5.4.2 - Speciation

Question 1

What Is Meant By ‘Speciation’?
(3 Points)

Answer 1

~ The development of a new species, from pre-existing species overtime.

~ Occurs, due to isolation, reducing the gene flow between two populations.

~ Natural selection, then acts on each population separately, creating a new species.

Question 2

What Is Meant By ‘Gene Flow’?

Answer 2

Exchange of genes.

Question 3

What Needs To Happen, In Order For Speciation To Occur?
(2 Points)

Answer 3

~ Two populations of the same species must be isolated from each other.

~ Meaning there is no longer exchange of genes (gene flow) between the 2 populations.

Question 4

What May Cause Isolation Of Populations?
(2 Points)

Answer 4

~ Geographical isolation.

~ Random mutations that prevent individuals from interbreeding with each other.

Question 5

What Type Of Speciation Does Geographical Isolation Lead To?

Answer 5

Allopatric speciation.

Question 6

What Type Of Speciation Does Random Mutations That Prevent Individuals From Interbreeding With Each Other Lead To?

Answer 6

Sympatric speciation.

Question 7

Describe Allopatric Speciation
(4 Points)

Answer 7

~ Occurs when populations, become separated from each other by geographical barriers. E.g Natural barriers or man-made barriers.

~ The 2 populations will experience different selection pressures, changing the gene pools of the 2 populations.

~ Changing allele frequencies, will result in changes to the phenotypes of the 2 populations.

~ These 2 populations will eventually, no longer be able to breed with each other, so they become separate species.

Question 8

Describe Sympatric Speciation
(4 Points)

Answer 8

~ Occurs when random changes in the alleles of some individuals, prevent them successfully breeding with others in the population.

~ Phenotypes can change due to seasonal, mechanical and behavioural changes.

~ Meaning there are no longer able to reproduce with others, even though they are in the same habitat.

~ So they become separate species.

Question 9

Describe How Phenotypes Can Change Due To ‘Seasonal Changes’, Within Sympatric Speciation

Answer 9

Individuals in the population develop different mating or flowering seasons, to the rest of the population.

Question 10

Describe How Phenotypes Can Change Due To ‘Mechanical Changes’, Within Sympatric Speciation

Answer 10

Changes in genitalia, preventing successful mating.

Question 11

Describe How Phenotypes Can Change Due To ‘Behavioural Changes’, Within Sympatric Speciation

Answer 11

Individuals develop courtship behaviours, that aren’t attractive to the main population.