Question

In a species of the Darwin’s finches (Geospiza fortis), the narrow-sense heritability of bill depth has been estimat- ed to be 0.79. Bill depth is correlated with the ability of the finches to eat large seeds. The mean bill depth for the population is 9.6 mm. A male with a bill depth of 10.8 mm is mated with a female with a bill depth of 9.8 mm. What is the expected value for bill depth for the offspring of this mating pair?

Answer 1

10.15

Step-by-step explanation:

If the narrow-sense heritability (h2) would have been 1.0, then we could have concluded that the expected value for the offspring would be midway between the means of the two parent.

But in this case, as h2 is less than one, i.e 0.79, it means that it is somewhat closer to the population mean.

So,the expected bill depth can be calculated as below:

Female deviation = 10.8 – 9.6

= 1.2

Male deviation = 9.8 – 9.6

= 0.2

Mean deviation = (Female deviation + Male deviation) ÷ 2

= (1.2 + 0.2) ÷ 2

= 0.7

When h2 = 1.0 , the expected deviation from the population mean with would be 0.7.

When h2 = 0.79, the expected deviation from the population mean would be:

= 0.79 × 0.7

= 0.55

Therefore, the expected value for bill depth for the offspring of this mating pair:

= 9.6 + 0.55

= 10.15