Adapting to a Varying Environment

1. FIELD BIOLOGY & METHODOLOGYFall 2013 Althoff Lecture 09 Adapting to a Varying Environment

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

3. _______changes – response of giant red velvet mite to changing environmental conditions Ricklefs Fig. 9.2, p181, 5th edition

4. …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.

5. ____________________ tochangesin light and surface reflectance = change in environmental conditions Ricklefs Fig. 6.17, p128

6. Homeostasis 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.

7. How does a rabbit do this? • “Internal adjustments” a) hourly b) daily c) seasonally

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

9. Desert iguana regulates body temperature by _____________________ Ricklefs Fig. 9.5, p185, 5th edition

10. 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”

11. SET POINT Negative Feedback System

12. ______________--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...

13. Source of Heat? Advantage? • Ectotherms: ___________ ex: reptiles & amphibians & insects advantage(s): • Endotherms: ___________ ex: birds & mammals advantage(s):

14. 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

15. ________________- 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 temperature.

16. 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)

17. Metabolism temperature FDVMK Fig. 9.2, p158

18. 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.

19. 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

20. __________________ 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.

21. 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

22. Ricklefs Fig. 3.24, p57

23. _________ - 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)

24. Ricklefs Fig. 3.24, p57

25. 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

26. 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

27. Microhabitats • __________________ 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

28. Microhabitat Selection • Choosing one “habitat” ________________ to its availability • Contrasts habitat “use” • Example: Verdin nest opening orientation

29. 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