Adaptive population structure shifts in invasive parasitic mites, Varroa destructor

Comparative studies of genetic diversity and population structure can shed light on the ecological and evolutionary factors governing host–parasite interactions. Even though invasive parasites are considered of major biological importance, little is known about their adaptive potential when infesting the new hosts. Here, the genetic diversification of Varroa destructor, a novel parasite of Apis mellifera originating from Asia, was investigated using population genetics to determine how the genetic structure of the parasite changed in distinct European populations of its new host. To do so, mites infesting two categories of hosts in four European regions were compared: (i) adapted hosts surviving through means of natural selection, thereby expected to impose strong selective pressure on the mites, and (ii) treated host populations, surviving mite infestations because acaricides are applied, therefore characterized by a relaxed selection imposed by the host on the mites. Significant genet...