concatenated analysis sheds light on early metazoan evolution and fuels a modern “urmetazoon” hypothesis连接分析揭示了早期后生动物的进化和燃料的现代u201curmetazoonu201d假说.pdfVIP

PLoS BIOLOGY Concatenated Analysis Sheds Light on Early Metazoan Evolution and Fuels a Modern ‘‘Urmetazoon’’ Hypothesis 1,2,3* 1 1 ¨ 1 1 2 Bernd Schierwater , Michael Eitel , Wolfgang Jakob , Hans-Jurgen Osigus , Heike Hadrys , Stephen L. Dellaporta , 3 3 Sergios-Orestis Kolokotronis , Rob DeSalle ¨ 1 ITZ, Ecology and Evolution, Tierarztliche Hochschule Hannover, Hannover, Germany, 2 Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, United States of America, 3 Sackler Institute for Comparative Genomics and Division of Invertebrate Zoology, American Museum of Natural History, New York, New York, United States of America For more than a century, the origin of metazoan animals has been debated. One aspect of this debate has been centered on what the hypothetical ‘‘urmetazoon’’ bauplan might have been. The morphologically most simply organized metazoan animal, the placozoan Trichoplax adhaerens, resembles an intriguing model for one of several ‘‘urmetazoon’’ hypotheses: the placula hypothesis. Clear support for a basal position of Placozoa would aid in resolving several key issues of metazoan-specific inventions (including, for example, head–foot axis, symmetry, and coelom) and would determine a root for unraveling their evolution. Unfortunately, the phylogenetic relationships at the base of Metazoa have been controversial because of conflicting phylogenetic scenarios generated while addressing the question. Here, we analyze the sum of morphological evidence, the secondary structure of mitochondrial ribosomal genes, and molecular sequence da