Biodiversity emergence and maintaining

Team leader: Nicolas Navarro

Assistant: Stéphane Garnier

Research

The
main research questions of the FED group concern biodiversity, its implementation, diversification and maintenance, from the level of the individual up to the clade, integrating various spatiotemporal scales of analysis, and using several parameters to describe biodiversity (morphology, taxonomy and genetics). There is considerable interaction between the three main axes, focusing on specific domains: evolution and development, differentiation and phylogeny, and biodiversity dynamics.

1. Evolution and development

The Evolution and Development axis focuses on the study of developmental processes at various taxonomical scales. Some projects at the macroevolutionary scale concentrate on the role of ontogenetic modifications on morphological expression and
macroevolutionary dynamics. Other projects concentrate on the study of modularity and morphological integration at the clade scale, or at a finer scale. The third group of projects is at the microevolutionary scale, focusing on the study of mechanisms controlling development stability. The morphometric approach, shared by all these projects, has earned international recognition for the laboratory. The genetic facet can also be integrated through external collaboration.

The EVO/DEVO approach is of particular interest for research questions at a macroevolutionary scale. The emergence of large-scale organisational plans, the study of developmental constraints, the structuring of morphological space or the use of the
temporal dimension of development in the understanding of divergences between species (heterochronism), are themes which may now be re-examined in the light of new morphometric approaches. More recently EVO/DEVO has also endeavoured to answer questions about microevolution.
The characterisation of phenotypic variation and the understanding of the processes that determine its origin and control are the focus of this research.

Various projects centred on three major aspects of development are included under this heading.

• The study of ontogenetic processes
  – Biomineralisation and ontogenesis
  model organisms: bivalves, crustaceans
  – Morphological space and ontogenetic disparities
  model organisms: extant and fossil cephalopods
• The evolution of modularity and of morphological integration
  model organisms: echinoderms, cephalopods, rodents
• The study of developmental stability control
  model organisms: sea urchins, ground beetles, fruit flies (Drosophila)

2. Differentiation and phylogeny

Phylogenetic approaches, combined with ecological, geographical or behavioural information, allow the general causes of differentiation to be studied. The task of obtaining well-resolved phylogenies that are operational therefore seems primordial. These diverse phylogenetic approaches are necessary to identify general tendencies and to consider all the processes leading to specific diversity among clades (the biodiversity dynamics axis).
The validity of studies dealing with differentiation of populations, speciation and phylogenetic relationships is heavily dependent on the quality and quantity of morphological or genetic data. Defining a character or a number of informative characters is a prerequisite to the study of the evolutionary history of taxa, whether individuals within populations, populations, subspecies or species. Estimating levels of differentiation (e.g. morphological, genetic, karyological) between individuals or populations remains a key problem. A general appreciation of the mechanisms that induce differentiation, or, on the contrary, create homogeneity in populations, is important for the understanding of how diversity (genetic or morphological) is structured.

Two groups of projects are identified under this heading.

• Differentiation and speciation mechanisms
  model organisms: rodents, sea urchins
  What
  do phylogenies reflect? Do the differences between taxa coincide with
  specific events such as great environmental changes? How and in what
  context do species become established?
  How is the morphological pool of a species organised and what information can be gathered about events affecting its history?
• Phylogenetic reconstructions
  model organisms: echinoderms, cephalopods

3. Biodiversity Dynamics

The aim of this research axis is to describe and analyse biodiversity dynamics on various spatiotemporal scales. More specifically, this will mean the structuring of diversity (morphological, genetic, or specific) with palaeoenvironmental variations at local, regional and global scales. The contribution of the temporal dimension to the study of evolutionary processes will then allow the study of biodiversity fluctuations in periods of crises (extinctions, migrations) and reconquest.

Two major themes are included under this heading.

• Biomineralisation
  model organisms: molluscs
  The
  general aim will be to classify in families the proteins of calcifying
  matrixes, depending on their primary structure but also their function
  in mineralisation, and to propose a coherent model of carbonate
  biomineralisation.
• Biodiversity over time
  model organisms: rodents, molluscs, echinoderms
  Projects
  will seek to test various models of community response to environmental
  change and will examine 1) collections of Jurassic and Cretaceous
  invertebrates, 2) biodiversity and global change through the example of
  Antarctic echinoids, and 3) the impact of climate change on biodiversity
  and also on morphological and genetic evolutionary rhythms in voles.

Interface projects

There will be three interface projects, one with the ECO/EVO team, the others with the SEDS team.

With the ECO/EVO group
– Interactions between organisms: the impact of symbiotic associations on biodiversity in extreme environments.

With the SEDS group
– carbonate biomineralisation and organo-mineral diagenesis
– the LIAS project