Environmental Physiology Flashcards
In the context of an allometric analysis, what does the slope in a log-log plot signify?
It measures the average or expected relationship between two traits in a relatively homogeneous group of animals.
In the context of an allometric analysis, what does the offset in a log-log plot signify?
It measures the effects of variables on the trait in question. E.g. metabolic rate, that are consistently different between animal groups
Why would you want to correct for temperature when comparing the metabolic rates across different animal groups?
- It helps them to become more comparable when considering aspects other than
temperature. - It helps partitioning the variation in offsets.
- Different groups of animals have different optimum temperature ranges for metabolism
- When you correct for temperature, you can compare the groups more closely, to see if there is still a significant difference in groups – and if so, there must be another variable at play
Why is the within species slope of Body mass vs BMR 0.67?
- We expected 0.75 (surface/volume ratio)
- Changes in size (volume) require more expensive adjustment than what just surface can account for
- The best hypothesis is that the adjustment of the BMR to take advantage of the larger mass is not trivial and requires the adjustment of many components of the cellular machinery, which takes too much time
advantages of 2-species comparison
- Simple
- Easy to execute
- Allows in depth studies to take place
- Understand the limitations to the study
- Result is consistent with the hypotheses – never proves it
disadvantages of 2-species comparison
unable to interpret the results
Why do we need to adjust our methods/statistics for phylogeny?
- Achieve independence of data for testing
is adjusting for phylogeny fundamentally different than adjusting for mass?
- When you adjust for mass, you remove a confounding variable/effect – this is the same when you adjust for phylogeny (these adjustments are fundamentally the same)
3 crucial aspects of experimental design
- replication
- randomisation
-control
Why do I believe more in an experiment that is embedded in theory?
- Without theory, if I randomly pick two variables, my probability of a false positive is almost 5%
- With theory, the probability drops by a lot, because if the theory is right, I mostly test on existing correlations
Why is the ecological cost of transport (ECT) as a percentage of total field metabolic rate (FMR) higher in reptiles than in mammals?
- If they use the same amount of energy to move as metabolic rate, this is a higher proportion
- Therefore, reptiles have a higher ECT over FMR
What are the two fundamental mechanisms with which you can take up water?
- Fluid and food intake (preformed water)
- Metabolic water
Why does kidney size (medulla) correlate with urine concentration?
Longer loop of Henle, which allows a stronger gradient of concentration to be built up
What is a receptive field?
The portion of sensory space in which the presence of a stimulus can modify a neuron’s response
How do spiking neurons transmit information?
- By adjusting the rate of spikes according to the input strength
- There is also information in the timing of the response
What would happen if you were able to project a letter of a certain colour very accurately onto a part of the retina,
so it will stay there irrespective of head and eye movements?
- Your perception of the letter will quickly fade over time and you would not see it any
more. - This is due to sensory adaptation of the photoreceptors
What does sensory adaptation mean and what is its purpose?
- Sensory adaptation means the neurons adapt to the current stimulation levels such
that they are operating in the linear range of their response range - Its purpose is to increase/maximise sensitivity to (time) local contrasts and extend the ability to perceive stimulus changes over a large input range.
Can you give a few examples of sensory adaptation?
- Speed perception after travelling on a highway for an extended period
- Dark / light adaptation
- Colour after effects (after looking at a patch of colour for an extended period)
- Temperature perception (entering a cold/hot shower)
What are the main differences between anaerobic and aerobic metabolisms
Aerobic:
– Requirement of oxygen
– Slower
– More efficient 36 vs 2‐6 ATP per glucose
– Takes place inside mitochondria (after common startpoint)
What is the biggest consequence of the evolution of the aerobic metabolism?
– Large, multicellular animals
Fiddler crabs can breath in the water as well as in the air.
So why do we transport fiddler crabs in containers with
only very little water?
The molecular concentration of oxygen in water depends on temperature.
When the water heats up it loses oxygen. If the crabs are submerged, they will drown
Why do we have a circulation system?
Reduce diffusion distance. Use convection to deliver oxygen and other substances close to or away from cells
Why do we have lungs?
- Optimise common surface area between blood and air.
- Because gills don’t work in air.
What is the main difference between a lung and a trachea?
- Lungs are compact
- No convection mechanism
How do elasmobranchs make sure their blood never stops circulating?
The bulbus cordis is elastic and slowly contracts when the ventricular pressure is low
Why does frog skin have a high evaporative water loss ?
The skin itself presents no barrier to water loss (low diffusion resistance), so the outside is effectively a water film. There is effectively no diffusion barrier
