ANTHROPOLOGY 201 – Chapter Summaries – Submitted by Steph

These are some great chapter summaries submitted by Steph, Thanks!

Chapter 6– Primate Ecology

• The Distribution of Food
• The total amount of energy that an animal requires depends on four components:
• 1) Basal metabolism: Basal metabolic rate is the rate at which an animal expends energy to maintain life when at rest.
• 2) Active metabolism – when animals become active, their energy needs rise above baseline levels.  The number of additional calories required depends on how much energy the animal expends.
• 3) Growth rate – Growth imposes further energetic demands on organisms.  Infants and juveniles who are gaining weight require more energy than would be expected.
• 4) Reproductive effort – Female primates the energetic costs of reproduction are substantial.   Example. During lactation females requires 50% more calories than usual.
• Primates cannot synthesize amino acids from simpler molecules therefore must consume them from foods.
• Many plants produce toxins called secondary compounds to protect themselves from being eaten.
• Primates get most of there protein from insects and young leaves.
• Prosimian obtain protein generally from insects and carbohydrates from gum and fruit.
• Activity Pattern
• Fact that many prosimians are nocturnal suggests they evolved from a nocturnal ancestor.
• Common daily cycle is wake up, eat, nap when sun gets hot, resume eating in later afternoon, find sleeping site in evening and sleep
• Ranging Behaviour
• All primates have home ranges but only some are territorial.
• Some species like gibbons maintain exclusive access to a fixed area = territories
• Nonterritorial species such as squirrel monkeys and long-tailed macaques may fight if they encounter or mingle peacefully.
• Two main reasons for territoriality is resources and mate defence.
• Predation
• Primate Sociality
• Most primates except for oragutans and some prosimians spend most of their lives in stable groups of familiar individuals.
• Grouping provides safety from predators because of the 3 D`s: detection, deterrence and dilution.
• Distribution of Females
• Scramble competition – resources are distributed evenly across the landscape. Ex. Scrambling for candy when a piñata breaks, but nobody fights over candy.
• Contest competition – occurs when resources are limited and can be monopolized profitably, generating direct confrontation over access of them.
• Resource competition is expected to generate dominance relationships
• When a dominance encounter had a predictable outcome we say that a dominant relationship has been established.
• When contest competition within groups is stronger than between groups, females will remain in their natal group and cooperate with kin in contest with unrelated females in their group over resources.
• Philopatry – the tendency to remain in their natal group throughout their lives. Common in Old World Monkeys.
• When between group competition is greater than within group, competition dominance will be less important but female philopatry will still be favoured.
• When both are strong females must compete for both.
• Distribution of Males
• Ecological factors shape the distribution of females and males go where the females are.
• Found that groups facing the highest risk of predators lived in the largest groups and had the most males.
• Resource competition also influences male dispersal strategies because inbreeding is a disadvantage.
• Terms to know in Chapter 6
• Basal Metabolic Rate – the amount of energy use required to maintain life when an animal is at rest.
• Secondary Compounds – toxins produced in plants as a defence mechanism so animals will not eat them.
• Frugivore – an animal who diets mostly on fruit
• Folivore – an animal who diets mostly on leaves.
• Insectivore – an animal who diets mostly on insects.
• Gummivore – an animal who diets mostly on gum.
• Cathemeral – Active both during the day and at night.
• Socioecology – the study of how social structure is influenced by ecological conditions.
• Scramble Competition – a form of competition that occurs when resources are distributed evenly through space and not worth defending.
• Contest Competition – a form of competition that occurs when resources are clumped in space and worth defending.
• Dominance– The ability of one individual to intimidate or defeat another individual in a pair wise encounter.
• Dominance hierarchies – a ranking of individuals in a group that reflects their relative dominance.
• Philopatry – the tendency to remain in their natal group throughout their lives. Common in Old World Monkeys
• Inbreeding – mating between closely related individuals.

Chapter 7– Primate Mating Systems

• Darwin’s theory – complex adaptation exists because they evolve step by step by natural selection
• Mating Systems play a crucial role in our understanding of primate societies.
• Reproductive strategies are influenced by their phylogentic heritage as mammals.
• The Language of Adaptive Explanations
• In evolutionary biology the term strategy is used to refer to behavioural mechanisms that lead to particular courses of behaviour in particular functional contexts, such as foraging or reproducing.
• Strategy implies a conscious plan and a goal-directed course of action.
• Biologist believe there is an underlying mechanism in monkeys that allow them to just know how much and what to eat.  They do not have any conscious knowledge of it.
• The terms cost and benefit refer to the effect of particular behavioural strategies on reproductive success.
• The Evolution of Reproductive Strategies
• Males do not care for their offspring when
  
  • (a) they can easily use their resources to acquire many additional matings, or
    
  • (b) when caring for their offspring would not appreciably increase the offspring’s fitness.
• Investing vs. Noninvesting males
• Reproduction Strategies of Females
• Often invest more to their offspring than males do.
• Pregnancy and lactation are tiring time consuming activities for females.
• Because primates brains are larger for their body size it takes extra time for them to grow.
• High ranking females tend to reproduce more successfully than low ranking.
• Group size is shown to effect reproductive success..ideal is small group with a high ranking.
• Reproductive Trade-offs
• Must balance the quality and quantity
• Parent-offspring conflict – conflict between mother and infants over the amount and extent of maternal investment.
• Some animals perform altruistic acts that increase other individuals fitness and reduce their own fitness. à Kin selection provides one mechanism for evolution of altruism.
• Altuism will be favoured when the benefits to the recipient (b) multiplied by the degree of relatedness between the actor and the recipient (r) is greater than the cost to the actor(c). Rb>c
• Sexual Selection and Male Mating Strategies
• Sexual Selection is a special category of natural selection that favors traits that increase success in competition for mates.
• Two types of sexual selection
• 1) Intrasexual selection results from competition among males.
• 2) Intersexual selection results from female choice.
• 1)Intrasexual Selection
• Competition among males for access to females favors large body size, large canine teeth and other weapons that enhance male competitive ability.
• Most intense among males
• Leads to the evolution of sexual dimorphism.
• The fact that sexual dimorphism is greater in primates species forming one-male or multimale groups tan in monogamous species indicates that intrasexual selection is the likely cause of sexual dimorphism in primates.
• In species that form one-male groups there are many bachelor males which are males that don’t belong to social groups. They exert constant pressure on resident males.
• the species where the sexual dimorphism is more similar they are commonly in monogamous relationships.
• Estrus – period of time where a female is able to reproduce.
• 2) Intersexual Selection
• Favours 3 kinds of traits in males:
  
  • a) traits that increase fitness of their mates,
    
  • b) traits that indicate good genes and thus increase the fitness of the offspring, and
    
  • c) nonadaptive traits that make males more conspicuous to females.
• Only a few morphological traits among primates have evolved because they help males attract females.
• Is possible that these traits evolved in response to female preference.
• Male Reproductive Tactics
• Investing Males
• Monogamous pair-bonding is generally associated with high levels of paternal investment.
• Males do no compete over females, more so over the territory, finding mates and having viable offspring.
• Mate guarding may be an important component of pair-bonded males. Seen in titi monkeys and gibbons
• In cooperatively breeding species, males invest heavily in offspring, but the reproductive benefits to males are not clear.
• Male-Male Competition in Nonmonogamous Groups
• In nonmonogamous groups the reproductive success of males depends on their ability to gain access to groups of unrelated females and mating with receptive females.
• Infanticides
• Shortens interbrith intervals
• Is linked to change in male membership and status
• Do not kill their own infants
• Gain reproductive benefits
• Can sometimes be a substantial source of mortality
• Females have evolved a battery of responses to infanticidal threats.
• Paternal care in Nonmonogamous Groups
• The existence of male care of offspring varies in nonmonogamous species.
• Female Mate Choice
• Female preferences include male competitive tactics.
• Little idea of what traits are more preferred. We just know that they have preferences.
• Terms for Chapter 7
• Mating System – the form of courtship, mating and parenting behaviour that characterizes a species.
• Strategy – a complex of behaviours deployed in a specific functional context such as mating, parenting or foraging.
• Parent-Offspring Conflict – conflict that arises between parents and their offspring over how much the parent will invest in their offspring.
• Sexual Selection – a form of natural selection that results from differential mating success in one gender.
• Intrasexual Selection – a form of sexual selection in which males compete with other males for access to females.
• Intersexual Selection – A form of sexual selection in which females choose who they mate with.  The results is that traits making males more attractive to females are selected for.
• Sexual Selection Infanticide Hypothesis – A hypothesis postulating that infanticide has been favoured by sexual selection because males who kill unweaned infants are able to enhance their own reproductive prospects if they 1)kill infants whose deaths hasten their mothers resumption of cycling, 2)do not kill their own infants, and 3)are able to mate with the mothers of the infants that they kill.
• Infanticide – practise of intentionally killing an infant.
• Mating Effort – efforts made to secure access to a mate.
• Parenting effort – efforts made to secure the survival of offspring

Chapter 8 – The Evolution of Social Behaviour

• Kinds of Social Interactions
• Interactions that involve two individuals is called dyadic or pairwise interactions.
• 4 types of pairwise interaction that are based on the effects of the actor and the recipient
• (Actor/Recipient) Selfish=+/- , Mutualistic = +/+ , Altruistic -/+ and Spiteful -/-
• Altruism:  A Conundrum
• Altruistic behaviour cannot evolve by ordinary natural selection.
• May arise by accident
• Kin Selection
• Natural Selection can favour altruistic behaviour if altruistic individuals are more likely to interact with each other than chance alone would dictate.
• Hamilton’s Rule
• Theory of Kin selection predicts that altruistic behaviours will be favoured by selection if the cost of performing the behaviour are less than the benefits discounted by the coefficient of relatedness between actor and recipient.
• Rb>c
• 2 important insights:
  
  • 1) altruism is limited to kin
    
  • 2) closer kinship facilitates more costly altruism.
• Food Sharing occurs among chimpanzees, tamarins and marmosets.
• Evidence of Kin Selection in Primates
• Kin-based support in conflicts has far-reaching effects on the social structure of many primate groups.  Evidence of these effects come from studies of macaque, vervets and baboon groups
• Maternal rank is transferred with great fidelity to offspring, esp. Daughters
• Maternal kin occupy adjacent ranks in the dominance hierarchy and all the members of one matrilineage rank above or below all members of other matrilineages.
• Ranking this way is often predictable.
• Kinship influences howler males in important ways:  Red howlers 2-4 females 1-2 males
• Reciporcal Altruism
• Altruism can evolve if altruistic acts are reciprocated.
• 3 conditions together favour the development
  • 1)individuals must have an opportunity to interact often
  • 2) have the ability to keep track of support given and received
  • 3) Provide support only to those who help them.
• Term for Chapter 8
• Dyalic- describing an interaction that involves two individuals.
• Pairwise – describing an interaction that involves two individuals a.k.a dyadic
• Actor – the individual performing a given behaviour.
• Recipient – the individual whom a particular behaviour is directed.
• Selfish – a behaviour that increases the fitness of the actor and decreases the fitness of the recipient.
• Altruistic – behaviour that reduces the fitness of the individual performing the behaviour
• Spite – costly to both individuals.
• Mutualistic –  beneficial to both individuals.