Meeting Abstract

P2.105  Tuesday, Jan. 5  Molecular phylogenetics inside the “Cliona viridis complex” (Porifera, Demospongiae, Hadromerida) ESCOBAR, D.A.*; SANCHEZ, J.A.; Universidad de los Andes; Universidad de los Andes dai-esco@uniandes.edu.co

A species “complex” is a group of closely related species, where intraspecific variability overlaps with interspecific variation. Frequently, members of a species complex do not have complete reproductive isolation. In contrast, the complex may go through extensive gene flow and hybridization. This study examined the phylogenetics of the Caribbean members of the “Cliona viridis complex” (C. caribbaea, C. tenuis, C. aprica, and C. varians) based on nuclear sequences (ITS2). The intragenomic ITS2 variation and its secondary structure were evaluated using a mixed approach of Denaturing Gradient Gel Electrophoresis (DGGE), sequencing and structure prediction. Abundant intragenomic variation was found in all the species, which comprised apparently functional ITS2 secondary structures. Despite the evident morphological differentiation in these excavating sponges, the intragenomic copies of every individual had a polyphyletic placement in the ITS2 geneology. Genetic distances revealed that part of the interspecific variation overlapped with both intraespecific and intragenomic variation, which suggest either incomplete lineage sorting or extensive gene flow. To corroborate the species limits in the complex, as well as to sort out the nature of the intragenomic variation, an analysis of ITS2 nucleolar dominance is needed in order to tell which of the copies are actually expressed and functional. In addition, mitochondrial sequences will be obtained to check for mito-nuclear discordance and gene flow directionality in the complex.