Primate Mating Systems Overview
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Questions and Answers

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?

  • 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?

  • 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?

    <p>Low birth rates and longer intervals. (A)</p> Signup and view all the answers

    How can socializing positively affect a female primate's reproductive strategy?

    <p>By insulating females from the costs associated with low rank. (A)</p> Signup and view all the answers

    What is a characteristic feature of solitary primate mating systems?

    <p>Lack of permanent social groups (D)</p> Signup and view all the answers

    What defines polygyny in primate mating systems?

    <p>One male mating with multiple females (A)</p> Signup and view all the answers

    In which primate mating system is cooperative breeding observed?

    <p>Polyandry (B)</p> Signup and view all the answers

    What impact does sexual selection have compared to natural selection?

    <p>Sexual selection emphasizes reproduction and mate choice (C)</p> Signup and view all the answers

    How is reproductive success (RS) typically measured in evolutionary terms?

    <p>Number of offspring surviving to reproductive age (B)</p> Signup and view all the answers

    Which of the following is NOT a type of mating system in primates?

    <p>Communal mating (B)</p> Signup and view all the answers

    What does the term 'fission-fusion' refer to in primate social systems?

    <p>Variable group composition and social structure (C)</p> Signup and view all the answers

    What distinguishes uni-female/multi-male systems from uni-male/multi-female systems?

    <p>The female has the exclusive mating rights (D)</p> Signup and view all the answers

    What is a primary limiting factor for female reproductive success?

    <p>Access to food (D)</p> Signup and view all the answers

    Which selection form is specifically related to mate competition among males?

    <p>Intrasexual Selection (B)</p> Signup and view all the answers

    What trait is emphasized by sexual selection that may not contribute to survival?

    <p>Secondary sexual characteristics (D)</p> Signup and view all the answers

    Which type of selection is primarily driven by female choice?

    <p>Intersexual Selection (B)</p> Signup and view all the answers

    How does sexual selection primarily affect the sexes?

    <p>More strongly in the sex with limited access to mates (D)</p> Signup and view all the answers

    What is the primary focus of male reproductive strategies?

    <p>Access to mates (D)</p> Signup and view all the answers

    Which statement about natural selection and sexual selection is true?

    <p>Natural selection favors reproduction-related phenotypes more strongly (D)</p> Signup and view all the answers

    Why do female primates invest more in offspring care than males?

    <p>Males often find it easier to attract additional mates. (A), Female reproductive strategies require more time and energy for nursing. (B)</p> Signup and view all the answers

    Why are some traits, favored by sexual selection, considered maladaptive?

    <p>Both B and C (B)</p> Signup and view all the answers

    What factors contribute to the lesser investment of primate males in offspring care?

    <p>Paternity uncertainty makes investment risky. (A), Females are often unable to rear young alone. (C)</p> Signup and view all the answers

    Under what circumstance might male primates invest more in the care of their offspring?

    <p>When female primates are unable to provide enough care. (B), When attracting additional mates is difficult. (C)</p> Signup and view all the answers

    What is a common result of the reproductive strategies between male and female primates?

    <p>Female investment tends to be higher due to resource securing. (A)</p> Signup and view all the answers

    How does the mammalian reproductive system influence female primate behavior?

    <p>It allows for higher maternal contributions to overall fitness. (D)</p> Signup and view all the answers

    Why might a female primate produce fewer offspring over her lifetime?

    <p>The need for high-quality care can limit offspring numbers. (A), Extended gestation and nursing period requires more resources. (D)</p> Signup and view all the answers

    In terms of reproductive strategies, what is one primary concern for female primates?

    <p>Securing adequate resources for their young. (B)</p> Signup and view all the answers

    What often drives male primates to invest less in offspring care?

    <p>Their focus on securing more mating opportunities. (A)</p> Signup and view all the answers

    In multi-male groups, what factor primarily increases competition among males regarding access to females?

    <p>Dominance hierarchies (D)</p> Signup and view all the answers

    Which reproductive strategy involves males killing dependent offspring of females?

    <p>Infanticide (B)</p> Signup and view all the answers

    What is a common reproductive strategy among pair-bonded species like gibbons?

    <p>Mate guarding (D)</p> Signup and view all the answers

    In multi-male/multi-female groups, what does intrasexual selection favor?

    <p>Increased sperm production (C)</p> Signup and view all the answers

    Which factor can lead to the formation of dominance hierarchies among males in primate groups?

    <p>Age and physical condition (B)</p> Signup and view all the answers

    What is one potential counter-strategy females may use against infanticide?

    <p>False estrus signaling (B)</p> Signup and view all the answers

    Which primate reproductive strategy is characterized by reduced competition for female access?

    <p>Pair bonding (A)</p> Signup and view all the answers

    What outcome does infanticide enable for the infanticidal male in a group takeover scenario?

    <p>Quicker access to mating opportunities (D)</p> Signup and view all the answers

    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.

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