Final answer:
Life-history traits are directly tied to an organism's fitness and are likely conserved through natural selection, leading to less genetic variation compared to other trait types.
Step-by-step explanation:
Life-history traits are more intimately connected with fitness because they directly affect an organism's ability to survive and reproduce. Since these traits are closely tied to natural selection, they should, in theory, show less genetic variation than other kinds of traits. This is because advantageous life-history traits are more likely to be conserved within a population due to providing a survival or reproductive advantage, leading to a reduction in variance over time through selective pressures. Other traits such as behavioral, physiological, or morphological may show more variation as they might not be as closely linked to the immediate survival and reproductive success. Therefore, the correct answer to the question is that life history traits should show less genetic variation than other kinds of traits.