A Functional Analysis of Morphological Variation and Differential Niche Utilization in Basilisk Lizards

Abstract

The functional basis for the relationship between morphological variation and differential niche utilization within and between two species of Basilisk lizards was studied. Variation in body size and allometric changes in the size of functional elements of the hindlimb are correlated with interspecific and intraspecific differences in habitat distribution as well as the behavioral preference and functional ability for use of the adaptive strategy of running onwater. Elongated pes, orientation of the toe, and lateral toe fringes provide the drag forces necessary for support and propulsion on water. The functional size of adaptive features within and between species was compared by standardizing measurements of the functional elements as a ratio of body size. Differences in the magnitude of the functional ratios are related directly to the value of the adaptive features to provide for support and propulsion. Least—squares regressions of the relationship of the functional size of adaptive features thatcorrelate highly with observed habitat preferences as well as the behavioral preference and ability for running on water.