Lecture 16 Flashcards
When they looked at thermal images of emperor penguins which part of the body did they find to be at a lower temp than the air?
The flippers
Why are the flippers of emperor penguins kept at a lower temp than the air?
Because if there is a temp difference then there is heat flow so their skin temp is lower than the environment so the heat flow is bringing heat into the animal so they have a positive heat flux so heat is coming from the environment into the animal
Explain how the body temp differs in emperor penguins
These animals are significantly warmer than the environment but there are components of the body that are colder than the environment as particularly the areas of the body that are exposed
(They have a positive heat flux so heat is coming from the environment into the animal)
Animals have circadian rhythms, what does this mean?
Means that they have periods where they are active and have a high body temp and then have periods of sleep and their body temp falls
Describe the strategy for reducing energy expenditure: sleep
(Who does it, what happens in it)
. Regular periods characteristic of birds and mammals (and reptiles as well)
. Reduction in activity
. Reduction in oxygen consumption
- even a small (1-2 degrees) decrease in body temperature can have a significant effect on energy expenditure (7-15% reduction, or higher depending on the animals). Declines in body temp can represent huge saving in terms of their metabolic rate and hence the rate in which they use up their resources and therefore the rate in which they can last on their stores
What does the reduction in MR during sleep tend to be? And what might it be due to?
Around 10% allowing body temp to reduce by just a few degrees, may be due to reduction in muscular activity
Why don’t animals that go into torpor overnight need to put on massive amounts of fat to last them overnight?
Because during this period they are not using up many of their resources
What is arousal from torpor always accompanied by?
. Increase in metabolic rate or oxygen consumption
. Both loss and regain of body temperature (fairly rapid: <1-3h)
. Mixture of shivering and non thermal neogenesis (mammals)
. Cooling and warming possibly related to photoperiod
. Increase in Vo2
What does the overshoot in metabolism in arousal from torpor depend on?
Body size
Why is there an overshoot in metabolism when animals are arousing from torpor?
Essentially for most of the animals they start shivering and that increases their body temp but that shivering costs because it is muscle activity.
What controls the duration of torpor?
It is potentially cooling and warming related to photoperiod that might trigger the animals but it may be external temps as well (as seen in the dunnets).
The duration of the torpor certainly seems to link to temp but could be related to photoperiod
Give the aspects of torpor (when it is used/ not used, how does it differ between animals)
. Not used by animals during reproduction
. More frequent in winter than summer
. Larger animals have shorter and lower periods of torpor (lower temp drop)
. Juvenile animals show longer and deeper periods of torpor
. Allows small animals to exploit areas that would otherwise be inaccessible
. However, there are many latitude animals that do not exhibit torpor
Why to animals not use torpor during reproduction? Give an example
Because if they did their body temp would drop and it would reduce the rate in which their foetus develops.
In the case of birds if they reduce their body temp during incubation or brooding then they will reduce the rate in which their egg develops
Why is torpor more frequent and longer duration in winter than in summer?
Because the periods of time the animals have to contend with low temps and reduced food availability tend to be longer
Why do juveniles tend to show much longer and deeper levels of torpor than adults?
Because they have limited resources and the resources that are there are for them to grow and develop not necessarily for them to be using for thermoregulation
What is sympatric speciation?
Is the evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region
What is torpor related to?
Food (at least the depth they go into torpor is related to food)
How does food effect torpor?
Food is related to the depth animals go into torpor
What happens to brain temp and the overall body temp of an animal as fast continues?
The brain temp and overall body temp decline as they are trying to prolong the resources that they have put on before they start having to utilise the proteins and going into that starvation mode
Why does the brain and overall temp of an animal decline as fast continues?
Because they are trying do reduce their overall energy expenditure and they are doing that by allowing their body temp to decrease lower and lower and their metabolic rate starts to decline as well
Give an example of a bird that huddles and the largest recorded huddle and what was found
The ren.
Largest was 67 individuals in one nest box and in the middle was a dead one that had suffocated probs by overheating so huddling is good but you can overdo it
Give an example of a species that had changed its migratory pathway in our lifetime. What is this an example of?
Blackcaps.
Example of natural selection and evolution process
When do animals spend more time in torpor?
When temperatures are low
In small animals where their normal thermal temp is between about 35-45 degrees depending on the species how does it change when they are in torpor?
When they are in torpor the temps are a lot lower
