Lesson 5 Microevolution

Question 1

Population

Answer 1

A population is defined as a
localized group of a single species
occupying a particular area.

Factors affecting population
genetics:

Immigration and Emigration

Mutations

Genetic Drift

Non – Random Mating

Question 2

Immigration and
Emigration

Answer 2

The movement of individuals into a
population (Immigration) introduces
new alleles to the population.

The movement of individuals out of a
population (Emigration) removes
alleles from a population.

This movement of alleles is called
Gene Flow.

Question 3

Mutations

Answer 3

If a mutation is inheritable it may
introduce new alleles to a population.

The expression of these alleles
may be neutral, favourable or
unfavourable.

Mutations increase variation in
the allele frequency of a species.

Not likely to cause a change in
allele frequency unless the
mutation provides a selective
advantage.

Question 4

Genetic Drift

Answer 4

Allele frequency is dramatically
changed by chance alone.

Occurs only in small
populations

Types of genetic drift include
the Bottleneck Effect and the
Founder Effect

Question 5

Bottleneck Effect

Answer 5

As a result of random chance, certain
alleles are overrepresented and others
are underrepresented in a reduced
population.

How this happens:

A large population is drastically
reduced.

The surviving population is not
representative of the gene pool of the
original population.

Genetic Drift occurs as the population’s
genetic variation is reduced to that of
the surviving population.

Question 6

Founder Effect

Answer 6

Genetic Drift due to a small group
of individuals colonizing a new
area.

The founder effect is often
compounded by the selective
pressures ( Natural Selection) of the
new environment.

Question 7

Non-Random
Mating

Answer 7

Many populations do not reproduce
randomly. Sexual reproduction is usually
selective.

Types of Non – Random Mating

1. Assortative Mating
2. Sexual Selection
3. Inbreeding
4. Artificial Selection

Question 8

Assortative Mating

Answer 8

Individuals choose partners that
have a particular phenotype.

Reduces genetic diversity as
individuals who do not possess
this phenotype do not
successfully reproduce.

Question 9

Sexual Selection

Answer 9

Reproduction based on Sexual Dimorphism. The display of distinct male and female behavioural characteristics and mating displays.

Alleles of the most reproductively well adapted species are passed on, not always the best suited to the environment.

Question 10

Inbreeding

Answer 10

Mating between two closely related
individuals.

Does not change allele frequency
but it does result in more
homozygous individuals.

Ex. Self – fertilization in plants

Question 11

Artificial Selection

Answer 11

Human selection of particular traits by
the selective breeding of individuals.

Human action selects the trait.

Ex. dogs