new information for a2 biology : adaptation and selection 1

Question 1

what are the three types of selection? which is new for a2 biology?

Answer 1

stabilising selection, directional selection, disruptive selection

disruptive selection is new for a2 biology

Question 2

what is disruptive selection?

Answer 2

this is the opposite of stabilising selection. it favours extreme phenotypes at the expense of the intermediate phenotypes. although the least common form of selection, it is the most important in bringing about evolutionary change.

Question 3

example : explain the graphs for disruptive selection

Answer 3

1 when there is a wide range of temperatures throughout the year, there is continuous variation in fur length around a mean of 1.5cm

2 where the summer temperature is static around 15˚C and the winter temperature is static around 5˚C, individuals with two distinct fur lengths predominate - 1.0cm types, which are active in summer, and 2.0cm types, which are active in winter

3 after many generations two distinct sub-populations are formed