Comparison of genetic diversities in native and alien populations of hoary mustard (Hirschfeldia incana [L.] Lagreze-fossat)

Increased selfing and inbreeding and, consequently, depauperate genetic diversities are commonly expected for alien colonies. We compared RAPDs data for native (southern Europe) and alien (British Isles) populations of hoary mustard (Hirschfeldia incana). This species is normally out-breeding, but it is capable of self-fertilization. Contrary to the common expectations, genetic diversities in native and alien populations were similar, without any strong evidence of decreased levels of genetic diversities in alien populations. A variety of factors may have contributed to this observation, including high variation in founding groups, founders originating from multiple H. incana source populations, and high rates of past and/or current gene flow. A review of other studies showed that this pattern of similar genetic diversities in native and alien populations was not unusual but has been regularly observed in other invasive plant species.