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AIM: SWBAT define lek mating and sexual selection

Please Do Now: 1) Define polyandry. 2) What kind of mating system would you expect a polar bear to engage in? Why?. AIM: SWBAT define lek mating and sexual selection. Agenda. Do Now Sexual Selection and Lek Mating Notes Lek Mating videos Experimental Design.

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AIM: SWBAT define lek mating and sexual selection

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  1. Please Do Now: 1) Define polyandry. 2) What kind of mating system would you expect a polar bear to engage in? Why? AIM: SWBAT define lek mating and sexual selection

  2. Agenda • Do Now • Sexual Selection and Lek Mating Notes • Lek Mating videos • Experimental Design

  3. What is typical Reproductive Behavior? • When ready to mate, animals produce signalsto communicate with potential partners. • Each species usually produces a unique courtship signal that ensures that individuals do not mate with individuals of another species. • Many species of insects, amphibians, and birds produce unique sounds or songs to attract mates. • During the breeding season, animals make several important “decisions” concerning mating and parenting. • These include how many mates to have and how much time and energy to devote to rearing offspring. • These decisions are all aspects of an animal’s reproductive strategy, a set of behaviors that have evolved and that maximize reproductive success.

  4. What is Mate Choice? • Males and females usually differ in their reproductive strategies. • In many animals, females do not mate with the first male they encounter. • Instead, the female seems to evaluate the male before she decides whether to mate. • This behavior, called mate choice, has been observed in many invertebrate and vertebrate species.

  5. What is Sexual Selection? • More than a century ago, Darwin noticed that males often have extreme characteristics that they use in their courtship displays. • Darwin recognized that extreme traits could have evolved if they helped males attract or acquire mates. • Sexual selection is a mode of natural selection in which some individuals outreproduce others of a population because they are better at getting mates • Traits that increase the ability of individuals to attract or acquire mates appear with increased frequency. • Even traits that have a negative effect on survival can evolve in this way, provided that their benefits to reproduction are high enough.

  6. Sexual Selection • It is usually females that select mates based on their physical traits. • Probably because reproduction has a greater cost and requires a greater investment from females. • Males may show mate choice as well if their parental involvement is high.

  7. What is lek mating? • A lek is a gathering of males, of certain animal species, for the purposes of competitive mating display. Leks assemble before and during the breeding season, on a daily basis. • Once a dominant male wins a female or a set of females, he will often have to defend them for the rest of mating season to ensure he is the only one who inseminates them. • In some species, a male can gain a reproductive advantage over other males by interfering with their reproduction. • For example, in some species of worms, butterflies, and snakes, the male seals the female’s reproductive tract after mating, thus preventing other males from mating with her.

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