(Chapter 2.2) Evolution of Species

Question 1

Define population

Answer 1

A group of interacting individuals of a species living in a particular area

Question 2

Define species

Answer 2

Organisms that can reproduce to produce offspring that are both viable and fertile

Question 3

Recall the requirements for natural selection proposed by Charles Darwin

Answer 3

• Variation exists between individuals in a population
• Many differences between individuals in a population are inherited
• Not all individuals in a population survive to produce offspring
• Those individuals in a population that are ‘fitter’ (better adapted to the environment) contribute more to the next generation than those that are less fit

Question 4

Define gene pool

Answer 4

A collection of the genetic information in the population

Question 5

“Natural selection does not increase or decrease the frequency of neutral mutations” Explain why this statement is true

Answer 5

Natural selection does not increase or decrease the frequency of neutral mutations as it does not impact the individuals’ chances for survival or reproduction and therefore, there is no need to change the frequency

Question 6

Identify the factors that may cause variation among individuals in a population

Answer 6

The factors are mutations and allele frequency

Question 7

Define gene flow

Answer 7

Any movement of individuals, and/or the genetic material they carry, from one population to another

Question 8

Identify the types of isolating mechanism

Answer 8

The types are temporal isolation, mechanical isolation, behavioural isolation, and geographic isolation

Question 9

Define temporal isolation

Answer 9

When individuals of different populations reproduce at different times

Question 10

Define mechanical isolation

Answer 10

A physical incompatibility between the reproductive organs of potential mates or pollinators

Question 11

Define geographic isolation

Answer 11

The physical separation of members of a population

Question 12

Define behavioural isolation

Answer 12

The prevention of gene flow between related species living in the same territory through differences in behaviour

Question 13

Identify the types of speciation

Answer 13

The types are allopatric and sympatric speciation

Question 14

Define allopatric speciation

Answer 14

When one species divides into two or more through some form of geographic isolation

Question 15

Define sympatric speciation

Answer 15

When new species arise within an existing species that share the same geographical location, perhaps due to failure of chromosome separation, cross between species, or adaptions for a niche

Question 16

“Sympatric speciation is more common in plants than animals” Explain why this statement is true

Answer 16

The most common cause of
sympatric speciation is cross-breeding between species and this is more likely to occur in plants

Question 17

Explain why Darwin’s finches are an example of both allopatric and sympatric speciation

Answer 17

Darwin’s finches are physically separated to individual islands, a feature of allopatric speciation and the development of beak shape and size for niches is a feature of sympatric speciation