Abstract:
Individuals of populations may completely or partially isolate from other
populations due to biogeographic barriers such as mountains, rivers,
physicochemical barriers etc. resulting variations in phenotypic and genetic
characters of the populations. Fish populations particularly show morphological
heterogeneity resulted from such isolations. The degree of morphological variation
of catfish Pseudarius jella among four estuarine locations along the Southern coast
of Sri Lanka was evaluated using selected morphometric and meristic characters.
Results of the univariate and multivariate analyses of variance revealed highly
significant heterogeneity among the localities. Fish from Nilwala river mouth can
easily be separated from other localities (Garanduwa lagoon, Koggala lagoon,
Walawa river mouth) by using selected shape variables (head length, head width,
body depth, etc.). The morphometric discriminant function correctly classified 56%
(average) in to their localities of origin. Morphometric discriminant functions
defined regional stocks of Pseudarius jella for further verification of the stock
structure. These results of this study revealed that demonstrated of population
specific morphological traits among Pseudarius jella from different localities
indicating some degree of restriction for inter-population movement. The results
were discussed with regard to the possible isolating mechanisms among estuarine
populations.
