BABBITT, C.C.; PATEL, N.H.; University of Chicago; University of California, Berkeley/HHMI: Developmental phylogenetics of the Malacostraca (Crustacea): using development to construct phylogeny

By understanding developmental processes in a phylogenetic framework, “developmental systematics” can provide novel information about both evolution and development. The goal of this project is to define and explore developmental characters, and to analyze how those characters can shed light on the evolution of development of a specific group. To this end, we have defined and collected developmental characters, such as cell lineage, developmental gene expression, and morphological events during ontogeny from a taxonomically diverse group of malacostracan crustaceans. The Malacostraca are an excellent group in which to explore these questions because it is a morphologically diverse class, with approximately 30,000 described species, and has a rich embryological literature. The phylogeny derived from the developmental data was tested by congruence with a molecular phylogeny that we assembled from a larger data set of 18S and 28S rDNA from 68 taxa. This combined developmental and molecular phylogenetic study is a way to a) examine possible morphological convergences b) add new lines of evidence to address the major questions in malacostracan systematics, and c) illuminate what roles changes in development have had in the history of this group. An important prerequisite, however, is the demonstration that developmental processes provide a phylogenetic signal. This study is an attempt to experimentally evaluate developmental characters for multiple groups over a series of ontogenetic stages. Preliminary results show that the developmental and molecular data are highly congruent. Thus, developmental characters appear to have phylogenetic signal.