Genetic signatures of a range expansion in natura: when clones play leapfrog

Ronan Becheler (1) , Constance Xhaard (1) , Etienne K. Klein (2) , Katherine J. Hayden (1) , Pascal Frey (1) , Stéphane de Mita (1) , Fabien Halkett (1)

1 IAM - Interactions Arbres-Microorganismes
2 BioSP - Biostatistique et Processus Spatiaux

The genetic consequences of range expansions have generally been investigated at wide geographical and temporal scales, long after the colonization event. A unique ecological system enabled us to both monitor the colonization dynamics and decipher the genetic footprints of expansion over a very short time period. Each year an epidemic of the poplar rust (Melampsora larici-populina) expands clonally and linearly along the Durance River, in the Alps. The colonization dynamics observed in 2004 showed two phases with different genetic outcomes. Upstream, fast colonization maintained high genetic diversity. Downstream, the colonization wave progressively faltered, diversity eroded, and differentiation increased, as expected under recurrent founder events. In line with the high dispersal abilities of rust pathogens, we provide evidence for leapfrog dispersal of clones. Our results thus emphasize the importance of colonization dynamics in shaping spatial genetic structure in the face of high gene flow.

Mots clés: Biological invasions; colonization; dispersal; fungal plant pathogen; genetic diversity; range expansion; fungal pathogen

Mots clés: melampsora larici populina; champignon pathogène; vallée de la durance; alpes; dynamique de la colonisation; dispersion des populations; structure génétique des populations

Domaines: Sciences du Vivant [q-bio]

Ronan Becheler, Constance Xhaard, Etienne K. Klein, Katherine J. Hayden, Pascal Frey, et al.. Genetic signatures of a range expansion in natura: when clones play leapfrog. Ecology and Evolution, 2016, 6 (18), pp.6625-6632. ⟨10.1002/ece3.2392⟩. ⟨hal-01512000⟩