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FIELD BIOLOGY & METHODOLOGY Fall 2013 Althoff. Lecture 09. Adapting to a Varying Environment. Background considerations. Each type of organism has an ___________ --the habitats which sustain its population

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background considerations
Background considerations...
  • Each type of organism has an ___________--the habitats which sustain its population
  • Environmental conditions _______: a) hourly b) daily c) seasonally d) annually

_______changes – response of giant red velvet mite to changing environmental conditions

Ricklefs Fig. 9.2, p181, 5th edition

in response to change
…in response to change
  • Individuals can make “________” adjustments (shiver, sweat, lower body temperature, etc.) and stay-put
  • Individuals can _____ to “_______” conditions require less internal adjustments
  • ….or some _____________ of these responses.

____________________ tochangesin light and surface reflectance = change in environmental conditions

Ricklefs Fig. 6.17, p128



The ability of an individual to maintain constant __________ conditions in the face of a varying __________ environment

Not all animals do this constantly…when they don’t they may become inactive (think of “cold-blooded” species) and/or physiological functions not as efficient or finely-tuned.

how does a rabbit do this
How does a rabbit do this?
  • “Internal adjustments” a) hourly

b) daily c) seasonally

how does a rabbit do this1
How does a rabbit do this?
  • “External adjustments--habitat selection” a) hourly b) daily c) seasonally

Desert iguana regulates body temperature

by _____________________

Ricklefs Fig. 9.5, p185, 5th edition

based on negative feedback
Based on negative feedback
  • Analogous to thermostat in a house
  • Influence by internal conditions and external environment
  • Examine Fig. 3.22, page 565 a) hypothalamus b) body organs c) body temperature “____________ GOAL”


Negative Feedback System


______________--maintain constant body temperature

  • ______________--use of elevated metabolism to counteract cooling
  • ______________--reliance on external sources to maintain body temp.
  • ______________--failure to regulate body temperature. Often referred to as “cold-blooded” but...
source of heat advantage
Source of Heat? Advantage?
  • Ectotherms: ___________ ex: reptiles & amphibians & insects advantage(s):
  • Endotherms: ___________ ex: birds & mammals advantage(s):
rates of cooling
Rates of Cooling
  • Newton’s law of cooling: “heat loss varies in direct proportion to the gradient between body and ambient temperature”
  • Endotherms counteract this with the varying rate of metabolism
  • To maintain a constant “internal” temperature, a BMR must be achieved

________________- BMR

The amount of energy expended by an animal at

____________, that is required to maintain its body

temperature at least at the lower ambient critical


bmr ambient temperature
BMR & Ambient Temperature
  • Tlc- _______________________Temperature When body temperature goes below Tlc then metabolism must increase (i.e., heat production must increase) to maintain Tlc
  • See next slide….
  • This applies to homeothermic species (i.e., birds and mammals)



FDVMK Fig. 9.2, p158

bmr t lc
BMR & Tlc
  • Body produces sufficient heat to maintain body temperature above Tlc
  • Influenced by __________________: as body size increases, BMR increases more rapidly than body surface area. ___________ fur and feathers reduce thermal conductance.
bmr t lc con t
BMR & Tlc…con’t
  • By reducing thermal conductance, Tlc decreases with increasing size of the animal.
  • Comparison: a) sparrow Tlc is 30C b) penguin Tlc is 0C
heat exchange
__________________ Heat Exchange
  • Evolved as an adaptation for homeotherms when more energy required than an individual can provide. It is an “__________ _____________”
  • Some portion of the body, usually an “uncovered, uninsulated” extremity, can survive at ___________ temperatures than the rest of the body.
countercurrent heat exchange
Countercurrent Heat Exchange
  • Example of gulls, ducks, other birds without feathers on tarsa as illustrated in Fig. 3.24, page 57
  • Arterial blood vessels anatomically in ______ ________ to venous blood vessels allows for “transfer of heat” before blood goes out to extremity and “warming up” on way back
another adaptation
_________ - another adaptation
  • DEFINED = a voluntary, reversible condition of lowered body temperature and inactivity. Differs from hibernation in length of time and degree of “shutdown” by the body
  • Exhibited by some species, in cool climates (or occasionally cool climates) that would starve otherwise (Fig. 3.23, page 57 - hummingbirds)
activity space

Activity Space

The “space” which an organism ___________. It is usually a limited range of conditions. The concept applies to all aspect’s of the individual’s life…

….have somewhat already introduced this concept with the “zone of tolerances” material

activity space examples
Activity Space - examples
  • Seeds of a plant: “everything must be just right to germinate & grow” (Jack pine -- soil, light, fire, etc.)
  • Southern Flying Squirrel
  • Grasshoppers
  • __________________ of the habitat
  • Create ___________________ (temperature, light, pH, DO2, wind velocity, availability of foods etc.) that enable the individual to most efficiently obtain food (energy intake) or reduce heat loss (energy expended)…or some combination
microhabitat selection
Microhabitat Selection
  • Choosing one “habitat” ________________ to its availability
  • Contrasts habitat “use”
  • Example: Verdin nest opening orientation
in summary
In summary…
  • Most traits of organisms ________ in response to environments
  • Individual organisms can respond to changes in their environment by altering their ___________________________________.
  • Organisms have characteristic activity spaces defined by the conditions within they can ______ AND ______________
  • Animal ___________________ whose physical conditions fall within their activity space