Over generations, female reindeer in a Finnish population give birth to larger offspring. Which type of selection is occurring, and how would a distribution curve for this trait change over time?

Question

A. directional selection; the curve would shift to the right
B. stabilizing selection; the curve would become taller in the middle
C. stabilizing selection; the curve would become shorter in the middle
D. directional selection; the curve would shift to the left

Answer 1

A. directional selection; the curve would shift to the right

Directional selection occurs when individuals at one end of the spectrum for a trait have higher fitness, leading to a shift in the average value of that trait over time. In this case, as female reindeer with larger offspring have higher fitness, the trait of offspring size is being selected for, causing the distribution curve to shift to the right towards larger offspring sizes.