Question

Fishing appears to have caused selection for smaller size at first reproduction in Atlantic cod. Cod now reproduce at an average body size of 28.4 cm, when historical records from the 1940 s indicate an average size at first reproduction of 41.7 cm. Over the 30 or so generations separating these two samples, the change in the mean body size at first reproduction represents: _______ Assuming 30 generations have passed, then the per-generation estimate of this variable is_______ cm.[to 2 decimal places] If the heritability of this trait is 0.22 , then the we can estimate the per-generation response to selection using the breeder's equation, and obtain: _______cm.(to one decimal place) Over the 30 or so generations separating body size at first reproduction represents: ________ Assuming 30 menerations have passed, then the per-generation estimate of this variable is ______cm.[to 2 decimal places] If the heritability of this trait is 0.22 , then the we can estimate the per-generation response to selection using the breeder's equation, and obtain: ______cm.(to one decimal place)

Answer 1

The change in mean body size at first reproduction in Atlantic cod over 30 generations has been 13.3 cm. The per-generation change in body size has been approximately 0.44 cm, and with a heritability of 0.22, the per-generation response to selection is approximately 0.10 cm.

Step-by-step explanation:

The changes in average body size at first reproduction in Atlantic cod from 41.7 cm in the 1940s to 28.4 cm now can be calculated as follows:

The change in the mean body size over 30 generations = historical size - current size = 41.7 cm - 28.4 cm = 13.3 cm.

The per-generation change in body size = (change in mean body size) / number of generations = 13.3 cm / 30 generations = 0.4433 cm per generation.

To calculate the per-generation response to selection, we can use the breeder's equation: R = h2 * S, where 'R' is the response to selection, 'h2' is the heritability of the trait, and 'S' is the selection differential (assumed to be the change in mean body size).

Assuming a heritability of 0.22 and taking our per-generation change as 'S', the per-generation response to selection (R) would be R = 0.22 * 0.4433 cm = 0.0975 cm (to one decimal place, this is approximately 0.10 cm).

Over 30 generations, the total response to selection would be 30 * R = 30 * 0.0975 cm = 2.925 cm.