigate the relative effect of both factors by genotyping individuals of a flightless and forest specialist beetle Carabus problematicus from 29 populations, sampled in 21 different forest fragments in Belgium, at eight microsatellite loci.3. A high degree of genetic differentiation among fragments was observed, with populations from smaller forests being considerably more differentiated and characterised by a lower genetic diversity compared to those of larger forests.4. A more detailed study on forest remnants of a former historic continuous woodland area revealed that population differentiation was high among, but not within remnants, irrespective of geographical distance. This suggests that patch fragmentation rather than geographical distance is the ultimate factor that hampers gene flow in this species.5. The results indicate that gene flow among suitable habitat patches is primarily reduced by the inability of this specialised species to traverse the landscape matrix. This lack of dispersal may pose a serious threat for the persistence of C. problematicus and ecologically similar species, and suggests that present populations can best be protected by securing or increasing the size of existing habitat patches.

Local extinction processes rather than edge effects affect ground beetle assemblages from fragmented and urbanised old beech forests

“…The importance of local extinction followed by a lack of re‐colonisation was also confirmed in a previous population genetic study conducted on the forest specialist C. problematicus where we showed not only strong effects of forest isolation on population isolation but also a significant lower genetic diversity indicating larger stochastic effects in smaller populations (Gaublomme et al ., ).…”

Consequences of extensive habitat fragmentation in landscape‐level patterns of genetic diversity and structure in the Mediterranean esparto grasshopper

“…Thus, a general recommendation derived from both this and previous studies in the area would be implementing management practices aimed to promote the conservation of organisms that are ecologically dissimilar, but prioritizing those species that are dispersal‐limited and more likely to benefit from increasing or maintaining population connectivity (Gaublomme et al. ; Keller et al. ).…”

“…The extraordinarily deep genetic structure previously reported for the highly specialist M. wagneri suggests that local extinctions are not likely to be compensated by recurrent recolonizations in this species (Ortego et al 2010(Ortego et al , 2012, a pattern that considerably differs from the remarkable gene flow and metapopulation dynamics characterizing the more widespread R. hispanica (present study). Thus, a general recommendation derived from both this and previous studies in the area would be implementing management practices aimed to promote the conservation of organisms that are ecologically dissimilar, but prioritizing those species that are dispersal-limited and more likely to benefit from increasing or maintaining population connectivity (Gaublomme et al 2011;Keller et al 2013b). Given that most lands are private properties devoted to agriculture, management should Figure 3 Genetic structure of the studied populations of esparto grasshopper (Ramburiella hispanica).…”

Genomic population structure and conservation of the red listed Carabus arcensis (Coleoptera: Carabidae) in island–mainland habitats of Northern Europe

“…Using GBS data of the ground beetle C. arcensis from island and mainland sites in Denmark and Sweden we found an overall significant isolation by distance (partial Mantel test of F ST and geographic distance, when controlling for transoceanic distance, P = 0.0461, r = 0.582), but a lack of any significant impact of an ocean water barrier on isolation (partial Mantel test of F ST and transoceanic distance, when controlling for geographic distance, P = 0.134, r = 0.436). Isolation by distance plot across continuous stretches of land (range from 10 km to 160 km) has been found in other studies of flightless carabids, Carabus auratus , C. soleiri and C. problematicus using microsatellites and amplified fragment length polymorphism (AFLP) (Garnier et al ., ; Sander et al ., ; Gaublomme et al ., ). Our study is the first where IBD has been investigated across a water barrier in a flightless carabid species and it represents the first time that genome‐wide SNPs have been used in the population structuring of carabid beetles.…”