7B Speciation and Genetic Drift

Question 1

Define speciation

Answer 1

The development of a new species from an existing species

Question 2

When does speciation occur?

Answer 2

When populations of the same species become reproductively isolated due to geographical isolation which leads to allopatric speciation

It can also occur without any physical separation. This is known as sympatric speciation

Question 3

What does allopatric speciation require

Answer 3

Geographical isolation
Different climate on different sides of separation
Allele for fur length depending on climate

Question 4

What does sympatric speciation not require

Answer 4

Geographical isolation

Question 5

In what way does reproductive isolation occur seasonally

Answer 5

Seasonal- different mating and flowering seasons and individuals become sexually active at different times

Question 6

In what way does reproductive isolation occur mechanically

Answer 6

Changes in genitalia prevent successful mating

Question 7

In what way does reproductive isolation occur behaviourally

Answer 7

A group of individuals develop courtship rituals that aren’t attractive to the main population

Question 8

How does genetic drift lead to speciation?

Answer 8

Individuals within a population show variation in their genotypes
By chance the allele for one genotype is passed on to the offspring more often than others
So the number of individuals with the allele increases
Changes in allele frequency in two isolated populations can lead to reproductive isolation and speciation

Question 9

How has evolutionary change led to a great diversity of organisms

Answer 9

The diversity of life on earth today is the result of appreciation and evolutionary change over millions of years

To start with there was one population the population was divided and the new population evolved into separate species the new species were then divided again and the new populations evolved into more separate species