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Combined Use of Morphological and Molecular Tools to Resolve Species Mis-Identifications in the Bivalvia The Case of Glycymeris glycymeris and G . pilosa

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ABSTRACT

Morphological and molecular tools were combined to resolve the misidentification between Glycymeris glycymeris and Glycymeris pilosa from Atlantic and Mediterranean populations. The ambiguous literature on the taxonomic status of these species requires this confirmation as a baseline to studies on their ecology and sclerochronology. We used classical and landmark-based morphometric approaches and performed bivariate and multivariate analyses to test for shell character interactions at the individual and population level. Both approaches generated complementary information. The former showed the shell width to length ratio and the valve asymmetry to be the main discriminant characters between Atlantic and Mediterranean populations. Additionally, the external microsculpture of additional and finer secondary ribs in G. glycymeris discriminates it from G. pilosa. Likewise, landmark-based geometric morphometrics revealed a stronger opisthogyrate beak and prosodetic ligament in G. pilosa than G. glycymeris. Our Bayesian and maximum likelihood phylogenetic analyses based on COI and ITS2 genes identified that G. glycymeris and G. pilosa form two separate monophyletic clades with mean interspecific divergence of 11% and 0.9% for COI and ITS2, respectively. The congruent patterns of morphometric analysis together with mitochondrial and nuclear phylogenetic reconstructions indicated the separation of the two coexisting species. The intraspecific divergence occurred during the Eocene and accelerated during the late Pliocene and Pleistocene. Glycymeris pilosa showed a high level of genetic diversity, appearing as a more robust species whose tolerance of environmental conditions allowed its expansion throughout the Mediterranean.

No MeSH data available.


Bayesian posterior probabilities and bootstrap support for MrBayes and Maximum Likelihood analyses.Illustration of tree topology based on COI haplotypes of G. glycymeris (Gg), G. pilosa (Gp), G. nummaria (Gn), G. bimaculata (Gb) and outgroups. Posterior probabilities followed by bootstrap values are included at the nodes. The origin of the haplotypes (H) is indicated as follow: UK, United Kingdom; FR, France; AD, Adriatic Sea; AT, Atlantic Sea; PA, Pag; PS, Pašman.
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pone.0162059.g008: Bayesian posterior probabilities and bootstrap support for MrBayes and Maximum Likelihood analyses.Illustration of tree topology based on COI haplotypes of G. glycymeris (Gg), G. pilosa (Gp), G. nummaria (Gn), G. bimaculata (Gb) and outgroups. Posterior probabilities followed by bootstrap values are included at the nodes. The origin of the haplotypes (H) is indicated as follow: UK, United Kingdom; FR, France; AD, Adriatic Sea; AT, Atlantic Sea; PA, Pag; PS, Pašman.

Mentions: For COI gene, the dated topology (BEAST), Bayesian and ML analysis gave congruent results. Phylogenetic reconstructions distinguished four strongly supported species of Glycymerididae (bootstrap support 97% to 99%, posterior probabilities 0.95–0.99) in the ingroup (Fig 8). Also, the analyses of COI data supported close relationship between G. glycymeris and G. bimaculata, having G. pilosa species as a sister clade. By contrast, deep genealogical divergence among G. nummaria and other Glycymeris species were recorded. The ITS2 tree (S2 Fig) was much less resolved, with three well-supported groups recognized, among which G. glycymeris and G. bimaculata were grouped into one clade. The G. glycymeris specimen (FN667988.1) originating from Tuscan Archipelago, Mediterranean Sea was assigned in G. pilosa clade, suggesting species mislabeling in the GenBank database.


Combined Use of Morphological and Molecular Tools to Resolve Species Mis-Identifications in the Bivalvia The Case of Glycymeris glycymeris and G . pilosa
Bayesian posterior probabilities and bootstrap support for MrBayes and Maximum Likelihood analyses.Illustration of tree topology based on COI haplotypes of G. glycymeris (Gg), G. pilosa (Gp), G. nummaria (Gn), G. bimaculata (Gb) and outgroups. Posterior probabilities followed by bootstrap values are included at the nodes. The origin of the haplotypes (H) is indicated as follow: UK, United Kingdom; FR, France; AD, Adriatic Sea; AT, Atlantic Sea; PA, Pag; PS, Pašman.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036790&req=5

pone.0162059.g008: Bayesian posterior probabilities and bootstrap support for MrBayes and Maximum Likelihood analyses.Illustration of tree topology based on COI haplotypes of G. glycymeris (Gg), G. pilosa (Gp), G. nummaria (Gn), G. bimaculata (Gb) and outgroups. Posterior probabilities followed by bootstrap values are included at the nodes. The origin of the haplotypes (H) is indicated as follow: UK, United Kingdom; FR, France; AD, Adriatic Sea; AT, Atlantic Sea; PA, Pag; PS, Pašman.
Mentions: For COI gene, the dated topology (BEAST), Bayesian and ML analysis gave congruent results. Phylogenetic reconstructions distinguished four strongly supported species of Glycymerididae (bootstrap support 97% to 99%, posterior probabilities 0.95–0.99) in the ingroup (Fig 8). Also, the analyses of COI data supported close relationship between G. glycymeris and G. bimaculata, having G. pilosa species as a sister clade. By contrast, deep genealogical divergence among G. nummaria and other Glycymeris species were recorded. The ITS2 tree (S2 Fig) was much less resolved, with three well-supported groups recognized, among which G. glycymeris and G. bimaculata were grouped into one clade. The G. glycymeris specimen (FN667988.1) originating from Tuscan Archipelago, Mediterranean Sea was assigned in G. pilosa clade, suggesting species mislabeling in the GenBank database.

View Article: PubMed Central - PubMed

ABSTRACT

Morphological and molecular tools were combined to resolve the misidentification between Glycymeris glycymeris and Glycymeris pilosa from Atlantic and Mediterranean populations. The ambiguous literature on the taxonomic status of these species requires this confirmation as a baseline to studies on their ecology and sclerochronology. We used classical and landmark-based morphometric approaches and performed bivariate and multivariate analyses to test for shell character interactions at the individual and population level. Both approaches generated complementary information. The former showed the shell width to length ratio and the valve asymmetry to be the main discriminant characters between Atlantic and Mediterranean populations. Additionally, the external microsculpture of additional and finer secondary ribs in G. glycymeris discriminates it from G. pilosa. Likewise, landmark-based geometric morphometrics revealed a stronger opisthogyrate beak and prosodetic ligament in G. pilosa than G. glycymeris. Our Bayesian and maximum likelihood phylogenetic analyses based on COI and ITS2 genes identified that G. glycymeris and G. pilosa form two separate monophyletic clades with mean interspecific divergence of 11% and 0.9% for COI and ITS2, respectively. The congruent patterns of morphometric analysis together with mitochondrial and nuclear phylogenetic reconstructions indicated the separation of the two coexisting species. The intraspecific divergence occurred during the Eocene and accelerated during the late Pliocene and Pleistocene. Glycymeris pilosa showed a high level of genetic diversity, appearing as a more robust species whose tolerance of environmental conditions allowed its expansion throughout the Mediterranean.

No MeSH data available.