Meeting Abstract

94.6  Thursday, Jan. 7  Resolving species identities in the Porifera Tree of Life: a comparison of mitochondrial and nuclear barcodes REDMOND, N.E.*; COLLINS, A.G.; DIAZ, M.C.; THACKER, R.W.; Smithsonian Institution, National Museum of Natural History, Washington, DC; National Systematics Laboratory of NOAA’s Fisheries Service and Smithsonian Institution, National Museum of Natural History; Museo Marino de Margarita, Venezuela; University of Alabama at Birmingham, AL redmondn@si.edu

The Porifera Tree of Life (PorToL) project is a large, collaborative effort investigating phylogenetic relationships among sponges at multiple taxonomic levels. One of the main aims of this project is to address numerous outstanding species-level questions, such as species identity and generic and subgeneric affiliations. The low number of morphological characters highlights the importance of establishing informative DNA barcoding markers for this phylum. The 5’ end of the mitochondrial cytochrome oxidase I (mtCOI) marker is the chosen genetic marker for DNA based identification of species or ‘DNA barcoding’. However, strong evidence suggests that this gene region evolves at a slower rate in early diverging metazoans (e.g. anthozoan cnidarians and Porifera), rendering it less informative for sponges at the species level than it is for many other clades. In an effort to improve signal derived from the mtCOI gene, we are routinely sequencing approximately 600 additional basepairs of mtCOI. In addition, we are investigating the potential use of variable regions of the 28S rRNA gene in our species-level analyses. Results from preliminary analyses of mtCOI and 28S rRNA gene sequences from a variety of taxa (representing multiple sponge orders) indicate that the D1-D3 region of this gene evolves faster than mtCOI. We conclude that the 28S D1-D3 region may be a better alternative for studies seeking to discriminate between closely related sponge species.