Lemurs are arboreal which means that they spend most of their lives in trees and bushes; therefore they strive in forest environments. These highly adaptable primates can reside in a range of different forest types such as tropical, dense brush, spiny or limestone forests however all Lemurs can be found in habitats located in Madagascar and surrounding islands which contain these varying ranges of environments. Their high adaptability also allows them to withstand a varying range of temperatures, resource seasonality and drought.
The Lemurs social groups (between 11-17 lemurs) are established around female philopatry, which is a system where the females remain in the same unit they were born into, making the females within the groups all related in some form while the male offspring of this unit leave at sexual maturity and discover new groups to mate in. The friendliness of the female group encourages closeness displayed by female grooming and socializing within close proximity of each other, however aggressive encounters do occur, especially with unrelated and distant related females within the same unit. The social order of dominance and hierarchy is lead by the females in Lemur groups, as adult females are always superior to the adult males. Usually, there are no more than three high-ranking males within a group. These high-ranking males experience benefits that lower ranking males do not, such as increased social interactions with high-ranking females, which can lead to increased access to necessary resources such as food and reproductive available females. When the group reaches numbers larger than 15 to 25, lower ranking females are ostracized and forced to create new units, which can be a detriment to their survival as larger well established groups have better access to food and protection of predators. Younger males which tend to be the lower ranking lemurs, transfer from group to group generally every 1.5 years, while older, higher ranking males in their prime, stay within a group for longer and immigrate every 3.5 years. High levels of migration occur during a six-month window between December and May. Breeding season usually lasts from 7 to 21 days while most of the female Lemurs within the forest are at their maximum sexual receptivity, which is called estrus. All female lemurs within the same forest experience estrus at roughly the same time, this is when males looking to mate approach a female, investigate their genitals and then attempt sexual interaction, at which time the female is ether receptive and proceeds or is not receptive and reacts aggressively. Females instigate mating by lifting their tails and showing their genitals to prospective mates. The highest-ranking male is the first within a unit to successfully mate, followed by the second highest-ranking male and so on.
Due to the range and variety of environments that lemurs habitat, they have high reproductive fertility with gestation periods lasting anywhere between 135 to 145 days. This results in the majority of females giving birth each year, which compensates for the high mortality rate due to environmental stressors. Lemur’s time birthing periods according to season high peaks and lows, by giving birth at the end of the dry season and the beginning of the wet season, when food and water are in abundance. This decreases some of the physical stress the mother lemur goes through while breast-feeding the infant.

Spider monkeys prefer living in moist tropical forests, however, they can also be found in high rainforests, high mountain savanna forests and some marsh and swamp forests. Spider Monkeys present in mountain savanna forests tend to be smaller species due to the limited growth of trees. A common factor of all environments that the spider monkey resides in is distinct and consistent rainy and dry seasons.
Spider Monkey’s conform to a fission-fusion social system which is a large group divided by smaller temporary sub-groups which is where the monkeys spend the majority of their time travelling, socializing and foraging. These sub groups usually consist of an adult male, an adult female and her dependant offspring. Studies show that Spider Monkeys may have separate dominant hierarchies, one for females, and one for males however some females show dominance in sub groups and she can displace other monkeys from specific grazing areas. It is common that female Spider Monkeys of the same group, share the same estrus cycle where the ovarian cycle lasts 26 to 27 days and the sexual mating peak lasts within an 8 to 10 day period. Mating begins with the female Spider Monkey approaching the male and showing him her genitals, if the male is interested, the two monkeys isolate themselves for anywhere between a few minutes for up to several days.
The use of the fission-fusion social system has probably evolved directly from the season changes in the habitat in which the Spider Monkeys live. Due to seasonal fruit shortages, competition between groups increases, and the need for smaller groups used to forage for fruits becomes necessary. For example, smaller groups with access to one fruit tree have larger meals and there is less food to share compared to a larger group feeding from the same tree. The benefit of still being a part of a larger group however is beneficial in terms of protection from predators and larger numbers to increase chances of reproducing and mating.
Baboon’s habitat a vast range of habitats including moist evergreen forests however they are partial to grassland savanna environments near wooded areas. These grassy plains have many shrubs and bushes and few trees. The climate is mostly dry but rain seasons do replenish the habitat in certain months within the year.
Baboons congregate in groups called troops which range with anywhere between 15 to 150 baboons. The group consists of male and female adults, including their offspring. Males transfer to other groups to mate whereas the females usually stay within the groups they are born into, leading to close relationships with the other females in the troop which are of relation (mothers, sisters, aunts. etc.). Since there is a close nit of family, closeness and affection within the group is visible by grooming and unity while foraging and traveling. Long lasting relationships also occur within between males and females. Mating occurs when the female presents her swollen rump to a male baboon while grooming or when during her estrus cycle. This relation can last a while until the females cycle is over or until she forms a new relationship with a younger, and newer transitioned male. Males leave at sexual maturity to other groups to mate and continue emigrating to other groups to avoid mating with their own offspring. Both males and females have multiple mates.
During mating, the male is protective of his mate and wards off other possible mates during her most fertile time within her cycle. These close relationships between male and female baboons have developed through the need to procreate, as female baboons prefer mating with a known male baboon as apposed to a higher-ranking male as in other species. There is also no reproduction cycle and females give birth year round, so mating occurs through closeness and proximity. Higher ranking females however tend to breed more often than lower ranking females, and their interbirth interval (time elapsed between births) is lower, possible due to greater access to necessary resources such as food. Higher ranks offer increased access to food and therefore higher reproductive rates.

Gibbons live in a range of areas, from Burma to Cambodia, and Indonesia to Malaysia. They prefer old growth tropical rainforest in Southeast Asia, as they are tree dwellers. Ample trees are important in their habitat as they spend most of their lives in them. Gibbons remain within a given territory and defend it rigorously; they do not migrate to other areas, and stay near their feeding trees. This can be detrimental to them as they remain in the same areas, even when opposing gibbons are causing conflict, or lose of habitat due to human interaction.
Gibbons are diurnal primates that are active during the day and sleep during the night, however, unlike other apes, gibbons do not make sleeping nests; they just huddle in small groups, between the branches of a tree and sleep sitting upright. These small groups consist of a mated pair, male and female, whom mates for life, and their dependant offspring, all those under the age of 7 years old. Like other apes, they participate in grooming. The mated pair reproduces one offspring at a time that remains with the family until the age of about 6-7 years where they wither leave on their own or they are forced out by the corresponding same sex parent. The monogamous couple shares some responsibility with the offspring, as the males participate in rearing the young.
Since Gibbons stay with their families for long periods of times, sometimes up to ten years, it can be beneficial to the newly sexually matured gibbon in highly populated gibbon areas. Gibbons also retain their residence and stay within their feeding tree’s range, therefore the male spends most time defending the territory and both share the responsibility of leading the routs towards food and water. This calm existence provides the pair with high reproductive success rates. The long-term attachment of offspring to parents is largely in debt to the father’s maintenance of their territory and food supply. Without male protection, females would spend less time with their young and would have to focus more on defending their feeding grounds, which result in low reproduction rates.

Due to their ability to adapt well, Chimpanzees live in a variety of habitats such as swamps, savannas, rainforests and dry woodlands. They are known to live in low altitude rainforests where there is little change in temperature throughout the seasons and dry temperatures where the average rainfall is a little less than 4 ft. Long-term research is being conducted in chimpanzee habitats that are more woodland areas higher in the mountains.
There seem to be many costs and benefits to the group living that chimpanzees are accustomed to. These large numbers cause lower chances of feeding efficiency yet higher rates of reproduction success due the number of chimpanzees available. For this reason, chimpanzees partake in fission-fusion social groups, which are smaller subgroups under a larger umbrella group. The sub groups range between 5 to 8 members that travel, feed and socialize together. Unlike the other species mentioned above, the males are the ones that stay within their natal communities (groups that they are born in) while the females transfer to other groups for mating and living purposes. This cause a closer relationship between males than what would normally be found among females. Chimpanzees exhibit unisexual and bisexual tendencies, and females are more social during their estrus cycle, however return to their bisexual parties when they are not. Reproduction seems to have no set schedule throughout the year, as when a female is ready to mate, her genitals (rear end) become enlarged. This promiscuous species tend to mate when there is an abundance of food available. Males have been known to kill offspring that are not their own
Higher reproduction levels arise when there is an increase of food, most likely related to higher energy levels. Chimpanzees mating and daily social groups do not necessarily coincide with one another as females can leave their emigrated group to nearby communities to mate. This may arise due to the continuous mating within the same group, which lowers the reproductive success. Also due to male hierarchy, when male chimpanzees decide which males mate with which females, depending on the position of each chimp in order of dominance. These different mating strategies increases the number of available male mates, while maintaining the support of protection and availability to food resources in the female’s original community.

Environmental influence greatly affects the social and mating habits of all the species discussed. Each species has accommodated their mating patterns to coincide with available resources and need. For example, the lemur coincide their breeding patterns in regards to the seasons of abundant and scarce feeding, water availability. On the other hand, Gibbons and baboons mate throughout the year with no discernible breeding patterns as steady food sources are available and secure year round. The behavioral traits are affected in regards to size of groups and troops. Even when large groups are necessary for protection and mating opportunities, smaller sub groups are preferred for travel and feeding activities, providing the members of these groups with the close attachment and benefits of larger mating opportunities. An interesting observation is when a species is apart of a larger group, the species tends to be promiscuous and the need to procreate and search for new and different mates is required, they travel beyond their groups to nearby communities. Monogamous species tend to be smaller and more of a close nit structure, even sexually maturing offspring is out casted to maintain the balance within the family. These groups tend to be possessive, both in partnering mates and territorially.
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