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Dr. Julien CLAUDEInstitut des Sciences de l'EvolutionUniversité de Montpellier 2This page is no more updated, please visit this page to know who I am and what I am doing nowcontact: julien.claude(at)univ-montp2.fr |
My interests concern mostly phenotypic evolution at different levels (individual, intraspecific, interspecific) and the evolutionary history of testudinoid turtles.
Testudinoid turtles are indeed a good model for studying morphological evolution since they display numerous and iterative convergence patterns in behavior, habitat and diet. This group has undergone an important radiation in the Early Eocene and has a good fossil record (see publication 1). It is thus a suitable group to estimate rates of morphological evolution, as well as the sequence in the divergence in habitat, diet, morphology, and in genotype.
My studies aims to go on the evolution of the intraspecific variation and covariation patterns in turtles and other groups of organisms, within a phylogenetic frame. In other words, I wish to address questions on the evolution of the morphological integration at the macroevolutionary scale. These prospective studies are dependent on a good knowledge on phylogeny (in terms of topology and branch length) and should allow to understand the mechanisms of phenotypic divergence gathering the historical, ecological developmental and micro-evolutionary point of views.
I follow currently my studies in the University of Mahasarakham, faculty of Science, department of biology as a teacher and scientist. I spend also a lot of time in the dinosaur research center in Phu Kum Kao (near Kalasin) to understand the turtle fossil record in South-East Asia.
Although the turtle body plan is rather conservative, this group is extraordinary diverse in ecology. Turtles can be marine, terrestrial, and freshwater. In addition, clades within turtles have evolved very different diets and feeding modes. In studying the fossil record and the phylogeny of this group, I am developing the framework to for testing adaptive scenarios, rates of evolution, and many other evolutionary questions (see for examples, publications 2 and 7). Knowledge in the phylogeny of turtles is still in progress, and so far, the study of testudinoid phylogeny cannot focus on only one approach but should combine several disciplines (molecular phylogeny, paleontology, stratigraphy, paleobiogeography...) for appraising both the topology and the branch lengths of their tree, and for considering intraclade competition and possible character displacement as well. Several international colleagues are currently or were working on molecular phylogenies in this group: among others: Minh Le, Jim Parham, Phil Spinks, Masanao Honda, Yuichirou Yasukawa.
I am working on the fossil record of this group in several localities in Thailand, and keep going on with European ones. The Indochinese fossil record for turtles has a great relevance because it is one the less known (although living turtles are quite diverse in this area).
My student Wilailuck Naksri is currently working with me on the fossil record of Testudinidae and Geoemydidae during the late tertiary of Thailand. As well, I am working with my colleagues Haiyan Tong and Varavudh Sutheetorn on mesozoic and palaeogene turtles. The fossil record in Thailand for turtles is rather exceptional since it ranges from their early evolution (Late Triassic) to nowadays, with several spots in Jurassic, Cretaceous, Palaeogene, and Neogene.
More theoretically, I am interested in the evolution of morphological integration and relationships between traits of organisms at the macroevolutionary scale (see publication 3). Developmental biology, adaptive landscapes, morphological integration are fields for an exploration of the phenotypes evolution from a rather new point of view. I am interested in methods too, such as phylogenetic comparative methods, estimation of ancestral character state, and geometric morphometrics. I am taking part in the Ape project lead by Emmanuel Paradis (see software development and publication 4), for implementing comparative methods and estimation of ancestral character states reconstitution, using R (download it, it is free, and you are welcome to bring your contribution).
Two of my 4th year students are going to work on inter and intraspecific variation of insect wings to understand relationships between developmental noise and intraspecific variation. We are currently working on alternative methods than current superimposition methods.
Since more than twenty years, my colleagues Varavudh Suteethorn and Eric Buffetaut have undergone a very active research in vertebrate paleontology in Thailand. The continental mesozoic fossil record in Thailand is now the best known for south east Asia, and can be considered as a reference. However, new localities and new fossils are discovered every years, and the vertebrate paleontology is still in its early beginnings. My students and I are taking part in this project, together with other French scientists: Haiyan Tong, Jean Le-loeuff, Gilles Cuny, Lionel Cavin, Marc Philippe, and Thai experts: Ruchat Ingavat, Assanee Meesook, Paladej Srisuk, Sasidhorn Khansubha, Jintasakul Pratueng. I am still working on European Late Cretaceous fauna with the museum of Cruzy and the musée des dinosaures d'esperaza (see publication 9).
APE (Analyses of Phylogenetics and Evolution) is a package written in R. APE aims to be both a computing tool to analyze phylogenetic and evolutionary data, and an environment to develop and implement new analytical methods.
I welcome you to discover R and Ape as soon as possible. To my opinion, R should be teach as soon as college school for its incredible possibilities. If R was never running on your computer, then do yourself a favour today: install it! This is really easy: see the instructions on the CRAN (Comprehensive R Archive Network) Web site.
You can download R for beginners, written by E. Paradis if you desire to begin to learn R language. You can find other program for phylogeny and evolution on the phylip homepage (a reference in the domain).
