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Film Handout - “The Gorilla King” As you watch the film, answer the following questions. You can use your answers to these questions to help study for the next exam. 1) What is the climate like where mountain gorillas live? Freezing cold, battered daily by torrential rain 2) How old is Titus at the time of the film? Why is his position in his group unusual for a male of his age? 33 years old, Most silverbacks his age would have been deposed by now 3) At the start of the film, what is the relationship like between Titus and the number two male, Kuryama? Titus needs Kuryama to help him defense the group 4) When did Dian Fossey first begin studying mountain gorillas? 1967 5) What percentage of gorillas die in infancy? 40% 6) Why do gorillas sometimes enter bamboo forest? To cash in the bamboo’s new shoots 7) Why don’t researchers make physical contact with mountain gorillas today like they did in Dian Fossey’s era of studying the gorillas? Because of the risk of gorrilas catching human infections is too great. The apes are too vulnerable 8) Why is it rare for males to immigrate into a new group in mountain gorilla society? Because it never the case before 9) What happened to a male gorilla named Digit in the late 1970s? Was this an isolated incident. Killed by the poachers 10) How did Flossie’s infant die? How long did she carry the infant after its death? her arm hit the baby on the back as she is fending off Beetsme. Carried her dead infant for 2 days 11) Why were researchers surprised that Titus, Beetsme, and several other males lived together in an allmale band for years? Because without female, there will be no reproduction and no family life. Never seen st like this before 12) What happened to the relationships among the males once they were joined by females? What happened to the females’ infants? Battle of supremacy. Beetsme killed 2 of the infants 13) How do researchers determine the fathers of the infants in gorilla groups? By paternity test. Needed gorilla’s dump and used that for DNA analysis to map out 14) Why did gorilla research stop at Karisoke for 15 months in the 1990s? How many people died and over what period? Because of the Rwandan Civil War. 900,000 people died in 100 days 15) What happened to Titus’s group during the Rwandan genocide? Most of them survived by avoiding the areas 16) What are some reasons tourism is good for gorillas? Incomes, 17) What is the danger to gorillas of remaining too long at the top of the mountain? Too cold 18) During the film, the relationship between Titus and Kuryama, the male who is challenging him for dominance over his group, is revealed. What is it? Uneasy toward at each other 19) Titus’s group divides towards the end of the film. Who or what was the driving force behind this division? Kurvama

TPA Chapter 2 Questions 1. What seems to determine which male becomes group leader in mountain gorilla society? Leadership appears to be linked more with the age and experience of the silverback and the group’s confidence in him. 2. In multi-male mountain gorilla groups, how many males typically mate with the females? 3. Which sex/sexes disperse(s) from their natal groups and what is the purpose of this dispersal? Female, the purpose isavoids inbreeding and reduces competition for mates, as if they will, that are either his mother, full sister, or daughter. Also enables blood realtives to remain in a tight organized group. TPA Chapter 9 1. Bonobo diets and dispersal patterns are very similar to those of common chimpanzees. What is Kano's explanation for the fact that bonobos' within-group and between-group social relationships are far less antagonistic than those of common chimpanzees? 2. What feature of Kano's research design might lead some primatologists to question whether he discovered much about the natural behavior of bonobos in the wild? TPA Chapter 25 1. How do male squirrel monkeys obtain their larger size during the breeding season? can gain up to 20% of their body weight and the larger they appear, the more attractive they are to females. Taking on a "fatted" appearance from water and fat stored between the muscle and skin on their head, shoulders, upper arms, and ribs. Insects 2. Why does Boinski believe that birth synchrony occurs in Costa Rican squirrel monkeys? Females within a group exhibit birth synchrony and increased vigilance during the birth season because neonates are particularly susceptible to predation. 3. Why do female squirrel monkeys chase after big males? Why do they prefer larger males? Most enlarged ones are the ones that lived in the tropp for long periods, at least 3 years, regularly resisting challenges from outside males that try to oust them. A diff one is that they consistently vigilant throughout the year and most likely to intervene directly when babies or troop members are threatened. TPA Chapter 4 1. Why do some young howler monkey females emigrate while others stay in their natal troops? Both sexes of red howlers emigrate from their natal troops, but in different proportions. Around 70-80% of females will breed outside of their natal group while for males the figure is 98% (Crockett 1996). If a female breeds within a group, she will remain in that group for the rest of her or the group's life (Pope 2000). Females rarely are able to integrate into established troops and must form new troops while males are usually able to join existing troops, often by challenging resident males with another non-group male Solitary females are actively prevented from joining established groups by group females and as a result, non-troop females have a relatively high rate of physical injuries (Rudran 1979; Sekulic 1982a; Crockett & Pope 1988). As a result, females must emigrate farther than males to establish new groups while males are able to join existing groups, often adjacent to their natal group (Pope 2000). In addition, after emigration from the natal troop, a significant amount of time can be spent solitary (Crockett 1996). Most females emigrate from their natal group between 2-4 years old while males emigrate between 4-6 years old (Crockett & Pope 1993). 2. According to the author, why might infanticidal red howler males have greater reproductive success than non-infanticidal males? females attempt to resist infanticide but are not usually successful

READING QUESTION Why is infanticide so widespread among primates, including the great apes? Why do female primates mate with infant-killing males? Females mate preferentially with males most likely to commit infanticide because of factors such as dominance status or spatial proximity

Why is infanticide rare in some populations of baboons (e.g., olive baboons), but common among other baboon populations (e.g., chacma baboons)?

In chacmas, once an alpha male takes control of a group, he is the only one that mates with the group's females, and thus he can feel confident that he'll be the father of any infants conceived during his tenure. But his tenure as alpha is short, averaging only seven or eight months. So it's to a new alpha's benefit to kill unweaned young. "If a male comes into the group and almost all the females are lactating," Palombit says, "he should try very hard to eliminate kids, because [otherwise] he won't have any reproductive success. Or he should leave the group." In olive baboons, Palombit says, an alpha's tenure lasts a lot longer, up to two years, so he can afford to wait until mothers wean their infants and resume cycling. Moreover, in olives, two lower-ranking males can join forces and unseat the alpha while females are ovulating, and thus an olive alpha can never enjoy the same degree of confidence regarding paternity that a chacma alpha enjoys. These reasons may be why infanticide is rarely seen among olives, Palombit says.

Does the practce of infanticide exist in humans? YES

PPT: Week 1 STUDY QUESTIONS 1. What are the two kinds of female reproductive cycles? What are the two time scales of female reproductive cycles? How much of her adult life does a typical nonhuman primate female spend cycling? What is post-partum amenorrhea? Physiological, behavioral. Seasonal (mating and birth) cycles & Monthly (ovarian) cycles For most of a NHP female’s adult life, she is not cycling (either pregnant or nursing) Lactational (post-partum) amenorrhea 2. What are the two hypotheses proposed to explain why births should be seasonal? Provide evidence from primate field studies to support each hypothesis. 1. Ensure abundant food supply for (energetically demanding) late pregnancy/early postpartum period •

can time births for the time of year when food is most abundant

•

e.g., patas monkeys are the guenons with the most variable food supply and they have the strictest birth seasonality too

2. Anti-predation strategy: if many females have infants at once they are more likely to cooperate in being vigilant and in deterring predators 

e.g., most females in squirrel monkey groups give birth within 10 days of one another, then cooperate in vigilance and mobbing of would-be predators

3. What are the 3 different ways through which seasonality of births can be achieved? What is social facilitation? Provide an example of social facilitation of mating in primates? What is social stimulation? Provide an example of social stimulation of birth synchrony in primates. What are pheromones? Case of social facilitation leading to mating synchrony social stimulation can lead to synchrony of births (e.g. squirrel monkeys)

4. What are monthly physiological cycles? How long do they last in most primates? Which natural grouping of primates does not fit the typical primate pattern for ovarian cycle length? Physiological cycles = cycles of the ovaries - Last ~1 month in most primates

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NWM a notable exception – 20 days in capuchins –

9 days in squirrel monkeys

5. What are the 2 phases to the ovarian cycle? How long does the follicular phase last and what major events occur during it? How long does the luteal phase last and what major events occur during it? What is implantation? What are hormones and what is their role in the ovarian cycle? Ovarian follicular maturation -> OVULATION (1) Follicular phase – –

lasts ~ 2 weeks development of egg to point of ovulation

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ovulation

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at ovulation, a female can become pregnant if a male’s sperm reaches and fertilizes her egg.

& Formation of corpus luteum (2) Luteal phase – –

lasts exactly 2 weeks uterus builds itself up for pregnancy

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if implantation occurs

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egg is fertilized and embryo attaches to wall of uterus

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uterine lining kept

if NO implantation –

uterine lining is shed (aka menstruation)

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cycle starts all over again

Hormones = chemicals produced in one part of the body which travels through the bloodstream and acts in another part of the body Some reproductive hormones are produced in the brain, and some in the ovaries 6. Which phase of the ovarian cycle is variable in length? What are the factors that sometimes extend the length of this phase? In her experiment on captive female baboons, what factor did Rowell find was responsible for lengthening the follicular phase of her study animals? How does the process of shedding the uterine lining differ among the 6 natural groupings of primates? The follicular phase varies in length Can be extended by illness, injury, and stress

Rowell Removed females from social group and put them in isolation; follicular phases immediately get longer

7. What is estrus? What 3 factors are used to determine whether a female is in estrus? What are attractivity, proceptivity, and receptivity? How might we measure the attractivity of a female primate during a given time period? What are some examples of proceptive behaviors from primates? (e.g. geladas? howlers? lemurs?) What is the relationship between behavioral estrus and ovulation in lemurs, lorises, and tarsiers? What is the relationship between behavioral estrus and ovulation in Old World monkeys, apes, and humans? Which nonhuman primate species exhibits the greatest decoupling (least tight synchrony) of estrus from ovulation? Why do we assume that sexual behavior has been co-opted to play more roles than just procreation in the life of this species? Estrus = "heat“ • •

when females are receptive to males, AND eager to mate usually coincides w/ ovulation

Attractivity = how attractive a female is as a sexual stimulus to males Proceptivity = how often a female directs appetitive behaviors in response to nearby males and their behaviors Receptivity = how often a female engages in acts designed to facilitate copulation itself •

e.g., lemurs, lorises, and tarsiers – estrus is brief and tightly correlated with ovulation

8. What are some examples of behavioral solicitations when female primates are in estrus and which species do them? Olfactory cues of estrus? Visual/morphological cues of estrus? Behavioral solicitations 

e.g., presenting of rump in geladas, tongue-flicking in howlers

Olfactory cues 

e.g., increased scent-marking by female lemurs

Visual cues 

e.g., swelling of bare skin of perineum (baboons, chimps) or chest (geladas)

9. Which major natural groupings of primates have sexual swellings? What sorts of groups do they live in? When do swellings reach their maximal tumescence? When does male sexual interest in swollen females peak? What is D-day and how does male and female behavior change once that day is reached? How do we know that males respond specifically to the visual cues of a sexual swelling and not just the olfactory cues that might be associated with it? What are some possible functions of sexual swellings?

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>24 species of OW monkeys (baboons) and apes (chimps) have large swellings reach maximal tumescence 1-2 days before ovulation

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depend on hormones, and are direct indicators of underlying physiological cycles

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swellings ‘indicate’ to males when females are ovulating

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Males most interested when swellings at their largest

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male interest wanes at D-day (detumescence day)

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EXPT: large plastic swellings strapped onto female baboons w/out ovaries – males become very interested!

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swellings only occur in species with multi-male groups

10. When female primates in zoos stop reproducing for long periods of time, what tactics do zoos sometimes use to try and encourage them to reproduce again? What is the ‘Coolidge Effect’? What is the biological basis for the Coolidge Effect? What are the hypotheses for why females are sometimes excited by strange males? What are some of the negative consequences of promiscuity for nonhuman primates? What is the evidence that some primates have evolved defenses to combat STDs? What sort of mating patterns do these primates exhibit? 

When a female primate in a zoo stops reproducing, introducing a new male sometimes works

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After a male takeover, females sometimes come into estrus very quickly

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“Coolidge Effect” = novel partners increase male sexual interest and performance WHY? o

Access to females is major limitation on male reproductive success

Hypotheses: •

Encourages competition among males so she can choose the best one?

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Makes infanticide less likely?

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Increases chances of conception since sperm differs in quality?

Negative consequences of promiscuity STDs • •

BUT, a comparison across 41 primate species found… most promiscuous species had highest white blood cell counts

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perhaps promiscuous species evolved stronger immune systems to cope with STDs?

11. What are the stages of labor in nonhuman primates? During what period of the daily cycle do most births occur? Why might it be adaptive for primates to give birth at this time? What happens to the placenta after birth and why? •

3 stages of labor

(1) enlarging of birth canal (2) expulsion of infant (3) expulsion of placenta • •

Births tend to occur at night Females often eat placenta

Most monkeys and apes give birth at night, probably because it's adaptive for new mothers to have time to rest and recover from labor before having to keep up during group travel and, possibly, confront predators. 12. What factors influence male sexual activity? What happens to the testes and sperm production in macaques during the non-mating season? In what ways do primates differ from one another in their copulation patterns? Factors influencing male sexual activity •

signals that females are in estrus – sexual swellings, solicitations by females, etc.

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time of year

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in macaques, testes become larger and produce more sperm during mating season!

presence of other males –

faced w/ competitors, males initiate more copulations and mate more frequently

Copulation Patterns • •

from single (geladas) to multiple mounters (macaques) from 10 seconds (geladas) to 1 hour (aye-aye)

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who initiates sex? –

varies across primates

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chimps: males

gorilla: females

PPT week 2 STUDY QUESTIONS 1. What are the two components of mating systems? What are the factors most critical to reproductive success for (a) females and (b) males? What is differential investment? In what ways do the two sexes invest differentially in their offspring both prior to conception and after conception? What is anisogamy? Why are females referred to as ‘gamete storehouses’ and males as ‘gamete factories’? Why are females referred to as the ‘limiting’ sex? 

pattern of who mates with whom

 

pattern of who reproduces with whom the critical factor that determines reproductive success in o

♀♀ is obtaining enough FOOD

o

♂♂ is access to MATES

Differential investment •

♂♂ and ♀♀ invest differentially in offspring

Anisogamy = gamete size dimorphism – –

Mammalian egg 125,000 times heavier than sperm Even before conception, ♀♀ have invested much more energy into each offspring than ♂♂

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♀ produce few large gametes (eggs);

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♂ produce many small gametes (sperm)

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♀ = gamete storehouse;

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♂= gamete factory

Because there are more sperm than eggs –

♀♀ are LIMITING sex – eggs are a resource sperm must compete for –

thus, ♀♀ have the luxury of choice

2. What are the consequences of differential reproductive investment (a) for males? (b) for females? What does it mean that males are expected to be ‘ardent’ and females are expected to be ‘coy’? Why is it not only a luxury for females to be choosy but also a necessity? What is the evidence that humans meet the predictions of differential investment theory that males should be ardent and females should be coy? How does evidence from some birds like emus show that it is differential investment in particular that influences the reproductive strategies of males and females? Male: • •

•

Mate with as many females as possible Great variance in reproductive success among males –

e.g., Barbary macaques: 0-20 infants per male; 47% of males with 2 infants

♀♀ do not need to compete over mates - the choice in mates is theirs

• •

♂♂ ...