Evaluating possible anthropogenic impacts on gene flow and loss of genetic diversity in endangered Madla Cave Meshweaver spiders (Hahniidae, Cicurina madla)

• Published in: Conservation genetics 2024-02, Vol.25 (1), p.149-164
• Main Authors: Azevedo, Guilherme H. F., Blair, Jennifer, Hedin, Marshal
• Format: Article
• Language: English
• Subjects: Animal Genetics and Genomics; Anthropogenic factors; Biodiversity; Biomedical and Life Sciences; Conservation; Conservation Biology/Ecology; Ecology; Economic importance; Evolutionary Biology; Gene flow; Genetic diversity; Genomics; Heterozygosity; Human influences; Human populations; Karst; Life Sciences; Nucleotides; Plant Genetics and Genomics; Population; Population decline; Population dynamics; Population genetics; Populations; Research Article; Urbanization; Wildlife conservation
• ISSN: 1566-0621; 1572-9737
• DOI: 10.1007/s10592-023-01561-y

Karst systems have great ecological, cultural and economic importance, but are constantly threatened by human development. Northwestern Bexar County, Texas (USA), is an example of a region where urbanization threatens an essential karst landscape. Many studies have provided substantial contributions to the understanding and conservation of biodiversity in this area, including the delineation of Karst Fauna Regions (KFRs). However, no study has evaluated fundamentally important measures of genetic diversity, changes in population sizes, and gene flow for listed regional species. Here we used population genomic data derived from the sequence capture of ultraconserved elements (UCEs) to describe patterns of structure and connectivity among cave populations of Cicurina madla , and to estimate demographic and phylogeographic processes underlying those patterns. In addition, we evaluated if population genetic processes could have been influenced by human activities. Although there is weak phylogenomic differentiation between populations, the distribution of genetic diversity and patterns of gene flow within and between areas suggest important differences in population dynamics among KFRs. Our genomic data show that populations of C. madla in Bexar County currently carry comparatively low levels of heterozygosity and nucleotide diversity, and that these might have been influenced by human activities. Ultimately, we present genomic evidence for declining cave spider population sizes perhaps coincident with increases in an expanding human population and discuss implications of our findings for conservation.