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Reproduction

Learn about reproductive investment - from sperm production to egg laying strategies. Explore r/K selection theories, egg types, and mating behaviors in various environments. Prepare for SAC with this comprehensive guide.

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Reproduction

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Presentation Transcript

  1. Reproduction How much should be invested in each offspring?

  2. Why so many sperm? • Why do males produce thousands of sperm rather than one sperm for one egg? • Listen to the following audio recording to learn more. • Apply this information to complete the worksheet.

  3. How much to invest in an egg? • Animals have a certain amount of resources for reproduction • They can lay many small eggs, of which only a few will be fertilised and then survive • Invest little per egg • They can lay larger eggs (with more yolk) or give birth to live young, producing less eggs, but each one having a larger chance of being fertilised and surviving. • Invest a lot per egg

  4. What environmental conditions lead to a smaller/ larger investment? • Read notes from page 374-376 • Why broadcast spawn at sea? • Why broadcast spawn during flood events? • What sort of conditions would be best for laying demersal eggs? • What sort of increased investment is seen in species that lay demersal eggs?

  5. R or K- selection? • Read your notes from 381-382 • Animals that have one breeding season are likely to be ____________________ • Define fecundity • A risk of r-selection is self fertilisation. How can this be avoided?

  6. Linking r/K-selection to understanding oviparous and viviparous animals • Read notes from 383-387 • Why do animals that lay eggs in a terrestrial environment have to invest more in each egg? • What would be the difference between the eggs of r-selected species and K-selected species? • What is the difference between egg-yolk viviparity and placental viviparity? • Would these strategies show r or K-selection?

  7. SAC • We have a SAC next Monday • This will cover all of chapter 11 and 12 • You will be expected to be able to • Identify types of behaviour (both innate and learned) • Mating systems • Plant behaviour (data analysis) • Discuss reproductive investment (r of K selected) • You will be given scenarios or data and be asked to predict behaviour or reproductive strategies. • Marks will be awarded on your ability to use the language and argue your theory

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