5-2-1 Evolution and Genetics

Question 1

Define “Population”

Answer 1

A group of individuals living in the same area. Its members can interbreed and produce fertile offspring.

Question 2

Define “species”

Answer 2

One or more populations of interbreeding organisms that are reproductively isolated in nature from all other organisms.

Question 3

Define “gene pool”

Answer 3

The sum of all the genetic information carried by members of a population.

Question 4

What is “population genetics”?

Answer 4

The study of genetic variation within populations by examining changes in the frequency of alleles within the gene pool.

Question 5

What gives rise to varied genotypes and phenotypes in a population?

Answer 5

1. Genetic recombination

(This happens during meiosis involving crossing over and random sorting and pairing of gametes.)

2. Gene mutation

Mutations can occur at the gene level (changes in gene sequence) or at the chromosomal level (chromosomal non-disjunction).

Gene mutation (mutation at the gene level) is the main source of genetic variation in a population.

Question 6

The Hardy-Weinberg Principle

Answer 6

Developed independently by Godfrey Hardy and Wilhelm Weinberg, the Hardy-Weinberg Principle states: Allele frequencies in the gene pool of a population will remain constant if 5 conditions are met,

1. No mutation
2. No gene flow (defined in the next section)
3. Random mating
4. No genetic drift (defined in the next section)
5. No selection

These conditions are rarely met in nature. So, allele frequencies in a population’s gene pool often do change from one generation to another.

Question 7

Equation for predicting the genotype frequency within a population

Answer 7

p² + 2pq + q² = 1

The variable “p” represents the dominant allele

The variable “q” represents the recessive allele

Any change in allele frequencies in a gene pool indicates that evolution has occurred.

Question 8

What does a change of allele frequency in a gene pool indicate?

Answer 8

It indicates that evolution has occurred.