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Testing the emergence of New Caledonia: fig wasp mutualism as a case study and a review of evidence.

Cruaud A, Jabbour-Zahab R, Genson G, Ungricht S, Rasplus JY - PLoS ONE (2012)

Bottom Line: These partners are distributed in the Paleotropics and Australasia, suggesting that their presence on New Caledonia could result from Gondwanan vicariance.Our results show that successful long-distance dispersal of obligate mutualists may happen further suggesting that presence of intimate mutualisms on isolated islands should not be used as a priori evidence for vicariance.Comparing our results to a review of all the published age estimates for New Caledonian plant and animal taxa, we showed that support for a vicariant origin of the island biota is still lacking.

View Article: PubMed Central - PubMed

Affiliation: INRA-UMR Centre de Biologie et de Gestion des Populations, CBGP, INRA/IRD/CIRAD/Montpellier SupAgro, Campus international de Baillarguet, Montferrier-sur Lez, France. cruaud@supagro.inra.fr

ABSTRACT
While geologists suggest that New Caledonian main island (Grande Terre) was submerged until ca 37 Ma, biologists are struck by the presence of supposedly Gondwanan groups on the island. Among these groups are the Oreosycea fig trees (Ficus, Moraceae) and their Dolichoris pollinators (Hymenoptera, Agaonidae). These partners are distributed in the Paleotropics and Australasia, suggesting that their presence on New Caledonia could result from Gondwanan vicariance. To test this hypothesis, we obtained mitochondrial and nuclear markers (5.3 kb) from 28 species of Dolichoris, used all available sequences for Oreosycea, and conducted phylogenetic and dating analyses with several calibration strategies. All our analyses ruled out a vicariance scenario suggesting instead that New Caledonian colonization by Dolichoris and Oreosycea involved dispersal across islands from Sundaland ca 45.9-32.0 Ma. Our results show that successful long-distance dispersal of obligate mutualists may happen further suggesting that presence of intimate mutualisms on isolated islands should not be used as a priori evidence for vicariance. Comparing our results to a review of all the published age estimates for New Caledonian plant and animal taxa, we showed that support for a vicariant origin of the island biota is still lacking. Finally, as demonstrating a causal relationship between geology and biology requires independent evidence, we argue that a priori assumptions about vicariance or dispersal should not be used to constrain chronograms. This circular reasoning could lead to under or overestimation of age estimates.

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Related in: MedlinePlus

Review of the divergence time estimates for 50 New Caledonian clades.Taxon names refer to the list provided in Table S4. “Dolichoris 2” refers to the present study.
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pone-0030941-g002: Review of the divergence time estimates for 50 New Caledonian clades.Taxon names refer to the list provided in Table S4. “Dolichoris 2” refers to the present study.

Mentions: Our review includes 47 studies focusing on 54 different taxa (6 vertebrates, 24 arthropods, 24 plants) with different levels of endemicity (species, genus, family) (see Table S4 for details). Figure 2 summarizes the estimates of crown and/or stem divergence times obtained for each taxon. In about 75% of the groups in which divergence ages have been estimated using different markers, dating methods, and calibration points, both crown and stem mean ages postdate New Caledonia emergence (ca 37 Ma). About 16% of the groups had mean stem ages that predate New Caledonia emergence but their mean crown ages date back at most to 41.1 Ma. For five groups, the literature only reports stem ages, and three of them, namely Amborella trichopoda, Oncotheca balansae, and Beauprea montana, exceed 80 Ma.


Testing the emergence of New Caledonia: fig wasp mutualism as a case study and a review of evidence.

Cruaud A, Jabbour-Zahab R, Genson G, Ungricht S, Rasplus JY - PLoS ONE (2012)

Review of the divergence time estimates for 50 New Caledonian clades.Taxon names refer to the list provided in Table S4. “Dolichoris 2” refers to the present study.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3285151&req=5

pone-0030941-g002: Review of the divergence time estimates for 50 New Caledonian clades.Taxon names refer to the list provided in Table S4. “Dolichoris 2” refers to the present study.
Mentions: Our review includes 47 studies focusing on 54 different taxa (6 vertebrates, 24 arthropods, 24 plants) with different levels of endemicity (species, genus, family) (see Table S4 for details). Figure 2 summarizes the estimates of crown and/or stem divergence times obtained for each taxon. In about 75% of the groups in which divergence ages have been estimated using different markers, dating methods, and calibration points, both crown and stem mean ages postdate New Caledonia emergence (ca 37 Ma). About 16% of the groups had mean stem ages that predate New Caledonia emergence but their mean crown ages date back at most to 41.1 Ma. For five groups, the literature only reports stem ages, and three of them, namely Amborella trichopoda, Oncotheca balansae, and Beauprea montana, exceed 80 Ma.

Bottom Line: These partners are distributed in the Paleotropics and Australasia, suggesting that their presence on New Caledonia could result from Gondwanan vicariance.Our results show that successful long-distance dispersal of obligate mutualists may happen further suggesting that presence of intimate mutualisms on isolated islands should not be used as a priori evidence for vicariance.Comparing our results to a review of all the published age estimates for New Caledonian plant and animal taxa, we showed that support for a vicariant origin of the island biota is still lacking.

View Article: PubMed Central - PubMed

Affiliation: INRA-UMR Centre de Biologie et de Gestion des Populations, CBGP, INRA/IRD/CIRAD/Montpellier SupAgro, Campus international de Baillarguet, Montferrier-sur Lez, France. cruaud@supagro.inra.fr

ABSTRACT
While geologists suggest that New Caledonian main island (Grande Terre) was submerged until ca 37 Ma, biologists are struck by the presence of supposedly Gondwanan groups on the island. Among these groups are the Oreosycea fig trees (Ficus, Moraceae) and their Dolichoris pollinators (Hymenoptera, Agaonidae). These partners are distributed in the Paleotropics and Australasia, suggesting that their presence on New Caledonia could result from Gondwanan vicariance. To test this hypothesis, we obtained mitochondrial and nuclear markers (5.3 kb) from 28 species of Dolichoris, used all available sequences for Oreosycea, and conducted phylogenetic and dating analyses with several calibration strategies. All our analyses ruled out a vicariance scenario suggesting instead that New Caledonian colonization by Dolichoris and Oreosycea involved dispersal across islands from Sundaland ca 45.9-32.0 Ma. Our results show that successful long-distance dispersal of obligate mutualists may happen further suggesting that presence of intimate mutualisms on isolated islands should not be used as a priori evidence for vicariance. Comparing our results to a review of all the published age estimates for New Caledonian plant and animal taxa, we showed that support for a vicariant origin of the island biota is still lacking. Finally, as demonstrating a causal relationship between geology and biology requires independent evidence, we argue that a priori assumptions about vicariance or dispersal should not be used to constrain chronograms. This circular reasoning could lead to under or overestimation of age estimates.

Show MeSH
Related in: MedlinePlus