Origins and patterns of endemism in New Caledonia Contribution to a new paradigm of island biogeography Hervé Jourdan Jérôme Murienne, Tony Robillard, Laure Desutter-Grandcolas, Eric Guilbert, Louis Deharveng & Philippe Grandcolas
New Caledonia: such a nice story Myers, N. Myers et al. 2005. Nature 403 It is recognised as one of the major hotspots for biodiversity
New Caledonia: such a nice story Island Surface (Km 2 ) Species Island Surface (Km 2 ) Species New Caledonia 18760 2975 New Caledonia 18760 77 New Zealand 269057 2066 Fidji 18274 1302 Hawaii 16705 956 Flowering plants Solomons 37694 76 Fidji 18287 27 Vanuatu 12201 26 Terrestrial Squamata High level of endemism at both regional and short-range scales, with flora and fauna retaining ancestral or archaic traits
New Caledonia: such a nice story A large and isolated continental island on the Norfolk Ridge, separated from Australia 80 My ago, Pelletier 2006
New Caledonia: such a nice story Time Stebbins 1974 Museum Model versus Craddle model The classical story rely on many gondwanan groups trapped on this continental fragment The museum hypothesis leading to evolution of paleoendemics or relicts especially by adaptating and refuging on metalliferous soils
New Caledonia: such a nice story Geological facts are not consistent with this story. From recent studies (Paris 1981, Crawford et al. 2003, Schellrt et al 2006, Pelletier 2006) it appears that New Caledonia has been submerged during paleocene, then during Eocene when the obduction of oceanic mantle cover the mainland which later lead to the constitution in modern time to metalliferous soils.
Biogeography and/or Geology We need to consider biogeographic and phylogenetic evdence to understand wether : Phylogenetic patterns tell us something independently of the geological knowledge - If so, Do they corroborate this knowledge - If not, what inferrential conclusions can be drawn hoever, even if they are less robust Let us avoid the usual circular reasonning : Considered as relicts, some taxa are used for assuming the existence of refuges which are in turn used to confirmed the relictual nature of taxa. And so on
Regional patterns In recent years, numerous phylogenetic studies involving New Caledonia, Australia, New Zealand, Papua and other regional lands increases rapidly for both animal and plants. Three different patterns have been found in those monophyletic groups One large New Caledonian Clade (Araucaria, crickets, Opilionides, Skinks) Setoguchi et al. 1998. Am. J. Bot.
Regional patterns Several large clades (Cockroaches, Diving beetles, Skinks) Smith et al 2007
Regional patterns Multiple nested relationships(sapotaceae) Bartish et al. 2007
How can these patterns can be interpreted by themselves? Murienne et al. 2005 - Cladistics Angustonicus spp. One or two clades could be vicariance when the sister group is Australia or New Zealand, or long distance when the sister group is situated in young islands such as Loyalty with Cockroach or Norfolk as shown with Araucariaceae Multiple nested relationship could be ong or short distance dispersal
How can these patterns can be interpreted by themselves? These patterns do show that some diversification was reent in NC (even if the group can be old) but not assess that it was generally reclonised after submersion 40 my ago Some dispersal occured since most studies infer more than one local clade, with topologies that often exclude extinctions in other territories and that some other studies point relationship to recent islands
Some more intringuing patterns Some other patterns are more intringuing : they relate some New Caledonian taxa - therefore considered as relicts to distant areas or worldwide distrbuted groups The most emblematic of them being the plant, Amborella trichopoda, sister group of all other flowering plants and which is only found in NC (Qiu et al. 1999) This plant is absent from all adjacent territories and no fossil are known
Some more intringuing patterns The second most emblematic example is the well know Kagu (Rhynochetos jubatus) All recent studies point that the sister group of this Nc and NZ flightless bird group is South America. It has been interpreted as a dispersal (Fain et Houde 2004) or vicariance (Cracraft 2001) Most interesting but still unclear fossil evidence could suggest extinctions elsewhere
Some more intringuing patterns Boyer et al 07 found an intringuing pattern for the Troglosironidae with the NC clade sister group to the neotropical one, not to other regional ones (Australia or NZ This group is not absent from other territories as with Amborella )
The ghost of past extintions These last patterns tell us a necessarily complicated history In the old paradigm (Nc as a safe Gondanan refuge), it imply regional extinctions and survival in NC But this scenario could be however not very accurate since these extinctions could have occured from Cretaceous to Miocene In the revised paradigm of New Caledoni as a shaky piece of Gondwana most of these patterns imply suppression of terrestrial life until 37 My ago and only then recolonisation from remaining close biota And the finally extinction of close relative with survival of the New Caledonian so called relict This scenario is complicated with many ad hoc events relatively to the phylogeny itself, one could difficultly propose it without strong geological evidences We can however look at a similar scenario also involving relicts but substantited by fossil.. Such as the genus Mastotermes (termites) only known from Australia at the present day but found in amber all around the world
Perspectives These scenarios suggest fascinating hypotheses: - New Caledonia relicts point out at large extinctions in the region, such extinctions could date back and take part to the Oligocene or Miocene major events - With geological auxiliary evidence, these extinctions followed recolonisation of NC from short or long distance dispersal it does not matter! - Relicts are remnants of old and large groups existing today in a restricted way, it does not mean that they are autchthonous or permanent in their present day area - It would be most interesting to link these histories with original traits shown by many endemic species; did these traits were developed as a local adaptation or did they favor local survival?
Perspectives New Caledonia is a good place for better understanding of the origin of biodiversity, especially according to its exceptionnal high microendemism level. Its remarkable position and history suggest scenario that we would never hypothetise otherwise Vicariance is still by necessity the null hypothesis but dispersal should be carefully considered Geology should bring auxilliary evidence that we keep as far as possible logically independent
Murienne et al. 2008 Cladistics Local endemism An example of analysis of specis repartition in phylogenetical context
Perspectives We start for 3 years a big program BIONEOCAL with the support of the ANR and it involves 11 research teams from CNRS, MnHN,, IRD, INRA, Harvard, Villanova university, Australian museum Origins of endemism to track speciation in a adaptative context To Test hypothesis regarding regional paleogeographical and biological contexts : Gondwanian acummulation species or recent radiations/dispersions To look at the determism and dynamic of local speciation through genetic studies of divergence between parent species To look at Adaptation to metalliferous soils,, to climate and to biotic interactions We are studying various models (Tenebrionids, chrysomelids, formicids, Gryllids, Phytoseid mites, Skinks, geko and some plant famillies )) to fit into each other in taxonomic analysis, phylogenetic and genetic approaches
Implications and Perspectives for conservation
MAURURU for your attention!!!! Thanks you to Jean Yves Rasplus, Gael Kergoat, Laurent Soldati, Fabien Condamine and Jerome Munzinger