Life Sciences- Factors that affect evolution

Evolution in terms of alleles

Changes in the relative frequency of alleles in a population’s gene pool

Alleles

Variations of a gene (ex. Gene for eye colour would have brown, blue, and green alleles)

Inheritable mutation

An inheritable change to DNA that occurs in germ cells (eggs and sperm)

Passed on. From parent to offspring

The source of new alleles in a population, leading to an increase in a population's genetic variation (ex. New fur colour, slightly longer neck, better hearing)

Three types of mutation

Beneficial, neutral, or harmful depending on the environment

Factors of inheritable mutations

• Radiation

• Chemicals

• During DNA replication

Radiation

X-rays, UV exposure

Chemicals causing inheritable mutations

Pesticides, herbicides, nicotine

Mutation during DNA replication

• Happens often

• Most changes have no effects but some do

Beneficial mutation

Positively impacts the organisms ability to survive in its environment

Harmful mutation

Negatively impacts the organisms ability to survive in its environment

Neutral mutation

Most of the time, neutral mutations result in no physical change (not noticeable)

Gene pool

Consists of all the alleles in all the individuals that make up a population. This is where genetic variation is stored

The hat from which generation draws its genes

Factors that affect the frequency of certain alleles in a population’s gene pool

• Natural selection

• Gene flow

• Genetic drift: genetic bottleneck, and founder effect

• Inbreeding

Change in allele frequency

Causes populations to evolve

Gene flow

Exchange of alleles between 2 populations of the same species

Result of gene flow

Increased genetic variation in both populations

Gene drift

A change in a population’s gene pool due to random chance

Has a major impact on small populations

• Genetic bottleneck, founder effect

Genetic bottleneck

Occur when an event, like a natural disaster, significantly reduce a population’s size and gene pool

By chance, the survivors will have certain alleles which will change the gene pool

Result of genetic bottleneck

Decreased genetic variation found in the population after a natural distaster (or random occurrence)

Founder effect

Happens when a small number of individuals move to a new habitat and start a new population

They are now the founding population

The gene pool of the new population depends on the alleles found in the founding population

Result of the founder effect

Decreased genetic variation found in the population

Inbreeding

Reproduction of closely related animals over multiple generations

Deleterious alleles

An allele that makes an animal less “fit”

Diploid organisms

Organisms that have 2 copies of every gene (ex.humans)