Anthro2050 1st Edition Lecture 19 Outline of Last Lecture I The Apes Continued Outline of Current Lecture II Primate Social and Reproductive Behavior Current Lecture Primate Social and Reproductive Behavior home range the fixed area a group of animals constantly occupy It is not territorially defended in general and often overlaps with the home ranges of other groups territory a home range specifically occupied by a single group and the borders are defended by members of the group there is a lot of variation in the size of these areas and how vigorously the groups defend them factors believed to influence this includes the size of the group the body size of the species food availability and other factors reasons to defend a territory may include defending resources especially rare or scarce recourses from competitors as well as defending mates from competing individuals reasons not to defend a territory may include food type an abundant resource is not worth the energy to defend it and ease of getting around for example slow moving animals primates are highly social and like to live in groups there is better access to resources better defense against predators however increased competition within the group and an increased ability to spread diseases it is best if the group is small enough to minimize in group competition and large enough to fight off predators and defend resources In most groups one sex usually female stays with the group from birth to death while the other sex leaves the group and joins another This subconscious action allows for greater genetic These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute diversity in the populations and decreases inbreeding There are 5 main group structures we see in animals and primates The group structure is also a factor in the level of sexual dimorphism in that species Solidarity single males and single females with their offspring this is usually due to a sparse food source that would be used up too quickly in larger groups Ex Orangutans mouse lemurs and bushbabies Monogamy one pair bonded couple and their offspring living together mostly they are only monogamous socially as some research has found monogamous couples where the male is not the father of all of the offspring Ex gibbons titi monkeys and some strepsirhines Polygyny One male living with multiple females The male defends the harem strongly being the most likely father to all of the females offspring If a new male usurps the dominant male sometimes he will kill all offspring under a certain age relieving the mothers of their duties to the previous male s offspring so the new male can mate with them and produce his own offspring Multi Male Female Groups multiple males and females in a group together Consist of a firmly established dominance hierarchy The higher one is in the hierarchy the better access to mates they get Polyandry one female and multiple usually two males The female always produces twins and the males are the primary caregivers to the offspring Other females can hang around and help the dominant female but the dominant female can release a pheromone that suppresses the other females fertility so they cannot mate with her males The twins are chimeras meaning they pass genetic information in the womb so they are both genetically two different individuals This has rarely happened in humans where one twin will absorb the other leaving one person with both genetic codes