Transcript Chapter 50
Chapter 50 An Introduction to Ecology and the Biosphere Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 50.1: • Ecology is the study of interactions between organisms and the environment 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 Climate in northern Australia is hot and wet, with seasonal drought. Southern Australia has cool, moist winters and warm, dry summers. 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 Figure 50.2 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 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 (a) Organismal ecology. How do humpback whales select their calving areas? Figure 50.3a 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 Figure 50.3b Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings (b) Population ecology. What environmental factors affect the reproductive rate of deer mice? • Community ecology – Deals with the whole array of interacting species in a community Figure 50.3c Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings (c) Community ecology. What factors influence the diversity of species that make up a particular forest? • Ecosystem ecology – Emphasizes energy flow and chemical cycling among the various biotic and abiotic components Figure 50.3d Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings (d) Ecosystem ecology. What factors control photosynthetic productivity in a temperate grassland ecosystem? • Landscape ecology – Deals with arrays of ecosystems and how they are arranged in a geographic region (e) Landscape ecology. To what extent do the trees lining the drainage channels in this landscape serve as corridors of dispersal for forest animals? Figure 50.3e 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 Concept 50.2: • Interactions between organisms and the environment limit the distribution of species 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 An Ecological Experiment 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 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. Figure 50.8 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 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 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 Microclimate • Microclimate – Is determined by fine-scale differences in abiotic factors Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 50.3: • Varying combinations of both biotic and abiotic factors – Determine the nature of Earth’s many biomes • Biomes – Broad geographic regions defined by their biotic and abiotic associations Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Earth’s aquatic biomes 30N Tropic of Cancer Equator Tropic of Capricorn Continental shelf 30S Key Lakes Rivers Estuaries Coral reefs Oceanic pelagic zone Intertidal zone Figure 50.15 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Abyssal zone (below oceanic pelagic zone) Lakes LAKES An oligotrophic lake in Grand Teton, Wyoming A eutrophic lake in Okavango delta, Botswana Figure 50.17 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Wetlands WETLANDS Okefenokee National Wetland Reserve in Georgia Figure 50.17 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Streams and rivers STREAMS AND RIVERS A headwater stream in the Great Smoky Mountains The Mississippi River far form its headwaters Figure 50.17 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Estuaries ESTUARIES An estuary in a low coastal plain of Georgia Figure 50.17 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Intertidal zones INTERTIDAL ZONES Rocky intertidal zone on the Oregon coast Figure 50.17 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Oceanic pelagic biome OCEANIC PELAGIC BIOME Open ocean off the island of Hawaii Figure 50.17 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Coral reefs CORAL REEFS A coral reef in the Red Sea Figure 50.17 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Marine benthic zone MARINE BENTHIC ZONE A deep-sea hydrothermal vent community Figure 50.17 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 50.4: • 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 • This climograph shows the relationship between different biomes and two climatic factors. 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 Savanna Desert Chaparral Temperate grassland Temperate broadleaf forest Coniferous forest Figure 50.19 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Tundra High mountains Polar ice 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 A typical savanna in Kenya Figure 50.20 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