Abstracts (first author)
Clinal analysis of a temporary contact zone between two invading outbreaks to estimate dispersal of a major pest of maize
Dispersal is a key parameter involved in invasion, persistence and evolution of species. Despite the interest of obtaining dispersal estimates, measuring dispersal remains a real challenge due to its complexity and associated technical constraints. Some biological invasions may, however, be useful to estimate the dispersal. The western corn rootworm (WCR), Diabrotica virgifera virgifera, is one of the most destructive pests of corn and is invading Europe. The two main European invasive outbreaks of WCR are located in North-Western Italy and Central Europe and they originated from independent introductions from North America. Recently it was demonstrated that a secondary contact probably occurred between these two expanding outbreaks in 2008, in Northern Italy and led to the formation of an admixture zone. Here, we exploit this ongoing process to infer the dispersal of the WCR by analysing temporary frequency clines at 13 microsatellite markers. A measure of the clines slope and the linkage disequilibrium between microsatellites at the centre of the contact zone provided two estimates of WCR dispersal. Simulations with various non Gaussian dispersal kernels and population density heterogeneity in space showed that these estimations are robust to several deviations from the diffusion approximation. The order of magnitude of this estimation is then compared to others estimates of WCR dispersal and is discussed in the context of biological invasions. We conclude that secondary contacts between colonizing populations, which are common in invasive species, are very useful and could be used to infer dispersal parameters in many species.