Phylogenetics and dating
Recent molecular phylogenetic studies dating diversification and geological data indicating important events of submergence during the Paleocene and Eocene (until 37 Ma) brought evidence to dismiss this old hypothesis.
In spite of this, some authors still insist on the idea of a local permanence of a Gondwanan biota, justifying this assumption through a complex scenario of survival by hopping to and from nearby and now-vanished islands.
This view mainly relies on NC’s old geological basement and the local occurrence of relicts.
Despite the progressive accumulation of independent phylogenetic evidence for post-emergence colonization (reviewed in refs 13, 27 and 28), some authors are still reticent to adopt this new view, as epitomized by M. This author argued that i) molecular dating could be corrupted by poor calibrations and ii) lineages could be considered to be locally permanent if they hopped between neighbouring islands.
But it might reveal interesting scenarios involving a succession of multiple short-distance dispersals.
The likelihood of such island-hopping scenarios, first formulated by biogeographers e.g.
lower than 2.00), indicating a very small departure from the 37 ± 3 Ma range.
The tremendous ecological and morphological diversity of this clade, with apparent specializations for burrowing, terrestrial, semi-aquatic, and arboreal lifestyle, suggests an evolutionary process of adaptive radiation.Despite this spectacular diversity, this and many other questions of evolutionary processes have received little formal study because until now the phylogeny of this spececies-rich clade has remained uncertain.Here we reconstruct a phylogeny for Asterophryinae with greatly increased taxon and genetic sampling relative to prior studies.Lastly, we found that adding taxa to the analysis produced more robust phylogenetic results over adding loci.For a long time, New Caledonia was considered a continental island, a fragment of Gondwana harbouring old clades that originated by vicariance and so were thought to be locally ancient.Only a few inclusive Pacific clades (6 out of 40) were older than the oldest existing island.We suggest that these clades could have extinct members either on vanished islands or nearby continents, emphasizing the role of dispersal and extinction in shaping the present-day biota. The biogeographical paradigm for the origin of the New Caledonian biota has been profoundly revisited over the last ten years e.g. The traditional perspective considers the main island Grande Terre (hereafter NC) to be a small piece of the Gondwanan continent that separated from Australia 80 million years ago.We aimed to answer two main questions: (1) How old is the New Caledonian biota?(2) Are regional insular clades older than the oldest island in the region?The second statement refers to a less commonly broached topic which needs to be clearly formulated in order to be subjected to a more rigorous hypothesis testing.Island-hopping, there and back, is not equivalent to permanence on the same piece of land.