Sapotaceae biogeography supports New Caledonia being an old Darwinian island

AimPanbiogeographers suggest that the biome in New Caledonia is of vicariant origin, dating from the Cretaceous - rather than being the result of repeated dispersal since c. 37Ma, when the area is postulated to have re-emerged after c. 15million years of submergence. Distributions of the plant family Sapotaceae were used as a model system to test this, and to elucidate the probabilities of ancestral areas, all phrased in six hypotheses. LocationAustralasia and the Pacific. MethodsWe used a recently published dataset with extensive sampling (168 terminals) from the subfamily Chrysophylloideae and three nuclear ribosomal DNA markers. Phylogenetic divergence times and ancestral areas were estimated in a Bayesian framework using beast, a relaxed clock method, and with fossil calibration points. Area transition probabilities were modelled using a reversible rate matrix, assigning equal prior probability to each transition between two areas. ResultsOur analyses suggest that Sapotaceae arrived and diversified in New Caledonia nine times during the period 4.2-33.1Ma. All crown-node radiations occurred in the Miocene or Pliocene, with stem splits reaching back into the Oligocene. Australia and New Guinea are the most likely source areas for Sapotaceae in New Caledonia, but this archipelago has never acted as a stepping stone for Sapotaceae to disperse into the Pacific. Main conclusionsRepeated dispersal is the only mechanism able to explain the range expansion of Sapotaceae into New Caledonia. The family has successfully colonized the main island nine times since its re-emergence in the Eocene. We reject the panbiogeographical hypotheses that representatives of Sapotaceae in New Caledonia originated in the Cretaceous, differentiated due to vicariance, and were of Pacific origin. We therefore argue that New Caledonia is an old Darwinian island. The Pacific has been colonized repeatedly and terminal lineages are never older than the islands they inhabit (except for Hawaii). Chrysophylloideae extended across Wallace's Line into Southeast Asia around 20Ma, when the Australian continent came into juxtaposition with Eurasia

Frequency of recovery of each gene-tree topology across 50 genes and proportion of trees with bootstrap support greater than 80%.

<p>Frequency of recovery of each gene-tree topology across 50 genes and proportion of trees with bootstrap support greater than 80%.</p

The 50 loci proposed with the respective linkage group, gene reference in Mt3.0 annotation, captured portion of the gene (bp positions in the reference sequence), alignment length, substitution rate ([subst./site/year] E-9),G-C content, number and % of parsimony-informative (PI) sites, % of exon based on the reference sequence, Consistency index (CI) and Retention index (RI).

<p>The 50 loci proposed with the respective linkage group, gene reference in Mt3.0 annotation, captured portion of the gene (bp positions in the reference sequence), alignment length, substitution rate ([subst./site/year] E-9),G-C content, number and % of parsimony-informative (PI) sites, % of exon based on the reference sequence, Consistency index (CI) and Retention index (RI).</p

On the Biogeography of Centipeda: A Species-Tree Diffusion Approach

Abstract.—Reconstructing the biogeographic history of groups present in continuous arid landscapes is challenging due to the difficulties in defining discrete areas for analyses, and even more so when species largely overlap both in terms of geography and habitat preference. In this study, we use a novel approach to estimate ancestral areas for the small plant genus Centipeda. We apply continuous diffusion of geography by a relaxed random walk where each species is sampled from its extant distribution on an empirical distribution of time-calibrated species-trees. Using a distribution of previously published substitution rates of the internal transcribed spacer (ITS) for Asteraceae, we show how the evolution of Centiped