Genetic variability in the natural populations of Carinotetraodon travancoricus revealed using itochondrial COI sequences

Abstract

Carinotetraodon travancoricus or Malabar puffer fish is an endemic species described from rivers originating from the Western Ghats in South India. This species is captured extensively as an aquarium fish and is having substantial demand in global markets. However, being prone to overfishing and impacts of anthropogenic alterations in its habitats, IUCN has categorized it as a threatened/vulnerable species. Since, knowledge on variability of wild populations could help in their conservation and management, morphometric and genotypic analyses were carried out in natural populations of C. travancoricus inhabiting two geographically separated rivers Pamba and Chalakkudy. Mean values of eleven length parameters measured in 456 males and 439 females inhabiting these rivers revealed significant difference (ANOVA, F�=�10.2 p�<�.001) between sexes and between females inhabiting two rivers. Principal component analysis revealed two factors in males and three factors in females, explained variance of 83.62% and 89.94% in respective sexes. Results of both PCA and discriminant function analysis indicated perceptibly high degree of separation between individuals inhabiting the two rivers. A total of 25 COI sequences were generated from C. travancoricus collected from rivers Pamba (n�=�14) and Chalakkudy (n�=�11). Sequence alignment revealed considerable base substitutions between samples from both rivers, indicating possibility of population differences. AMOVA analysis also provided significant Fst value (0.622; p-value .00) in support of population difference between individuals of both rivers. Interpopulation genetic distance reached upto 2.50%, high enough to confirm genetic diversity among individuals, revealing perceptible population events within this species. The present results indicated high degree of population difference between C. travancoricus inhabiting geographically separated rivers Pamba and Chalakkudy as evidenced from both morphometric and genotypic analyses.