Limits...
The evolutionary origins of the southern ocean Philobryid bivalves: hidden biodiversity, ancient persistence.

Jackson JA, Linse K, Whittle R, Griffiths HJ - PLoS ONE (2015)

Bottom Line: The A. nitens species complex is identified as at least seven morpho-species through morphological and genetic analysis of taxon clustering.Phylogenetic analyses resolve Philobryidae as a strongly supported monophyletic clade and sister taxon to the Limopsidae, as anticipated by their classification into the superfamily Limopsoidea.Bayesian relaxed clock analyses of divergence times suggest that genus Adacnarca radiated in the Southern Ocean from the Early Paleogene, while P. sublaevis and P. wandelensis clades radiated in the late Miocene, following the formation of the Antarctic Circumpolar Current.

View Article: PubMed Central - PubMed

Affiliation: British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom.

ABSTRACT
Philobryids (Bivalvia: Arcoida) are one of the most speciose marine bivalve families in the Southern Ocean and are common throughout the Southern Hemisphere. Considering this diversity and their brooding reproductive mode (limiting long-distance dispersal), this family may have been present in the Southern Ocean since its inception. However Philobrya and Adacnarca appear only in the Quaternary fossil record of the Antarctic, suggesting a much more recent incursion. Molecular dating provides an independent means of measuring the time of origin and radiation of this poorly known group. Here we present the first combined molecular and morphological investigation of the Philobryidae in the Southern Ocean. Two nuclear loci (18S and 28S) were amplified from 35 Southern Ocean Adacnarca and Philobrya specimens, with a combined sequence length of 2,282 base pairs (bp). Adacnarca specimens (A. nitens and A. limopsoides) were resolved as a strongly supported monophyletic group. Genus Philobrya fell into two strongly supported groups ('sublaevis' and 'magellanica/wandelensis'), paraphyletic with Adacnarca. The A. nitens species complex is identified as at least seven morpho-species through morphological and genetic analysis of taxon clustering. Phylogenetic analyses resolve Philobryidae as a strongly supported monophyletic clade and sister taxon to the Limopsidae, as anticipated by their classification into the superfamily Limopsoidea. Bayesian relaxed clock analyses of divergence times suggest that genus Adacnarca radiated in the Southern Ocean from the Early Paleogene, while P. sublaevis and P. wandelensis clades radiated in the late Miocene, following the formation of the Antarctic Circumpolar Current.

No MeSH data available.


Divergence time analysis using 28S with multiple fossil constraints and an uncorrelated lognormal relaxed clock.Rate variation across the phylogeny is depicted using branch thickness. Posterior support values over 80% are shown. Bars at key nodes represent 95%-iles on estimated divergence times. Fossil constraints are indicated by stars with details given in the text.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4390230&req=5

pone.0121198.g007: Divergence time analysis using 28S with multiple fossil constraints and an uncorrelated lognormal relaxed clock.Rate variation across the phylogeny is depicted using branch thickness. Posterior support values over 80% are shown. Bars at key nodes represent 95%-iles on estimated divergence times. Fossil constraints are indicated by stars with details given in the text.

Mentions: While the Bayesian analysis of 28S produced a polyphyletic Arcidae (Fig. 6), SH testing did not reject the monophyly of Arcidae for any of the datasets analysed (Table 2), and this family is reconstructed as a monophyletic group with divergence time analysis (Fig. 7). There is some evidence supporting the existence of superfamily Arcoidea (here comprising Arcidae, Cucullaeidae and Glycymeridae, with no sampling of Noetiidae) [44]. SH testing does not reject this hypothesis, but at present taxonomic sampling is too limited to make further inferences about arcoid phylogenetic groupings.


The evolutionary origins of the southern ocean Philobryid bivalves: hidden biodiversity, ancient persistence.

Jackson JA, Linse K, Whittle R, Griffiths HJ - PLoS ONE (2015)

Divergence time analysis using 28S with multiple fossil constraints and an uncorrelated lognormal relaxed clock.Rate variation across the phylogeny is depicted using branch thickness. Posterior support values over 80% are shown. Bars at key nodes represent 95%-iles on estimated divergence times. Fossil constraints are indicated by stars with details given in the text.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390230&req=5

pone.0121198.g007: Divergence time analysis using 28S with multiple fossil constraints and an uncorrelated lognormal relaxed clock.Rate variation across the phylogeny is depicted using branch thickness. Posterior support values over 80% are shown. Bars at key nodes represent 95%-iles on estimated divergence times. Fossil constraints are indicated by stars with details given in the text.
Mentions: While the Bayesian analysis of 28S produced a polyphyletic Arcidae (Fig. 6), SH testing did not reject the monophyly of Arcidae for any of the datasets analysed (Table 2), and this family is reconstructed as a monophyletic group with divergence time analysis (Fig. 7). There is some evidence supporting the existence of superfamily Arcoidea (here comprising Arcidae, Cucullaeidae and Glycymeridae, with no sampling of Noetiidae) [44]. SH testing does not reject this hypothesis, but at present taxonomic sampling is too limited to make further inferences about arcoid phylogenetic groupings.

Bottom Line: The A. nitens species complex is identified as at least seven morpho-species through morphological and genetic analysis of taxon clustering.Phylogenetic analyses resolve Philobryidae as a strongly supported monophyletic clade and sister taxon to the Limopsidae, as anticipated by their classification into the superfamily Limopsoidea.Bayesian relaxed clock analyses of divergence times suggest that genus Adacnarca radiated in the Southern Ocean from the Early Paleogene, while P. sublaevis and P. wandelensis clades radiated in the late Miocene, following the formation of the Antarctic Circumpolar Current.

View Article: PubMed Central - PubMed

Affiliation: British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom.

ABSTRACT
Philobryids (Bivalvia: Arcoida) are one of the most speciose marine bivalve families in the Southern Ocean and are common throughout the Southern Hemisphere. Considering this diversity and their brooding reproductive mode (limiting long-distance dispersal), this family may have been present in the Southern Ocean since its inception. However Philobrya and Adacnarca appear only in the Quaternary fossil record of the Antarctic, suggesting a much more recent incursion. Molecular dating provides an independent means of measuring the time of origin and radiation of this poorly known group. Here we present the first combined molecular and morphological investigation of the Philobryidae in the Southern Ocean. Two nuclear loci (18S and 28S) were amplified from 35 Southern Ocean Adacnarca and Philobrya specimens, with a combined sequence length of 2,282 base pairs (bp). Adacnarca specimens (A. nitens and A. limopsoides) were resolved as a strongly supported monophyletic group. Genus Philobrya fell into two strongly supported groups ('sublaevis' and 'magellanica/wandelensis'), paraphyletic with Adacnarca. The A. nitens species complex is identified as at least seven morpho-species through morphological and genetic analysis of taxon clustering. Phylogenetic analyses resolve Philobryidae as a strongly supported monophyletic clade and sister taxon to the Limopsidae, as anticipated by their classification into the superfamily Limopsoidea. Bayesian relaxed clock analyses of divergence times suggest that genus Adacnarca radiated in the Southern Ocean from the Early Paleogene, while P. sublaevis and P. wandelensis clades radiated in the late Miocene, following the formation of the Antarctic Circumpolar Current.

No MeSH data available.