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The Mitochondrial Genomes of the Nudibranch Mollusks, Melibe leonina and Tritonia diomedea, and Their Impact on Gastropod Phylogeny.

Sevigny JL, Kirouac LE, Thomas WK, Ramsdell JS, Lawlor KE, Sharifi O, Grewal S, Baysdorfer C, Curr K, Naimie AA, Okamoto K, Murray JA, Newcomb JM - PLoS ONE (2015)

Bottom Line: Both Bayesian and maximum likelihood analyses resulted in similar tree topologies.In Gastropoda, two of the three traditional subclasses, Opisthobranchia and Pulmonata, were not monophyletic.In contrast, four of the more recently named gastropod clades (Vetigastropoda, Neritimorpha, Caenogastropoda, and Heterobranchia) were all monophyletic, and thus appear to be better classifications for this diverse group.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology and Health Science, New England College, Henniker, New Hampshire, United States of America.

ABSTRACT
The phylogenetic relationships among certain groups of gastropods have remained unresolved in recent studies, especially in the diverse subclass Opisthobranchia, where nudibranchs have been poorly represented. Here we present the complete mitochondrial genomes of Melibe leonina and Tritonia diomedea (more recently named T. tetraquetra), two nudibranchs from the unrepresented Cladobranchia group, and report on the resulting phylogenetic analyses. Both genomes coded for the typical thirteen protein-coding genes, twenty-two transfer RNAs, and two ribosomal RNAs seen in other species. The twelve-nucleotide deletion previously reported for the cytochrome oxidase 1 gene in several other Melibe species was further clarified as three separate deletion events. These deletions were not present in any opisthobranchs examined in our study, including the newly sequenced M. leonina or T. diomedea, suggesting that these previously reported deletions may represent more recently divergent taxa. Analysis of the secondary structures for all twenty-two tRNAs of both M. leonina and T. diomedea indicated truncated d arms for the two serine tRNAs, as seen in some other heterobranchs. In addition, the serine 1 tRNA in T. diomedea contained an anticodon not yet reported in any other gastropod. For phylogenetic analysis, we used the thirteen protein-coding genes from the mitochondrial genomes of M. leonina, T. diomedea, and seventy-one other gastropods. Phylogenetic analyses were performed for both the class Gastropoda and the subclass Opisthobranchia. Both Bayesian and maximum likelihood analyses resulted in similar tree topologies. In the Opisthobranchia, the five orders represented in our study were monophyletic (Anaspidea, Cephalaspidea, Notaspidea, Nudibranchia, Sacoglossa). In Gastropoda, two of the three traditional subclasses, Opisthobranchia and Pulmonata, were not monophyletic. In contrast, four of the more recently named gastropod clades (Vetigastropoda, Neritimorpha, Caenogastropoda, and Heterobranchia) were all monophyletic, and thus appear to be better classifications for this diverse group.

No MeSH data available.


Opisthobranch phylogeny based on nucleotide sequences of the thirteen protein-coding genes of the mitochondrial genome.Both Bayesian and maximum likelihood analyses resulted in identical topologies, shown here as a consensus tree with branch lengths depicted from the maximum likelihood analysis. All sampled orders were found to be monophyletic groups. Numbers at nodes indicate posterior probabilities (Bayesian) followed by bootstrap values (maximum likelihood), indicating statistical confidence in that particular node.
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pone.0127519.g004: Opisthobranch phylogeny based on nucleotide sequences of the thirteen protein-coding genes of the mitochondrial genome.Both Bayesian and maximum likelihood analyses resulted in identical topologies, shown here as a consensus tree with branch lengths depicted from the maximum likelihood analysis. All sampled orders were found to be monophyletic groups. Numbers at nodes indicate posterior probabilities (Bayesian) followed by bootstrap values (maximum likelihood), indicating statistical confidence in that particular node.

Mentions: For the opisthobranchs, Bayesian and maximum likelihood analyses resulted in identical topologies with all nodes highly supported and a distinction of five monophyletic orders within Opisthobranchia (Nudibranchia, Notaspidea, Cephalaspidea, Sacoglossa, and Anaspidea) (Fig 4). Nudibranchia was a sister taxon to Notaspidea and together formed a monophyletic group that was sister to the remaining orders. Anaspidea was a sister taxon to the Sacoglossa and together formed a clade sister to the Cephalaspidea. Within Nudibranchia, M. leonina and T. diomedea were found to form a monophyletic group separate from the remaining nudibranch taxa, and the previously described Anthobranchian and Cladobranchian clades were supported.


The Mitochondrial Genomes of the Nudibranch Mollusks, Melibe leonina and Tritonia diomedea, and Their Impact on Gastropod Phylogeny.

Sevigny JL, Kirouac LE, Thomas WK, Ramsdell JS, Lawlor KE, Sharifi O, Grewal S, Baysdorfer C, Curr K, Naimie AA, Okamoto K, Murray JA, Newcomb JM - PLoS ONE (2015)

Opisthobranch phylogeny based on nucleotide sequences of the thirteen protein-coding genes of the mitochondrial genome.Both Bayesian and maximum likelihood analyses resulted in identical topologies, shown here as a consensus tree with branch lengths depicted from the maximum likelihood analysis. All sampled orders were found to be monophyletic groups. Numbers at nodes indicate posterior probabilities (Bayesian) followed by bootstrap values (maximum likelihood), indicating statistical confidence in that particular node.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4440745&req=5

pone.0127519.g004: Opisthobranch phylogeny based on nucleotide sequences of the thirteen protein-coding genes of the mitochondrial genome.Both Bayesian and maximum likelihood analyses resulted in identical topologies, shown here as a consensus tree with branch lengths depicted from the maximum likelihood analysis. All sampled orders were found to be monophyletic groups. Numbers at nodes indicate posterior probabilities (Bayesian) followed by bootstrap values (maximum likelihood), indicating statistical confidence in that particular node.
Mentions: For the opisthobranchs, Bayesian and maximum likelihood analyses resulted in identical topologies with all nodes highly supported and a distinction of five monophyletic orders within Opisthobranchia (Nudibranchia, Notaspidea, Cephalaspidea, Sacoglossa, and Anaspidea) (Fig 4). Nudibranchia was a sister taxon to Notaspidea and together formed a monophyletic group that was sister to the remaining orders. Anaspidea was a sister taxon to the Sacoglossa and together formed a clade sister to the Cephalaspidea. Within Nudibranchia, M. leonina and T. diomedea were found to form a monophyletic group separate from the remaining nudibranch taxa, and the previously described Anthobranchian and Cladobranchian clades were supported.

Bottom Line: Both Bayesian and maximum likelihood analyses resulted in similar tree topologies.In Gastropoda, two of the three traditional subclasses, Opisthobranchia and Pulmonata, were not monophyletic.In contrast, four of the more recently named gastropod clades (Vetigastropoda, Neritimorpha, Caenogastropoda, and Heterobranchia) were all monophyletic, and thus appear to be better classifications for this diverse group.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology and Health Science, New England College, Henniker, New Hampshire, United States of America.

ABSTRACT
The phylogenetic relationships among certain groups of gastropods have remained unresolved in recent studies, especially in the diverse subclass Opisthobranchia, where nudibranchs have been poorly represented. Here we present the complete mitochondrial genomes of Melibe leonina and Tritonia diomedea (more recently named T. tetraquetra), two nudibranchs from the unrepresented Cladobranchia group, and report on the resulting phylogenetic analyses. Both genomes coded for the typical thirteen protein-coding genes, twenty-two transfer RNAs, and two ribosomal RNAs seen in other species. The twelve-nucleotide deletion previously reported for the cytochrome oxidase 1 gene in several other Melibe species was further clarified as three separate deletion events. These deletions were not present in any opisthobranchs examined in our study, including the newly sequenced M. leonina or T. diomedea, suggesting that these previously reported deletions may represent more recently divergent taxa. Analysis of the secondary structures for all twenty-two tRNAs of both M. leonina and T. diomedea indicated truncated d arms for the two serine tRNAs, as seen in some other heterobranchs. In addition, the serine 1 tRNA in T. diomedea contained an anticodon not yet reported in any other gastropod. For phylogenetic analysis, we used the thirteen protein-coding genes from the mitochondrial genomes of M. leonina, T. diomedea, and seventy-one other gastropods. Phylogenetic analyses were performed for both the class Gastropoda and the subclass Opisthobranchia. Both Bayesian and maximum likelihood analyses resulted in similar tree topologies. In the Opisthobranchia, the five orders represented in our study were monophyletic (Anaspidea, Cephalaspidea, Notaspidea, Nudibranchia, Sacoglossa). In Gastropoda, two of the three traditional subclasses, Opisthobranchia and Pulmonata, were not monophyletic. In contrast, four of the more recently named gastropod clades (Vetigastropoda, Neritimorpha, Caenogastropoda, and Heterobranchia) were all monophyletic, and thus appear to be better classifications for this diverse group.

No MeSH data available.