Question

64. You are studying the effects of global warming on butterflies by exposing them to ation, mean adult body size for the entire population was 45 mg. However reproductive individuals had a mean body size of 35 mg. Mean adult body size in the second generation was 40 mg. (a) What was the selection differential on body size? (b) What was the narrow-sense heritability of body size?

Answer 1

(a) the average genetic value of animal selected for breeding and average genetic value of all the animals in the species is called as selection differential.

and it is also difference of base population size mean (45) and mean of selected parents which is, in first generation is 35 and in second generation it is 40 so mean of both is 37.5

so the difference would be 7.5

selection difference = 45-37.5 = 7.5

(b) for first generation it would be

when we consider equation R=h2S

h2=R/S

R=Response to selection (the difference of mean in first generation is 10)

S=Selection difference (7.5)

h2= 10/7.5= 1.3 for the first generation and so heritability = -1.1

h2= 5/7.5= 0.66 for second generation and here it would be = -0.8.