Rebecca M Varney1, Bastian Brenzinger2, Manuel António E Malaquias3, Christopher P Meyer4, Michael Schrödl2,5, Kevin M Kocot6,7. 1. Department of Biological Sciences, The University of Alabama, Campus Box 870344, Tuscaloosa, AL, 35487, USA. 2. SNSB-Bavarian State Collection of Zoology, Münchhausenstr. 21, 81247, München, Germany. 3. Department of Natural History, University Museum of Bergen, University of Bergen, 5020, Bergen, Norway. 4. National Museum of Natural History, Smithsonian Institution, 10th St. & Constitution Ave. NW, Washington, D.C., 20560, USA. 5. BioGeoCenter LMU (Ludwig Maximillion University Munich), University of Munich, Biozentrum, Großhaderner Str. 2, 82152, Planegg-Martinsried, Germany. 6. Department of Biological Sciences, The University of Alabama, Campus Box 870344, Tuscaloosa, AL, 35487, USA. kmkocot@ua.edu. 7. Alabama Museum of Natural History, Campus Box 870344, Tuscaloosa, AL, 35487, USA. kmkocot@ua.edu.
Abstract
BACKGROUND: Heterobranchia is a diverse clade of marine, freshwater, and terrestrial gastropod molluscs. It includes such disparate taxa as nudibranchs, sea hares, bubble snails, pulmonate land snails and slugs, and a number of (mostly small-bodied) poorly known snails and slugs collectively referred to as the "lower heterobranchs". Evolutionary relationships within Heterobranchia have been challenging to resolve and the group has been subject to frequent and significant taxonomic revision. Mitochondrial (mt) genomes can be a useful molecular marker for phylogenetics but, to date, sequences have been available for only a relatively small subset of Heterobranchia. RESULTS: To assess the utility of mitochondrial genomes for resolving evolutionary relationships within this clade, eleven new mt genomes were sequenced including representatives of several groups of "lower heterobranchs". Maximum likelihood analyses of concatenated matrices of the thirteen protein coding genes found weak support for most higher-level relationships even after several taxa with extremely high rates of evolution were excluded. Bayesian inference with the CAT + GTR model resulted in a reconstruction that is much more consistent with the current understanding of heterobranch phylogeny. Notably, this analysis recovered Valvatoidea and Orbitestelloidea in a polytomy with a clade including all other heterobranchs, highlighting these taxa as important to understanding early heterobranch evolution. Also, dramatic gene rearrangements were detected within and between multiple clades. However, a single gene order is conserved across the majority of heterobranch clades. CONCLUSIONS: Analysis of mitochondrial genomes in a Bayesian framework with the site heterogeneous CAT + GTR model resulted in a topology largely consistent with the current understanding of heterobranch phylogeny. However, mitochondrial genomes appear to be too variable to serve as good phylogenetic markers for robustly resolving a number of deeper splits within this clade.
BACKGROUND: Heterobranchia is a diverse clade of marine, freshwater, and terrestrial gastropod molluscs. It includes such disparate taxa as nudibranchs, sea hares, bubble snails, pulmonate land snails and slugs, and a number of (mostly small-bodied) poorly known snails and slugs collectively referred to as the "lower heterobranchs". Evolutionary relationships within Heterobranchia have been challenging to resolve and the group has been subject to frequent and significant taxonomic revision. Mitochondrial (mt) genomes can be a useful molecular marker for phylogenetics but, to date, sequences have been available for only a relatively small subset of Heterobranchia. RESULTS: To assess the utility of mitochondrial genomes for resolving evolutionary relationships within this clade, eleven new mt genomes were sequenced including representatives of several groups of "lower heterobranchs". Maximum likelihood analyses of concatenated matrices of the thirteen protein coding genes found weak support for most higher-level relationships even after several taxa with extremely high rates of evolution were excluded. Bayesian inference with the CAT + GTR model resulted in a reconstruction that is much more consistent with the current understanding of heterobranch phylogeny. Notably, this analysis recovered Valvatoidea and Orbitestelloidea in a polytomy with a clade including all other heterobranchs, highlighting these taxa as important to understanding early heterobranch evolution. Also, dramatic gene rearrangements were detected within and between multiple clades. However, a single gene order is conserved across the majority of heterobranch clades. CONCLUSIONS: Analysis of mitochondrial genomes in a Bayesian framework with the site heterogeneous CAT + GTR model resulted in a topology largely consistent with the current understanding of heterobranch phylogeny. However, mitochondrial genomes appear to be too variable to serve as good phylogenetic markers for robustly resolving a number of deeper splits within this clade.
Authors: Felipe Zapata; Nerida G Wilson; Mark Howison; Sónia C S Andrade; Katharina M Jörger; Michael Schrödl; Freya E Goetz; Gonzalo Giribet; Casey W Dunn Journal: Proc Biol Sci Date: 2014-11-07 Impact factor: 5.349
Authors: Tracy R White; Michele M Conrad; Roger Tseng; Shaina Balayan; Rosemary Golding; António Manuel de Frias Martins; Benoît A Dayrat Journal: BMC Evol Biol Date: 2011-10-10 Impact factor: 3.260
Authors: Patrick J Krug; Serena A Caplins; Krisha Algoso; Kanique Thomas; Ángel A Valdés; Rachael Wade; Nur Leena W S Wong; Douglas J Eernisse; Kevin M Kocot Journal: Proc Biol Sci Date: 2022-04-06 Impact factor: 5.349