1. Ecological Theory of Population Distributions

2. The Concept of “Niche” Elton’s (1927) –Emphasized animal’s place in the biotic community –What does the animal do for a living? Hutchinson’s (1957) –N-dimensional hypervolume –What environmental conditions does the critter occupy?

3. But… Relationships Are Dynamic The environment is dynamic (i.e., changing) Site fidelity may prevent immediate response Animal’s may acclimate producing different responses

6. Factors Limiting Distributions 1.Mobility/dispersal 2.Habitat Temperature, moisture, light, oxygen, vegetation, aquatic/lithic substrates 3. Interactions with other animals

7. Limiting Factors – Dispersal

8. Limiting Factors – Dispersal (e.g., Westslope and Yellowstone Cutthroat)

9. Limiting Factors – Dispersal (e.g., Chihuahua Darter)

10. Limiting Factors - Habitat Temperature, Moisture, Light, Oxygen Vegetation, Aquatic or Lithic Substrates

13. Normal Response

14. Logistic Response

15. Limiting Factors – Other Organisms Intraspecific Interactions –Fretwell’s Ideal Free Distribution –The Ideal Despotic Distribution

16. Limiting Factors – Other Organisms Interspecific Interactions –Competition Gause’s Competitive Exclusion –MacArthur (1958) northeastern warblers Character displacement

17. Interspecific Competition Character Displacement

18. Interspecific Competition Character Displacement – Darwin’s Finches

19. Limiting Factors – Other Organisms Predation Disease

20. Limiting Factor? or Factors? Leibig’s Law –Stressed importance of single factors limiting distributions Does not work for interacting factors

21. A Final Note: Hierarchy of Scales