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Reproductive strategies for survival

Reproductive strategies for survival. Chapter 12. Reproductive adaptations. Refers to any strategy that aims to increase the chance of successful reproduction and the survival of the offspring. Sex at sea.

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Reproductive strategies for survival

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  1. Reproductive strategies for survival Chapter 12

  2. Reproductive adaptations • Refers to any strategy that aims to increase the chance of successful reproduction and the survival of the offspring.

  3. Sex at sea • Broadcast spawning refers to organisms releasing their eggs and sperm into the water (where there is a strong current) • Mass spawning refers to a large group of the one organism gathering together in one location to simultaneously release eggs and sperm • Pelagic eggs are eggs that can float within the water column • Demersal eggs do not float and are often ‘nested’ (in sand, the surface of a rock)

  4. Mating systems • Monogamy • Where one male mates with one female for one or more breeding seasons (or for life) • Seen in species where the survival of the young depends on the care given by both parents (think of the penguins!) • Examples of this care include: defending a nest, incubating eggs, feeding offspring • Polygamy • Where one male or female has multiple mating partners during a breeding season • Polygyny: male that has multiple female partners • Polyandry: female that has multiple male partners

  5. Polygyny: one male, many females • Two kinds: harem and serial • Harem refers to a dominant male living with a group of females • Serial refers to one male attracting passing females • Serial polygyny often requires the male to have ‘advertising’ features. Ie visual or vocal signals • Lekking occurs when males gather in one area a perform a display (visual/vocal) to attract passing females

  6. Offspring: how many? How often? • r-selection: ‘quick & many’ • K-selection ‘slower & fewer’ • r-selection is typical of species • That mature quickly • Produce large numbers of offspring • Don’t put much parent care into offspring • The strategy means more offspring are produced but there is a higher mortality rate

  7. K-selection is typical of species: • Mature slowly • Require parental care • Breed later

  8. Eggs or liveborn young? • Oviparity- ‘egg bearing’ Young develop outside mother • Viviparity- ‘living bearing’ young are born live

  9. Questions: • Pg 376- Q1-3 • Pg 381 Q 4-5 • Pg 383 Q 6-8 • Pg 387 Q 9-13 • Pg 393 Q 14-16

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