Rapid increase in dispersal during range expansion in the invasive ladybird Harmonia axyridis.
The evolutionary trajectories associated with demographic, genetic and spatial disequilibrium have become an issue of growing interest in population biology. Invasive species provide unique opportunities to explore the impact of recent range expansion on life-history traits, making it possible to test for a spatial arrangement of dispersal abilities along the expanding range, in particular. We carried out controlled experiments in laboratory conditions to test the hypothesis of an increase in dispersal capacity with range expansion in Harmonia axyridis, a ladybird that has been invading Europe since 2001. We found a marked increase in the flight speed of the insects from the core to the front of the invasion range in two independent sampling transects. By contrast, we found that two other traits associated with dispersal (endurance and motivation to fly off) did not follow the same spatial gradient. Our results provide a striking illustration of the way in which predictable directional genetic changes may occur rapidly for some traits associated with dispersal during biological invasions. We discuss the consequences of our results for invasion dynamics and the evolutionary outcomes of spatially expanding populations.
UMR 1355 ISA, Inra, Sophia-Antipolis, France.|UMR ISA, Université de Nice Sophia Antipolis, Sophia-Antipolis, France.|UMR 7254 ISA, CNRS, Sophia-Antipolis, France.
E
E
Lombaert
UMR CBGP (INRA/IRD/CIRAD/Montpellier SupAgro), Inra, Montferrier-sur-Lez, France.
A
A
Estoup
UMR CBGP (INRA/IRD/CIRAD/Montpellier SupAgro), Inra, Montferrier-sur-Lez, France.
B
B
Facon
UMR 1355 ISA, Inra, Sophia-Antipolis, France.|UMR ISA, Université de Nice Sophia Antipolis, Sophia-Antipolis, France.|UMR 7254 ISA, CNRS, Sophia-Antipolis, France.
B
B
Joubard
LUBIES laboratory, Université Libre de Bruxelles, Brussels, Belgium.
J-C
JC
Grégoire
LUBIES laboratory, Université Libre de Bruxelles, Brussels, Belgium.
A
A
Jannin
UMR 1355 ISA, Inra, Sophia-Antipolis, France.|UMR ISA, Université de Nice Sophia Antipolis, Sophia-Antipolis, France.|UMR 7254 ISA, CNRS, Sophia-Antipolis, France.
A
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Blin
UMR 1355 ISA, Inra, Sophia-Antipolis, France.|UMR ISA, Université de Nice Sophia Antipolis, Sophia-Antipolis, France.|UMR 7254 ISA, CNRS, Sophia-Antipolis, France.
T
T
Guillemaud
D000818:Animals; D001517:Coleoptera / Q000235:genetics / Q000502:physiology*; D005260:Female; D005426:Flight, Animal; D058865:Introduced Species; D008297:Male
biological invasion; expansion front; flight speed; harlequin ladybird; spatial sorting