8.1.2 Energy Flow

Metabolism

1. Endotherm

2. Ectotherm

Endotherm

use metabolism to keep a stable body temp

Baseline - Basal Metabolic Rate (BMR)

• Metabolism at rest

Ectotherm

does NOT use metabolism to keep a stable body temp

Baseline - Standard Metabolic Rate (SMR)

• minimum metabolism needed to sustain life at a given temperature

Smaller organisms

these organisms have higher metabolic rates per mass

• Applies to both ectotherms and endotherms

Torpor

state of decr activity and metabolism that allows animals to survive unfavorable conditions

1. Hibernation

2. Estivation

Hibernation

torpor during winter

Estivation

torpor during summer

types of Heat exchange

1. Radiation

2. Conduction

3. Evaporation

Radiation

exchange heat via infrared radiation

Conduction

exchange heat via direct contact

Evaporation

exchange heat via evaporation of water

Heat regulation methods

1. Behavioral changes

2. thermogenesis

3. vasoconstriction/vasodilation

4. countercurrent heat exchange

5. insulation and evaporation adaptations

Behavioral changes

changing behavior to increase or decrease body temperature

• very impt in ectotherms

Thermogenesis

• only in endotherms

  • thermogenesis uses metabolism to create heat

• deliberate movements

  • walking around, continuous motion, rubbing hands together

• Shivering

  • Nondeliberate muscle movements

• non-shivering thermogenesis

  • burning of special fat tissue - brown fat

  • brown fat is found in many hibernating mammals

Non-shivering thermogenesis

burn brown fat to generate heat

• found in many hibernating mammals

vasoconstriction

Countercurrent heat exchange

Arterial blood heats up venous blood returning from extremities

→ arterial blood loses less heat as it goes to extremities

→ venous blood is warmed up before it returns to body’s core

insulation adaptations

hairs, feathers, fat insulate heat

evaporation adaptations

sweating helps regulate heat

Reproductive life histories (patterns)

1. Energy investment per offspring

2. fecundity

3. reproductive timing

4. semelparity vs iteroparity

Energy investment vs fecundity tradeoff 2 strategies

1. Low energy investment / high fecundity

2. high energy investment / low fecundity

reproductive timing

• breed earlier in life

• breed later in life — risk dying before you can breed

Semelparity

breed once in a lifetime

Iteroparity

Breeds multiple times in one lifetime