Distribution and Conservation of Genetic Diversity Among UK Calcareous Grassland Regions: A Case Study Using Insects

Abstract

Conservation strategies for whole communities at the landscape scale have rarely been able to take into account genetic diversity because of the number of species involved. However, if species can be grouped together by geographic distribution of genetic diversity and patterns of relatedness, then landscape and genetic conservation might be more effectively combined to cope with problems of fragmentation. We report on a study that measures how genetic diversity is distributed at national and regional scales in four unrelated species of calcareous grassland insects. Samples were obtained from sites within six UK calcareous grassland regions. Genetic diversity was measured using mtDNA sequencing (four species) and allozyme analysis (two of the four species). A striking difference in mtDNA diversity was found between the chrysomelid beetle Aphthona herbigrada (23 haplotypes; mean per region 5.5) and the cicadellid bug Batracomorphus irroratus (27 haplotypes; mean per region 6.2), with high haplotype richness, and the brown argus butterfly Aricia agestis (4 haplotypes; mean per region 1.7) and the cistus forester moth Adscita geryon (5 haplotypes; mean per region 2.4) with low. At the UK scale, patterns of diversity were species specific with no general conservation strategy emerging for the community. However, there was little differentiation among regions and any splitting into more than one management unit was not clearly justified, questioning whether distribution of genetic diversity should be a concern at this spatial scale.

Evidence for evolutionary change associated with the recent range expansion of the British butterfly, Aricia agestis, in response to climate change

“…These results are consistent with the low estimates of genetic differentiation and diversity seen using mtDNA and allozyme variation among six UK metapopulations of A. agestis (Lai & Pullin 2005). Their estimates of expected heterozygosity within metapopulations (ranging from 0.175 to 0.254) are very similar to the estimates of expected heterozygosity at our sites (0.204–0.227; Table 1).…”

“…Diversity estimates for A. agestis were slightly lower in central Europe, with expected heterozygosity ranging from 0.145 to 0.178, but with slightly higher estimates of F ST and evidence for IBD (Habel & Schmitt 2009). Conversely, the low F ST values observed among A. agestis populations throughout the UK in this study and by Lai & Pullin (2005) suggest patterns of high gene flow with many individuals dispersing relatively short distances among long‐established populations, rather than fewer long‐distance colonists (Hill et al. 2011).…”

Effect of agricultural intensification on the genetic diversity of Helicoverpa armigera

“…Moreover, habitat loss significantly reduced the genetic variability in harvested populations of Santalum album collected in Indonesia (Indrioko & Ratnaningrum, 2015). In a changing landscape, species may exhibit genetic changes, including loss of genetic diversity, changes in the population genetic structure, and loss of genetic variation among members in the same population (Lai & Pullin, 2005). These effects might be particularly strong in agricultural pests in agroecosystems if agricultural intensification changes substantially over time (Crossley et al., 2019).…”

Genetic diversity and differentiation in the leaf litter weevil Geochus politus across an urban-rural gradient

“…Habitat fragmentation generally has negative effects on populations, genetic diversity, and gene flow; however the nature and magnitude of these effects often differ considerably in different taxa (Keller et al 2004;Noël et al 2007;Vandergast et al 2007), even for similar species within the same landscape (Bates 2002;Lai & Pullin 2005). Urbanised native species present in habitat fragments are thought to be vulnerable to extinction due to declines in their original population size (Haddad et al 2015).…”

“…Gene flow between fragments is therefore typically reduced or absent, and the resulting isolated populations then become differentiated from each other and are prone to higher inbreeding and a loss of genetic diversity (Delaney et al 2010). The degree to which taxa are affected is heavily influenced by the level of habitat connectivity (Coulon et al 2004), their dispersal capability (Uezu et al 2005), and their population size (Lai & Pullin 2005).…”