Population 1 has a higher heritability of body length at 19 mm compared to Population 2's 15 mm. Differences may be due to parental nutrition - females and males raised on poor diets produce larger offspring. Population 1 is more likely to evolve over time if larger size increases survival, as larger females have more offspring transmitting their genes for large body size, leading to response to selection for increased size.

1. What is the approximate heritability of body length for:
A) population 1
B) population 2
What factors might contribute to the difference in heritability of body size between the 2
populations of insects in the question above
For the populations shown in the figure above, if larger body size confers a survival advantage in
this species, which population would be more likely to show evolutionary change over time?
Explain. 18 14 10 100 18 16 14 12 Mid parent body length (mm) Population 1 Population 2
Solution
(1) The approximate heritability of body length for: population 1 is 19 mm and for population 2
is 15 mm
(2) The factors that contribute to the difference in heritability of body size include: diet, female
fecundity and male mating success.
The parental early nutrition (poor vs. standard) contribute to the difference in the heritability of
body size. A study shows that the female (parent) raised on poor diet produced larger offspring
than females that were raised on standard diet and males raised on poor diet sired larger sons
than males that were raised on standard diet. The females raised on a poor diet produced larger
offspring than females that were raised on a standard diet.
(3) if larger body size confers a survival advantage in this species, then the population 1 is more
likely to show evolutionary change over time. The female fecundity advantage model depends on
the clutch size and increases with female body size. The larger females will have more copies of
their own genes in succeeding generations than the smaller females, resulting in genes for large
body. The body size is evolutionarily labile and responds rapidly to natural and artificial
selection.