Currently, I am a postdoctoral researcher interested in how climate change and direct human disturbance interact to affect species distributions and assemblages.
My research interests are centred on conservation biology and macroecology. I use various approaches (species distribution modelling, landscape ecology, population genetics, etc.) to study the effect of anthropogenic disturbance on local and macrogeographic processes such as species assemblages and distributions, in order to predict future species’ responses and inform conservation actions.
Anthropization of habitats and climate change act at different spatial and temporal scales and are both responsible for shifts or fragmentation of distributional ranges. In this context, a particular focus of my work is to understand how land-use and climate change interact to shape current and future biodiversity.
My current research deals with these questions, in collaboration with Erik Öckinger.
Population dynamics at species' range margins
Marginal populations are especially interesting since their distribution and dynamics are expected to be limited by climatic factors. However, processes acting at a more local scale such as dispersal constrains or biotic interactions can also be key limiting factors and thus play a crucial role in species' reponse to future changes.
In this context, we study the joint effects of climate, land-use and habitat quality on the dynamics of a population of Oberthür's Grizzled Skipper butterfly (Pyrgus armoricanus) at its northern range margin in southern Sweden. By studying population processes acting at the range margin, we aim to can gain insights into the drivers of range limits and the potential response of species to global change.
Shift in pollinator communities over 50 years of climate and land-use change
The ongoing biodiversity crisis is characterised not only by an elevated extinction rate, but also by an increasing similarity of species assemblages, a process known as biotic homogenisation. This is an issue of major concern, especially when it affects providers of ecosystem services such as pollinators.
We aim to gain insights into the drivers of pollinator decline and homogenisation by monitoring the spatiotemporal turnover of bumblebee communities over a large environmental gradient and a long period of time. We describe how the assemblages of these critical pollinator species changed over the last 50 years in Norway, in relation to species' traits and to climate and land-use change that occurred during this period.
Community dynamics in a changing climate
Climate change induces a reorganisation of biological communities as species shift their distributions to track their climatic niches. Habitat fragmentation may potentially be a major barrier to this process by preventing range-shifting species to disperse and colonise new habitats.
Moreover, community restructuring that occurs as a result of climate change may also contribute to restructuring local interaction networks. It can be the cause of additional, overlooked, threats to community resilience if it results in the extinction of mutalistic interactions or in the emergence of new competitive interactions.
We use long-term monitoring data of butterfly and birds assemblages to investigate the effects of habitat fragmentation on climate-related species turnover and how this turnover impacts local interspecific interactions.
I conducted my PhD (2011-2014) at the University of Angers, France, under the supervision of Jean Secondi. This project aimed at improving knowledge for the conservation of the Corncrake (Crex crex), a grassland bird which experiences various levels of threat in Europe depending on the intensity of agriculture.
I used a wide range of approaches and methodologies, at both large and regional scales, to answer various questions relevant to the conservation of the species and to describe the interactions between agricultural activity and habitat suitability, population size, inbreeding or parasite infection in central and marginal populations. Analyses included: species distribution modelling at various spatial scales to assess the reliability of expert-based range maps and to predict the value of potential umbrella species, using genetic data to infer population structure and demography, describing the continental–scale drivers of pathogen prevalence or comparing edge avoidance patterns in grassland birds.
During my Master project at the University of Angers, France, I used simulations to test the effect of the fractal geometry of river networks on the ability of outlier tests to detect loci under selection.
Fourcade, Y., Richardson, D.S., Secondi, J. (2019) No evidence for a loss of genetic diversity despite a strong decline in size of a European population of the corncrake Crex crex. Bird Conservation International. In press. doi: 10.1017/S0959270919000327
Alhajeri, B.H., Fourcade, Y. (2019) High correlation between species-level environmental data estimates extracted from IUCN expert range maps and from GBIF occurrence data. Journal of Biogeography, 46, 1329–1341. doi: 10.1111/jbi.13619
Fourcade, Y., Åström, S. & Öckinger, E. (2019) Climate and land-cover change alter bumblebee species richness and community composition in subalpine areas. Biodiversity and Conservation, 28, 639–653. doi: 10.1007/s10531-018-1680-1
Fourcade, Y., Besnard, A.G., Beslot, E., Hennique, S., Mourgaud, G., Berdin, G. & Secondi, J. (2018) Habitat selection in a dynamic seasonal environment: vegetation composition drives the choice of the breeding habitat for the community of passerines in floodplain grasslands. Biological Conservation, 228, 301-309. doi: 10.1016/j.biocon.2018.11.007
Obiakara, M.C. & Fourcade, Y. (2018) Climatic niche and potential distribution of Tithonia diversifolia (Hemsl.) A. Gray in Africa. PloS ONE, 13, e0202421. doi: 10.1371/journal.pone.0202421
Fourcade, Y., Besnard, A.G. & Secondi, J. (2018) Paintings predict the distribution of species, or the challenge of selecting environmental predictors and evaluation statistics. Global Ecology and Biogeography, 27, 245–256. doi: 10.1111/geb.12684
Fourcade, Y., Ranius, T. & Öckinger, E. (2017) Temperature drives abundance fluctuations, but spatial dynamics is constrained by landscape configuration: implications for climate-driven range shift in a butterfly. Journal of Animal Ecology, 86, 1339-1351. doi: 10.1111/1365-2656.12740
Fourcade, Y., Öckinger, E. (2017) Host plant density and patch isolation drive occupancy and abundance at a butterfly’s northern range margin. Ecology and Evolution, 7, 331-345. doi: 10.1002/ece3.2597
Fourcade, Y.*, Besnard, A.G.* & Secondi, J. (2017) Evaluating interspecific niche overlaps in environmental and geographic spaces to assess the value of umbrella species. Journal of Avian Biology, 48, 1563–1574. (*equal contribution) doi: 10.1111/jav.01153
Fourcade, Y. (2016) Comparing species distributions modelled from occurrence data and from expert-based range maps. Implication for predicting range shifts with climate change. Ecological Informatics, 36, 8-14. doi: 10.1016/j.ecoinf.2016.09.002
Fourcade, Y., Richardson, D.S., Keišs, O., Budka, M., Green, R.E., Fokin, S. & Secondi, J. (2016) Corncrake conservation genetics at a European scale: the impact of biogeographical and anthropological processes. Biological Conservation, 198, 210-219. doi: 10.1016/j.biocon.2016.04.018
Besnard, A.G.*, Fourcade, Y.* & Secondi, J. (2016) Measuring difference in edge avoidance in grassland birds: the Corncrake is less sensitive to hedgerow proximity than passerines. Journal of Ornithology, 157, 515-523. (*equal contribution) doi: 10.1007/s10336-015-1281-7
Fourcade, Y., Keiss, O., Richardson, D.S. & Secondi, J. (2014) Continental-scale patterns of pathogen prevalence: a case study on the corncrake. Evolutionary Applications, 7, 1043-55. doi: 10.1111/eva.12192
Fourcade, Y., Engler, J.O., Rödder, D. & Secondi, J. (2014) Mapping species distributions with MAXENT using a geographically biased sample of presence data: a performance assessment of methods for correcting sampling bias. PLoS ONE, 9, e97122. doi: 10.1371/journal.pone.0097122
Budka, M., Mikkelsen, G., Turcokova, L., Fourcade, Y., Dale, S. & Osiejuk, T.S. (2014) Macrogeographic variations in the call of the corncrake Crex crex. Journal of Avian Biology, 45, 65-74. doi: 10.1111/j.1600-048X.2013.00208.x
Fourcade, Y., Engler, J.O., Besnard, A.G., Rödder, D. & Secondi, J. (2013) Confronting expert-based and modelled distributions for species with uncertain conservation status: A case study from the corncrake (Crex crex). Biological Conservation, 167, 161-171. doi: 10.1016/j.biocon.2013.08.009
Fourcade, Y., Chaput-Bardy, A., Secondi, J., Fleurant, C. & Lemaire, C. (2013) Is local selection so widespread in river organisms? Fractal geometry of river networks leads to high bias in outlier detection. Molecular Ecology, 22, 2065-2073. doi: 10.1111/mec.12158
Fourcade, Y. (2014) Approche intégrative de la stratégie de conservation du Râle des genêts. Université d'Angers, PhD thesis, 254 pp, defended on 2/9/2014