Life-history evolution and mitogenomic phylogeny of caecilian amphibians.
We analyze mitochondrial genomes to reconstruct a robust phylogenetic framework for caecilian amphibians and use this to investigate life-history evolution within the group. Our study comprises 45 caecilian mitochondrial genomes (19 of them newly reported), representing all families and 27 of 32 currently recognized genera, including some for which molecular data had never been reported. Support for all relationships in the inferred phylogenetic tree is high to maximal, and topology tests reject all investigated alternatives, indicating an exceptionally robust molecular phylogenetic framework of caecilian evolution consistent with current morphology-based supraspecific classification. We used the mitogenomic phylogenetic framework to infer ancestral character states and to assess correlation among three life-history traits (free-living larvae, viviparity, specialized pre-adult or vernal teeth), each of which occurs only in some caecilian species. Our results provide evidence that an ancestor of the Seychelles caecilians abandoned direct development and re-evolved a free-living larval stage. This study yields insights into the concurrent evolution of direct development and of vernal teeth in an ancestor of Teresomata that likely gave rise to skin-feeding (maternal dermatophagy) behavior and subsequently enabled evolution of viviparity, with skin feeding possibly a homologous precursor of oviduct feeding in viviparous caecilians.
Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom. Electronic address: dsanmauro@ub.edu.
Diego
D
San Mauro
Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom.
David J
DJ
Gower
Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität Jena, Erbertstrasse 1, 07743 Jena, Germany.
Hendrik
H
Müller
University of Basel, Biogeography Research Group, Department of Environmental Sciences, Basel 4056, Switzerland.
Simon P
SP
Loader
Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales - CSIC, José Gutiérrez Abascal 2, 28006 Madrid, Spain.
Rafael
R
Zardoya
Museum of Zoology, University of Michigan, 1109 Geddes Ave., Ann Arbor, MI 48109-1079, United States.
Ronald A
RA
Nussbaum
Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom.
Mark
M
Wilkinson
D000663:Amphibians / Q000145:classification* / Q000235:genetics* / Q000254:growth & development; D000818:Animals; D005075:Biological Evolution; D019143:Evolution, Molecular; D005247:Feeding Behavior; D005260:Female; D054629:Genome, Mitochondrial / Q000235:genetics*; D007814:Larva / Q000235:genetics / Q000502:physiology; D010057:Oviducts; D010802:Phylogeny; D012750:Seychelles; D012867:Skin; D052286:Viviparity, Nonmammalian
Gymnophiona; Larval re-evolution; Maternal dermatophagy; Mitochondrial genome; Reproduction; Viviparity