Primate Mating Systems

Question 1

What is noyau?

Answer 1

Solitary (oragutans, lorises)

Question 2

What is monogamy?

Answer 2

Pair-bonded (Gibbons, owl monkeys)

Question 3

What is polyandry?

Answer 3

Uni-female/multi-male
(Tamarins)

Question 4

What is polygyny?

Answer 4

Uni-male/multi-female
(Langurs, Gorillas)

Question 5

What is polygynandry?

Answer 5

Multi-male/multi-female
(Vervets, Macaques, Spider monkeys, Chimpanzees)

Question 6

What are “strategies” in relation to primates?

Answer 6

Set of behaviours occurring in a specific functional context
- Strategies are products of selection, not conscious plans

Question 7

Who provide care for primate young?

Answer 7

Primate females always provide lots of care for their young. Primate males do so in very few species.

Question 8

Why do primate females invest more in offspring?

Answer 8

Mammalian reproductive system constrains female strategies
- Must carry offspring
- Must lactate for offspring
- Infants are altricial

Question 9

What are some other reasons female primates invest more in offspring?

Answer 9

Extended pregnancy (large brain), extra time/energy per infant, relatively small number of surviving infants produced over lifetime, each fitness is a greater portion of lifetime fitness

Question 10

Why do primate males invest less in offspring?

Answer 10

• Care less
• Time, energy, and resources limited
• Paternity uncertain
• Better strategy to use their resources to access other female to increase their reproductive success

Question 11

When will male primates be less involved?

Answer 11

1. When attracting additional mates is relatively low (uni-male, multi-female more often)
2. When fitness of offspring raised by one parent is high
   When benefits of investment outweigh costs of seeking new matings, males will provide more care (females can’t provide enough care)

Question 12

What are female primates reproductive strategies?

Answer 12

Female reproductive success depends on ability to obtain resources for her and her offspring.
- Dominance hierarchies often form to compete for food resources
- High ranking females get more and better food

Question 13

Is there change in female hierarchies?

Answer 13

Female hierarchies rarely change, males hierarchies shift over time however
- If your mother is low rank, you are low rank

Question 14

What can positively influence reproductive success in primate females?

Answer 14

Socializing can positively influence reproductive success. May insulate some females from cost of low rank

Question 15

What are male reproductive strategies?

Answer 15

All about access to mates, have traits that increase success in competition for mates evolve through sexual selection

Question 16

What is sexual selection?

Answer 16

Category of natural selection, features with no obvious survival functions, traits that seem maladaptive

Question 17

Why is sexual selection more prevelant in male primates?

Answer 17

Their reproductive success depends on access to females, they are affected more strongly when their access to males is limited

Question 18

What are components of sexual selection?

Answer 18

Intrasexual selection: competition within gender (gain more masculine features to compete), stronger among males, common in primates
Intersexual selection: mate choice, stronger in females, common in birds

Question 19

What is intersexual selectin?

Answer 19

High female investment, reproduce slowly, choose quality mates (don’t want to waste reproductive oppertunities on unhealthy males that could produce less competitive offspring)

Question 20

Why do females choose their mates in intersexual selection?

Answer 20

To reproduce with an individual that will increase their fitness (defend resources, prevent infanticide), will produce more fit offspring (good genetic quality)

Question 21

What is intrasexual selection?

Answer 21

male-male competition in primates to fight and drive other males away, winners have advantage in mating oppertunities, favours traits that enable males to be effective fighters

Question 22

What other traits are present in intrasexual selection?

Answer 22

Bigger male body size and canine size (leads to sexual dimorphism)

Question 23

Where would sexual dimorphism be more pronounced?

Answer 23

Single male/multi female groups (where males compete the most)

Question 24

What are reproductive strategies in single male groups?

Answer 24

• Male tries to establish residence in an unrelated group of females then restricts access to other males
• Other males constantly try to take over

Question 25

What are reproductive strategies in multi-male groups?

Answer 25

• Females have estrus
• Multi-male/multi-female females mate with multiple males
• Less direct competition over access to females
• Intrasexual favours increased sperm production (bigger testes)

Question 26

What males rank higher in multi male groups?

Answer 26

Younger males have higher ranks cause of physical condition
- RS related to age

Question 27

What are reproductive strategies of pair-bonded males?

Answer 27

RS depends on finding mates, defending territory and rearing surviving offspring
- Mate guarding is a common strategy

Question 28

What are some infanticide counter strategies?

Answer 28

Concealed ovulation, regularly sexually receptive with multiple males (unknown paternity), terminate pregnancy after takeover (spontaneous abortion), social supports/friendships to try to avoid infanticide