ANTRHO105 Exam 3 - Section 1 Social Behavior & Reproductive Strategies

Audited against the teacher’s Lecture 12 review. Read the revised Section 1 guide and required supplemental (pages 5–8) before studying. The review’s approximately 65% threatened-species statistic belongs in this section. Cards include the prerequisites explained in that supplemental.

What usually limits female primate reproductive success?

Access to food and energy, because pregnancy and nursing are costly.

What usually limits male primate reproductive success?

Access to receptive mates; females are not equally available for reproduction at all times.

What is natural selection?

Differential survival and reproduction that favors advantageous heritable traits.

What is sexual selection, and how does it relate to natural selection?

A subset of natural selection favoring traits that improve mating or fertilization success.

What is intrasexual selection?

Competition within one sex for reproductive success, such as male-male competition.

What is intersexual selection?

Mate choice: traits are favored because they attract or are preferred by potential mates.

Male-male fighting versus female preference for a male trait: which type of selection is each?

Fighting = intrasexual selection; mate preference = intersexual selection.

What is infanticide?

Killing an infant; in the lecture example, a new male kills infants he probably did not father.

Why can infanticide benefit a new male in a one-male, multi-female group?

Loss of a nursing infant can let its mother reproduce sooner, giving the new male a chance to father her next infant.

What four conditions make infanticide potentially adaptive for a male?

The infant is probably not his; its loss lets the female reproduce sooner; he is likely to father her next infant; his injury risk is low.

How can female primates counter infanticide?

Defend infants, avoid new males, form protective male friendships, confuse paternity through multiple mating or post-conception estrus; geladas may terminate pregnancy after takeover.

How does mating with multiple males help protect an infant?

It confuses paternity: males that could be the father may be less likely to kill the infant.

What is estrus?

A period of sexual receptivity, when a female is receptive to mating.

What is post-conception estrus, and how can it counter infanticide?

Sexual receptivity after becoming pregnant; mating can confuse paternity and reduce infanticide risk.

Which pregnancy response to a male takeover is shown in the gelada example?

Pregnancy termination after takeover, avoiding further investment in offspring at risk.

What does high reproductive skew mean?

One or a few individuals account for most reproduction.

What does low reproductive skew mean?

Reproductive success is distributed relatively evenly among individuals.

What is polygynandry?

A mating system in which both males and females have multiple mating partners.

What does a multi-male, multi-female social group mean?

Multiple adult males and multiple adult females live in the same social group.

Does a multi-male, multi-female group automatically mean equal reproductive success?

No. Group composition does not tell you how evenly reproduction is shared; reproductive skew measures that.

What does male philopatry mean in muriquis?

Males stay in their birth group rather than dispersing from it.

What is unusual about muriqui social and reproductive behavior?

Despite multi-male, multi-female groups, males rarely fight, aggression-based ranks are unclear, sexual dimorphism is low, and reproductive success is relatively even.

What does egalitarian mean in the muriqui example?

Little male aggression and no clear dominance ranks based on aggression, with relatively evenly shared reproductive success.

What do relatively large testes in muriquis suggest?

Sperm competition: reproductive competition can occur through sperm even when males rarely fight.

What is sperm competition?

Competition between sperm from different males to fertilize the same egg.

What is sexual dimorphism?

Physical differences between males and females of the same species, such as body or canine size.

A male-to-female canine-size ratio near 1 indicates what?

Low canine-size dimorphism: males and females have similarly sized canines.

What is a reproductive strategy in biology?

Physical or behavioral traits involved in obtaining mates and producing or raising offspring; it need not be a conscious plan.

What is reproductive success?

Success in contributing offspring to later generations; producing offspring and their survival both matter.

What is a mating system?

The pattern of mating relationships: who mates with whom, rather than simply who lives together.

What is polygyny?

One male mating with multiple females.

What is polyandry?

One female mating with multiple males.

What is alloparental care?

Care of offspring by an individual other than their parents.

According to the Lecture 12 review, approximately what percentage of primate species are threatened with extinction?

Approximately 65%. Use the course statistic for this review question; estimates depend on the assessment date.