GENETIC VARIABILITY IN THE KENTUCKY CAVE BEETLE NEAPHAENOPS TELLKAMPFII (COLEOPTERA: CARABIDAE).

Abstract

This paper reports data on genetic variability and genetic similarity in five populations of Neaphaenops tellkampfii, a troglobitic carabid beetle which occurs in many caves of the Central Kentucky Karst, including those of Mammoth Cave National Park. Previous studies have found that cave species generally show lower genetic variability than similar surface species. In the Central Kentucky Karst Region (Quinlan, 1970), Laing et al. (1976a) reported average frequencies of heterozygous loci per individual, H, of 0.008 and 0.056, respectively, for two populations of the obligate cave dwelling (i.e., troglobitic) millipede Scoterpes copei. Likewise, Laing et al. (1976b) reported average H values of 0.048 for six populations of the troglobitic scavenger beetle Ptomaphagus hirtus (Leiodidae) another central Kentucky species. Avise and Selander (1972) compared genetic variability of surface and cave populations of the Mexican cavefish Astyanax mexicanus. Whereas surface populations maintained average H values of 0. 112, cave populations of the same species were much less variable with H values averaging only 0.036. In addition to showing low variability, comparisons of genetic similarity between sets of populations of each of the above species showed low levels of similarity, particularly when contrasted with comparable surface species. An exception to the pattern of low variability and similarity in populations of troglobitic species emerges from preliminary data on Rhadine subterranea (Coleoptera: Carabidae) (Avise and Selander, 1972). This species is a predator in terrestrial communities of a Texas cave system (Mitchell, 197 la; 1971b; 1971c), preying on the eggs of cave crickets. Calculations of H from the data for three loci presented by Avise and Selander (1972) yield values :0.20 for R. subterranea. In addition, the two populations sampled appear to be nearly identical genetically.