CERoPath

WP4.1. Influence of spatial heterogeneity

Demographic changes  in hosts (and in parasites) induced by landscape or habitat changes  are expected to drive significant changes on the genetic structure and diversity as shown in rodents [6] [7]. This may have important consequences on adaptive genetics [7] [44]. Landscape change is thus expected to drive significant impact of the host community and its adaptive genetics regarding host/pathogen interactions.

The influence of spatial heterogeneity  will be investigated using landscape genetics . The GIS (WP3) will give the landscape elements, in which the genetic information on both hosts and pathogens will be mapped. This genetic information will be summarised using new diversity indices which integrate phylogeny into three measures of biodiversity: species variability, richness, and evenness [34]. These metrics can be used in conjunction with permutation procedures to test for phylogenetic community structure. With the help of the methodology of [18] [32] developed by partner 2, we will be able to detect discontinuities between landscape elements that may promote barriers to gene flux, for rodents and for their pathogens using both neutral and adaptive genetic variation (WP2).

WP4.2. Environmental envelope or niche of communities

The influence of spatial heterogeneity on host-pathogen communities will be investigated using the GIS (WP3), taking into account phylogenetic information by using community phylogenetics’ method [68] [69] that will be developed by partner 1.

Using spatial information on habitats, we will estimate the environmental envelope  (or niche) for i) rodent species 2) pathogen species and 3) communities of interactive species. We will use the methodology developed by partners 3 and 4 [42] [60] [63].

WP4.3. Community vulnerability

The vacant niches hypothesis  suggests that species-poor communities cannot offer biological resistance to invasion. Recent evidence indicates that high species diversity may reduce exposure to parasites and pathogens , by a mechanism of “dilution effect ”, which predicts that infection rates will be lower in highly diverse host communities [57]. It has also been hypothesized that the severity of diseases decreased with the increase of host diversity, i.e. the diversity-disease hypothesis . Decreased diversity allows the remaining species to achieve higher abundance, which facilitates the spread of pathogens specific to these hosts. [22]

WP4.4. Prediction: patterns of interactive communities in changing environment

GIS offer the opportunity for modelling. We will investigate changes in landscape elements (WP3) and give projections of community changes, using the characterization of the environmental envelopes. As landscape structure may likely affect the risks of emergence [26], we hope to give some useful insights for rodent and pathogens management strategies.

Specific outputs regarding this WP4

  1/ Landscape barriers for gene flows

  2/ Role of biodiversity for health ecology: biodiversity insurance (dilution effect) or biodiversity risk (vacant niches)

  3/  projections of changes: biodiversity changes and host-pathogen interactions