Lecture 15

Question 1

What did Shapley discover?

Answer 1

• Harlow Shapley realized ants move more slowly when they’re in the shade than when they were in the sun
• set up a set of instruments to measure temp & humidity etc. around the grounds of the observatory and he plotted the running speed of ants as a function of temp
• the ant running rate initially doubled or tripled for every 10 degree change in temp
• but eventually, the ant started to slow down and he couldn’t actually get them to run much after about 40 degrees
• he characterized the first temperature response curve using ants

Question 2

What happens if organisms can’t find the right set of environments within that optimal range?

Answer 2

• may be unable to survive
• may be unable to move to find enough food
• or might spend too much energy / water regulating their body temp
• may survive but not reproduce quickly enough
• these areas just outside the OPTIMAL region are called the SOFT limits (can’t stay forever in these suboptimal limits)

Question 3

Why are temperature response curves useful?

Answer 3

• one of the reasons is that they help us work out to which area toads are likely to spread

Question 4

What does poikilothermic mean?

Answer 4

variable temperature

Question 5

What does ectotherm mean?

Answer 5

It gets its heat from the outside NOT the inside - it cannot generate enough heat internally to raise its body temp much above its surroundings

Question 6

What are 2 ways of avoiding extreme temps for lizards?

Answer 6

Going up higher into the grass where there’s more wind or going deeper underground where it is cooler

Question 7

Why does the koala lie limp and flat against the tree branch?

Answer 7

• koala jams its bottom right into the coolest part of the tree trunk
• tries to regulate its body temp through conduction by dumping its heat into the cold tree and that requires a temp gradient

Question 8

What is an advantage that endotherms have over ectotherms?

Answer 8

They can elevate their metabolic rate when it gets cold to keep warm

• tradeoff is that they have to eat more and have a more reliable source of food
• endotherms might die if they release too much water to try and cool down

Question 9

Why is there a rise in metabolic rate after the thermoneutral zone?

Answer 9

• they start to do behaviours like licking and panting which cost energy
• that only adds to the heat problem
• that extra energy they’re using to behaviourally regulate that muscular activity

Question 10

The thermal tolerance of species living in the tropics is. . .

Answer 10

NARROWER
- you have more ‘generalists’ in the high latitude areas
- more ‘specialists’ in the low latitude areas (along equator)

• greatest effect of global warming is actually on the tropical species bc of their narrow thermal tolerance (even tho it’s not warming as extremely as it is at the poles)