Podcast
Questions and Answers
How does access to food impact female reproductive strategies?
How does access to food impact female reproductive strategies?
- High access leads to low birth rates.
- Low food availability guarantees high reproductive success.
- Females compete for food, which can increase birth rates. (correct)
- Food access does not influence reproductive strategies.
What effect does social hierarchy have on reproductive success (RS) among female primates?
What effect does social hierarchy have on reproductive success (RS) among female primates?
- Lower rank often leads to higher RS.
- Dominance hierarchies are unrelated to RS.
- Rank is positively correlated with RS. (correct)
- High-ranking females often have lower RS.
Which factor is suggested to influence the reproductive success of chimpanzee offspring?
Which factor is suggested to influence the reproductive success of chimpanzee offspring?
- The age of the offspring.
- The mother’s social rank. (correct)
- The offspring's physical strength.
- The mother's access to water.
What is a consequence of resource crashes on the reproductive behavior of female primates?
What is a consequence of resource crashes on the reproductive behavior of female primates?
How can socializing positively affect a female primate's reproductive strategy?
How can socializing positively affect a female primate's reproductive strategy?
What is a characteristic feature of solitary primate mating systems?
What is a characteristic feature of solitary primate mating systems?
What defines polygyny in primate mating systems?
What defines polygyny in primate mating systems?
In which primate mating system is cooperative breeding observed?
In which primate mating system is cooperative breeding observed?
What impact does sexual selection have compared to natural selection?
What impact does sexual selection have compared to natural selection?
How is reproductive success (RS) typically measured in evolutionary terms?
How is reproductive success (RS) typically measured in evolutionary terms?
Which of the following is NOT a type of mating system in primates?
Which of the following is NOT a type of mating system in primates?
What does the term 'fission-fusion' refer to in primate social systems?
What does the term 'fission-fusion' refer to in primate social systems?
What distinguishes uni-female/multi-male systems from uni-male/multi-female systems?
What distinguishes uni-female/multi-male systems from uni-male/multi-female systems?
What is a primary limiting factor for female reproductive success?
What is a primary limiting factor for female reproductive success?
Which selection form is specifically related to mate competition among males?
Which selection form is specifically related to mate competition among males?
What trait is emphasized by sexual selection that may not contribute to survival?
What trait is emphasized by sexual selection that may not contribute to survival?
Which type of selection is primarily driven by female choice?
Which type of selection is primarily driven by female choice?
How does sexual selection primarily affect the sexes?
How does sexual selection primarily affect the sexes?
What is the primary focus of male reproductive strategies?
What is the primary focus of male reproductive strategies?
Which statement about natural selection and sexual selection is true?
Which statement about natural selection and sexual selection is true?
Why do female primates invest more in offspring care than males?
Why do female primates invest more in offspring care than males?
Why are some traits, favored by sexual selection, considered maladaptive?
Why are some traits, favored by sexual selection, considered maladaptive?
What factors contribute to the lesser investment of primate males in offspring care?
What factors contribute to the lesser investment of primate males in offspring care?
Under what circumstance might male primates invest more in the care of their offspring?
Under what circumstance might male primates invest more in the care of their offspring?
What is a common result of the reproductive strategies between male and female primates?
What is a common result of the reproductive strategies between male and female primates?
How does the mammalian reproductive system influence female primate behavior?
How does the mammalian reproductive system influence female primate behavior?
Why might a female primate produce fewer offspring over her lifetime?
Why might a female primate produce fewer offspring over her lifetime?
In terms of reproductive strategies, what is one primary concern for female primates?
In terms of reproductive strategies, what is one primary concern for female primates?
What often drives male primates to invest less in offspring care?
What often drives male primates to invest less in offspring care?
In multi-male groups, what factor primarily increases competition among males regarding access to females?
In multi-male groups, what factor primarily increases competition among males regarding access to females?
Which reproductive strategy involves males killing dependent offspring of females?
Which reproductive strategy involves males killing dependent offspring of females?
What is a common reproductive strategy among pair-bonded species like gibbons?
What is a common reproductive strategy among pair-bonded species like gibbons?
In multi-male/multi-female groups, what does intrasexual selection favor?
In multi-male/multi-female groups, what does intrasexual selection favor?
Which factor can lead to the formation of dominance hierarchies among males in primate groups?
Which factor can lead to the formation of dominance hierarchies among males in primate groups?
What is one potential counter-strategy females may use against infanticide?
What is one potential counter-strategy females may use against infanticide?
Which primate reproductive strategy is characterized by reduced competition for female access?
Which primate reproductive strategy is characterized by reduced competition for female access?
What outcome does infanticide enable for the infanticidal male in a group takeover scenario?
What outcome does infanticide enable for the infanticidal male in a group takeover scenario?
Study Notes
Primate Mating Systems
- Solitary or "noyau" - Orangutans, lorises
- Pair-bonded (monogamy) - Gibbons, owl monkeys
- Uni-female/multi-male (polyandry) - Tamarins
- Cooperative breeding
- Uni-male/multi-female (polygyny) - Langurs, mountain gorillas
- Non-resident males may form "bachelor groups"
- Multi-male/multi-female (polygynandry) - Vervets, macaques
- Special case: fission-fusion (spider monkeys, chimpanzees)
Reproductive Strategies
- Strategies are products of selection, not conscious plans
- Fitness = an individual's genetic contribution to the next generation
- Strategies may be different for males and females, and in different group compositions
Female Investment
- Female primates invest more in offspring than males due to constraints of the mammalian reproductive system
- Females must carry offspring to term and nurse them
- Extended pregnancy (large brain), altriciality, and relatively small number of surviving infants produced over lifetime
- This means each infant represents a greater portion of lifetime fitness for females
Male Investment
- Males are typically less involved in the care of offspring due to:
- Male care often less important for offspring survival
- Time, energy, and resources are limited
- Paternity uncertainty
- It is often a better strategy to seek new mates
- Male investment is higher when the benefit of investment outweighs the cost of seeking new mates (tamarins, owl monkeys)
Female Reproductive Strategies
- Female reproductive success depends on the ability to obtain enough resources (especially food) to support herself and her offspring
- Access to food is important, so females often compete for this access
- Dominance hierarchies often form among females, where high-ranking females gain access to more/better quality food
- Rank is positively correlated with reproductive success in macaques, Hanuman langurs, and chimpanzees.
- Socializing can also positively influence female reproductive success by providing benefits from association with high-ranking females.
Male Reproductive Strategies
- Male reproductive success is all about access to mates
- Traits that increase success in competition for mates evolve through sexual selection
Sexual Selection
- Sexual selection is a special category of natural selection.
- It favors phenotypes that increase success in competition for mates
- It affects one sex more strongly (typically the one whose access to mates is limited)
Components of Sexual Selection
- Intrasexual Selection
- Competition within the same sex
- Usually stronger among males
- Common in primates
- Intersexual Selection
- Mate choice
- Usually stronger in females
- Common in birds, but also plays a role in some primate species
Reproductive Strategies in Multi-male Groups
- Estrus cycle: Females in most primates experience estrus, making them receptive to mating
- In multi-male groups, females can mate with several males in a group
- This leads to less direct competition for access to females
- Intrasexual selection favors increased sperm production in these cases ("sperm competition")
- Dominance hierarchies also form among males in multi-male groups, determining access to estrous females
Reproductive Strategies in Pair-bonded Species
- In pair-bonded species (e.g. gibbons), males don't compete for access to females
- Their reproductive success depends on finding mates, defending territory, and rearing offspring.
- Mate guarding is a common reproductive strategy in pair-bonded species
- Grooming is also significant in maintaining pair bonds
Infanticide
- Infanticide is an adaptive strategy for males in some species.
- After group takeovers, males may kill dependent offspring
- This allows infanticidal males to reproduce more quickly before being ousted.
- Infanticide is costly for females, leading to counter-strategies:
- False estrus
- Female coalitions
- Spontaneous abortions
- Male "friendships"
- These counter-strategies are observed in many primate species, both in the wild and in provisioned populations.
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Description
Explore the diverse mating systems found in primates, including solitary, pair-bonded, polyandrous, polygynous, and polygynandrous arrangements. Understand the reproductive strategies influenced by natural selection and the significant investment female primates make in their offspring. This quiz covers various aspects of primate behavior and reproductive ecology.
