Reconstruction of Family-Level Phylogenetic Relationships within Demospongiae (Porifera) Using Nuclear Encoded Housekeeping Genes

Authors

Malcolm Hill, University of RichmondFollow
April L. Hill, University of RichmondFollow
et. al.

DOI

10.1371/journal.pone.0050437

Abstract

Background: Demosponges are challenging for phylogenetic systematics because of their plastic and relatively simple morphologies and many deep divergences between major clades. To improve understanding of the phylogenetic relationships within Demospongiae, we sequenced and analyzed seven nuclear housekeeping genes involved in a variety of cellular functions from a diverse group of sponges.

Methodology/Principal Findings: We generated data from each of the four sponge classes (i.e., Calcarea, Demospongiae, Hexactinellida, and Homoscleromorpha), but focused on family-level relationships within demosponges. With data for 21 newly sampled families, our Maximum Likelihood and Bayesian-based approaches recovered previously phylogenetically defined taxa: Keratosa^p, Myxospongiae^p, Spongillida^p, Haploscleromorpha^p (the marine haplosclerids) and Democlavia^p. We found conflicting results concerning the relationships of Keratosa^p and Myxospongiae^p to the remaining demosponges, but our results strongly supported a clade of Haploscleromorpha^p+Spongillida^p+Democlavia^p. In contrast to hypotheses based on mitochondrial genome and ribosomal data, nuclear housekeeping gene data suggested that freshwater sponges (Spongillida^p) are sister to Haploscleromorpha^p rather than part of Democlavia^p. Within Keratosa^p, we found equivocal results as to the monophyly of Dictyoceratida. Within Myxospongiae^p, Chondrosida and Verongida were monophyletic. A wellsupported clade within Democlavia^p, Tetractinellida^p, composed of all sampled members of Astrophorina and Spirophorina (including the only lithistid in our analysis), was consistently revealed as the sister group to all other members of Democlavia^p. Within Tetractinellida^p, we did not recover monophyletic Astrophorina or Spirophorina. Our results also reaffirmed the monophyly of order Poecilosclerida (excluding Desmacellidae and Raspailiidae), and polyphyly of Hadromerida and Halichondrida.

Conclusions/Significance: These results, using an independent nuclear gene set, confirmed many hypotheses based on ribosomal and/or mitochondrial genes, and they also identified clades with low statistical support or clades that conflicted with traditional morphological classification. Our results will serve as a basis for future exploration of these outstanding questions using more taxon- and gene-rich datasets.

Document Type

Article

Publication Date

1-2013

Publisher Statement

This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

This article first appeared in PLoS ONE 8, no. 1 (January 2013): E50437. doi:10.1371/journal.pone.0050437.

Recommended Citation

Hill, Malcolm S., April L. Hill, Jose Lopez, Kevin J. Peterson, Shirley Pomponi, Maria C. Diaz, Robert W. Thacker, Maja Adamska, Nicole Boury-Esnault, Paco Cárdenas, Andia Chaves-Fonnegra, Elizabeth Danka, Bre-Onna De Laine, Dawn Formica, Eduardo Hajdu, Gisele Lobo-Hajdu, Sarah Klontz, Christine C. Morrow, Jignasa Patel, Bernard Picton, Davide Pisani, Deborah Pohlmann, Niamh E. Redmond, John Reed, Stacy Richey, Ana Riesgo, Ewelina Rubin, Zach Russell, Klaus Rützler, Erik A. Sperling, Michael Di Stefano, James E. Tarver, and Allen G. Collins. "Reconstruction of Family-Level Phylogenetic Relationships within Demospongiae (Porifera) Using Nuclear Encoded Housekeeping Genes." PLoS ONE 8, no. 1 (January 2013): e50437. doi:10.1371/journal.pone.0050437.