Inferring the Phylogenetic Position of the Acoelomate Bilateria with Mitochondrial Gene Arrangements

Virginia Commonwealth University, Richmond VA

Investigators

Abstract

DEB-0089654 James M. Turbeville Dr. James Turbeville of the University of Arkansas has been awarded a grant to study the phylogenetic relationships of invertebrate animals by using gene rearrangement data. The animal groups lacking a body cavity (acoelomate phyla) have been considered the most primitive bilaterally symmetrical animals and have played a central role in theories of animal evolution. These animals (e.g., flatworms and ribbon worms) are an important component of animal biodiversity, yet their position in the tree of life (phylogenetic position) remains uncertain after years of intensive research. Mitochondria are structures in cells (organelles) responsible for energy production. They possess a small genome (DNA) which contains 37 genes encoding proteins and structural components involved in energy generation. Recent studies have indicated that mitochondrial gene rearrangements will yield reliable features for clarifying the relationships of major animal groups (phyla). To further evaluate the potential of this approach for estimating the phylogeny of animals, mitochondrial genomes of the acoelomate flatworms (Platyhelminthes), ribbon worms (Nemertea) and the enigmatic Xenoturbella will be sequenced and the arrangements of genes determined. These data will be compared with mitochondrial gene arrangements available for other multicellular animals (metazoans) using appropriate methods to reconstruct a phylogeny for these groups. The data will allow a test of many long-standing hypotheses of animal relationships. The results of this study will contribute to our knowledge of these poorly understood animals, by increasing our understanding of patterns of diversification and providing insight into the evolution of morphological traits, patterns of gene evolution, developmental mechanisms and body plans.