Population Genetics of the Three Endemic Land Snails of GenusDiscula(Pulmonata: Hygromiidae) on the Archipelago of Madeira

Abstract

Abstract: The population structure of three endemic land snail species of the genus Discula (Lowe,1831) on the archipelago of Madeira were studied. Ten allozyme loci were screened in 13 populations (11 from Madeira Island and two from the adjacent Desertas Islands) of D. polymorpha (Lowe, 1831), two populations of D. attrita (Lowe, 1831) and one population of D. calcigena (Lowe, 1831) from Porto Santo Island. All populations, except those from the Desertas, showed high levels of genetic variability. Deviation from Hardy- Weinberg equilibrium due to heterozygote deficiency was detected in all D. polymorpha populations from Madeira and populations of D. attrita. This deficiency was mainly attributed to inbreeding within the populations. No heterozygote deficiency was found in D. calcigena, probably due to the larger population size of this species in the recent past. The FST values were significant in many pairwise comparisons between the populations of D. polymorpha, with the highest values occurring betwe...