Evolution & Speciation

Question 1

Why may individuals within a population of a species may show a wide range of variation in phenotype?

Answer 1

Environmental factors

Mutations

Random fertilisation of gametes

Crossing over

Question 2

3 types of adaptations

Answer 2

Anatomical

Physiological

Behavioural

Question 3

Properties of directional selection

Answer 3

One of the extremes has an advantage

Changing environment

Modal trait changes

Question 4

Properties of stabilising selection

Answer 4

Modal trait has the selective advantage

No change in environment

Modal trait remains the same

SD decreases

Question 5

Properties of disrusptive selection

Answer 5

Both extremes have the selective advantage

Changing environment

Modal traits change two ways

Can lead to speciation

Question 6

What is speciation

Answer 6

The creation of a new species

Question 7

How does speciation occur

Answer 7

An original population becomes reproductively isolated.

Differences to gene pools (via mutations)

Unable to interbreed to make fertile offspring

Question 8

2 ways population can become reproductively isolated

Answer 8

Allopratic (geographically)

Sympatric (changes in reproductive mechanisms)

Question 9

What is genetic drift

Answer 9

Change in allele frequency within a population between generations

Question 10

What does continuous, substanital genetic drift lead to?

Answer 10

Evolution

Question 11

When does genetic drift have the biggest impact

Answer 11

On smaller population