2. Current researches

Ecosystems of oceanic islands are more susceptible to biological invasions than their continental counterparts. Oceanic islands are often ecologically non-saturated and food webs are usually poorly developed with few primary consumers, few predators, and a dominance of decomposers that recycle the large amount of organic matter available. Moreover, native insular species are naive to a wide range of human-introduced enemies (predators, competitors or parasites), and climate change in the subpolar regions likely facilitates the permanent establishment and dispersal of alien plant and invertebrate species. At the community scale, the dynamics in species replacement can be accelerated by climate change, with native species suffering more from changes, and more particularly from summer droughts, than invasive ones, and as such, they are more driven to extinction. The range of anthropogenic modifications encountered at the subantarctic Islands, from null at protected areas to extreme at the research station provide an exciting opportunity to fundamentally improve our understanding of invasion processes.

We are studying the terrestrial biodiversity (fauna and flora) of the French subantarctic islands and the environmental factors shaping the geographical repartition of the species (Program IPEV 136). The dispersal-related trade-offs in invertebrate species and the cost-driven trade-off between reproduction and dispersion in invertebrate species is considered. In addition, based on our previous work, we address the interactions between alien and native species and study the effects of climate change on the original subantarctic biotas. Our researches use field-based and experimental approaches to examine the six following aspects:

WP01. Native biodiversity of the subantarctic islands and biological invasions

1. Native biodiversity

2. Biological invasions: detection of the establishment of alien species (sources, extent) - Geographical expansion of invasive species

3. Food webs at the subantarctic islands and their alteration in response to biological invasions

WP02. Dispersal-related trade-offs in invertebrate species

1. Are dispersers selected at the front distribution during invasion processes?

2. Neutral, quantitative and functional genetic variations

3. Flightlessness syndrome

4. Modelling spread rate

WP03. The cost-driven trade-off between reproduction and dispersion in invertebrate species

1. Energetic challenges of dispersal

2. Optimal foraging

WP04. Ecological responses to environmental parameters

1. Phenotypic plasticity of the thermal tolerance in alien species

2. Phenotypic plasticity of the thermal tolerance among alien versus native invertebrates

3. What is the adaptative value of shell ecophenotype in heat tolerance of the land snail Notodiscus hookeri?

WP05. Consequences of environmental changes on subantarctic biodiversity

1. Long-term monitoring of the plant species and plant communities subjected to a range of environmental perturbations

2. Broad-scaled monitoring of the vegetation by satellite images and field observations

3. House mouse and climate change

WP06. Providing data and policy adivce on subantarctic environment

Collaborative work with the Nature Reserve, within the framework of the agreement between IPEV and TAAF (Convention Cadre 2009-C65).