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Overview: The Scope of Ecology • What is Ecology? – The study of the interactions between organisms and the environment • These interactions – Determine both the distribution of organisms and their abundance Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Organisms and the Environment • What does the environment of an organism include? – Abiotic, or nonliving components – Biotic, or living components – All the organisms living in the environment, the biota Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • The biosphere – Is the global ecosystem, the sum of all the planet’s ecosystems Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Ecosystems (Biomes) focus on energy flow and chemical cycling among the various ______ and __________components in broad geographic regions of land or water (d) Ecosystem ecology. What factors control photosynthetic productivity in a temperate grassland ecosystem? Figure 50.3d Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Why are particular terrestrial biomes are found in certain areas? 30N Tropic of Cancer Equator Tropic of Capricorn 30S Key Tropical forest Savanna Desert Chaparral Temperate grassland Temperate broadleaf forest Coniferous forest Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Tundra High mountains Polar ice Aquatic Biomes – largest part of the biosphere in terms of area – Can contain fresh or salt water (ocean = 75%) 30N Tropic of Cancer Equator Tropic of Capricorn Continental shelf 30S Key Figure 50.15 Lakes Rivers Estuaries Coral reefs Oceanic pelagic zone Intertidal zone Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Abyssal zone (below oceanic pelagic zone) • Community ecology – Deals with the whole array of interacting species in a community (c) Community ecology. What factors influence the diversity of species that make up a particular forest? Figure 50.3c Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Population ecology – Concentrates mainly on factors that affect how many individuals of a particular species live in an area (b) Population ecology. What environmental factors affect the reproductive rate of deer mice? Figure 50.3b Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Subfields of Ecology • Organismal ecology – Studies how an organism’s structure, physiology, and (for animals) behavior meet the challenges posed by the environment Figure 50.3a (a) Organismal ecology. How do humpback whales select their calving areas? Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ecology and Environmental Issues • Ecology – Provides the scientific understanding underlying environmental issues • Rachel Carson – Is credited with starting the modern environmental movement Figure 50.4 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • How do environmental components affect the distribution and abundance of organisms? Kangaroos/km2 > 20 10–20 5–10 Climate in northern Australia is hot and wet, with seasonal drought. 1–5 0.1–1 < 0.1 Limits of distribution Southern Australia has cool, moist winters and warm, dry summers. Figure 50.2 Red kangaroos occur in most semiarid and arid regions of the interior, where precipitation is relatively low and variable from year to year. Southeastern Australia has a wet, cool climate. Tasmania Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Biogeography – Provides a good starting point for understanding what limits the geographic distribution of species Species absent because Yes Dispersal limits distribution? No Area inaccessible or insufficient time Behavior limits distribution? Yes Habitat selection Yes No Biotic factors (other species) limit distribution? No Predation, parasitism, Chemical competition, disease factors Water Abiotic factors limit distribution? Oxygen Salinity pH Soil nutrients, etc. Temperature Physical Light factors Soil structure Fire Moisture, etc. Figure 50.6 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Dispersal and Distribution • What is Dispersal? – movement of individuals away from their area of origin – Contributes to distribution of organisms New areas occupied Year 1996 1989 1974 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Invasive Species or Species transplants – organisms intentionally or accidentally relocated – Can often disrupt the communities or ecosystems to which they have been introduced Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Biotic Factors • Biotic factors that affect the distribution of organisms may include – Interactions with other species – Predation – Competition Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings What limits the seaweed distribution? EXPERIMENT W. J. Fletcher tested the effects of two algae-eating animals, sea urchins and limpets, on seaweed abundance near Sydney, Australia. In areas adjacent to a control site, either the urchins, the limpets, or both were removed. RESULTS Fletcher observed a large difference in seaweed growth between areas with and without sea urchins. 100 Sea urchin Seaweed cover (%) 80 Both limpets and urchins removed Only urchins removed 60 Limpet 40 Only limpets removed Control (both urchins and limpets present) 20 Removing both limpets and urchins or removing only urchins increased seaweed cover dramatically. Almost no seaweed grew in areas where both urchins and limpets were present, or where only limpets were removed. 0 August 1982 Figure 50.8 February 1983 August 1983 February 1984 CONCLUSION Removing both limpets and urchins resulted in the greatest increase of seaweed cover, indicating that both species have some influence on seaweed distribution. But since removing only urchins greatly increased seaweed growth while removing only limpets had little effect, Fletcher concluded that sea urchins have a much greater effect than limpets in limiting seaweed distribution. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Abiotic Factors • Abiotic factors that affect the distribution of organisms may include – Temperature – Water – Sunlight – Salinity – Wind – Rocks and soil Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Wind • Wind – Amplifies the effects of temperature on organisms by increasing heat loss due to evaporation and convection – Can change the morphology of plants Figure 50.9 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Rocks and Soil • Many characteristics of soil limit the distribution of plants and thus the animals that feed upon them – Physical structure – pH – Mineral composition Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Climate patterns can be described on two scales – Macroclimate • global, regional, and local level – Microclimate • very small, ie community of organisms underneath a fallen log Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Solar Energy impacts global climate • Sunlight intensity determines the Earth’s climate patterns LALITUDINAL VARIATION IN SUNLIGHT INTENSITY North Pole 60N Low angle of incoming sunlight 30N Tropic of Cancer Sunlight directly overhead 0 (equator) Tropic of Capricorn 30S Low angle of incoming sunlight 60S South pole Figure 50.10 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Atmosphere SEASONAL VARIATION IN SUNLIGHT INTENSITY 60N June solstice: Northern Hemisphere tilts toward sun; summer begins in Northern Hemisphere; winter begins in Southern Hemisphere. 30N 0 (equator) 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. 30S 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. Figure 50.10 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings December solstice: Northern Hemisphere tilts away from sun; winter begins in Northern Hemisphere; summer begins in Southern Hemisphere. • Air circulation and wind patterns – Play major parts in determining the Earth’s climate patterns GLOBAL AIR CIRCULATION AND PRECIPITATION PATTERNS 60N 30N Descending dry air absorbs moisture 0 (equator) 30S 0 60S Figure 50.10 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ascending moist air releases moisture Descending dry air absorbs moisture Arid zone Tropics Arid zone GLOBAL WIND PATTERNS Arctic Circle 60N Westerlies 30N Northeast trades Doldrums 0 (equator) Southeast trades 30S Westerlies 60S Antarctic Circle Figure 50.10 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Bodies of Water • Oceans and their currents, and large lakes – Moderate the climate of nearby terrestrial environments 2 Air cools at high elevation. 3 Cooler air sinks over water. 4 Cool air over water moves inland, replacing rising warm air over land. Figure 50.11 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 1 Warm air over land rises. Mountains • Mountains have a significant effect on – The amount of sunlight reaching an area – Local temperature – Rainfall 1 As moist air moves in off the Pacific Ocean and encounters the westernmost mountains, it flows upward, cools at higher altitudes, and drops a large amount of water. The world’s tallest trees, the coastal redwoods, thrive here. 2 Farther inland, precipitation increases again as the air moves up and over higher mountains. Some of the world’s deepest snow packs occur here. 3 On the eastern side of the Sierra Nevada, there is little precipitation. As a result of this rain shadow, much of central Nevada is desert. Wind direction East Pacific Ocean Sierra Nevada Coast Range Figure 50.12 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Lakes – Are sensitive to seasonal temperature change – Experience seasonal turnover Lake depth (m) In winter, the coldest water in the lake (0°C) lies just below the surface ice; water is progressively warmer at deeper levels of the lake, typically 4–5°C at the bottom. O2 (mg/L) 0 4 Spring Winter 8 12 8 16 2 4 4 4 4C 24 O2 concentration 0 Lake depth (m) 1 2 In spring, as the sun melts the ice, the surface water warms to 4°C and sinks below the cooler layers immediately below, eliminating the thermal stratification. Spring winds mix the water to great depth, bringing oxygen (O2) to the bottom waters (see graphs) and nutrients to the surface. O2 (mg/L) 0 4 8 12 8 16 4 4 4 4 4 4C 24 High Medium O2 (mg/L) 0 4 8 12 8 16 24 Figure 50.13 4 Autumn 4 4 4 4C 4 In autumn, as surface water cools rapidly, it sinks below the underlying layers, remixing the water until the surface begins to freeze and the winter temperature profile is reestablished. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 4 Thermocline 3 22 20 18 8 6 5 4C Summer Lake depth (m) Lake depth (m) Low O2 (mg/L) 0 4 8 12 8 16 24 In summer, the lake regains a distinctive thermal profile, with warm surface water separated from cold bottom water by a narrow vertical zone of rapid temperature change, called a thermocline. Long-Term Climate Change • One way to predict future global climate change – Is to look back at the changes that occurred previously Current range Predicted range Overlap Figure 50.14 (a) 4.5C warming over next century Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings (b) 6.5C warming over next century Aquatic Biomes – largest part of the biosphere in terms of area – Can contain fresh or salt water (ocean = 75%) 30N Tropic of Cancer Equator Tropic of Capricorn Continental shelf 30S Key Figure 50.15 Lakes Rivers Estuaries Coral reefs Oceanic pelagic zone Intertidal zone Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Abyssal zone (below oceanic pelagic zone) • Many aquatic biomes – Are stratified into zones or layers defined by light penetration, temperature, and depth Intertidal zone Neritic zone Littoral zone Limnetic zone 0 Oceanic zone Photic zone 200 m Continental shelf Pelagic zone Benthic zone Photic zone Aphotic zone Pelagic zone Benthic zone Aphotic zone 2,500–6,000 m Abyssal zone (deepest regions of ocean floor) (a) Zonation in a lake. The lake environment is generally classified on the basis of three physical criteria: light penetration (photic and aphotic zones), distance from shore and water depth (littoral and limnetic zones), and whether it is open water (pelagic zone) or bottom (benthic zone). Figure 50.16a, b Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings (b) Marine zonation. Like lakes, the marine environment is generally classified on the basis of light penetration (photic and aphotic zones), distance from shore and water depth (intertidal, neritic, and oceanic zones), and whether it is open water (pelagic zone) or bottom (benthic and abyssal zones). • Lakes LAKES Figure 50.17 An oligotrophic lake in Grand Teton, Wyoming Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A eutrophic lake in Okavango delta, Botswana • Wetlands WETLANDS Figure 50.17 Okefenokee National Wetland Reserve in Georgia Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Streams and rivers STREAMS AND RIVERS Figure 50.17 A headwater stream in the Great Smoky Mountains Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Mississippi River far form its headwaters • Estuaries ESTUARIES Figure 50.17 An estuary in a low coastal plain of Georgia Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Intertidal zones INTERTIDAL ZONES Figure 50.17 Rocky intertidal zone on the Oregon coast Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Oceanic pelagic biome OCEANIC PELAGIC BIOME Figure 50.17 Open ocean off the island of Hawaii Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Coral reefs CORAL REEFS Figure 50.17 A coral reef in the Red Sea Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Marine benthic zone MARINE BENTHIC ZONE Figure 50.17 A deep-sea hydrothermal vent community Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Why are particular terrestrial biomes are found in certain areas? 30N Tropic of Cancer Equator Tropic of Capricorn 30S Key Tropical forest Savanna Desert Chaparral Temperate grassland Temperate broadleaf forest Coniferous forest Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Tundra High mountains Polar ice Climate and Terrestrial Biomes • What impact does Climate have on the distribution of organisms in the climograph? Temperate grassland Desert Tropical forest Annual mean temperature (ºC) 30 Temperate broadleaf forest 15 Coniferous forest 0 Arctic and alpine tundra 15 100 Figure 50.18 200 300 Annual mean precipitation (cm) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 400 Major terrestrial biomes • Are named for major physical or climatic factors and for their predominant vegetation 30N Tropic of Cancer Equator Tropic of Capricorn 30S Key Tropical forest Figure 50.19 Savanna Desert Chaparral Temperate grassland Temperate broadleaf forest Coniferous forest Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Tundra High mountains Polar ice Tropical forest • Focus on the stratification in terrestrial biomes TROPICAL FOREST Copyright © 2005 Pearson Education, publishing as Benjamin A Cummings FigureInc. 50.20 tropical rain forest in Borneo • Desert DESERT Figure 50.20 The Sonoran Desert in southern Arizona Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Savanna SAVANNA Figure 50.20 A typical savanna in Kenya Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Chaparral CHAPARRAL Figure 50.20 An area of chaparral in California Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Temperate grassland TEMPERATE GRASSLAND Figure 50.20 Sheyenne National Grassland in North Dakota Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Coniferous forest CONIFEROUS FOREST Rocky Mountain National Park in Colorado Figure 50.20 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Temperate broadleaf forest TEMPERATE BROADLEAF FOREST Figure 50.20 Great Smoky Mountains National Park in North Carolina Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Tundra TUNDRA Figure 50.20 Denali National Park, Alaska, in autumn Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
