When new human-modified habitats favour the expansion of an amphibian pioneer species: Evolutionary history of the natterjack toad (Bufo calamita) in a coal basin

Leslie Faucher (1) , Laura Hénocq (1) , Cédric Vanappelghem (1) , Stéphanie Rondel (2) , Robin Quevillart (3) , Sophie Gallina (1) , Cécile Godé (1) , Julie Jaquiéry (4) , Jean-François Arnaud (1)

1 Evo-Eco-Paléo (EEP) - Évolution, Écologie et Paléontologie (Evo-Eco-Paleo) - UMR 8198
2 CPIE - Centre Permanent d'Initiatives pour l'Environnement
3 Groupe ornithologique et naturaliste du Nord – Pas-de-Calais
4 ECOBIO - Ecosystèmes, biodiversité, évolution [Rennes]

Human activities affect microevolutionary dynamics by inducing environmental changes. In particular, land cover conversion and loss of native habitats decrease genetic diversity and jeopardize the adaptive ability of populations. Nonetheless, new anthropogenic habitats can also promote the successful establishment of emblematic pioneer species. We investigated this issue by examining the population genetic features and evolutionary history of the natterjack toad (Bufo [Epidalea] calamita) in northern France, where populations can be found in native coastal habitats and coalfield habitats shaped by European industrial history, along with an additional set of European populations located outside this focal area. We predicted contrasting patterns of genetic structure, with newly settled coalfield populations departing from migration-drift equilibrium. As expected, coalfield populations showed a mosaic of genetically divergent populations with short-range patterns of gene flow, and native coastal populations indicated an equilibrium state with an isolation-by-distance pattern suggestive of postglacial range expansion. However, coalfield populations exhibited (i) high levels of genetic diversity, (ii) no evidence of local inbreeding or reduced effective population size and (iii) multiple maternal mitochondrial lineages, a genetic footprint depicting independent colonization events. Furthermore, approximate Bayesian computations suggested several evolutionary trajectories from ancient isolation in glacial refugia during the Pleistocene, with biogeographical signatures of recent expansion probably confounded by human-mediated mixing of different lineages. From an evolutionary and conservation perspective, this study highlights the ecological value of industrial areas, provided that ongoing regional gene flow is ensured within the existing lineage boundaries.

Mots clés: nuclear and mitochondrial diversity; man-made habitats; amphibians; spoil heaps; colonization process; genetic structure

Domaines: Biodiversité et Ecologie; Evolution [q-bio.PE]

Leslie Faucher, Laura Hénocq, Cédric Vanappelghem, Stéphanie Rondel, Robin Quevillart, et al.. When new human-modified habitats favour the expansion of an amphibian pioneer species: Evolutionary history of the natterjack toad (Bufo calamita) in a coal basin. Molecular Ecology, 2017, 26 (17), pp.4434-4451. ⟨10.1111/mec.14229⟩. ⟨hal-01579438⟩