ANT301 1nd Edition Lecture 8Outline of Last Lecture I. Niche parameter: dieta. Niche factori. Home range ii. Territory 1. Mate defense territoriality II. Asymmetry in parental investment Outline of Current Lecture III. Primates in groupsa. Predation defense modelb. Resource defense model IV. Female bonded groupsV. Male bonded groups VI. Socioecologya. 2 conditions Current Lecture: Social Structures I. True sociality (established relationships and indiv recognition) less common among mammals…mammals form aggregationsII. Social mammals: some carnivoresa. Dolphins/ elephants III. For some, benefits are obviousa. Cooperative hunting b. Cooperative infant care 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.IV. Why do many primates live in groups?a. There are definitely many costs for being in social groups:i. Competition for food increasesii. Competition for matesiii. Enhanced disease transmissioniv. More conspicuous to predators1. 2 current models for primate sociality a. Predation defense model- primates live in groups to protect themselves from predators by Carel Van Schaiki. More eyes and ears to spot a predatorii. Physical defenseiii. Dilution effect (probabilities)- group helps you avoid being eaten by predators b. Resource defense model- primates live in groups to have better access to food by Richard Wrangham i. Large groups of primates can displace small groups at clumped resources like food treesii. Solitary= no within group competition for foodiii. But, it may be to your benefit to out up with some within groups competition in order to win between group contests1. Good empirical support for both model2. Group size often seems to be determined bybalancing costs with benefitsV. So: many primates are socialVI. Next: how primatologists classify primate groupsa. See terminology on of 129-130 of textb. Female bonded groups:i. Many primate species live in female bonded kin groups that remain stableover timeii. Females stay in their natal (birth) group their entire lives, so that females live with their relatives 1. Female philopatry (remain in the group you are born into to)2. Philopatric: remain in the natal group as an adulta. In primates at least 1 sex typically disperses to a new socialgroup before reaching sexual maturity b. Key: inbreeding avoidance- avoiding inbreeding depressioni. So in females-bonded primate groups, females are philopatric and males disperse1. Q: Why would females prefer to stay with their relatives?a. Females are limited by access to foodb. If food is clumped/patchy, females can form cooperative alliances to defend food patchedc. If you have to form an alliance, do it with family membersd. WHYi. Inclusive fitness- fitness the likelihood that you will survive to produce offspringii. Says that if your main goal (evol speaking) is to pass on your genes and there are 2 ways:iii. 1. Reproduceiv. 2. Assist close relatives in reproducing v. Key: relatives and their offspring share some of your own genetic material vi. Key to understanding (kin selection as one explanation for altruisme. Coalition of related females: Japanese macaquesc. Male bonded groupsi. Fewer primate species live in male bonded kin groupsii. Males stay in their natal (birth) group their entire lives, so that males love with their relatives1. Male philopatry 2. Female dispersal iii. Why are male bonded groups rare?1. Females compete for access to food2. Males compete for access to females3. Food can be shared among several females, but most female primates can only be impregnated by one malea. Mate guarding: Attempts by individual males to monopolize access to females may prevent formation of male alliances4. Remember: competition between males for access o females can be very intense, and may result in death males from outside thesocial group did this (Pinky)VII. Next: the other main body of theory that primatologist use to understand the evolution of primate social behavior (socioecology)a. Socioecology- descries the effects of ecology (feeding, predation, dist resources) on social behaviori. Food quality and distribution plays a major role in what type of social group a primate species will formii. Two basic types of competition for food: 1. Contest competition- competition for resources that are high quality, clumped and defensible/ often involves aggression 2. Scramble competition- competition for resources that are more evenly distributed space and not worth/ cant be defended/ may involve a “race” to consume resources/ hardly aggressionb. Starting condition 1:i. Food is distributed in patches and is thus defensible (ripe fruit is the prime high quality resources)ii. Females will then bond with their relatives in order to defend food patches (contest competition)iii. Males accordingly have to avoid inbreeding iv. Dispersing males are looking for groups of females to attach themselves to 1. As far as the male is concerned, the females are now a “patchy” resources2. The more clumped the females are, the easier it is for males to monopolize access to females (contest competition for females)3. Social organization: MM/MF or SM/MF 4. Mating system: often polygynous c. Starting condition 2: i. Food is dispersed and thus not defensible ii. Females spread out and try not to compete with each other for food (scramble competition)1. Environment females males iii. As far as males are concerned, the females are not dispersed resourceiv. Individual males are not able to monopolize access to groups of females1. So: males will monopolize access to one female (monogamy) or will share access to females with other males (polygynandry) v. Even in a polygynandrous mating system, there is still intense reproductive competition among males (sperm competition- look at the size of testes) 1. Gorillas don't need to evolve reproductively to get females because he is the only one mating vs. chimps who have large testes2. Hard copulatory plugs- males counter strat to keep other males out a. Ground squirrel b. Mouse lemurd. Basic idea of socioecologyi. Females organize themselves according to the distribution of food resourcesii. Males organize themselves according to the distribution of females 1. Ex. 2 species of squirrel monkeys a. Red backed squirrel monkey: i. Costa riceii. Widely dispersed ripe fruit in small patches (does not make sense to fight) iii. Low food competitioniv.