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Modelling the functional connectivity of habitats is crucial for biodiversity conservation. By modelling potential dispersal paths among habitat patches, landscape graphs are often used to quantify landscape connectivity. While this approach seems promising, it often lacks biological validation. To ensure its ecological relevance, we assessed the ability of connectivity metrics calculated from landscape graphs to predict population genetic structure that closely reflects the dispersal of individuals, and thus functional connectivity. We modelled the habitat network of a forest bird species (Plumbeous warbler, Setophaga plumbea) in Guadeloupe using three graphs constructed either from expert opinion, habitat specialization indices, or a species distribution model (SDM). Genetic data (microsatellites) were also collected on 712 individuals in 27 populations. This genetic dataset was used as an empirical validation tool for the three landscape graphs, using two approaches: i) relating the cost-distances obtained from the graphs to between-population genetic distances, ii) relating the connectivity metrics obtained from the graphs to within-population genetic diversity. The large proportion of variance in genetic distances explained by least-cost paths and the strong correlation between connectivity metrics and genetic diversity indices demonstrate the ability of landscape graphs to model the influence of landscape connectivity on dispersal. In addition, our results provide insight into the relationships between construction costs and ecological relevance of landscape graphs, as the most complex approach (SDM) is not always the most efficient.

The Eurasian Collared Dove (Streptopelia decaocto) is one of the most successful biological invaders among terrestrial vertebrates. However, little information is available on the genetic diversity of the species. A total of 134 Eurasian Collared Doves from Europe, Asia and the Caribbean (n = 20) were studied by sequencing a 658-bp length of mitochondrial DNA (mtDNA) cytochrome oxidase I (COI). Fifty-two different haplotypes and relatively high haplotype and nucleotide diversities (Hd±SD = 0.843±0.037 and π±SD = 0.026±0.013) were detected. Haplotype Ht1 was particularly dominant: it included 44.03% of the studied individuals, and contained sequences from 75% of the studied countries. Various analyses (FST, AMOVA, STRUCTURE) distinguished 2 groups on the genetic level, designated 'A' and 'B'. Two groups were also separated in the median-joining network and the maximum likelihood tree. The results of the neutrality tests were negative (Fu FS = -25.914; Tajima D = -2.606) and significantly different from zero (P≤0.001) for group A, whereas both values for group B were positive (Fu FS = 1.811; Tajima D = 0.674) and not significant (P>0.05). Statistically significant positive autocorrelation was revealed among individuals located up to 2000 km apart (r = 0.124; P = 0.001). The present results provide the first information on the genetic diversity and structure of the Eurasian Collared Dove, and can thereby serve as a factual and comparative basis for similar studies in the future.

14 pages; International audience; Within the framework of landscape genetics, resistance surface modelling is particularly relevant to explicitly test competing hypotheses about landscape effects on gene flow. To investigate how fragmentation of tropical forest affects population connectivity in a forest specialist bird species, we optimized resistance surfaces without a priori specification, using least-cost (LCP) or resistance (IBR) distances. We implemented a two-step procedure in order (i) to objectively define the landscape thematic resolution (level of detail in classification scheme to describe landscape variables) and spatial extent (area within the landscape boundaries) and then (ii) to test the relative role of several landscape features (elevation, roads, land cover) in genetic differentiation in the Plumbeous Warbler (Setophaga plumbea). We detected a small-scale reduction of gene flow mainly driven by land cover, with a negative impact of the nonforest matrix on landscape functional connectivity. However, matrix components did not equally constrain gene flow, as their conductivity increased with increasing structural similarity with forest habitat: urban areas and meadows had the highest resistance values whereas agricultural areas had intermediate resistance values. Our results revealed a higher performance of IBR compared to LCP in explaining gene flow, reflecting suboptimal movements across this human-modified landscape, challenging the common use of LCP to design habitat corridors and advocating for a broader use of circuit theory modelling. Finally, our results emphasize the need for an objective definition of landscape scales (landscape extent and thematic resolution) and highlight potential pitfalls associated with parameterization of resistance surfaces.

Analysis of molecular variance (AMOVAs). Results of the AMOVAs performed, testing for significant genetic differences among the three main flyways (using mitochondrial and nuclear DNA data). (DOC 41 kb)

Posterior probability of scenario choice in DIYABC. Direct estimation approach that uses 0.1 % of the closest simulations to the observed data. (b) The logistic regression uses 1 % of the closest simulations. (DOC 211 kb)

MaxEnt habitat suitability models for European Turtle doves. Niche modelling analysis based on additional climate models: CC (CCSM4), MR (MIROC-ESM) and MI (MPI-ESM-P). Models available on http://www.worldclim.org/ . (DOC 729 kb)

Background: Understanding how past climatic oscillations have affected organismic evolution will help predict the impact that current climate change has on living organisms. The European turtle dove, Streptopelia turtur, is a warm-temperature adapted species and a long distance migrant that uses multiple flyways to move between Europe and Africa. Despite being abundant, it is categorized as vulnerable because of a long-term demographic decline. We studied the demographic history and population genetic structure of the European turtle dove using genomic data and mitochondrial DNA sequences from individuals sampled across Europe, and performing paleoclimatic niche modelling simulations. Results: Overall our data suggest that this species is panmictic across Europe, and is not genetically structured across flyways. We found the genetic signatures of demographic fluctuations, inferring an effective population size (Ne) expansion that occurred between the late Pleistocene and early Holocene, followed by a decrease in the Ne that started between the mid Holocene and the present. Our niche modelling analyses suggest that the variations in the Ne are coincident with recent changes in the availability of suitable habitat. Conclusions: We argue that the European turtle dove is prone to undergo demographic fluctuations, a trait that makes it sensitive to anthropogenic impacts, especially when its numbers are decreasing. Also, considering the lack of genetic structure, we suggest all populations across Europe are equally relevant for conservation.