Populations and evolution

Question 1

what conditions have to be met if the genes in a population are going to remain the same?

Answer 1

– no mutations arise
– the population is isolated
– there is no selection
– the population is large
– mating within the population is random

Question 2

what are the two most important Hardy-Weinberg equations?

Answer 2

p + q = 1
p2 + 2pq + q2 = 1

Question 3

what causes genetic variation?

Answer 3

– mutations
– meiosis
– random fertilisation

Question 4

what are the factors that natural selection depends on?

Answer 4

– produce more offspring than can be supported by supply of food etc
– genetic variety within the population of all species
– a variety of phenotypes that selection operates against

Question 5

what are the three main types of selection?

Answer 5

– stabilising
– directional
– disruptive

Question 6

what is stabilising selection?

Answer 6

prevents the average phenotype of a population by favouriting average individuals

Question 7

what is directional selection?

Answer 7

changes the phenotypes of a population by favouriting phenotypes that vary in one direction of the mean

Question 8

what is disruptive selection?

Answer 8

favours individuals with extreme phenotypes rather than those with phenotypes around the mean

Question 9

what is the allelic frequency?

Answer 9

the number of times an allele occurs within the gene pool

Question 10

what is speciation?

Answer 10

the evolution of new species from existing ones.

Question 11

what is allopatric speciation?

Answer 11

two populations become geographically separated

Question 12

what is sympatric speciation?

Answer 12

speciation that results within a population in the same area leading to them becoming reproductively separated.