Meeting Abstract

S8-1.1  Sunday, Jan. 6  Assembling the Poriferan Tree of Life: Integrative Taxonomy and Systematics Reveal New Patterns of Sponge Evolution THACKER, R.W.*; Univ. of Alabama at Birmingham

The highly collaborative research sponsored by the NSF-funded Assembling the Porifera Tree of Life (PorToL) project is providing insights into some of the most difficult questions in metazoan systematics. Our understanding of phylogenetic relationships within the Phylum Porifera has changed considerably with increased taxon sampling and additional molecular markers. PorToL researchers have falsified earlier phylogenetic hypotheses, discovered novel phylogenetic alliances, found phylogenetic homes for enigmatic taxa, and provided a more precise understanding of the evolution of skeletal features, secondary metabolites, body organization, and symbioses. These exciting new discoveries will be shared during the talks that form this symposium. Specific case studies will be drawn from our analyses of nearly 1000 28S ribosomal subunit gene sequences. We recovered monophyletic clades for all four classes of sponges, as well as the four major clades of Demospongiae (Keratosa [G1], Myxospongiae [G2], Haploscleromorpha [G3], and Heteroscleromorpha [G4]), but our phylogeny differs in several aspects from traditional classifications. In most major clades of sponges, families within orders appear to be paraphyletic. While additional gene and taxon sampling are needed to establish whether this pattern results from a lack of phylogenetic resolution or from a paraphyletic classification system, many of our results are congruent with those obtained from 18S ribosomal subunit gene sequences and complete mitochondrial genomes. These data provide further support for a revision of the traditional classification of sponges.