Analysis of geographic shape-variation in Vargula hilgendorfii (Ostr., Crust.).

Abstract

A means of determining the geographical validity of shape patterns based on landmark observations, using geometric morphometry and multivariate statistical analysis, is illustrated by data on the bioluminescent ostracod species Vargula hilgendorfii (Müller) from two marine localities (Karatsu and Tateyama) in Japan. Standard multivariate statistical analysis of the shape-data shows that there is a significant difference in means between sites. The latent vectors of the covariances of the data-matrices for shape-change were tested for collinearity under the hypothesis that external causes might influence covariances and hence the statistical distance between samples. There is a significant difference in the orientation of the ellipsoids for total shape-scatter. The reason for the differentiation in the shape-phenotype (for example, expressed as polymorphism) might have a microclimatological background. In addition to the difference in average shape, there is also a divergence in size between the samples from the two siles.