Molecular characterization and some environmental factors influencing distribution of the endangered and endemic gulella taitensis in Taita hills, Kenya

Abstract

Gulella taitensis is a land snail of the family Streptaxidae and genus Gulella. It is endemic to Taita hills and categorized as endangered on the IUCN Red List. The species is threatened by habitat loss and disturbance due to human activities. Two people sampled snails at four sampling plots using standard timed direct search for one hour. Soil samples were collected from four different points within these sampling plots, and its pH, calcium and electrical conductivity obtained using standard soil chemical analysis methods. Litter depth, litter cover, canopy cover, log and tree density were assessed. Distribution of G. taitensis varied significantly between all the forest fragments. Most of the environmental variables investigated recorded a positive association with the G. taitensis densities. Calcium is significant for the snail's survival and has a significant correlation with litter cover, canopy cover and log density and these influences the distribution between the forest fragments. Calcium, canopy cover, log density and tree density form the best combination of environmental variables (model) that influence the distribution and abundance of G. taitensis. Polymerase Chain Reaction of DNA extracted from these snails using microsatellite primers showed there is genetic diversity within this species. We predict that there could be genetic variations within this species since the phylogenetic tree shoed two major clades and samples from the same forest fragment clustered at different clades while others clustered closely together within the same clade. There is a possibility of the presence of a hybrid or sub-species within this species. This requires more specific primers to be used to confirm it as genetic work of this genus is scanty.