Queen development time and the Africanization of European honey bees

Organisms that inhabit an area thrive because they have become well adapted to the environmental conditions that surround them. The general rule is that the distinguishing characteristics of a species change very slowly over time. Suppose an individual of a particular species migrates into a territory in which that same species is established. If the migrant individual is similar to the current inhabitants, then the small differences in traits that the new arrival might bring will mix into the population and the distinguishing traits will rarely, if ever, be seen. On the other hand, if the immigrant has distinctive genetic characteristics, it often cannot compete for survival and reproduction with the resident population. Thus, these distinguishing characteristics are rapidly removed from the population's gene pool.