Meeting Abstract
P2.101 Monday, Jan. 5 Morphological Divergences among wild populations of zebrafish, Danio rerio BHAT, A.*; MARTINS, E.; Indiana University, Bloomington; Indiana University, Bloomington anuradha.bhat@gmail.com
Divergences in morphology among populations have been studied in several species of vertebrates and gradients in environmental features are known to be a major driving force for microevolutionary changes. Body shape variations among fish species are affected primarily by differences in water flow regimes, predation pressure and feeding habits. Here we measured variations in body shape and size among wild populations of zebrafish (Danio rerio) collected from moving and still water (streams and lakes) conditions in their natural habitats in northeast India. Geometric morphometric analyses conducted on male and female individuals from these populations were used to test predictions that habitat differences, particularly, in flow regimes between these populations can produce differences in body morphology. We conducted comparative analyses (using univariate ANOVA, t-test) of centroid size across lake and stream populations as well as between sexes. Multivariate analyses (discriminant function analysis) on partial warps were used to test effects of habitats on body morphology. One-way ANOVA showed a significant effect of habitat type on centroid size (F1,213 =16.4, p<0.01). Lake populations were significantly larger in centroid size than stream populations (independent t-test: t214 =4.05, p<0.01). While pooled data for lake and stream populations did not necessarily show significant differences in body shape, we found significant differences among some populations. These populations are subjected to fluctuations in water flow and high rainfall during some seasons can drive inter-population mixing. This could thus constrain morphological diversification. Inter-population (spatial) distances might also play an important role in determining morphological divergences.
