Download Reproduction - BiologyUnit2-TSC

Reproduction
How much should be invested in
each offspring?
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.
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
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?
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?
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?
SAC
• We have a SAC next Monday
• This will cover all of chapter 11 and 12
• You will be expected to be able to
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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