UMR CNRS 5805 EPOC
Environnements et Paléoenvironnements
Océaniques et Continentaux

        

Consignes de Sécurité et Numéros d'Urgence
(à l'usage des personnels du laboratoire)

le 20-05-2011 à 13:45

Lieu Salle Stendhal, DGO, Bâtiment B18 Intervenant(s) Stefanie WAGNER, UMR BIOGECO (Biodiversity, Genes and Communities), INRA Cestas, France; Steinmann Institute of Geology, Mineralogy and Paleontology, Bonn University, Germany

The aim of the talk is to give an introduction to an integrative approach using palaeoecological data and genetic data as well as spatial modelling to study consequences of past climate change on European tree populations by the example of European larch. Such retrospective approaches can help evaluate and calibrate models simulating human-induced climate change on tree distribution. A limitation of current studies dealing with forest trees is that they do not truly integrate, in a quantitative way, the different types of data, which are typically displayed and analyzed separately. In this study, we propose to use statistical approaches based on coalescent modelling to test hypotheses for the past demography and evolutionary history of tree populations. The coalescent modelling will rely on multilocus nuclear DNA information, with palaeoecological data and single locus genetic data (from chloroplast and mitochondria) representing extrinsic information that help frame a priori hypotheses. Trees present several advantages for such studies. In particular, they have left an abundant fossil record (both macrofossils and pollen) that can be used to reconstruct their past distribution with great precision. Among trees, Larix decidua is of special interest as it played an important role in the plains of north-central Europe during the first interstadials of the last ice age, and it is still represented in the lowlands of Poland by a group of differentiated populations whose status is unclear, often considered as a different subspecies (Larix decidua subsp. polonica). These lowland populations must have experienced a different demographical history than the populations from the remaining of the range, which have mainly expanded along altitudinal gradients during the Late glacial and the Holocene. The study focuses on the location of glacial refugia and range changes during the Weichselian and the Holocene. The projected palaeoecological and molecular genetic analyses will enable detailed inferences on the demography and evolution of the populations of this species, using precise quantitative approaches instead of ad hoc interpretations.