Chapter 5

Microclimate

Small scale changes in environmental conditions caused by interactions between climate and topography.

Examples of microclimates

• coastal areas

• urban heat islands

• caves

• mountain valleys/slopes

plants/animals using or creating microclimates in nature:

• Plant foliage provides shade

• small organisms create burrows that have their own microclimate

• weeds using exposed urban areas to spread.

• animals building dams that dry up streams (?)

Major contributing factors of microclimates

• ground color can create microclimates

• vegetation (shade)

• altitude (higher = lower temp.)

• aspect (direction of land)

Principle of allocation

If an organism allocates energy to one expense, this reduces the amount of energy available for other expenses.

Principle of allocation: temperature and performance

Temperature can have an affect on physiology and behavior of organisms

Thermoregulation

An organisms ability to regulate it’s body temperature by balancing heat gain and loss.

Ectotherms

Organisms that rely on external sources of energy to regulate body temperature. (snails, worms)

• use physical variations (body size, shape, pigmentation)

• behaviors (basking, burrowing, huddling)

Poikilotherms

Organisms whose body temperature varies directly with the environment. (snakes/frogs)

Endotherms

Rely mainly on internal sources of energy for regulating body temperature. (Birds and certain fish)

• physiological and behavioral mechanisms: vasoconstriction, insulation (fat, fur, feathers), shivering, fat metabolism, group huddling, sweating

Homeotherms

Endotherms that uses metabolic energy to maintain a relatively constant body temperature. (Humans, dogs, cats)

Thermal Neutral Zone

Range of environmental temps. over which the metabolic rate of endotherms does not change.

what category of species has a narrower thermal neutral zone and which one has a broader one?

• Narrower = Tropical - climate is relatively stable (less need to adapt)

• Broader = Arctic Tundra - climate fluctuates throughout seasons (greater need for adaptations)