Evolutionary Synthesis

Evolutionary synthesis is described as “a unified theory of evolution that combines genetics with natural selection” (Larson 2014:42) and points out that natural selection, ,gene flow, mutation and genetic drift are the four causes for evolution. Gene flow focuses on the spread of new genetic information between populations of the same kind (Larson 2014:44). This really is how genes spread from one population to the next. There are many factors that come into place when looking at gene flow. These factors can include population size, genetic variation, and the environmental context. Gene flow has many factors such as how it can promote or constrain adaptive divergence. Gene flow is a key factor in evolution because it can cause so many different effects. It can increase genetic variations and population size or …show more content…
Gene flow can decrease when a species moves to a new environment and has low fitness. This causes maladaptation of the species in their new environment (Garant et. al 2007:437). This leads to many theories about gene flow in nature and is the logic of ecological speciation (Garant et. al 2007:437). For one, the rate of dispersal showed be higher than the rate of gene flow, which is the case among many groups. Examples of this have been seem among pea aphid Acyrthosiphon pisum and in sockeye salmon Oncorhynchus nerka. With the pea aphid it was clear that the reason for this was the choice against maladapted migrants and hybrids. Secondly, “greater divergent selection should lead to greater adaptive divergence and hence lower gene flow” (Garant et. al 2007:437). There have been several studies to go along with this statement that show how “natural populations have found that measures of divergent selection or adaptive divergence are negatively correlated with measures of gene flow” (Garant et. al 2007:437). Apparently it is not also evident, and the necessary conditions needed are