evolutionary mechanisms

24/10/26

fitness

the ability to produce viable offspring

the genotype/phenotype/fitness connection

• Genotypes vary among individuals, and an individual's genotype has an important affect on its phenotype.

• The environment that an individual experiences has an important affect on its phenotype.

• An individual's phenotype affects it ability to thrive and/or produce viable offspring.

natural selection

the evolutionary process where organisms with inherited traits better suited to their environment tend to survive, reproduce, and pass those advantageous traits on to future offspring, changing allele frequencies

evolution

a change in allele frequencies

directional selection

Natural selection that favours an extreme phenotype.

stabilizing selection

natural selection that favours the average phenotype in the phenotype in the population and acts against extreme phenotypes

adaptation

A heritable trait that increases fitness in a particular environment.

theory

An explanation or set of hypotheses that attempt to explain a large and pervasive phenomenon, meaning they that tie together a large suite of observations about how the natural world works.

artificial selection

When humans actively and consciously select which individuals will be the parents of the next generation.

gene flow

An evolutionary process that changes allele frequencies through the movement of individuals and their alleles from one population to another. Homogenizes allele frequencies among populations.

maladaptive

Leading to lower fitness.

mutation

Any change in the sequence of DNA, and thus a change in genetic information. Introduces new alleles into population.

deleterious mutation

A mutation or other event that lowers fitness. 

genetic drift

Any change that occurs in allele frequencies that is due to chance.

has a much greater impact on smaller population that big ones. this can lead to gene fixation (100% freq.) or loss (0% freq.)

founder events

One of the evolutionary mechanisms. They occur when a relatively small number of individuals disperse to a new habitat and found a completely new population.

genetic bottlenecks

One of the evolutionary mechanisms. They occur when a species undergoes a large and rapid decrease in population size due to a disease epidemic, catastrophic storm, or other change.

sampling error

when looing for the rate or frequency of something, but you don’t take enough samples, or the individuals in your sample don’t accurately represent the population