Chapter 52

1. Chapter 52 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.

3. The Scope of Ecological Research • Ecologists work at levels ranging from individual organisms to the planet.

4. Organismal ecology studies how an organism’s structure, physiology, and (for animals) behavior meet environmental challenges.

5. Figure 52.1 Why do gray whales migrate? Fig. 52-1

6. Fig. 52-2 Organismal ecology Population ecology Figure 52.2 The scope of ecological research Community ecology Ecosystem ecology Landscape ecology Global ecology

7. Fig. 52-2a Figure 52.2 The scope of ecological research

8. A population is a group of individuals of the same species living in an area. • Population ecology focuses on factors affecting how many individuals of a species live in an area.

9. Fig. 52-2b Figure 52.2 The scope of ecological research

10. A community is a group of populations of different species in an area. • Community ecology deals with the whole array of interacting species in a community.

11. Fig. 52-2c Figure 52.2 The scope of ecological research

12. An ecosystem is the community of organisms in an area and the physical factors with which they interact. • Ecosystem ecology emphasizes energy flow and chemical cycling among the various biotic and abiotic components.

13. Fig. 52-2d Figure 52.2 The scope of ecological research

14. A landscape is a mosaic of connected ecosystems. • Landscape ecology deals with arrays of ecosystems and how they are arranged in a geographic region.

15. Fig. 52-2e Figure 52.2 The scope of ecological research

16. Figure 52.2 The scope of ecological research • The biosphere is the global ecosystem, the sum of all the planet’s ecosystems. • Global ecology examines the influence of energy and materials on organisms across the biosphere.

17. Fig. 52-2f Figure 52.2 The scope of ecological research

18. Concept 52.1: Ecology integrates all areas of biological research and informs environmental decision making • Ecology has a long history as a descriptive science. • It is also a rigorous experimental science.

19. Fig. 52-3 Figure 52.3 Studying how a forest responds to altered precipitation Trough Pipe “Dry” “Wet” “Ambient”

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

21. Ecology and Environmental Issues • Ecology provides the scientific understanding that underlies environmental issues. • Ecologists make a distinction between science and advocacy. • Rachel Carson is credited with starting the modern environmental movement with the publication of Silent Spring in 1962.

22. Fig. 52-4 Figure 52.4 Rachel Carson

23. Concept 52.2: 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. • Biogeography is a good starting point for understanding what limits geographic distribution of species. • Ecologists recognize two kinds of factors that determine distribution: biotic, or living factors, and abiotic, or nonliving factors.

24. Fig. 52-5 Kangaroos/km2 0–0.1 0.1–1 1–5 5–10 10–20 > 20 Limits of distribution Figure 52.5 Distribution and abundance of the red kangaroo in Australia, based on aerial surveys

25. Ecologists consider multiple factors when attempting to explain the distribution of species.

26. Fig. 52-6 Figure 52.6 Flowchart of factors limiting geographic distribution Why is species X absent from an area? Yes Area inaccessible or insufficient time Yes Habitat selection Does dispersal limit its distribution? Yes Predation, parasitism, competition, disease Chemical factors Does behavior limit its distribution? No Do biotic factors (other species) limit its distribution? Water Oxygen Salinity pH Soil nutrients, etc. No Do abiotic factors limit its 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. Fig. 52-7 Current Figure 52.7 Dispersal of the cattle egret in the Americas 1970 1966 1965 1960 1961 1943 1958 1937 1951 1956 1970

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. Fig. 52-8 RESULTS Figure 52.8 Does feeding by sea urchins limit seaweed distribution? 100 Both limpets and urchins removed 80 Sea urchin Only urchins removed 60 Seaweed cover (%) Limpet 40 Only limpets removed 20 Control (both urchins and limpets present) 0 August 1982 February 1983 August 1983 February 1984

34. Abiotic Factors • Abiotic factors affecting distribution of organisms include: • Temperature • Water • Sunlight • Wind • Rocks and soil • Most abiotic factors vary in space and time.

35. Temperature • Environmental temperature is an important factor in distribution of organisms because of its effects on biological processes. • Cells may freeze and rupture below 0°C, while most proteins denature above 45°C. • Mammals and birds expend energy to regulate their internal temperature.

36. Water • Water availability in habitats is another important factor in species distribution. • Desert organisms exhibit adaptations for water conservation.

37. Salinity • Salt concentration affects water balance of organisms through osmosis. • Few terrestrial organisms are adapted to high-salinity habitats.

38. Sunlight • Light intensity and quality affect photosynthesis. • Water absorbs light, thus in aquatic environments most photosynthesis occurs near the surface. • In deserts, high light levels increase temperature and can stress plants and animals.

39. Figure 52.9 Alpine tree Fig. 52-9

40. Rocks and Soil • Many characteristics of soil limit distribution of plants and thus the animals that feed upon them: • Physical structure: provide habitats, shelter, protection from predators, etc. • pH • Mineral composition

41. Climate • Four major abiotic components of climate are temperature, water, sunlight, and wind. • The long-term prevailing weather conditions in an area constitute its climate. • 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. • Sunlight intensity plays a major part in determining the Earth’s climate patterns. • More heat and light per unit of surface area reach the tropics than the high latitudes.

43. Fig. 52-10a Latitudinal Variation in Sunlight Intensity 90ºN (North Pole) 60ºN Low angle of incoming sunlight 30ºN 23.5ºN (Tropic of Cancer) Figure 52.10 Global climate patterns Sun directly overhead at equinoxes 0º (equator) 23.5ºS (Tropic of Capricorn) 30ºS Low angle of incoming sunlight 60ºS 90ºS (South Pole) Atmosphere Seasonal Variation in Sunlight Intensity 60ºN 30ºN March equinox 0º (equator) June solstice 30ºS December solstice Constant tilt of 23.5º September equinox

44. Fig. 52-10b Figure 52.10 Global climate patterns 90ºN (North Pole) 60ºN Low angle of incoming sunlight 30ºN 23.5ºN (Tropic of Cancer) Sun directly overhead at equinoxes 0º (equator) 23.5ºS (Tropic of Capricorn) 30ºS Low angle of incoming sunlight 60ºS 90ºS (South Pole) Atmosphere

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

46. Fig. 52-10c Figure 52.10 Global climate patterns 60ºN 30ºN March equinox 0º (equator) June solstice 30ºS December solstice Constant tilt of 23.5º September equinox

47. Global air circulation and precipitation patterns play major roles in determining climate patterns. • Warm wet air flows from the tropics toward the poles.

48. Fig. 52-10d Global Air Circulation and Precipitation Patterns Figure 52.10 Global climate patterns 60ºN 30ºN Descending dry air absorbs moisture Descending dry air absorbs moisture 0º (equator) Ascending moist air releases moisture 30ºS 0º 60ºS 23.5º 23.5º 30º 30º Arid zone Arid zone Tropics Global Wind Patterns 66.5ºN (Arctic Circle) 60ºN Westerlies 30ºN Northeast trades Doldrums 0º (equator) Southeast trades 30ºS Westerlies 60ºS 66.5ºS (Antarctic Circle)

49. Fig. 52-10e Figure 52.10 Global climate patterns 60ºN Descending dry air absorbs moisture Descending dry air absorbs moisture 30ºN 0º (equator) Ascending moist air releases moisture 30ºS 60ºS 0º 23.5º 23.5º 30º 30º Arid zone Arid zone Tropics

50. Air flowing close to Earth’s surface creates predictable global wind patterns. • Cooling trade winds blow from east to west in the tropics; prevailing westerlies blow from west to east in the temperate zones.