Exploring Ecology: Interactions and Environments

1. Chapter 50 An Introduction to Ecology and the Biosphere

2. Overview: The Scope of Ecology • Ecology is the scientific study of the interactions between organisms and the environment • These interactions determine distribution of organisms and their abundance • Ecology reveals the richness of the biosphere

4. Concept 50.1: Ecology is the study of interactions between organisms and the environment • Ecology has a long history as a descriptive science • It is also a rigorous experimental science

5. Ecology and Evolutionary Biology • Events that occur in ecological time affect life on the scale of evolutionary time

6. Organisms and the Environment • The environment of any organism includes: • Abiotic, or nonliving, components • Biotic, or living, components • All the organisms that are part of the individual’s environment are collectively called the biota • Environmental components affect the distribution and abundance of organisms

7. LE 50-2 Kangaroos/km2 > 20 10–20 5–10 1–5 0.1–1 < 0.1 Limits of distribution Tasmania

8. Ecologists use observations and experiments to test explanations for the distribution and abundance of species

9. Subfields of Ecology • Organismal ecology studies how an organism’s structure, physiology, and (for animals) behavior meet environmental challenges

10. LE 50-3a Organismal ecology

11. Population ecology focuses on factors affecting how many individuals of a species live in an area

12. LE 50-3b Population ecology

13. Community ecology deals with the whole array of interacting species in a community

14. LE 50-3c Community ecology

15. Ecosystem ecology emphasizes energy flow and chemical cycling among the various biotic and abiotic components

16. LE 50-3d Ecosystem ecology

17. Landscape ecology deals with arrays of ecosystems and how they are arranged in a geographic region

18. LE 50-3e Landscape ecology

19. The biosphere is the global ecosystem, the sum of all the planet’s ecosystems

20. Ecology and Environmental Issues • Ecology provides the scientific understanding underlying environmental issues • Rachel Carson is credited with starting the modern environmental movement

22. Most ecologists follow the precautionary principle regarding environmental issues • It states that humans need to be concerned with how their actions affect the environment

23. Concept 50.2: Interactions between organisms and the environment limit the distribution of species • Ecologists have long recognized global and regional patterns of distribution of organisms within the biosphere • Many naturalists began to identify broad patterns of distribution by naming biogeographic realms

24. LE 50-5 Palearctic Nearctic Tropic of Cancer (23.5°N) Oriental Ethiopian Equator Neotropical (23.5°S) Tropic of Capricorn Australian

25. Biogeography is a good starting point for understanding what limits geographic distribution of species

26. LE 50-6 Species absent because Area inaccessible or insufficient time Yes Yes Dispersal limits distribution? Habitat selection Yes Predation, parasitism, competition, disease Chemical factors Behavior limits distribution? No Biotic factors (other species) limit distribution? Water Oxygen Salinity pH Soil nutrients, etc. No Abiotic factors limit distribution? No Temperature Light Soil structure Fire Moisture, etc. Physical factors

27. Dispersal and Distribution • Dispersal is movement of individuals away from centers of high population density or from their area of origin • Dispersal contributes to global distribution of organisms

28. Natural Range Expansions • Natural range expansions show the influence of dispersal on distribution

29. LE 50-7 New areas occupied Year 1996 1989 1974

30. Species Transplants • Species transplants include organisms that are intentionally or accidentally relocated from their original distribution • Species transplants can disrupt the communities or ecosystems to which they have been introduced

31. Behavior and Habitat Selection • Some organisms do not occupy all of their potential range • Species distribution may be limited by habitat selection behavior

32. Biotic Factors • Biotic factors that affect the distribution of organisms may include: • Interactions with other species • Predation • Competition

33. LE 50-8 100 Sea urchin Both limpets and urchins removed 80 Only urchins removed 60 Seaweed cover (%) Limpet 40 Only limpets removed Control (both urchins and limpets present) 20 0 August 1982 February 1984 August 1983 February 1983

34. Abiotic Factors • Abiotic factors affecting distribution of organisms: • Temperature • Water • Sunlight • Wind • Rocks and soil

35. Temperature • Environmental temperature is an important factor in distribution of organisms because of its effects on biological processes

36. Water • Water availability in habitats is another important factor in species distribution

37. Sunlight • Light intensity and quality affects photosynthesis • Light is also important to development and behavior of organisms sensitive to photoperiod

38. Wind • Wind amplifies effects of temperature by increasing heat loss from evaporation and convection • Wind can change morphology of plants

40. Rocks and Soil • Many characteristics of soil limit distribution of plants and thus the animals that feed upon them: • Physical structure • pH • Mineral composition

41. Climate • Four major abiotic components of climate: temperature, water, sunlight, and wind • Climate is the prevailing weather in an area • Macroclimate consists of patterns on the global, regional, and local level • Microclimate consists of very fine patterns, such as those encountered by the community of organisms underneath a fallen log

42. Global Climate Patterns • Global climate patterns are determined largely by solar energy and the planet’s movement in space

43. Sunlight intensity plays a major part in determining the Earth’s climate patterns

44. LE 50-10a North Pole 60°N Low angle of incoming sunlight 30°N Tropic of Cancer Sunlight directly overhead at equinoxes 0° (equator) Tropic of Capricorn 30°S Low angle of incoming sunlight 60°S South Pole Atmosphere

45. Seasonal variations of light and temperature increase steadily toward the poles

46. LE 50-10b March equinox: Equator faces sun directly; neither pole tilts toward sun; all regions on Earth experience 12 hours of daylight and 12 hours of darkness. 60°N 30°N June solstice: Northern Hemisphere tilts toward sun; summer begins in Northern Hemisphere; winter begins in Southern Hemisphere. 0° (equator) 30°S December solstice: Northern Hemisphere tilts away from sun; winter begins in Northern Hemisphere; summer begins in Southern Hemisphere. Constant tilt of 23.5° September equinox: Equator faces sun directly; neither pole tilts toward sun; all regions on Earth experience 12 hours of daylight and 12 hours of darkness.

47. Global air circulation and wind patterns play major roles in determining climate patterns

48. LE 50-10c 60°N 30°N Descending dry air absorbs moisture Descending dry air absorbs moisture 0° (equator) Ascending moist air releases moisture 30°S 60°S 0° 23.5° 23.5° 30° 30° Arid zone Arid zone Tropics

49. LE 50-10d Arctic Circle 60°N Westerlies 30°N Northeast trades Doldrums 0° (equator) Southeast trades 30°S Westerlies 60°S Antarctic Circle

50. Regional, Local, and Seasonal Effects on Climate • Various features of the landscape contribute to local variations in climate • Seasonal variation also influences climate