Sexual Selection
Explain sexual selection as a form of natural selection: runaway selection for peacock tails, bird of paradise displays, and frog calls; explain kin selection and altruistic behaviour — why worker bees die to protect the hive, why meerkats stand guard at personal risk (Hamilton's rule, inclusive fitness); introduce game theory in animal behaviour using the hawk-dove model; define cognitive ethology and survey evidence for animal emotions, play, and culture
The lesson
You already know evolution favors traits that help animals survive. Sexual selection is a special case: it favors traits that help an animal get chosen as a mate, even when those traits make survival harder. A peacock's huge tail, a bird of paradise's wild dance, and a frog's booming call all cost energy and can attract predators. They stick around because they help win mates.
Say peahens (female peacocks) prefer males with longer tails. Males with longer tails get more mates and more chicks. Those chicks inherit both the long-tail trait and the preference for long tails. Over many generations, tails keep growing past the point where they help the bird survive. This spiral is called runaway selection: the trait and the preference for it push each other further each generation.
Some behavior isn't about surviving or mating at all. A worker bee stings a predator to protect the hive and dies doing it, even though she never has babies of her own. A meerkat stands guard and calls out warnings, risking an eagle attack. This is kin selection: helping close relatives survive helps copies of your own genes survive too, since relatives share genes. Scientists check this with Hamilton's rule: relatedness times benefit must beat the cost (r x B > C). A worker bee shares many genes with her sisters, so protecting the hive is worth the risk.
Cognitive ethology is the study of animal minds: do animals feel emotions, play for fun, or pass down culture? Scientists look for real evidence, like consistent behavior patterns or brain activity, before concluding an animal feels or thinks something, rather than just guessing based on how a human would feel.
Traits can spread because they win mates, because they protect relatives who share your genes, or because they work as a smart strategy, and scientists now find real evidence that animals think and feel more than once assumed.
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