Meeting Abstract
Geometric morphometric analysis uses Cartesian geometric coordinates of landmark features to analyze shape and has been used extensively in insect and vertebrate systems. We used MorphoJ, an integrated software package for geometric morphometrics, to examine differences in the shape of pluteus larvae during early development. We examined shape differences among the larvae of three congeneric species of Echinometra sea urchins that were collected from coastal waters off the Isthmus of Panama in 2005. These species vary in the length of larval food collection structures (larval arms), as well as in egg size and egg composition, which reflect pre-feeding egg energetic reserves used for morphogenesis. Our results indicate that species vary in their developmental shape trajectories, such that when normalized for size and age the overall shape differed between the congeners. These differences among species may be associated with egg size and/or composition. Shape differences may also be associated with differences in the larval feeding environment of the tropical western Atlantic and eastern Pacific oceans. This novel application of shape analysis sheds light on potential developmental, environmental, and biomechanical constraints on the evolution of larval form.
