Component 2.6 - Competition, Survival And Selection Pressures

Question 1

Inter-specific competition vs intra-specific?

Answer 1

Inter occurs between individuals of different species but intra is between individuals of the same species

Question 2

What is a selection pressure?

Answer 2

An environmental factor that can alter the frequency of the alleles present at a particular gene locus in a population, when it is limiting.

Question 3

Give examples of selection pressures

Answer 3

1) predation
2) overcrowding (diseases)
3) availability of nesting sites

Environmental factors, humans and competition all exert selection pressures

Question 4

What is a gene pool?

Answer 4

Total of all the alleles for all the genes in a population at a given time

Question 5

What is allele frequency?

Answer 5

It’s percentage of all the alleles of that gene in a gene pool

Question 6

What is genetic drift?

Answer 6

Chance variation in allele frequencies in a population e.g due to individuals dying or not reproducing

Question 7

In what circumstances is genetic drift most significant?

Answer 7

In small or isolated populations when a small number of alleles form a large proportion of the total

Question 8

What does the Hardy-Weinberg principle state the conditions are for frequencies of dominant and recessive alleles and genotypes remaining constant from one generation to the next?

Answer 8

1) Mating is random
2) Population size is very large
3) No selection for or against any phenotypes
4) No mutations
5) Population is isolates, no immigration or emigration

Question 9

How do you calculate Hardy-Weinberg values?

Answer 9

F(AA) - p^2
F(Aa) - 2pq
F(aa) - q^2

p + q = 1

Question 10

What happens if groups split up in terms of selection pressures?

Answer 10

They will be subject to different selection pressures and therefore different individuals will suit the environment better and the groups will have different allele frequencies