Abstract
Biological invasions of pests into climatically unsuitable areas can be facilitated by human-regulated environments, in which case there may be an impact on genetic structure through population processes and/or adaptation. Here, we investigated the population genetic structure of an invasive agricultural pest, Thrips palmi, in China, which has expanded its distribution range through using greenhouses. Early invaded populations showed a relatively higher level of genetic diversity than recently expanded greenhouse populations. Strong population genetic structure corresponded to a pattern of isolation by distance, with no recent gene flow and low historical gene flow among populations, reflecting limited ongoing dispersal. A genetic signature of population expansion was detected in early invaded populations and three northern populations from greenhouses, suggesting that the greenhouse environments facilitated expansion of this species. Redundancy analysis showed that the independent effects of environment and geography could explain 51.68% and 32.06% of the genetic variance, respectively. These findings point to climate- and greenhouse-related spatial expansion, with the potential for adaptation by T. palmi. They emphasize the contribution of human-regulated environments on the successes of this invasive species, a situation likely to apply to other invasive species that use greenhouse environments.