The purpose of this experiment was to see if there was sexual dimorphism in the feeding structure (jaw bite and skull length) of Arctic foxes between males and females. Our results showed that, in fact, there was a correlation as both p-values for the RAOT and the MA from the t-test came out less than 0.05. The mechanical advantage and the RAOT were larger in the males than that of females. The causes for evolution of sexual dimorphism in Arctic foxes can be explained through three hypotheses; sexual selection, reproductive role division (dimorphic niche), and competition for food availability.
Darwin’s theory states how sexual selection contributes to sexual dimorphism and has shown the occurrence of competition between males and their prey …show more content…
The study done on the jaw and jaw adductor muscles of Crotaphytus collaris from Sooner Lake, showed that the male lizards have larger bite size and larger heads than females this was found by comparing the correlation between their head size and their bite force. It turned out that males use this as a weapon to defend their territory when needed, which increases their mating success, and helped them get prey (Lappin & Husak, 2005). Sexual selection is important as perhaps the dimorphism in jaw bite and skull size evolved from female Arctic foxes choosing males who have these big features. The second hypothesis of dimorphic niche comes from the idea that in many species, the parenting roles are inversed, and the males take care of the offspring. Therefore, that’s why they are bigger (Hedrick & Temeles, 1989). This hypothesis could explain why the males have larger jaw bites as they could possibly use it to defend their offspring while protecting them instead of the females protecting their offspring. The third hypothesis was the idea that sexual dimorphism …show more content…
One experiment that could be done to test for sexual dimorphism is to compare the number of prey that a male and female catch (competition for food availability) in a certain habitat, if the males caught more this explains their fitness. A similar experiment was done to the Hogna helluo; they compared the sex of the spider to the number of prey killed (Walker & Rypstra, 2002). They found that the females caught more prey which explained their wider fang width compared to that of the male spider. To test for the hypothesis of reproductive role division you could compare the jaw bite of a male arctic fox and their mating and offspring success. These experiments could explain the sexual dimorphism that was present in Arctic Fox skulls. There has also been a study done in Japan on dragonets (Repomucenus valenciennei) to test for sexual dimorphism, they examined the growth of fin spines and rays in both males and females and discovered that the male grew faster and larger than the female (Ikejima & Shimizu, 1997). The males are bigger to be able to fight for prey for food and be capable to erect its wings for greater mating