Microevolution involves changes in allelic frequency within a gene pool for a given species in a relatively short period of geologic time by the alterations of successfully reproducing individuals within a population. The macroevolution involves large scale changes among groups of species. Co-evolution occurs when two or more species reciprocally affect each other's evolution through the process of natural selection. Phylogenetic evolution represents evolutionary relationships among organisms and reflects how species or other groups evolved from a series of common ancestors.