Factors that affect evolution

Evolution

Change in the relative frequency of alleles in a populations gene pool (ex. 70% brown and 30% white to 50% of both)

Alleles

Variation of the a gene ( like the color blue is a variation for eye color)

Homozygous

2 same allele

Heterozygous

2 different alllele with one dominant

Inheritable mutations

Inheritable change in DNA that occurs in germ cells (egg or sperm) that is passed from parent to offspring. Mutations are the source of new alleles in a populations gene and lead to an increase in genetic variation, they can be good bad or neutral

how new mutations occur

Radiation ( X-rays and UV), chemicals (pesticides, nicotine), and during DNA replications

Beneficial mutation

Positively impacts organisms ability to survive in environment

Harmful mutation

Negatively impacts organisms ability to survive in its environment

Neutral mutation

Does not impact the organisms ability to survive or reproduce in its environment

Gene pools

Consists of the total collection of all the alleles in a populations. This is where genetic variation is stored

What is the smallest level at which evolution can occur

A population

what are the 4 Factors that affect the frequency of certain alleles in a populations gene pool

Natural selection, gene flow, genetic drift, inbreeding

What happens to the gene pool and genetic variation when a populations size is reduced

It’s gene pool shrinks and genetic variation drops

Gene flow

Exchange of alleles between 2 populations of the same species due to migration of individuals. This increases genetic variation of both populations.

Genetic drift

A change in a populations gene pool due to random chance, there are 2 kinds of genetic drift ( genetic bottleneck and founder effect)

Genetic bottleneck

When an event like a natural disaster reduces a populations size and gene pool. By chances the survivors will have certain alleles which changes the gene pool. The result is decreased genetic variation.

Founder effect

When a small number of individuals move to a new habitat and start a new population. They are now know as the Founding Population. The gene pool of the new population depends on the alleles from the founding population. Result is decreased genetic variation

Inbreeding

Reproduction of closely related animals over multiple generations… if 2 siblings carrying recessive traits inbreed, the offspring has a higher chance to get the recessive deleterious

Deleterious alleles

Excessive allele that make the animal less “fit”

Artificial selection (selective breeding)

When humans decide which traits are useful (ex. Cabbage, Brussels sprouts, kale etc.)

Advantages of selective breeding

allows humans to choose which animals reproduce to bring out desirable traits

disadvantages of selective breeding

decreases genetic diversity in populations. Undesirable traits in both parents may appear in offspring. diseases and health problems can accumulate in the population like how there are many deaf dalmations.

mutation

random change in an organisms DNA that is the ultimate source of genetic variation because it creates completely brand new allleles.

mutagen

A mutagen is any outside force or substance that physically damages DNA and causes genetic mutations to happen at a much faster rate than normal. (UV radiation xray chemicals)

sickle cell anemia

a mutation in the gene that makes hemoglobin. causes red blood cells to have a sickle like shape which makes it difficult to navigate bloode vessels and carry oxygen. common in places with malaria because it is resistant