18.4 effects of different forms of selection on evolution

Question 1

describe stabilising selection

Answer 1

preserves the average phenotype of a population (phenotypes around the mean)
by favouring average individuals
selecting against extreme phenotypes

Question 2

describe directional selection

Answer 2

changes the phenotypes of a population
favouring phenotypes that vary in one direction from the mean of the population
selection for one extreme phenotype

Question 3

describe disruptive selection

Answer 3

favours individual with extreme phenotypes rather than those with phenotypes around the mean of the population

Question 4

effects of stabilising selection on evolution

Answer 4

capacity for evolutionary change smaller

Question 5

example of stabilising selection

Answer 5

baby weight

Question 6

when does stabilising selection tend to occur

Answer 6

when environmental conditions are constant over long period of time

Question 7

effect of directional selection on normal distribution curve

Answer 7

selection pressure favouring combination of alleles that results in the mean moving to either the left or right of its original position

Question 8

effects of disruptive selection on evolution

Answer 8

most important in bringing about evolutionary change
occurs when environmental factor takes two or more distinct forms
could lead to two seperate species