integrated lec 15 Flashcards
physiological ecology
Definition:
Study of how organisms acquire energy and nutrients while tolerating environmental conditions.
Examines physiological adaptations in an ecological context.
Core Concepts:
Tolerance Ranges: Distribution limits set by temperature, moisture, and other environmental factors.
Homeostasis: Maintaining stable internal conditions despite external variability.
Trade-offs: Adaptive compromises between competing functions
heat balance and thermal ecology
Key Principles:
Poikilotherms (e.g., reptiles, amphibians): Body temperature fluctuates with the environment.
Homeotherms (e.g., birds, mammals): Maintain constant internal temperature, requiring significant energy investment.
Modes of Heat Gain and Loss:
Radiation: Heat transfer via electromagnetic waves.
Conduction: Direct transfer through contact (e.g., feet on cold ground).
Convection: Heat exchange with moving air or water.
Evaporation: Cooling via water loss from surfaces.
Redistribution: Heat moved between body parts by the circulatory system.
Surface Area to Volume Ratio (SA:V)
Key Concept:
Smaller organisms (high SA:V): Lose heat quickly, equilibrate fast.
Larger organisms (low SA:V): Retain heat, equilibrate slowly.
bergmann’s rule
Homeotherms are larger at higher latitudes (colder climates) to reduce heat loss.
Example: Polar bear > Black bear > Sun bear.
shape and function
Adaptations:
Spherical shapes: Minimize SA:V for heat retention.
Specialized shapes: Enhance functionality (e.g., gliding snakes in warm tropics).
Allen’s Rule:
Appendages are shorter in colder climates to reduce heat loss (e.g., Arctic fox vs. Fennec fox).
insulation and cooling
Mechanisms:
Fur, Blubber, Feathers: Reduce heat loss in cold environments.
Countercurrent Circulation:
Heat conservation by transferring warmth between arteries and veins in appendages.
Evaporative Cooling:
Heat dissipated via sweating, panting, or other water-loss mechanisms.
Adaptive Trade-offs
Case Study: Weasel Body Shape:
Long, thin shape increases heat loss (high SA:V) but enhances hunting efficiency.
Trade-off: Energy cost of maintaining warmth is offset by improved predation success.
Constraints in Evolution
Limitations:
Adaptations are shaped by existing developmental pathways.
Evolution “tinkers” rather than creates entirely new designs.
What is Bergmann’s Rule?
A: Larger body sizes are found in colder climates to conserve heat, while smaller sizes occur in warmer climates.
What is Allen’s Rule?
A: Animals in colder climates have shorter appendages to reduce heat loss, while those in warmer climates have longer appendages for cooling
Why are spherical shapes beneficial in cold environments?
A: They minimize the SA:V ratio, reducing heat loss.
How does a snake’s elongated body shape benefit its function?
A: Enhances mobility and hunting efficiency, especially in warm environments.
How does countercurrent circulation conserve heat?
A: Warm blood from the body core transfers heat to cooler blood returning from extremities.
How does the weasel’s body shape illustrate trade-offs?
A: Its elongated shape increases heat loss but improves hunting agility in narrow spaces.
How does Bergmann’s Rule apply to fox species?
A: Arctic foxes are stockier with shorter ears, while fennec foxes have long ears to dissipate heat.