Rates Of Evolution Theory: The Rate Of Genetic Theory

Introduction

Evolution is defined as the process in which there is a change in allele frequency within a population over successive generations, in response to evolutionary forces (Ridley, 2004). The rate of evolution is a measure of how quickly these allele frequency changes take to establish within a population. Evolution is a highly complex process, due to the numerous contributing factors that influence it (Hamilton, 2009). Therefore the rate at which it occurs varies greatly, influenced by a combination of factors such as the mutation rate, the type of mutation, population size and life history traits of taxonomic groups (Frean, 2013). The rate at which evolution occurs is an aspect of Evolutionary Biology that remains highly disputed,

The first of these is phyletic gradualism, which states that evolution is a slow process that occurs at a fairly constant rate. Speciation is the formation of a new species, which in this theory arise via micromutations. These are small-scale mutations that occur over a period of time at a constant rate. Micromutations accumulate over time and lead to a series of intermediate forms, which transition the ancestor species into a new distinct species (McCabe, 2017).

The contrasting theory is punctuated equilibrium, which states that evolution occurs in disproportionate alternating periods of stasis and punctuation. A lineage will remain in stasis for the majority of the time, in which it is held in evolutionary equilibrium. This is where stabilizing selection is believed to occur, in which selection favours individuals with intermediate variant phenotypes, rather than extreme phenotypes. Stasis can alternate to the punctuation phase, in which stabilizing selection no longer constrains allele frequency changes, allowing for macromutations to occur. These are mutations that have a large phenotypic effect, giving rise to changes in allele frequency. The phenotype produced results in speciation, and the rate of evolution varies between slow and very rapid periods. (McCabe,