title: Genetic signatures of a range expansion in natura: when clones play leapfrog.
abstract: 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.
authors: UMR IAM INRA Université de Lorraine 54000 Nancy France.
authors: Ronan
authors: R
authors: Becheler
authors: UMR IAMINRA Université de Lorraine54000 Nancy France; Present address: INSERM U1018, CESP, Univ. Paris-Sud UVSQ, Université Paris-Saclay Institut Gustave Roussy Villejuif France.
authors: Constance
authors: C
authors: Xhaard
authors: UR Biostatistique et Processus Spatiaux INRA 84914 Avignon France.
authors: Etienne K
authors: EK
authors: Klein
authors: UMR IAMINRA Université de Lorraine 54000 Nancy France; Present address: Royal Botanic Garden Edinburgh 20a Inverleith Row Edinburgh EH3 5LR UK.
authors: Katherine J
authors: KJ
authors: Hayden
authors: UMR IAM INRA Université de Lorraine 54000 Nancy France.
authors: Pascal
authors: P
authors: Frey
authors: UMR IAM INRA Université de Lorraine 54000 Nancy France.
authors: Stéphane
authors: S
authors: De Mita
authors: UMR IAM INRA Université de Lorraine 54000 Nancy France.
authors: Fabien
authors: F
authors: Halkett
keywords: Biological invasions; colonization; dispersal; fungal plant pathogen; genetic diversity; range expansion