herpetology (bio 488), spring ‘11, poe & snell, l03 – energetics & performance continued...

Herpetology (Bio 488), Spring ‘11, Poe & Snell, L03 – Energetics & Performance continued 1

Energetics & Performance:Components of Heat Exchange Work in Concert

Herpetology (Bio 488), Spring ‘11, Poe & Snell, L03 – Energetics & Performance continued 2

• Behavioral Aspects of Thermoregulation– A large part of thermoregulation in amphibians and reptiles is behaviorally

controlled – Body temperature generally regulated within a narrow, optimum range of

temperatures. • Particularly true of reptiles. • Temperature sensitive region of brain is the hypothalamus (monitors

temperature of blood).

• Cardiovascular Control of Thermoregulation– In many reptiles, the cardiovascular system is also important in regulating

the rate of heating and cooling of the body.

• Heating and cooling rates are not equal. Why?

• 3 ways the cardiovascular system helps regulate these rates: – Higher heart rate during heating. – Intracardiac shunt: Blood transfer in heart that increases proportion of

blood going to skin and body (decrease amount going to lungs). – Vasodilatation in areas of skin that are warm.

Energetics & Performance:Physics of Heat Exchange & Behavior Yield Thermoregulation

Herpetology (Bio 488), Spring ‘11, Poe & Snell, L03 – Energetics & Performance continued 3

• Development of Our Understanding of Thermoregulation:

Energetics & Performance:Physics of Heat Exchange & Behavior Yield Thermoregulation

However, Skeptics found that:

Herpetology (Bio 488), Spring ‘11, Poe & Snell, L03 – Energetics & Performance continued 4

Energetics & Performance:Physics of Heat Exchange & Behavior Yield Thermoregulation

Australian Bearded Dragon (Poona barbate)

• This Lead to Research Into Physiological Adaptation:

Herpetology (Bio 488), Spring ‘11, Poe & Snell, L03 – Energetics & Performance continued 5

Energetics & Performance:Physics of Heat Exchange & Behavior Yield Thermoregulation

• And Research Into Behavioral Mechanisms:

Dipsosaurus dorsalis

Upper “Set Point”

Lower “Set Point”

Ameiva festiva

Herpetology (Bio 488), Spring ‘11, Poe & Snell, L03 – Energetics & Performance continued 6

Energetics & Performance:Physics of Heat Exchange & Behavior Yield Thermoregulation

• As Well As Behavioral Physiology:

Brooding female python

Non-brooding female

Herpetology (Bio 488), Spring ‘11, Poe & Snell, L03 – Energetics & Performance continued 7

Energetics & Performance:Physics of Heat Exchange & Behavior Yield Thermoregulation

More Behavioral Physiology:

Herpetology (Bio 488), Spring ‘11, Poe & Snell, L03 – Energetics & Performance continued 8

Energetics & Performance:Physics of Heat Exchange & Behavior Yield Thermoregulation

Then Completely Integrated Field Observational Studies:

Herpetology (Bio 488), Spring ‘11, Poe & Snell, L03 – Energetics & Performance continued 9

Energetics & Performance:Physics of Heat Exchange & Behavior Yield Thermoregulation

Similar Effects Exist for Water Balance:

Water Effects

Water Impacts Temperature Effects

Herpetology (Bio 488), Spring ‘11, Poe & Snell, L03 – Energetics & Performance continued 10

Energetics & Performance:Physics of Heat Exchange & Behavior Yield Thermoregulation

So What Does This Do For Reptiles & Amphibians?

TheoreticalReal (Ameiva festiva)

Herpetology (Bio 488), Spring ‘11, Poe & Snell, L03 – Energetics & Performance continued 11

Energetics & Performance:Physics of Heat Exchange & Behavior Yield Thermoregulation

Which Came First?Evolution of “Preferred” Body Temperature,

or

Convergence of Optimal Levels of Processes?

Natrix maura

Herpetology (Bio 488), Spring ‘11, Poe & Snell, L03 – Energetics & Performance continued 12

Energetics & Performance:Physics of Heat Exchange & Behavior Yield Thermoregulation

Either Way the Use of Exothermal Energy Partially Explains the Superiority of Reptiles and Amphibians!