Projet: Modèle isolement-migration de l’histoire des communautés de poissons des récifs coralliens : théorie et données
Zone d’Études: Indo-Pacific
Résumé: This project tackles with issues of a high dimensionality both in its theoretical and biological consequences. The deliverables of this project should concern a wide scientific community.
On the biological side, the current level of speculations in leading reviews on the management of fish biodiversity is surprising (i.e. Hoegh-Guldberg et al. 2007; Hughes et al. 2007). For instance, a recent review by Munday et al. (2008) concludes that “There are critical gaps in our knowledge of how climate change will affect tropical marine fishes. … Improved projections of how ocean currents and primary productivity will change are needed to better predict how reef fish population dynamics and connectivity patterns will change.” This lack of clarification calls for a better understanding of past processes in order to be able to predict the spectrum of responses of ecosystems to future changes.
As our main objectives, we will :
(1) set up a theoretical model to simultaneously evaluate population sizes (including the ancestral population size), isolation times and reciprocal migration rates in an equilibrium model, in contrast to currently available population genetic applications;
(2) set up a new practice in using molecular markers, based on the complementary of systems with different mutation rates (DNA sequence variation and microsatellites) in order to cover overlapping time scales, and to refine time estimates;
(3) use a population design adapted to testing this theoretical model and these markers;
(4) use new high-throughput sequencing techniques (454 - pyrosequencing) to scale up our genetic tools to the level of information adapted to upcoming technical standards.
The development of a new inference method using importance sampling will provide a new framework to infer demographic parameters under isolation with migration with various expected advantages:
(1) in contrast to the Bayesian approach currently implemented in the IM reference software, our method will use a maximum likelihood framework and allow for frequency tests between different models (e.g. complete isolation vs. migration, symmetric vs. asymmetric migration rates);
(2) our method should be much faster than IM; our preliminary results on microsatellites show a gain of an order of magnitude compared to IM (Leblois, unpublished results);
(3) results will be given both in terms of point maximum likelihood and in terms of multidimensional likelihood profiles, so as to indicate correlations between parameters, a point missing in IM.
- National: MNHN, CNRS, IRD
Source de Financement: ANR Blanc