Ecology and genetic identification of freshwater turtles in Pakistan

Abstract

Background: The turtle population plays an important role in sustaining the water ecosystem by minimizing pollution from water. The identification and molecular investigation of freshwater fauna is essential for conservation of the species that are near to extinction. The quality of water, type of flora, fauna, and environmental condition are the major factors that directly affect the distribution of freshwater turtles. Two families including eight species of freshwater turtles are found in Pakistan. The Geoemydidae (Geoclemys hamiltonii, Hardella thurjii, Pangshura smithii, and Pangshura tecta) and Trionychidae (Chitra indica, Nilssonia gangetica, Nilssonia hurum, and Lissemys punctata andersoni). Studies on the species diversity and habitat of freshwater turtle have not been focused previously in the region. The present study was the first conducted to estimate the habitat and genetic diversity of freshwater turtles using 12S rRNA (ribosomal RNA) gene in Pakistan. Materials, Methods & Results: A total of 26 samples were collected from various localities using hand net, cast net, gills net, steel hooks, thick chemical wire, using chicken intestine and small fishes. The collected turtle specimens were morpho-taxonomically categorized into two genera, Lissemys punctata andersoni (n=13, 50%) and Nilssonia gangetica (n=13, 50%). The collected species showed an aggressive and active behavior in captivity during summer. Genomic DNA was extracted from collected specimens and used in PCR reaction by using specific primers for the amplification of short fragments of 12S rRNA gene. Analysis of generated sequences confirmed the existence of L. p. andersoni in the region. The generated sequences of L. p. andersoni correspond to Clad A and showed a close resemblance among different species of the genus Lissemys. Discussion: The climatic change such as temperature and rainfall have great effects on the occurrence of turtles. Habitat degradation occurred due to various factors such as draining wetlands, deforestation, converting clear water rivers to stagnant multi-purpose reservoirs and mortality on roads when turtles move around to feed. Current study concluded that the freshwater turtles L. p. andersoni and N. gangetica are interested in natural feeds. The analysis of 359 bp of 12S rRNA gene of the genus Lissemys turtles showed relationships of these turtles with cyclanorbines flap shell turtles, which agrees with previous reports. The African taxa are paraphyletic with respect to the Asian Lissemys. The ancestors of the extant genus cyclanorbines spread from North America to Asia [26]. It should be expected that each of the 3 taxa, L. p. andersoni, L. p. punctata and L. scutata represents a distinct genetic lineage. Present molecular investigation concluded that Clad A comprising L. p. punctata, L. scutata, L. cylonensis also include L. p. andersoni species. Clad B also contains one sequence from India, identified as L. p. andersoni. Their classification as conspecific evolutionary lineages are suggested by similar genetic divergences, the observation of mismatches between morphology (spotted vs. unspotted) and mitochondrial haplotypes in clades A and B. The clades A and B provides evidence for gene flow between the spotted subspecies L. p. andersoni and adjacent populations with unspotted flap shell turtles. This study is the first investigation about the habitat and of the endemic turtle species L. p. andersoni and N. gangetica in Pakistan. The genetic identification followed by phylogenetic analysis based on 12S rRNA partial genes revealed a closest similarity with the sequences generated for the same species from the neighboring countries. This study provided information to conduct further molecular studies that are essential to provide significant genetic data about turtle species.