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A set of question-and-answer flashcards covering key concepts from chapters on sexual selection, sex vs. gender, Bateman's principle, intrasexual vs. intersexual selection, alternative mating tactics/strategies, direct and indirect benefits of female choice, and example species.
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What is anisogamy and what are its key reproductive implications for males and females?
Females produce relatively few, large, energetically costly eggs while males produce many small, inexpensive sperm. This leads to female choosiness and male competition for fertilizations.
Define Bateman's principle.
The idea that male reproductive success increases with the number of mates (more matings → higher fitness), while female reproductive success is limited by the number of eggs she can produce, leading to sex differences in mating strategies.
What is the difference between sex and gender in this context?
Sex refers to biological attributes (hormones, chromosomes, reproductive organs). Gender is a human social construct related to identity. In animals, and in scientific writing, gender is not used to describe non-human animals.
What is the distinction between intrasexual and intersexual selection?
Intrasexual selection involves competition within the same sex (often males) for access to mates. Intersexual selection involves traits that make individuals more attractive to the opposite sex.
Give examples of 'weapons' and 'ornaments' in sexual selection.
Weapons: horns, antlers, tusks used in male–male combat. Ornaments: bright colors and elaborate courtship displays that attract mates (e.g., bowerbirds).
What pattern was found regarding horn size and group size in bovids, and what does it imply?
A positive relationship between male horn size and group size, suggesting horn size is under sexual selection to monopolize access to many females; female horn size is more about anti-predator defense (natural selection).
Differentiate alternative mating tactics and alternative mating strategies with examples.
Tactics are condition-dependent, flexible behaviors (e.g., small males sneaking to mate in giraffe weevils). Strategies are genetically fixed morphs that persist across the lifetime (e.g., the three morphs in side-blotched lizards).
Describe the New Zealand giraffe weevil as an example.
Males have extremely long rostrums used in fights; females have shorter rostrums; illustrates condition-dependent alternative mating tactics (large males fight, small males sneak).
Describe the side-blotched lizard morphs and their dynamics.
Three genetically fixed male morphs: orange (dominant, large territories), blue (smaller territories), yellow (sneakers). Fitness is maintained by frequency-dependent selection in a rock–paper–scissors dynamic, with rarity influencing female choice.
What are direct benefits to females from male choice, with examples?
Direct benefits are tangible resources or parental assistance. Examples include nuptial gifts (nutritious meals during mating) and sexual cannibalism (e.g., red-backed spiders), which can increase fertilization success or offspring quality.
What are the two indirect benefits models in female choice, and how do they differ?
Good genes model: female benefits come from genes that improve offspring fitness ( ornaments signal high-quality genes). Sexy sons model: daughters gain fitness by producing sons who are themselves attractive to future mates, due to heritability of attractive traits.
Explain the Good Genes model using the pronghorn deer example.
Females prefer males with impressive courtship displays; offspring from attractive males tend to have higher survival, indicating superior genetic quality transmitted to progeny.
Explain the Sexy Sons hypothesis with a stalk-eyed fly example.
If a female mates with a male with long eye stalks, her daughters may have sons who inherit attractive traits, increasing the daughters’ future grand-offspring success even if there is no direct survival benefit to the daughters' offspring.
What is the core distinction between sexual selection and natural selection in this context?
Sexual selection is a form of natural selection focused on mating success and fertilization, often producing extravagant traits that may trade off with survival.