Concepts and complexities of population genetics

The concepts of population genetics and evolution seem simple from an abstract, academic perspective, but in reality, nature is too heterogeneous and dynamic to allow science to be so easy. To provide a reference scenario, we describe evolution by natural selection in patchy landscapes without consideration of pest density. Complications involving a variety of ecological processes are discussed. We describe random genetic drift and demographic Allee effects on evolution. We explore the complexities of genetic architecture for arthropods that evolve resistance. The roles of selection intensity, gene interaction, fitness costs, and dominance (expression of resistance) are presented. Even though most research has been on diploid arthropods, many species can be haplo-diploid (males are haploid, females are diploid). The relationship between generation time and resistance evolution is evaluated. We emphasize the importance of temporal and spatial scales for hypotheses and recommendations regarding evolution of resistance.