Chapter 4 - Temperature Relations

CNN is reporting that a chunk of ice shelf nearly the size of Manhattan has broken away from Ellesmere Island in Canada's northern Arctic. Just last month 21 square miles of ice broke free from the Markham Ice Shelf. Scientists are saying that Ellesmere Island has now lost more than 10 times the ice that was predicted earlier this summer.

Question of the Day

If the arctic ice cap melts completely,

Then, what do you think will be the worst thing that will happen to the global ecology?

Chapter 4 - Temperature Relations

Objectives:

1. List reasons why differences in temperature exist on a microscale

2. Explain why organisms perform best in a narrow range of temperature

3. Describe how organisms compensate for variations in environmental temperatures

Chapter 4 - Temperature Relations

Objectives:

4. Define resting stages and their applications

5. Identify where heat comes from and where is goes!!!

Temperature Microscales

Temperature Microscales

HotCool

Fig. 4.3

Fig. 4.1

Temperature Microscales

1. Altitude: temperatures decrease as altitude increases

2. Aspect: Shading parts of the land -

e.g., “North Facing Slope” and ski areas

Temperature Microscales

3. Vegetation: Plants create microclimate

Temperature Microscales

4. Color: e.g., ground

Warmest Coolest

Solar Radiation

Temperature Microscales

5. Boulders, burrows, or any other landscape feature that absorbs, reflects, or alters the sun’s radiant energy, alters temperature.

Temperature Microscales

6. Aquatic habitats:

• Evaporation of water surfaces cools “Latent heat of vaporization” - absorbs heat as it evaporates

• Freezing “Latent heat of fusion” gives up heat energy to the environment

• Thermal stability of water is greater than air

Fig. 4.7

What do we know so far?

1. Temperature can change dramatically over a very small distance.

2. Organisms may cause this change (e.g., plant and shade).

3. Colors, and other landscape features drive this change.

4. Aquatic Environments more resistant to changes in temperature.

2nd Question of the Day!!

“Micro” infers a very small area. Define how big this is (using a metric scale) defending your answer with examples.

Temperature Effects Range of Tolerance

Environmental range of biological processes:

Minimum Temperature - 0 C

Maximum Temperature - 40 C

Optimum Temperature* - 20-40 C

* different for each organism

Temperature Effects

Death at High Temperatures:

Primary cause is the denaturing of enzyme proteins necessary for metabolism

Death at Low Temperatures:

Formation of ice crystals within cells, rupturing membranes

Temperature Effects

Between the Extremes:

Temperature affects the organisms by controlling the rates of enzyme reactions in metabolic pathways!!

Fig. 4.10

Law of Tolerance

Shelford (1913)

“There are upper and lower bounds to physical factors that an organism can tolerate”

Law of Tolerance

Fig. 4.10

Adaptations Temp. Variations

Organisms must regulate temperature (if possible) for optimum growth.

How?

They can gain or lose heat in a variety of ways

Physics of Energy Exchange

• Radiation (Electromagnetic)

• Conduction

• Convection

• Evaporation

Radiation

Transfer of energy through electromagnetism

• Every object emits radiation

• Amount and type depends on the temperature of object

• Does not require the presence of matter

• Living organisms absorb solar radiation in the visible light range, and radiate energy as heat

Conduction

Movement of heat through matter

FROM: region of high temperature

TO: region of low temperature

RATE: proportional to gradient

proportional to surface area

conductivity of material

inversely proportional to distance

Convection

Transfer of heat by the circulation of a fluid--liquid or gas

Wind Chill

Convection

Transfer of heat by the circulation of a fluid--liquid or gas

WC = 91.4 - (0.474677 - 0.020425 * V + 0.303107 * SQRT(V)) * (91.4 - T)

where: WC = wind chill index V = wind speed (mph) T = temperature (° F)

Evaporation

Heat energy dissipated by converting water from liquid to gas:

e.g., sweat, evapotranspiration

539 kcal of heat consumed to covert one kg of water from liquid to vapor

Latent Heat of Vaporization

Thermal Budgets

If: an organism absorbs more energy than it emits or stores in chemical bonds

Then: Temperature increases

If: an organism absorbs less energy than it emits or releases from chemical bonds

Then: Temperature decreases

Temperature - The Formula

Hs = Hm + Hcd + Hcv + Hr + He

Where:

Hs = Total heat stored in body

Hm= Heat gained from metabolism

Hcd = Heat gained or lost from conduction

Hcv = Heat gained or lost from convection

Temperature - The Formula

Hs = Hm + Hcd + Hcv + Hr + He

Where:

Hr = Heat gained or lost through electromagnetic radiation

He = Heat lost through evaporation

Fig. 4.14

Thermal Regulation

How do organisms regulate temperature?

Have we answered this question?

Subject of lecture next Tuesday

What did we learn today?

• Microclimates

• Types of energy and heat transfer

• Minimum, maximum and optimum temperatures

• Read Chapter 4 for next Tuesday--------

Chapter 4

Temperature

Thermal inputs - Generating Heat!!:

Direct sunlight

Diffuse solar radiation

Heat radiation from surroundings

Conduction from environment

Heat of metabolism

Temperature

Thermal Outputs - Losing Heat!!!!:

Longwave radiation to surroundings

Conduction to environment

Convection

Evaporation