Abstract:
Intra-specific morphological variation and differentiation among eight populations
of the common freshwater fish Rasbora daniconius (Cyprinidae) were investigated.
Significant heterogeneity and differentiation was found among some of the
populations studied indicating limited geographic variation, as suggested by
relatively large overlap in canonical scores among most of the samples. However,
three populations could be separated convincingly from the rest; Pattiyapola,
Dediyagala and Godapitiya. Cluster analysis based on the pair-wise inter-location
morphological distinctiveness identified Dediyagala population as the most distinct
one from all others. Mavil Aru population formed a distinct branch as well. The
group of fish (P9) having close resemblance to R. daniconius but with a slightly
different lateral stripe also separated. The preliminary genetic analysis was done to
reveal existing genetic variation among three populations where eight enzymes
were detected, but only three (LDH-I, PGM, ME-I) were clearly polymorphic.
The present results show that R. daniconius in Sri Lanka is not phenotypically and
genotypically homogenous. The absence of differences between population
samples that experience highly limited present-day interchange may be partly
explained by colonization history or environmentally controlled variability.
