Models for describibg shape and allometry, illustrated by studies of Australian species of <i>Uca</i> (Brachyura : Ocypodidae)

Abstract

Morphometric data for males of three species of Uca and females of two species have been summarized in terms of concepts of shape and allometry using the multivariate linear model. Differences among species are greatest in the males where U. vocans develops a major chela with broad palm, greatly elongated fingers and large gape, while U. lactea produces a long narrow palm with long, widely separated fingers. The major chela of U. polita is approximately intermediate in shape between that of U. vocans and U. lactea. Differences among the patterns of development in the meral lengths of the supporting pereiopods are also marked and these relate not so much to the morphometric details of the major chela but to the crab's use of the major chela in agonistic interactions. Because the study is cross-sectional, the observed differences do not entirely describe growth patterns. Biases almost certainly exist due to differential death rates of given sizes and sampling difficulties. In this work there has been an emphasis on statistical procedures which reflects our expository aim.