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Mating Strategies Monogamy Polygamy Polygyny: one male, 2+ females Polyandry: one female, 2+ males

Mating Strategies Monogamy Polygamy Polygyny: one male, 2+ females Polyandry: one female, 2+ males Promiscuity: no pair bond. Sexual Selection. Females assess males b) Males battle for access to females. Life History Patterns. Reproductive effort. Cost of reproduction.

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Mating Strategies Monogamy Polygamy Polygyny: one male, 2+ females Polyandry: one female, 2+ males

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  1. Mating Strategies • Monogamy • Polygamy • Polygyny: one male, 2+ females • Polyandry: one female, 2+ males • Promiscuity: no pair bond

  2. Sexual Selection • Females assess males b) Males battle for access • to females

  3. Life History Patterns • Reproductive effort • Cost of reproduction • Senescence • age-related • experience-related • Previous breeding experience

  4. N. Elephant Seals • Polygynous, K-selected and long-lived • Iteroparous, one offspring per year, • 8-month gestation • Males breed at age 7-8, females at 2-3 • Sexual selection by male battles, only • female raises pup

  5. Western Gulls • Monogamous, K-selected and long-lived • Iteroparous, multiple offspring, lay 2-3 • eggs per year • Third Chick Disadvantage • Males breed at age 3-5, females at 4-6, • both sexes raise young

  6. New study by Dr. Tim Clutton-Brock (Cambridge Univ.) (2007,Proceedings of the Royal Society) Renowned expert on life history studies in long-lived mammals Review of polygynous vs monogamous species: males live longer in monogomous in 16 of 19 polygynous species, males have significantly shorter lifespan cost of reproduction—defending a harem

  7. Quiz • What is the difference between polygyny and polyandry breeding systems? What is sexual selection? • Explain the meaning for the following demographic characters: reproductive effort, cost of reproduction, senescence, and previous breeding experience. • Why do female elephant seals show no loss in reproductive success with age, but do with experience? • Why do female western gulls have greater lifetime reproductive success if they delay first breeding until age 5-6? Why do males have better success by breeding earlier? • What is the third chick disadvantage in western gulls and how is it reduced by older aged gulls?

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