title: Homoplasious colony morphology and mito-nuclear phylogenetic discordance among Eastern Pacific octocorals.
abstract: Octocorals are a diverse and ecologically important group of cnidarians. However, the phylogenetic relationships of many octocoral groups are not well understood and are based mostly on mitochondrial sequence data. In addition, the discovery and description of new gorgonian species displaying unusual or intermediate morphologies and uncertain phylogenetic affinities further complicates the study of octocoral systematics and raises questions about the role played by processes such as plasticity, crypsis, and convergence in the evolution of this group of organisms. Here, we use nuclear (i.e. 28S rDNA) and mitochondrial (mtMutS) markers and a sample of Eastern Pacific gorgonians thought to be remarkable from a morphological point of view to shed light on the morphological diversification among these organisms. Our study reveals the loss of the anastomosed colony morphology in two unrelated lineages of the seafan genus Pacifigorgia and offers strong evidence for the independent evolution of a whip-like morphology in two lineages of Eastern Pacific Leptogorgia. Additionally, our data revealed one instance of mito-nuclear discordance in the genera Leptogorgia and Eugorgia, which may be the results of incomplete lineage sorting or ancient hybridization-introgression events. Our study stresses the importance of comprehensive taxonomic sampling and the use of independent sources of evidence to address the phylogenetic relationships and clarifying the evolution of octocorals.
authors.affiliation: Department of Earth and Environmental Sciences, Paleontology and Geobiology, Ludwig-Maximilians-Universtität München, Richard-Wagner Str. 10, 80333 Munich, Germany.
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Ament-Velásquez
authors.affiliation: Centro de Investigación en Estructuras Microscópicas, Universidad de Costa Rica, San José, Costa Rica; Centro de Investigación en Ciencias del Mar y Limnología, Universidad de Costa Rica, San José, Costa Rica; Smithsonian Tropical Research Institute, P.O. Box 0843-03092, Panama, Panama.
authors.forename: Odalisca
authors.initials: O
authors.lastname: Breedy
authors.affiliation: Centro de Investigación en Ciencias del Mar y Limnología, Universidad de Costa Rica, San José, Costa Rica.
authors.forename: Jorge
authors.initials: J
authors.lastname: Cortés
authors.affiliation: Smithsonian Tropical Research Institute, P.O. Box 0843-03092, Panama, Panama.
authors.forename: Hector M
authors.initials: HM
authors.lastname: Guzman
authors.affiliation: Department of Earth and Environmental Sciences, Paleontology and Geobiology, Ludwig-Maximilians-Universtität München, Richard-Wagner Str. 10, 80333 Munich, Germany; Bavarian State Collections of Palaeontology and Geology, Richard-Wagner Str. 10, 80333 Munich, Germany; GeoBio-Center, LMU, Richard-Wagner Str. 10, 80333 Munich, Germany.
authors.forename: Gert
authors.initials: G
authors.lastname: Wörheide
authors.affiliation: Department of Earth and Environmental Sciences, Paleontology and Geobiology, Ludwig-Maximilians-Universtität München, Richard-Wagner Str. 10, 80333 Munich, Germany.
authors.forename: Sergio
authors.initials: S
authors.lastname: Vargas
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000033:anatomy & histology* / Q000145:classification / Q000235:genetics*; D002467:Cell Nucleus / Q000235:genetics*; D050259:Genes, Mitochondrial / Q000235:genetics*; D006824:Hybridization, Genetic; D010140:Pacific Ocean; D010802:Phylogeny; D012339:RNA, Ribosomal, 28S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D012339:RNA, Ribosomal, 28S
keywords: Colony morphology; Eastern Pacific; Homoplasy; Mito-nuclear discordance; Molecular systematics; Octocorals