Factors that Affect Evolution

What is another definition of evolution? Do individuals evolve or do populations evolve?

• Evolution is a change in the relative frequency of alleles in a population’s gene pool.

• Populations evolve, not individual organisms.

• Individuals may survive or reproduce, but evolution occurs when allele frequencies change across generations.

What are inheritablemutations? How can mutations happen? How can they affect organisms?

It is an inheritable change to DNA that Occurs in germ cell(Egg and sperm)

Mutations are the source of new aliens in a population, leading to an increase in a population’s genetic variation

• Beneficial → improves survival/reproduction

• Harmful → decreases survival/reproduction

• Neutral → no noticeable effect

What factors can change allele frequencies in a population’s gene pool?

The four main factors are:

1. Natural Selection

2. Genetic Drift

3. Gene Flow

4. Inbreeding

If a population becomes much smaller, what happens? How does inbreeding increase harmful recessive traits?

When population size decreases:

• The gene pool becomes smaller.

• Genetic variation decreases.

• Genetic drift becomes stronger.

Inbreeding increases the chance that two relatives carry the same harmful recessive allele, making it more likely for offspring to inherit two copies and express the trait.

How are artificial selection and natural selection similar? What are the advantages and disadvantages of artificial selection?

Similarity:

• Both change allele frequencies over generations by selecting certain traits.

Natural Selection:

• Environment selects.

Artificial Selection (Selective Breeding):

• Humans select.

Advantages

• Produces desirable traits.

• Improves crops and livestock.

Disadvantages

• Reduces genetic diversity.

• Increases inbreeding.

• Harmful traits may become more common.

What are the five types of evidence that support evolution?

1. Fossil Record

2. Homologous Structures

3. DNA (Molecular) Evidence

4. Embryological Development

5. Vestigial Structures