Lecture 2 & 3:Physical challenges of the environment
Animals Geographic ranges usually correspond to biomes (limit to climates or
vegetation), but sometimes it is also affected by other factors:
○ Pronghorns have a broad temperature tolerance range but a narrow
Other organisms ( enemies, friends)
○ Elf owls, gila woodpekers depends on cactus.
○ Tigers can live in any habitat either hot or cold.
Ways to gain or loss heat:
Radiation: emission of electromagnetic energy by a warm surface.
Conduction: transfer of the kinetic energy of heat between substances in contact
with one another.
Convection: transfer of heat by the movement of liquids and gases
Evaporation: efficient cooling from wet surface.
Redistribution: circulatory system redistributes heat among body parts.
Body size and thermal inertia:
Larger organisms tend to lose heat across their surfaces less rapidly than smaller
individuals this is because the surface-to-volume ratio is smaller(V 比 SA 大). It is
easier for them to maintain a constant internal environment in the face of
varying external conditions.
○ Bergmann’s Rule: Homeotherms tend to be larger at a higher altitude.
Polar bear lives in the Artic are bigger than Sun bear that live
in the tropics.
○ Allen’s Rule: appendages reduced in cold temperature.
Pika has spheri