| Abstract | Pisione is a scaleless group of small scale worms inhabiting sandy bottoms in shallow marine waters. This group was once considered rare, but now 45 described species can be characterized, among others, by their paired, segmental copulatory organs (one to multiple external pairs), which display a complexity of various accessory structures. The evolutionary significance of these unique organs was suggested in the late 1960s, but has been heavily debated since the late 1990s and remains controversial. In the present paper, we study the internal relationships within Pisione, employing combined phylogenetic analyses of both molecular and morphological data from 16 terminals of Pisione, as well as two terminals of Pisionidens, and eight additional scale worms as outgroups. Our taxon sampling covers all geographical areas where the genus has been reported, as well as most of their morphological and copulatory variability, including representatives of the "africana," "remota," "crassa," and "papuensis" groups, established previously by Yamanishi. We hereby provide a first insight into the relationships of the genus, testing previously proposed hypotheses on the evolutionary significance of male copulatory structures within Pisione, while attempting to understand patterns of distribution. The phylogenetic analyses using maximum likelihood and Bayesian methods consistently recovered two large clades spanning the East Atlantic (including the Mediterranean) and the Indo-Pacific-West Atlantic, respectively. Character optimization on our trees revealed a high degree of homoplasy in both non-reproductive and sexual characters of Pisione, with buccal acicula found to be the sole apomorphy among the morphological features assessed herein, with none defining the biogeographical subclades within. Overall, our comparative analyses highlight the high degree of morphological variation in this widely distributed genus, rejecting previous assertions of an increasing number and complexity of copulatory structures across the genus. |
| Text | 384181 2017 10.1002/ece3.2853 Scopus 2 s2.0 85016246059 ISI Web of Science WOS 000402548900003 Aphroditiformia comparative methods copulatory structures interstitial morphological evolution scale worm Phylogeny and biogeography of the scaleless scale worm Pisione Sigalionidae, Annelida Gonzalez B.C.; Petersen H.C.B.; Di Domenico M.; Martinez A.; Armenteros M.; Garcia Machado E.; Moller P.R.; Worsaae K. Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen Ø, , Denmark; Center for Marine Studies, Federal University of Parana, Parana, , Brazil; Molecular Ecology Group Italian National Research Council, Institute for Ecosystem Study CNR ISE, Verbania Pallanza, , Italy; Centro de Investigaciones Marinas, Universidad de La Habana, Habana, , Cuba; Evolutionary Genomics Section, Natural History Museum of Denmark, Copenhagen Ø, , Denmark Pisione is a scaleless group of small scale worms inhabiting sandy bottoms in shallow marine waters. This group was once considered rare, but now 45 described species can be characterized, among others, by their paired, segmental copulatory organs one to multiple external pairs , which display a complexity of various accessory structures. The evolutionary significance of these unique organs was suggested in the late 1960s, but has been heavily debated since the late 1990s and remains controversial. In the present paper, we study the internal relationships within Pisione, employing combined phylogenetic analyses of both molecular and morphological data from 16 terminals of Pisione, as well as two terminals of Pisionidens, and eight additional scale worms as outgroups. Our taxon sampling covers all geographical areas where the genus has been reported, as well as most of their morphological and copulatory variability, including representatives of the africana, remota, crassa, and papuensis groups, established previously by Yamanishi. We hereby provide a first insight into the relationships of the genus, testing previously proposed hypotheses on the evolutionary significance of male copulatory structures within Pisione, while attempting to understand patterns of distribution. The phylogenetic analyses using maximum likelihood and Bayesian methods consistently recovered two large clades spanning the East Atlantic including the Mediterranean and the Indo Pacific West Atlantic, respectively. Character optimization on our trees revealed a high degree of homoplasy in both non reproductive and sexual characters of Pisione, with buccal acicula found to be the sole apomorphy among the morphological features assessed herein, with none defining the biogeographical subclades within. Overall, our comparative analyses highlight the high degree of morphological variation in this widely distributed genus, rejecting previous assertions of an increasing number and complexity of copulatory structures across the genus. 7 Published version http //www.scopus.com/inward/record.url eid=2 s2.0 85016246059 partnerID=q2rCbXpz Articolo in rivista Wiley Blackwell 2045 7758 Ecology and evolution Ecology and evolution Ecology and evolution alejandro.martinezgarcia MARTINEZ GARCIA ALEJANDRO |
