Comparative Primate Blog

Lemurs 

        

You can find Lemurs on the island of Madagascar. They tend to live in tropical rainforests but can also be found in dry and hot desert areas. Most lemurs live in high trees. All lemurs, except the ring tailed lemur, live in the high canopies of the rainforest trying to stay away from the ground. Ring tailed lemurs on the other hand spends most of its time on the ground. They do not possess gripping tails to hang from trees but they do have long noses and are very keen to smell. Unlike most monkey species, lemurs are lead by one dominant female. She leads the group and has first pick on food and her mates.  The smallest species of lemur can weight as much as 1 ounce and the biggest species can weight up to 15 pounds. Female lemurs tend to have more coloration than males do. For instance, in one species of lemur, the male is completely black but the female has a ring of white around her face and she is brown the rest of her body. This shows that a sexual dimorphism has evolved.

Spider Monkey

A spider monkey can be found in tropical forests in South America, as high as Mexico and as low as Brazil. They live in the upper layer of the rainforest in the canopy. They like an undisturbed rainforest for living. In the largest species of spider monkey (black spider monkey), males average to be about 24 pounds and females average about 21 pounds. They are usually between 14-26 inches long and have abnormally long tails, arms, and legs. The sexual dimorphism for spider monkeys is not noticable. Males and females have pretty much the same body size, shape, and weight. Facial and body structural features are the same in both male and females also. Since the spider monkey lives in high trees and rarely come to the ground, they do not need to be bigger or stronger than other species that might be a threat to them. Because of the environment they live in, males and females do not need to have any specific or defining features apart from each other. In this case, the environment caused little if any sexual dimorphism between male and female spider monkeys. 

             Baboon







The baboon can be found in East Africa in high trees, savannahs, or sides of cliffs. Anywhere around a water source with a comfortable living area.They spend most of their time on the ground walking on all fours. They do not have a gripping tails like most monkeys do so they are not the greatest climbers but they still do climb trees. Most baboons range from 40 in to 70 in and weight up to 90 pounds. Males are predominantly larger than females, almost twice as large. Males are also much more aggressive. This is because they must defend their territory against other predators and also to fight for dominance over females. Even though females are half the size of males, they have almost the same appearance except for the males ruff around their neck (long hair around neck like a mane). Males tend to leave their troop and fight for hierarchy and mates in other troops. Females are the ones who stay in their same troops from life to death. The sexual dimorphism of females not having the ruff around their necks probably has to do with evolution. They have to carry their babies around on their stomach and backs so the ruff would just be in the way. Males leaving troops probably has to do with mating. If all the females in a troop are taken, the males must go to different troops to find mates.  It is not necessarily environment factors but the species must be repopulated and if there is no inter troop breeding , then the species will eventually die down.

 Gibbon

 Gibbons are found in old growth tropical rain forests in southeast Asia ranging from Burma to Thailand. They swing from branch to branch up high in the trees. They do not build nests to sleep in, they rest on bare tree branches and the horny pads on their butts help for cushion. Both male and female Gibbons are about the same size, males tending to be slightly larger than females. They weight anywhere from 10-20 pounds. They possess long, extremely strong arms to swing from trees in the forest. They mark their territory by a screeching song that they sing to allow others to recognize the species and sex of that individual. Female Gibbons have smaller throat sacs which amplifies the frequency of its calls. This trait probably adapted because of the environment that gibbons live in. Since they live high in the trees and they are fast, identifying an individual could be difficult. If a threat were to come into their territory and they had no way of determining who it was, that could cause many problems. They females probably developed a different frequency call so that the males know who exactly they are and can recognize them without any problems.

 







Chimpanzee

The Chimpanzee can be found in many countries of Africa. They mostly reside north of the Congo River. They have been found in closed canopy forests which are extremely humid, and depending on the season, in dry forests and the savannah. When seen on the savannah, chimpanzees are usually migrating to another forest area. Because the chimpanzee has varied taste, they do not have a certain habitat that they must always be in. They are open for variety.   Male Chimps are larger than females. A male's height ranges from about 3-4 ft and a female's ranges from about 2-3.5 ft tall. Males usually weigh from 90-115 pounds and females weight from 57-110 pounds. Male chimpanzees are lager than females because they eat more than females. A sexual dimorphism trait that explains why males are larger than females is that females tend to leave and mate with other males while the males stay and defend and protect its territory. This trait was probably formed because chimps needed to breed to keep their species from being extinct and the males needed to protect their territory and resources to stay alive in order to reproduce. By males being bigger, it helps to defend what is theirs and to make sure that they won't be killed off.

Summary

Throughout this post, I have noticed that depending on the habitat of the species, the body size and sexual dimorphism differ. For example, with spider monkeys, gibbons and lemurs, the males and females tend to be about the same height and weight. They both live in the high trees of the forests and mostly stay off the ground. Because of this, they have no need to defend territory which means that size in this case doesn't matter. If there is no need for a dominant sex, then a species probably won't evolve into having one. Chimpanzees and baboons, on the other hand, live on the ground mostly. They have a dominant sex which defends their territory and fights for mates.  Males are much larger than females. Since they live on the ground, both species have to be bigger built to walk around all day and find food. Depending on the type of environment they live in, body size and sexual dimorphism changes. Monkeys that live mostly in the trees tend to be smaller with both sexes being about the same size and those species who live mostly on ground tend to be bigger built with the male being predominantly larger than females.