Meeting Abstract

P3.196  Friday, Jan. 6  Nuclear 28S ribosomal subunit gene sequences support new relationships among families and orders of Porifera CARMACK, CA*; REDMOND, N; THACKER, RW; COLIN, L; COLIN, P; HILL, M; HILL, A; LOPEZ, J; DIAZ, MC; POMPONI, S; BANGALORE, P; Univ. of Alabama at Birmingham; Smithsonian Institution; Univ. of Alabama at Birmingham; Coral Reef Research Foundation; Coral Reef Research Foundation; Univ. of Richmond; Univ. of Richmond; Nova Southeastern Univ.; Museo Margarita; Harbor Branch Oceanographic Institute ; Univ. of Alabama at Birmingham

Our understanding of phylogenetic relationships within the Phylum Porifera is changing considerably with increased taxon sampling and additional molecular markers. We present new phylogenies constructed from a backbone of over 150 nearly complete 28S ribosomal subunit gene sequences, augmented with over 600 partial 28S sequences. We recovered monophyletic clades for all four classes of sponges, as well as the major clades of Demospongiae (G1, G2, G3, and G4). Our phylogeny differed in several aspects from traditional classifications. For example, a deep divergence within the marine Haplosclerida was associated with large-scale insertions that alter the structure of the ribosome. Although Keratosa (G1, containing Dictyoceratida and Dendroceratida) was constructed as a monophyletic clade, the family Dysideidae formed a clade separated from other Dictyoceratida, whose remaining families appeared paraphyletic. Indeed, families within orders appeared to be paraphyletic for most major clades, including Hexactinellida and Calcarea. 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.