Ecology is the study of interactions between organisms and the environment

1. Ecology is the study of interactions between organisms and the environment • Ecology reveals the richness of the biosphere • Ecology has a long history as a descriptive science • These interactions determine distribution of organisms and their abundance • Events that occur in ecological time affect life on the scale of evolutionary time • Rachel Carson is credited with starting the modern environmental movement

2. 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

3. Kangaroos/km2 > 20 10–20 5–10 1–5 0.1–1 < 0.1 Limits of distribution Tasmania

4. Subfields of Ecology • Organismal ecology studies how an organism’s structure, physiology, and (for animals) behavior meet environmental challenges • Population ecology focuses on factors affecting how many individuals of a species live in an area • Community ecology deals with the whole array of interacting species in a community • Ecosystem ecology emphasizes energy flow and chemical cycling among the various biotic and abiotic components • Landscape ecology deals with arrays of ecosystems and how they are arranged in a geographic region

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

6. Palearctic Nearctic Tropic of Cancer (23.5°N) Oriental Ethiopian Equator Neotropical (23.5°S) Tropic of Capricorn Australian

7. 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 • Natural range expansions show the influence of dispersal on distribution

8. New areas occupied Year 1996 1989 1974

9. 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 • Some organisms do not occupy all of their potential range • Species distribution may be limited by habitat selection behavior

10. Biotic Factors and Abiotic Factors • Biotic factors that affect the distribution of organisms may include: • Interactions with other species, predation and competition • Abiotic factors affecting distribution of organisms: • Temperature, water, sunlight, wind, rocks and soil

11. 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

12. Environmental temperature is an important factor in distribution of organisms because of its effects on biological processes • Water availability in habitats is another important factor in species distribution • Light intensity and quality affects photosynthesis, and it is also important to development and behavior of organisms sensitive to photoperiod • Wind amplifies effects of temperature by increasing heat loss from evaporation and convection. Wind can also change morphology of plants • Many characteristics of soil limit distribution of plants and thus the animals that feed upon them: physical structure, pH and mineral composition

14. 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 • 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

15. 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

16. Global air circulation and wind patterns play major roles in determining climate patterns 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. Seasonal variations of light and temperature increase steadily toward the poles

17. 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

18. Arctic Circle 60°N Westerlies 30°N Northeast trades Doldrums 0° (equator) Southeast trades 30°S Westerlies 60°S Antarctic Circle

19. Oceans and their currents and large lakes moderate the climate of nearby terrestrial environments

20. Mountains have a significant effect on the amount of sunlight reaching an area, the local temperature and rainfall. Wind direction East Pacific Ocean Sierra Nevada Coast Range

21. The angle of the sun leads to many seasonal changes in local environments. Lakes are sensitive to seasonal temperature change and experience seasonal turnover Spring Winter O2 (mg/L) O2 (mg/L) 0 4 8 12 0 4 8 12 Lake depth (m) Lake depth (m) 8 8 16 16 0° 4° 4° 2° 24 24 4° 4° 4° 4° 4° 4° 4°C 4°C O2 concentration High (>8 mg/L) Medium (4–8 mg/L) Low (<4 mg/L) O2 (mg/L) O2 (mg/L) 0 4 8 12 0 4 8 12 Lake depth (m) Lake depth (m) 4° 22° 8 8 4° 20° 18° 4° 8° 4° 16 16 6° 4° 5° 4°C 4°C 24 24 Summer Thermocline Autumn

22. Abiotic and biotic factors influence the structure and dynamics of aquatic biomes • Varying combinations of biotic and abiotic factors determine the nature of biomes • Biomes are the major ecological associations that occupy broad geographic regions of land or water • Aquatic biomes account for the largest part of the biosphere in terms of area • They can contain fresh water or salt water • Oceans cover about 75% of Earth’s surface and have an enormous impact on the biosphere

23. 30°N Tropic of Cancer Equator Continental shelf Tropic of Capricorn 30°S Key Lakes Abyssal zone (below oceanic pelagic zone) Estuaries Rivers Oceanic pelagic zone Intertidal zone Coral reefs

24. Littoral zone Limnetic zone Photic zone Pelagic zone Benthic zone Aphotic zone Zonation in a lake

25. Intertidal zone Neritic zone Oceanic zone 0 Photic zone 200 m Continental shelf Pelagic zone Benthic zone Aphotic zone 2,500–6,000 m Abyssal zone (deepest regions of ocean floor) Marine zonation

26. Many aquatic biomes are stratified into zones or layers defined by light penetration, temperature, and depth • Major aquatic biomes: lakes, wetlands, streams and rivers, estuaries, intertidal zones, oceanic pelagic biome, coral reefs and marine benthic zone

27. Climate largely determines the distribution and structure of terrestrial biomes • Climate is very important in determining why terrestrial biomes are found in certain areas • Climate has a great impact on the distribution of organisms, as seen on a climograph

28. Tropical forest Desert Temperate grassland 30 Temperate broadleaf forest 15 Annual mean temperature (°C) Coniferous forest 0 Arctic and alpine tundra –15 400 300 200 100 Annual mean precipitation (cm)

29. 30°N Tropic of Cancer Equator Tropic of Capricorn 30°S Chaparral Tundra Key Temperate grassland High mountains Tropical forest Polar ice Temperate broadleaf forest Savanna Coniferous forest Desert

30. General Features of Terrestrial Biomes • Terrestrial biomes are often named for major physical or climatic factors and for vegetation • Stratification is a key feature of terrestrial biomes • Terrestrial biomes usually grade into each other, without sharp boundaries • The area of intergradation, called an ecotone, may be wide or narrow • Major terrestrial biomes: tropical forest, desert, savanna, chaparral, temperate grassland, coniferous forest, temperate broadleaf forest and tundra

31. Animations and Videos • Chapter Quiz Questions – 1 • Chapter Quiz Questions – 2 • Bozeman – Ecosystems • Bozeman - Ecosystem Change • Earth's Four Convection Cells • How Ecosystems Work • Biomes