PhD project

Communities assembly rules : functional and evolutionary perspectives

Diversity patterns of alpine plant communities

1) Phylogenetic and functional diversity of communities

Recently, ecologists have moved beyond the assumption that species are equally distinct and take into account their functional or phylogenetic similarity as a proxy for their ecological niche similarity.
In my PhD, I am studying the functional and phylogenetic diversity of plant communities to understand how the ecological filters (especially the strong abiotic gradients typical of alpine ecosystems) have shaped these two features.

2) Impact of intra-specific trait variability and spatial scale on alpine plant communities

In community ecology, species are often thought as homogeneous entities with little functional trait variability. Thus intraspecific variability is considered to be negligible compared to inter-specific variability. This is however known to be untrue for major alpine plant species that display important trait variability along gradients. Another important feature of communities is the spatial scale at which it is studied. This is because the impact of some ecological processes such as micro-environmental variability or neighbors competition or facilitation is expected to be blurred at large spatial scales.

We conducted an important field survey in Valloire (France), to study these two features by sampling communities of individuals (rather than species) at various spatial scales. We hope to access the contribution of intra-specific trait variability on community diversity and to understand the fine ecological processes that are acting between co-occuring individuals depending on the spatial scale.

Developing methodologies for diversity patterns analyzes

1) Building expectations

The link between a pattern of diversity and an assembly rule is far from being straightforward. Various ecology processes can explain a diversity pattern making it difficult to interpret its origin. Using a model of community assembly built on strong theoretical hypotheses that was developed by Laure Gallien and Tamara Münkemüller, I (try to) access the efficiency of various statistical methodologies to disentangle assembly rules.

2) Developing methodologies

When analyzing the diversity structure of a community or a meta-community, a community ecologist need (at least) two things: a diversity index and a null model. There is however here a (very, very) wide array of possibilities to choose from. A big part of my PhD was to understand the literature on the subject and to come up with new methodologies to use them to capture multiple features of the diversity structure of communities.