|Home | People | Research | Publications | Software|
|Evolution of New Caledonian Eumolpinae|
Research sponsored by
the National Geographic Society (Committee for Research and Exploration),
and the Percy Sladen Memorial Fund (Linnean Society of London).
New Caledonia is an old (>70Myo) piece of Gondwana that migrated off the east coast of Australia with the opening of the Tasman sea. The island has a long history of isolation and the singularity of its flora and fauna constitutes one of the key elements of the theory of vicariant evolution in the Southern hemisphere. However, the high levels of endemicity and the presence of supposedly primitive representatives for both plants and animals are currently being reinterpreted by some authors as the result of dispersal in more recent geological times (<30Mya). This follows claims about marine transgressions and apparently the total submergence of the island in the Oligocene.
My research addresses precisely this question, the ancient (Gondwanian) vicariant or recent dispersive origins, for the phytophagous beetles in the subfamily Eumolpinae (Chrysomelidae), a group highly diversified in New Caledonia, by using molecular phylogenetics and the implementation of molecular clocks. The subfamily counts with over 50 endemic species currently in eight genera, five of them also endemic. Many species remain to be discovered and the current generic attributions require a thorough revision, and thus the project also involves taxonomic work which will be aided by the results of the molecular phylogenetic analyses.
In my first expedition to New Caledonia, the goal was to sample as much eumolpine diversity as was available, without restricting our search to specific habitats or plant communities. In a collecting trip at the end of the austral summer we visited well over 30 localities all over the island, with an emphasis on the central part, where the highest diversity of Eumolpinae has been recorded so far (possibly because of the sampling intensity in recent years by entomologists at Station des Recherches fruitières de Pocquereux, AIC, La Foa).
Field work in New Caledonia. Sclerophyle forest in Delta de la Nera (Province Sud).
This survey (4 March-14 April, 2008) produced a very high yield of samples for molecular studies from all known genera except one and several species of every genus. We particularly looked for species in the genus Dematochroma Baly, possibly the most diversified in the island, with 19 species described so far, and succeeded to get representatives of almost every known species. Two species of Dematochroma, D. terastiomerus Heller and D. laboulbenei Montrouzier, were abundantly collected in almost every studied locality, and shall be useful for detailed comparative phylogeographic analyses in Grande Terre.
Molecular phylogenetics of New Caledonian Eumolpinae will be based on the analysis of at least three molecular markers, including two mitochondrial and one nuclear. There is a chance that a large proportion of the genera and species in the island are actually monophyletic, because independently of the age of colonisation, Grande Terre exhibits a high degree of isolation for significant amounts of geological time. Suitable outgroups in surrounding parts of the world (Australia, Sundaland, New Guinea, New Zealand) should help to address this question. In the absence of fossil record for this beetle lineage, the age of the largest monophyletic assemblage of New Caledonian eumolpines will be estimated using geological events. The most suitable clock calibration points will be those representing the colonisation of islands surrounding Grande Terre, most relatively recent and of known geological age. For this reason, it will be critical to collect Eumolpinae in these younger islands.
Future work will aim sampling specific habitats, including the poorly explored Province Nord, but also the islands surrounding Grande Terre, particularly the Loyauté and Isle de Pine. To launch the study in its original aims, it will be critical and of highest priority to secure funding that will allow processing the samples already available to me.
Field work in New Caledonia. Beetle collectors at L'Aoupinié (Province Nord). From left to right: Mayon Jolivet, Christian Mille, me with my daughter Catarina, Pierre Jolivet, Anabela Cardoso and José Jurado.
This work is done in collaboration with Christian Mille (Station des Recherches fruitières de Pocquereux, La Foa, New Caledonia) and Pierre Jolivet (Paris, France). I counted with the valuable help in the field of Anabela Cardoso (IBMB, Barcelona, Spain) and José A. Jurado (Universitat de les Illes Balears, Palma de Mallorca, Spain), and occassionally Sylvie Cazères (SRFP, La Foa, New Caledonia) and Hervé Jourdan (IRD, Noumea, New Caledonia). The SRFP through the kindness of C. Mille and AIC staff provided us with logistics and accommodation facilities which contributed making a success of this expedition.