Sociality and Mating Patterns of Primates

   Lemurs are primitive primates that are only found on the Madagascar and Comores Islands. Lemurs are the only non human primates. There are different types of lemurs and they live in a variety of different habitats ranging from tropical rain forests to dry deserts. They spend most of their time in trees and bushes. The Ringtail lemur is the only one that spends most of its time on the ground. There are day lemurs and nocturnal lemurs. The day lemurs live in groups and the nocturnal lemurs usually live alone. Lemurs share some of social and behavioral characteristics with monkeys.  They form social groups, eat fruit and vegetation and are active during the day, unless they are nocturnal. Nocturnal lemurs tend to be smaller and more reclusive than the day lemurs. The day lemurs are very vocal. They grunt, chirp and wail. Their wailing has been compared to the song of a whale.  The females are known to be dominant in the social group and there is usually one top ranking female that initiates the direction of the group. The females reinforce their dominance through aggressive behaviors such as lunging, chasing, and biting the males. Reproduction success depends upon environmental conditions. The females are sexually receptive or one or two days per year. Breeding season usually lasts between 7 and 21 days. All of the adult females are ready to mate around the same time each year. The trait of sociality and mating is influenced by the environment the lemurs inhabit. The females usually give birth to only one baby because of the harsh environments. In captivity multiple births occur. You can see the adaption of the social traits just by comparing the day lemur to the nocturnal lemur. The day lemur gathers food and socializes during the day within their groups while the isolated nocturnal lemurs keep to themselves and are reclusive. There are benefits to being part of a group such as social interation, decreased predation risk and more food resources. The groups also have better mating chances.
http://www.thewildones.org/Animals/lemur.html  http://pin.primate.wisc.edu/factsheets/entry/ring-tailed_lemur/behav

Spider Monkeys live in rainforests. They mostly live in the upper canopy of the forests, as high as possible, preferring to be left undisturbed. The spider monkey rarely comes down to the jungle floor. They live in groups of about 30 that are loosely associated with each other. They tend to divide into sub groups of about 4 unless there is more food available. They climb and swing around independently generally in the same area unless it is a female, who will be accompanied by her offspring. The females of spider monkeys are often more dominant. Spider monkeys display wild behavior and make rough barking sounds to scare away predators, and if this doesn’t work they divide into sub groups and run. .  The female will choose a male from her group to mate with. They sniff each other to see if the other is ready for mating. Each female will give birth to one offspring every 3 or 4 years. The males are not involved in raising the offspring. This species’ social system has evolved and adapted according to food requirements.  The females plan highly economical routes of food foraging in advance and the routes differ from day to day. If food is scarce, spider monkeys will avoid overlapping of certain territories.  http://www.honoluluzoo.org/spider_monkey.htm

Baboons are highly adaptable primates and live in varied habitats of Africa and Arabia. They usually prefer savannas, but some live in tropical rain forests. Like humans, baboons are opportunistic eaters. Savanna baboons form large troops that that make up dozens to hundreds of baboons. These groups are governed by a very complex social hierarchy. They spend their entire lives in close proximity to each other. Members of these groups spend hours daily carefully grooming each other. Cliff dwelling baboons split up their groups to food forage during the day and they meet up again in small groups at night.  They use 10 different vocal sounds to communicate with other members of their group. Baboons are rarely monogamous. The males may live in several different groups throughout their lifespan but the females tend to stick on one matrilineal group and are very close to their maternal relatives. Surprisingly, paternal sisters seek each other out and are very close as well. The social trait on rank effects the adaptation and evolution of baboons. The higher ranked females can take food and water from lower ranked females. The differences in rank can have an effect on adaption of feeding behavior, stress physiology and reproduction success. http://animals.nationalgeographic.com/animals/mammals/baboon/

http://www.princeton.edu/~baboon/social_life.html

Gibbons are small tree-dwelling apes. These primates live in old growth tropical rain forests in Southeast Asia. They spend the majority of their lives in trees.  Gibbons are social animals that live in small, constant family like groups. These groups consist of a mated pair and their offspring.  They spend a lot of time grooming each other. Gibbon mates usually stay with the same mate for life. Female gibbons are pregnant for 7 months and have only one offspring at a time. The family unit will occupy a certain territory and defend it by vocal and visual displays. Gibbons are endangered and are not adapting to the loss of their rain forest habitat.

http://www.gibboncenter.org/about_gibbons.htm

Chimpanzees live in 21 different African countries. Their environments consist of humid closed canopy forests, seasonally dry forests and savanna woodlands. They are very social animals that are based upon a male bonded society. The adult males of this specie are dominant over the females. The females don’t have strong social bonds with each other, like the males do. Their communities consist of 15 to 150 members who all share the same social bond. The only members of the group allowed to go back and forth between communities are the adolescent females who haven’t given birth yet. The males stay with the group or life. The males defend the community from predators. The communities break up into smaller groups to hunt or food forage. The groups will vary in size depending upon the time of year and availability of food. Grooming is the most important social activity. The males groom each other more often.  Mating success has a positive relationship with the male dominance rank. Chimpanzees produce a single offspring. Chimpanzees are also endangered due to habitat destruction and due to their low reproductive rate. http://www.honoluluzoo.org/chimpanzee.htm


Overall it appears that environment has a huge impact on the sociality and mating patterns of these primates. Availability of food in and around the environment has a big influence. Reproductive success depends on environmental factors such as food and water availability. The gibbons and the chimpanzees are endangered species because their environments are being destroyed and they are not adapting well to a new environment. Rank has beneficial effects on the survival of certain species, offering more food and reproduction opportunities. The species that live in large groups have more chances of escaping predators and more members searching for food. The social activities are environmentally driven. Environment is key to the evolution and adaptation of these traits.