Publications of Flavien Collart
Bookmark and Share    
See detailOverview of my phD project
Collart, Flavien ULiege

Diverse speeche and writing (2020)

Detailed reference viewed: 18 (3 ULiège)
Full Text
See detailBryophytes are predicted to lag behind future climate change despite their high dispersal capacities
Zanatta, Florian ULiege; Engler, Robin; Collart, Flavien ULiege et al

in Nature Communications (2020), 11

The extent to which species can balance out the loss of suitable habitats due to climate warming by shifting their ranges is an area of controversy. Here, we assess whether highly efficient wind-dispersed ... [more ▼]

The extent to which species can balance out the loss of suitable habitats due to climate warming by shifting their ranges is an area of controversy. Here, we assess whether highly efficient wind-dispersed organisms like bryophytes can keep-up with projected shifts in their areas of suitable climate. Using a hybrid statistical-mechanistic approach accounting for spatial and temporal variations in both climatic and wind conditions, we simulate future migrations across Europe for 40 bryophyte species until 2050. The median ratios between predicted range loss vs expansion by 2050 across species and climate change scenarios range from 1.6 to 3.3 when only shifts in climatic suitability were considered, but increase to 34.7–96.8 when species dispersal abilities are added to our models. This highlights the importance of accounting for dispersal restrictions when projecting future distribution ranges and suggests that even highly dispersive organisms like bryophytes are not equipped to fully track the rates of ongoing climate change in the course of the next decades. [less ▲]

Detailed reference viewed: 56 (14 ULiège)
Full Text
See detailIntraspecific differentiation: Implications for niche and distribution modelling
Collart, Flavien ULiege; Hedenäs, Lars; Brönnimann, Olivier et al

in Journal of Biogeography (2014)

Aim: Mounting evidence suggests that failure of species distribution models to integrate local adaptation hinders our ability to predict distribution ranges, raising the <br />question of whether ... [more ▼]

Aim: Mounting evidence suggests that failure of species distribution models to integrate local adaptation hinders our ability to predict distribution ranges, raising the <br />question of whether modelling should be performed at the level of species (clade <br />models) or intraspecific lineages (subclade models), characterized by the restricted <br />availability of occurrence points. While Ensembles of Small Models (ESMs) offer an <br />attractive framework for small datasets, their evaluation remains critical. We address <br />these issues in the case of very small datasets inherent to subclade models and discuss <br />which modelling strategy should be applied based on niche overlap among lineages. <br />Location: Sweden. <br />Taxon: Mosses. <br />Methods: Ensembles of Small Models were evaluated by null models built from randomly sampled presence points. We compared the extent of suitable area predicted <br />by the projections of clade and subclade models. Niche overlap was quantified using <br />Schoener's D and Hellinger'sImetrics, and the significance of these metrics in terms <br />of niche conservatism or divergence was assessed by similarity tests. <br />Results: We introduced a simple procedure for evaluating ESMs based on the pooling of the statistics used to assess model accuracy from the replicates. Despite fairly <br />high AUC and TSS values, 2 of the 23 subclade models did not perform better than <br />null models and should be discarded. Combined predictions from subclade models <br />contributed, on average, five times more than clade models to the total suitable area <br />predicted by the combination of subclade and clade models. The D and I metrics averaged 0.45 and 0.71, with evidence for niche conservatism in half of the species and <br />no signal for niche divergence. <br />Main conclusions: In addition to the assessment of ESM accuracy based on the simple procedure described here, we recommend that ESMs should be systematically <br />evaluated against null models. Lumping or splitting occurrence data at the intraspecific level substantially impacted model projections. Given the poor performance of <br />models based on small datasets, even when employing ESMs, we pragmatically suggest that, in the absence of evidence for niche divergence during diversification of <br />closely related intraspecific lineages, SDMs should be based on all available occurrence data at the species level. [less ▲]

Detailed reference viewed: 55 (19 ULiège)