ADVANCE Fellows Award: Modularity of the Arthropod Body Plan: A Comparative Test

Yale University, New Haven CT

Investigators

Abstract

Ants, spiders, and lobsters (arthropods) are built from repeated parts called body segments. Typically each segment has one pair of limbs and these limbs define the lifestyles of different arthropods: they can be used for walking, swimming, feeding, etc. Comparisons of animals as different as crabs and flies, show that segments and limbs can be very differently specialized in different arthropod groups. However, it is still unknown whether segments can evolve such specializations independently. Are segments along the body axis free to evolve on their own or do evolutionary specializations of one segment cause neighboring segments to change? This question will be tested in selected groups of crustaceans by comparing changes to limb and segment structure in closely related species. From these data, the evolutionary pattern of segment evolution can be reconstructed to determine the degree to which segments can evolve independently. This evolutionary analysis will be coupled to a series of experiments on crustacean embryos to evaluate how evolutionary patterns of segmentation are linked to mechanisms that generate segments during development. The major groups of animals are distinct in the ways their bodies are built, that is, they show distinct body plans. Understanding how body plans are organized provides a tool for interpreting how they evolve. This works addresses a fundamental question about the evolution of arthropod body plans: do arthropods have a modular design? This work will then explicitly link the modularity shown in evolution to modularity in development.