Sexual selection Flashcards
(15 cards)
What is sexual selection?
A mode of natural selection focusing on finding a mate and reproducing, favoring traits that maximize reproductive success rather than survival
What is the difference between asexual and sexual reproduction?
Asexual reproduction involves one sex, usually no genetic recombination (e.g., hydra). Sexual reproduction involves two sexes, which can be in the same individual (e.g., snails), separate sexes (e.g., vertebrates), or individuals that change sex (e.g., some fish)
What is intersexual conflict in reproduction?
The asymmetry in reproductive investment causes males and females to have different reproductive interests
Describe monogamy in terms of mate competition and parental investment
Low competition for mates (both sexes may compete), sexes are similar in size and appearance (low dimorphism), and both sexes often care for young
What characterizes polygyny?
One male mates with many females, males compete intensely for mates, males show high sexual dimorphism, and females care for young
What characterizes polyandry?
One female mates with many males, females compete for mates, sexes are similar or females may be larger or more ornamented, and parental care can be from both sexes or just males.
What is polygynandry?
Both females and males have multiple mates
What is intrasexual selection?
Competition among males (male-male competition) for mates, often leading to development of secondary sexual characteristics.
What are the four types of intersexual selection (mate choice)?
- Indicator traits (e.g., red coloration indicating health)
- Sensory bias (preference for rare traits)
- Runaway selection (linked male trait and female preference genes)
- Genetic compatibility (choosing mates with different MHC genes).
What is cryptic female choice?
Post-mating female influence on which male’s sperm fertilizes eggs, through behavior, morphology, or physiology
What is sperm competition?
When females mate with multiple males in a fertile period, males compete via sperm quantity (larger testes often favored)
What do sexual swellings indicate?
Probabilistic signals of ovulation timing, conception probability within cycle, and individual female fertility ability
How do sex ratios affect reproductive success?
They are frequency-dependent; the rarer sex tends to have better reproductive success due to less competition
What is the handicap principle?
Traits that hinder survival but are favored by mate choice (e.g., peacock tails), signaling genetic quality or health
How do peacock tails support the handicap principle?
More elaborate tails with many eyespots correlate with mating success, better health, and improved offspring survival
