Wednesday, May 27, 2009

Types of Selection

Many factors affect how selection can operate on individual phenotypes in a population. The population can live in a stable environment for long periods of time or live in an environment that is constantly changing. Variable or diverse environments may favour multiple phenotypes. Competition for mates adds further selection pressures that influence the evolutionary pathway of populations. A number of general selection types are a result of different sets of conditions. The table below is an example changes in population, in terms of traits. It will be used as a "control" graph that will be referred to in other articles.
Types of Selection covered in this blog:
Stabilization Selection
Directional Selection
Disruptive Selection
Sexual Selection
Runaway Selection
Artificial Selection
Cumulative Selection

Natural selection is a natural process resulting in the evolution of organisms best adapted to the environment and conditions. Chance and selection play an important role in evolution. Anatomical, morphological and behaviour traits of organisms evolve chiefly through selection mechanisms like sexual dimorphism. The behavioural traits directly influence the daily survival and reproductive success of individuals. At the molecular level, roles of random chance and selection are less clear.
Some biologists think most differences in genome are because of neutral mutations. Others think there are differences because of selective pressures. The basis of evolution is that the ultimate fate of all genetic combinations rests in an organism’s ability to produce individuals that are best suited to survive and reproduce in their habitat. Natural selection is the mechanism that drives the evolution of species.