Chapter 50 An Introduction to Ecology and the Biosphere PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Overview: The Scope of Ecology • Ecology – Is the scientific 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 • Ecology – Is an enormously complex and exciting area of biology – Reveals the richness of the biosphere Figure 50.1 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Concept 50.1: Ecology is the study of interactions between organisms and the environment • Ecology – Has a long history as a descriptive science – Is also a rigorous experimental science Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ecology and Evolutionary Biology • Events that occur in ecological time – Affect life on the scale of evolutionary time Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Organisms and the Environment • The environment of any organism includes – 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 • Environmental components – Affect the distribution and abundance of organisms Kangaroos/km2 > 20 10–20 5–10 1–5 0.1–1 < 0.1 Limits of distribution Figure 50.2 Climate in northern Australia is hot and wet, with seasonal drought. Southern Australia has cool, moist winters and warm, dry summers. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 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 • Ecologists – Use observations and experiments to test explanations for the distribution and abundance of species 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 • 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 • 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 • Ecosystem ecology – Emphasizes energy flow and chemical cycling among the various biotic and abiotic components (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 • Landscape ecology – Deals with arrays of ecosystems and how they are arranged in a geographic region Figure 50.3e (e) Landscape ecology. To what extent do the trees lining the drainage channels in this landscape serve as corridors of dispersal for forest animals? 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 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 • Most ecologists follow the precautionary principle regarding environmental issues • The precautionary principle – Basically states that humans need to be concerned with how their actions affect the environment Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • 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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Many naturalists – Began to identify broad patterns of distribution by naming biogeographic realms Palearctic Nearctic Tropic of Cancer (23.5N) Oriental Ethiopian Equator Neotropical Figure 50.5 (23.5S) Tropic of Capricorn Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Australian • 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 • Dispersal – Is the movement of individuals away from centers of high population density or from their area of origin – Contributes to the global distribution of organisms Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Natural Range Expansions • Natural range expansions – Show the influence of dispersal on distribution New areas occupied Figure 50.7 Year 1996 1989 1974 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Species Transplants • Species transplants – Include organisms that are intentionally or accidentally relocated from their original distribution – Can often disrupt the communities or ecosystems to which they have been introduced Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Behavior and Habitat Selection • Some organisms – Do not occupy all of their potential range • Species distribution – May be limited by habitat selection behavior 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 • A specific case of an herbivore limiting distribution of a food species 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 – Wind – Rocks and soil Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Temperature • Environmental temperature – Is an important factor in the distribution of organisms because of its effects on biological processes Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Water • Water availability among habitats – Is another important factor in species distribution Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Sunlight • Light intensity and quality – Can affect photosynthesis in ecosystems • Light – Is also important to the development and behavior of organisms sensitive to the photoperiod 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 • Four major abiotic components make up climate – Temperature, water, sunlight, and wind • Climate – Is the prevailing weather conditions in a particular area Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Climate patterns can be described on two scales – Macroclimate, patterns on the global, regional, and local level – Microclimate, very fine patterns, such as those encountered by the community of organisms underneath a fallen log Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Global Climate Patterns • Earth’s global climate patterns – Are determined largely by the input of solar energy and the planet’s movement in space Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Sunlight intensity – Plays a major part in determining 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 Regional, Local, and Seasonal Effects on Climate • Various features of the landscape – Contribute to local variations in climate 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 Seasonality • The angle of the sun – Leads to many seasonal changes in local environments 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. Microclimate • Microclimate – Is determined by fine-scale differences in abiotic factors Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 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 • Concept 50.3: Abiotic and biotic factors influence the structure and dynamics of aquatic biomes • Varying combinations of both biotic and abiotic factors – Determine the nature of Earth’s many biomes • Biomes – Are the major types of ecological associations that occupy broad geographic regions of land or water Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • The examination of biomes will begin with Earth’s aquatic biomes 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) • Aquatic biomes – Account for the largest part of the biosphere in terms of area – Can contain fresh or salt water • Oceans – Cover about 75% of Earth’s surface – Have an enormous impact on the biosphere Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • 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 • Concept 50.4: Climate largely determines the distribution and structure of terrestrial biomes • Climate – Is particularly important in determining why particular terrestrial biomes are found in certain areas Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Climate and Terrestrial Biomes • Climate has a great impact on the distribution of organisms, as seen on a 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 • The distribution of major terrestrial biomes 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 General Features of Terrestrial Biomes • Terrestrial biomes – Are often named for major physical or climatic factors and for their predominant vegetation • Stratification – Is an important feature of terrestrial biomes Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Tropical forest TROPICAL FOREST Figure 50.20 A tropical rain forest in Borneo Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • 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
