19.1 The Hardy-Weinberg Principle

Question 1

What did Charles Darwin and Alfred Wallace explain about the mechanism by which species change over time?

Answer 1

Individuals with variations that make them better suited will more likely survive and reproduce, thereby pass on their favourable variations to the next generation.

Question 2

Evolution occurs….

Answer 2

When there are genetic changes in a population over time.

Question 3

Population

Answer 3

A group of organisms of the same species that live together in a defined area and time

Question 4

When a population becomes fragmented, (ex: road creates a barrier through a habitat) the individuals on either side….

Answer 4

may form separate populations.

Question 5

Genes

Answer 5

are carried on chromosomes and control the inheritance of traits such as flower colour in plants and fur colour in animals. A gene can have more than one form.

Question 6

Allele (which ex)

Answer 6

A form of a gene

- fur coat in mice can be black or white

Question 7

Gene Pool

Answer 7

The sum of all the allele for all the genes in a population

The sum of all the genetic variation that can be passed on to the next generation

Question 8

The more variety in a gene pool….

Answer 8

the better the population can survive in a changing environment.

Question 9

Genotype frequency (4) *with example

Answer 9

The proportion if a population with a particular genotype

• expressed as a decimal
• Can be expressed as the percentage of individuals with a particular genotype
• Sum of all three genotype frequencies is 1.00 or 100%

Ex: BB is 0.36. Bb is 0.48 and b is 0.16

Question 10

Phenotype frequency

Answer 10

The proportion of a population with a particular phenotype expressed as a decimal or percent.

Question 11

Allele frequency+ how is it found?

Answer 11

The rate of occurrence of a particular allele in a population with respect to a particular gene

Found by dividing the incidence of the allele by the total number of alleles in the sample.

Question 12

Relationship between allele and number of individuals:

Answer 12

Twice

Since diploid organisms have two possible alleles for every gene, the total number of alleles in a population is twice the number of individuals.

Question 13

as long as five conditions are met, allele frequencies will remain the same:

Answer 13

1. The population is large enough that chance events will not alter allele frequencies
2. Mates are chosen on a random basis
3. There are no net mutations
4. There is no migrations
5. There is no natural selection against any of the phenotypes

Question 14

Genetic Equilibrium aka Hardy Weinberg Equilibrium

Answer 14

If there is no change in allele frequencies over time, then the population is said to be at genetic equilibrium
- the population is not changing or evolving

Question 15

if there is a change in allele frequency over time then:

Answer 15

one of the conditions of the Hardy Weinberg principle is not being met and the population may be evolving.

Question 16

Microevolution

Answer 16

Gradual change in allele frequencies in a population

Ex: The development of DDT-resistance in mosquito populations.