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Evolution of Mating Strategies in Long-Lived Species: Insights from Elephant Seals and Western Gulls

Explore the contrasting mating behaviors of polygynous elephant seals and monogamous Western Gulls to understand sexual selection, life history patterns, and reproductive success in long-lived mammals. Learn from Dr. Tim Clutton-Brock's research comparing polygynous vs. monogamous species and discover the implications of breeding systems on male lifespan and reproductive outcomes. Test your knowledge with a quiz on mating strategies, sexual selection, and key demographic factors influencing breeding success in these fascinating species.

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Evolution of Mating Strategies in Long-Lived Species: Insights from Elephant Seals and Western Gulls

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Presentation Transcript

  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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