Neogastropod phylogenetic relationships based on entire mitochondrial genomes

<p>Abstract</p> <p>Background</p> <p>The Neogastropoda is a highly diversified group of predatory marine snails (Gastropoda: Caenogastropoda). Traditionally, its monophyly has been widely accepted based on several morphological synapomorphies mostly related with the dig...

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Main Authors: Zardoya Rafael, Grande Cristina, Cunha Regina L
Format: Article
Language:English
Published: BMC 2009-08-01
Series:BMC Evolutionary Biology
Online Access:http://www.biomedcentral.com/1471-2148/9/210
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author Zardoya Rafael
Grande Cristina
Cunha Regina L
author_facet Zardoya Rafael
Grande Cristina
Cunha Regina L
author_sort Zardoya Rafael
collection DOAJ
description <p>Abstract</p> <p>Background</p> <p>The Neogastropoda is a highly diversified group of predatory marine snails (Gastropoda: Caenogastropoda). Traditionally, its monophyly has been widely accepted based on several morphological synapomorphies mostly related with the digestive system. However, recent molecular phylogenetic studies challenged the monophyly of Neogastropoda due to the inclusion of representatives of other caenogastropod lineages (e.g. Littorinimorpha) within the group. Neogastropoda has been classified into up to six superfamilies including Buccinoidea, Muricoidea, Olivoidea, Pseudolivoidea, Conoidea, and Cancellarioidea. Phylogenetic relationships among neogastropod superfamilies remain unresolved.</p> <p>Results</p> <p>The complete mitochondrial (mt) genomes of seven Neogastropoda (<it>Bolinus brandaris</it>, <it>Cancellaria cancellata</it>, <it>Conus borgesi</it>, <it>Cymbium olla</it>, <it>Fusiturris similis</it>, <it>Nassarius reticulatus</it>, and <it>Terebra dimidiata</it>) and of the tonnoidean <it>Cymatium parthenopeum </it>(Littorinimorpha), a putative sister group to Neogastropoda, were sequenced. In addition, the partial sequence of the mitochondrial genome of the calyptraeoidean <it>Calyptraea chinensis </it>(Littorinimorpha) was also determined. All sequenced neogastropod mt genomes shared a highly conserved gene order with only two instances of <it>tRNA </it>gene translocation. Phylogenetic relationships of Neogastropoda were inferred based on the 13 mt protein coding genes (both at the amino acid and nucleotide level) of all available caenogastropod mitochondrial genomes. Maximum likelihood (ML) and Bayesian inference (BI) phylogenetic analyses failed to recover the monophyly of Neogastropoda due to the inclusion of the tonnoidean <it>Cymatium parthenopeum </it>within the group. At the superfamily level, all phylogenetic analyses questioned the taxonomic validity of Muricoidea, whereas the monophyly of Conoidea was supported by most phylogenetic analyses, albeit weakly. All analyzed families were recovered as monophyletic except Turridae due to the inclusion of Terebridae. Further phylogenetic analyses based on either a four mt gene data set including two additional Littorinimorpha or combining mt and nuclear sequence data also rejected the monophyly of Neogastropoda but rendered rather unresolved topologies. The phylogenetic performance of each mt gene was evaluated under ML. The total number of resolved internal branches of the reference (whole-mt genome) topology was not recovered in any of the individual gene phylogenetic analysis. The <it>cox2 </it>gene recovered the highest number of congruent internal branches with the reference topology, whereas the combined <it>tRNA </it>genes, <it>cox1</it>, and <it>atp8 </it>showed the lowest phylogenetic performance.</p> <p>Conclusion</p> <p>Phylogenetic analyses based on complete mt genome data resolved a higher number of internal branches of the caenogastropod tree than individual mt genes. All performed phylogenetic analyses agreed in rejecting the monophyly of the Neogastropoda due to the inclusion of Littorinimorpha lineages within the group. This result challenges morphological evidence, and prompts for further re-evaluation of neogastropod morphological synapomorphies. The important increase in number of analyzed positions with respect to previous studies was not enough to achieve conclusive results regarding phylogenetic relationships within Neogastropoda. In this regard, sequencing of complete mtDNAs from all closely related caenogastropod lineages is needed. Nevertheless, the rapid radiation at the origin of Neogastropoda may not allow full resolution of this phylogeny based only on mt data, and in parallel more nuclear sequence data will also need to be incorporated into the phylogenetic analyses.</p>
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spelling doaj.art-f5790a220dc54f77b701d9ac00fc67382022-12-21T20:47:54ZengBMCBMC Evolutionary Biology1471-21482009-08-019121010.1186/1471-2148-9-210Neogastropod phylogenetic relationships based on entire mitochondrial genomesZardoya RafaelGrande CristinaCunha Regina L<p>Abstract</p> <p>Background</p> <p>The Neogastropoda is a highly diversified group of predatory marine snails (Gastropoda: Caenogastropoda). Traditionally, its monophyly has been widely accepted based on several morphological synapomorphies mostly related with the digestive system. However, recent molecular phylogenetic studies challenged the monophyly of Neogastropoda due to the inclusion of representatives of other caenogastropod lineages (e.g. Littorinimorpha) within the group. Neogastropoda has been classified into up to six superfamilies including Buccinoidea, Muricoidea, Olivoidea, Pseudolivoidea, Conoidea, and Cancellarioidea. Phylogenetic relationships among neogastropod superfamilies remain unresolved.</p> <p>Results</p> <p>The complete mitochondrial (mt) genomes of seven Neogastropoda (<it>Bolinus brandaris</it>, <it>Cancellaria cancellata</it>, <it>Conus borgesi</it>, <it>Cymbium olla</it>, <it>Fusiturris similis</it>, <it>Nassarius reticulatus</it>, and <it>Terebra dimidiata</it>) and of the tonnoidean <it>Cymatium parthenopeum </it>(Littorinimorpha), a putative sister group to Neogastropoda, were sequenced. In addition, the partial sequence of the mitochondrial genome of the calyptraeoidean <it>Calyptraea chinensis </it>(Littorinimorpha) was also determined. All sequenced neogastropod mt genomes shared a highly conserved gene order with only two instances of <it>tRNA </it>gene translocation. Phylogenetic relationships of Neogastropoda were inferred based on the 13 mt protein coding genes (both at the amino acid and nucleotide level) of all available caenogastropod mitochondrial genomes. Maximum likelihood (ML) and Bayesian inference (BI) phylogenetic analyses failed to recover the monophyly of Neogastropoda due to the inclusion of the tonnoidean <it>Cymatium parthenopeum </it>within the group. At the superfamily level, all phylogenetic analyses questioned the taxonomic validity of Muricoidea, whereas the monophyly of Conoidea was supported by most phylogenetic analyses, albeit weakly. All analyzed families were recovered as monophyletic except Turridae due to the inclusion of Terebridae. Further phylogenetic analyses based on either a four mt gene data set including two additional Littorinimorpha or combining mt and nuclear sequence data also rejected the monophyly of Neogastropoda but rendered rather unresolved topologies. The phylogenetic performance of each mt gene was evaluated under ML. The total number of resolved internal branches of the reference (whole-mt genome) topology was not recovered in any of the individual gene phylogenetic analysis. The <it>cox2 </it>gene recovered the highest number of congruent internal branches with the reference topology, whereas the combined <it>tRNA </it>genes, <it>cox1</it>, and <it>atp8 </it>showed the lowest phylogenetic performance.</p> <p>Conclusion</p> <p>Phylogenetic analyses based on complete mt genome data resolved a higher number of internal branches of the caenogastropod tree than individual mt genes. All performed phylogenetic analyses agreed in rejecting the monophyly of the Neogastropoda due to the inclusion of Littorinimorpha lineages within the group. This result challenges morphological evidence, and prompts for further re-evaluation of neogastropod morphological synapomorphies. The important increase in number of analyzed positions with respect to previous studies was not enough to achieve conclusive results regarding phylogenetic relationships within Neogastropoda. In this regard, sequencing of complete mtDNAs from all closely related caenogastropod lineages is needed. Nevertheless, the rapid radiation at the origin of Neogastropoda may not allow full resolution of this phylogeny based only on mt data, and in parallel more nuclear sequence data will also need to be incorporated into the phylogenetic analyses.</p>http://www.biomedcentral.com/1471-2148/9/210
spellingShingle Zardoya Rafael
Grande Cristina
Cunha Regina L
Neogastropod phylogenetic relationships based on entire mitochondrial genomes
BMC Evolutionary Biology
title Neogastropod phylogenetic relationships based on entire mitochondrial genomes
title_full Neogastropod phylogenetic relationships based on entire mitochondrial genomes
title_fullStr Neogastropod phylogenetic relationships based on entire mitochondrial genomes
title_full_unstemmed Neogastropod phylogenetic relationships based on entire mitochondrial genomes
title_short Neogastropod phylogenetic relationships based on entire mitochondrial genomes
title_sort neogastropod phylogenetic relationships based on entire mitochondrial genomes
url http://www.biomedcentral.com/1471-2148/9/210
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