Midterm Question 1
1. Reproductive-aged women need more vitamin D than men. The reason is clear: Bone growth
and health are critically dependent on vitamin D, and moms must build the skeletons of their
fetuses—a selection pressure that never affects men. Interestingly, when women are pregnant
they often experience significant hair loss, especially on their heads. You are asked to consider
whether or not this maternal hair loss is a facultative adaptation.
A. In general, what are facultative adaptations and what do they do? (You may give an example
but, by itself, an example is not the general answer you are asked to provide.) [2]
Facultative adaptations are genetically programmed responses to patterns within the
lifetime of individuals which are built by the process of selection–they are fitness promoting
and respond to particular environmental circumstances. An example of facultative
adaptations include a darkened skin tone under a set of conditions where sun exposure is
intensified. Facultative adaptations develop in response to an environment therefore they
create a characteristic.
B. How do facultative adaptations evolve? Is it by the same or a different process than the way
non-facultative (obligate) adaptations evolve? [1]
All adaptations are built by the selection of favorable mutations, gene copying error change
amino acids and proteins and some are helpful and kept. Facultatives adaptations are
environmental effects designed by natural selection. Facultative adaptations are evolving
and changing at the pace of years, an annual cycle. Facultative traits are operating over a
historical range of variation–a slow response–we do not have the ability to respond quickly
to new variations as we only have facultative adaptations based on whether or not your
ancestors were exposed to the relevant environment. Therefore facultative adaptations
evolve differently than non-facultative adaptations. It is a different process as obligated
adaptations are required to happen in an organism's lifetime instead of evolving overtime.
C. Is hair loss in pregnant women a facultative adaptation? Defend your answer. [2]
A result of hair loss in pregnant women is considered a facultative adaptation. Considering
a woman's body is responding to the affects of being pregnant it can be also known as a
“short term” environmental change to the body. Since the mothers hormone level is high as
soon as the baby is born the hormones return to the baseline level. Thus causing the hair
loss to come to a hult since it was only occurring in response to the spike in hormone levels
during pregnancy.
