Population Structure of Denison’s barb, Puntius denisonii (Pisces: Cyprinidae): A Species Complex Endemic to the Western Ghats of India

Abstract

Genetic and morphologic variation, haplotype relationships, and structuring of populations within Puntius denisonii and its close related species Puntius chalakkudiensis have been tested using molecular and biometric data, to infer phylogeographic patterns. Sequences of mitochondrial DNA ATPase 8 and 6 genes, and morphometric data, were used to find population structuring. Specimens were collected from 7 locations in the southern region of Western Ghats, a global biodiversity hotspot in India. Biometric analysis revealed apparent heterogeneity in the morphology and color pattern between the species at juvenile and adult stages, and among different geographically separated populations of these species. High values for mean pair wise distances and a high proportion of the total variance attributed to differences between the geographically isolated populations with AMOVA, indicated clear population structuring within these species. Extremely high values for Pair wise FST and significantly lower Nm values observed among the populations studied, suggested little or no effective gene flow among them. Constructed phylogenies further confirmed a high degree of population structuring within the species, showing local endemism with population specific haplotypes forming a species complex. The present study thus estimates the validity of subpopulations within P. denisonii and P. chalakkudiensis; clarifies the relationships of populations of P. denisonii with that of P. chalakkudiensis, and also indicates the presence of four different independent evolutionary lineages forming cryptic species within P. denisonii. The study further emphasizes the need for a conservation policy to be developed for each population of both species, separately based on MUs (Management Units).