Daphnia and the Effects of Temperature

1
Daphnia and the Effects of Temperature

• What does increasing temperature do to the heart
  rate of an ectothermic organism and why?

2
What is daphnia?
3
What is a ectotherm vs an endotherm?

• An ectothermic organisms metabolism depends upon
  the temperature of the surroundings.
• Rate of metabolism increase 2X for every 10
  degree C increase
• Remember enzymes optimal temp. experiment?
• Endothermic organisms do not have to worry about
  this so much. They can maintain homeostasis
  (internal temp) so heart rate does not change
  much with increasing temperature.

4
Daphnia data
5
Calculating Q10

• Q10 Rate at higher temperature/Rate at lower
  temperature
• Here Q10 290/152 1.91
• What would the Q10 of an endotherm look like
  compared to that of the above ectotherm?
• Answer closer to 1. Remember that endotherms do
  not really need to increase heart rate because
  the temperature inside their bodies remains
  relatively constant.