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Chapter 52 An Introduction to Ecology and the Biosphere PowerPoint® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Overview: The Scope of Ecology • Ecology –the study of the interactions between organisms and the environment – • These interactions determine distribution and abundance of organisms Ecologists work at various levels, including: – Organismal Ecology – Population Ecology – Community Ecology – Ecosystem Ecology – Landscape Ecology – Global Ecology Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-2 Organismal ecology Population ecology Community ecology Ecosystem ecology Landscape ecology Global ecology • Organismal ecology studies how an organism’s structure, physiology, and (for animals) behavior meet environmental challenges How do hammerhead sharks select a mate? Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • Population ecology focuses on factors affecting how many individuals of a species live in an area (A population is a group of individuals of the same species living in an area) What environmental factors affect the reproductive rate of deer mice? Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • Community ecology deals with the whole array of interacting species in a community. (A community is a group of populations of different species in an area) What factors influence the diversity of species that make up a forest? Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • Ecosystem ecology emphasizes energy flow and chemical cycling among the biotic and abiotic components. (An ecosystem is the community of organisms in an area and the physical factors with which they interact) What factors control photosynthetic productivity in a temperate grassland ecosystem? Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • Landscape ecology deals with arrays of ecosystems and how they are arranged in a geographic region. (A landscape is a mosaic of connected ecosystems) To what extent do the trees lining a river serve as corridors of dispersal for animals? Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • Global ecology examines the influence of energy and materials on organisms across the biosphere. (The biosphere is the global ecosystem, the sum of all the planet’s ecosystems) How does ocean circulation affect the Global distribution of crustaceans? Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 52.1: Ecology integrates all areas of biological research and informs environmental decision making • Ecology is both a descriptive science (study observations in nature) and an experimental science (generate hypothesis, manipulate the environment and observe outcomes). Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-3 “Dry” “Wet” Trough Pipe “Ambient” Illustrated is an ecology experiment conducted over a 10 yr. period. In it, Scientists hypothesized that certain species of trees are susceptible to drought than others. They manipulated the environmental conditions by creating troughs that collect water from one area to mimic a drought and send it to another area to make it more wet. The ambient area is the normal rainfall. They then observed the results. Linking Ecology and Evolutionary Biology • Events that occur in ecological time affect life on the scale of evolutionary time – Ex: insect populations decrease after pesticide is used (ecological effect); insects develop resistance as a result of the pesticide forcing a change in the gene pool (evolutionary effect) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Ecology and Environmental Issues • Ecology provides the scientific understanding that underlies environmental issues • Ecologists make a distinction between science and advocacy – Ecologists educate society about environmental issues – Society must decide how to use the knowledge Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-4 • Rachel Carson is credited with starting the modern environmental movement with the publication of Silent Spring in 1962 • She educated society on the use of DDT and her efforts led to a ban on the pesticide. Concept 52.2: Interactions between organisms and the environment limit the distribution of species • Ecologists study the distribution of organisms. – They ask both where species live and why do they live there • Biogeography is a good starting point for understanding what limits geographic distribution of species • Two factors that determine distribution are: biotic, or living factors, and abiotic, or nonliving factors Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-5 Kangaroos/km2 What abiotic factors do you think contribute to The distribution pattern of the Red Kangaroo? Biotic factors? Abiotic factors: Red Kangaroos are found in semi-arid and arid regions of the interior where precipitation is low and variable from year to year. 0–0.1 0.1–1 1–5 5–10 10–20 > 20 Limits of distribution Biotic factors: Could pathogens, parasites, predators, competitors and food availability also be factors? Ecologists consider multiple factors when attempting to explain the distribution of species Fig. 52-6 Use the following flow chart to see how ecologists attempt to explain the distribution of a species. Why is species X absent from an area? Yes Does dispersal limit its distribution? No Area inaccessible or insufficient time Does behavior limit its distribution? Yes Habitat selection Yes No Do biotic factors (other species) limit its distribution? No Predation, parasitism, Chemical competition, disease factors Do abiotic factors limit its distribution? Water Oxygen Salinity pH Soil nutrients, etc. Temperature Physical Light factors Soil structure Fire Moisture, etc. Dispersal and Distribution • Dispersal is the actual movement of individuals away from centers of high population density or from their area of origin • Distribution is where the actually end up. i.e. where do we find them globally? – Physical barriers can impede dispersal – Organisms may not have had enough time to spread out. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Natural Range Expansions • Natural range expansions show the influence of dispersal on distribution – – Current 1970 1966 Observing the expansion of a natural range directly is rare because of the time factor. Ecologists often use experimental methods to understand the role of dispersal in limiting distribution Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 1965 1960 1961 1943 1958 1951 1956 1970 1937 Species Transplants • Species transplants include organisms that are intentionally or accidentally relocated from their original distribution • They can be used by ecologists to determine if the potential range of a species is larger than the actual range. i.e. a species could live in a certain area where it currently does not. • Species transplants can disrupt the communities or ecosystems to which they have been introduced. Thus the use of this technique is often limited to observations of an accidental transplant. Copyright © 2008 Pearson Education, Inc., publishing as Pearson 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 – Ex: Female corn borer beetles only lay eggs on corn plants, even though the larva could eat other plants. (They are attracted by a scent) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Biotic Factors • Biotic factors that affect the distribution of organisms may include: – Interactions with other species – Predation – Competition Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-8 RESULTS 100 Seaweed cover (%) 80 Both limpets and urchins removed Sea urchin Only urchins removed 60 Limpet 40 Only limpets removed Control (both urchins and limpets present) 20 0 August 1982 February 1983 August 1983 February 1984 Abiotic Factors • Abiotic factors affecting distribution of organisms include: – Temperature: effects biological processes and therefore limits distribution. Ex: Cells freeze and rupture below 0oC; proteins denature above 45oC. Endotherms must expend energy in order to regulate temperature. – Water: availability of water limits where many organisms can live. Ex: Desert organisms have adaptations for water conservation. – Salinity: Aquatic organisms are usually restricted to either saltwater or freshwater. Few terrestrial organisms are adapted to high salinity habitats – Sunlight: Light intensity and quality affect photosynthesis. Plants compete with others for sunlight. Water absorbs light, thus most photosynthetic aquatic organisms live near the surface. In deserts, high light levels increase temperature and can stress plants and animals. – Rocks and Soil: Physical structure, pH and mineral composition of soil limit plant distribution and thus the animals that feed upon them Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Climate • Climate—the long-term prevailing weather conditions in an area • Abiotic components of climate: temperature, water, sunlight, and wind • Two scales of climate patterns: – 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 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 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 – Ex: More heat and light per unit of surface area reach the tropics than the high latitudes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-10b 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 • Seasonal variations of light and temperature increase steadily toward the poles – Tropics get the most solar radiation and o the least variation due to the 23.5 tilt of the Earth on its axis. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-10c 60ºN 30ºN 0º (equator) March equinox: 12 hrs daylight and 12 hrs of darkness all regions of Earth June solstice North: long days/short nights South: short days/ long nights 30ºS December solstice Constant tilt of 23.5º North: short days/long nights South: Long days/short nights September equinox 12 hrs daylight/ 12 hrs darkness all regions of Earth Fig. 52-10e •Global air circulation and precipitation patterns play major roles in determining climate patterns •Warm wet air flows from the tropics toward the poles 60ºN 30ºN Descending dry air absorbs moisture 0º (equator) Ascending moist air releases moisture 30ºS 60ºS Descending dry air absorbs moisture 30º 23.5º Arid zone 0º Tropics 23.5º 30º Arid zone Fig. 52-10f 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 66.5ºN (Arctic Circle) 60ºN Westerlies 30ºN Northeast trades Doldrums Southeast trades 0º (equator) 30ºS Westerlies 60ºS 66.5ºS (Antarctic Circle) Regional, Local, and Seasonal Effects on Climate • Proximity to bodies of water and topographic features such as mountain ranges contribute to local variations in climate – The Gulf Stream carries warm water from the equator to the North Atlantic Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-11 Labrador current Gulf stream Equator Cold water The great ocean conveyor belt. Water is warmed at the equator, flows to the North Atlantic, cools, sinks thousands of meters for as long as 1,000 years and eventually returns to the surface. • Oceans and their currents and large lakes moderate the climate of nearby terrestrial environments – During the day, air rises over warm land and draws a cool breeze from the water across the land • As the land cools at night, air rises over the warmer water and draws cooler air from land back over the water, which is replaced by warm air from offshore Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-12 2 Air cools at 3 Cooler high elevation. air sinks over water. 1 Warm air over land rises. 4 Cool air over water moves inland, replacing rising warm air over land. Mountains • Mountains have a significant effect on the amount of sunlight reaching an area, the local temperature, and rainfall • Rising air releases moisture on the windward side of a peak and creates a “rain shadow” as it absorbs moisture on the leeward side Leeward side of mountain Wind direction Mountain range Ocean Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Seasonality • The angle of the sun leads to many seasonal changes in local environments • Lakes are sensitive to seasonal temperature change and experience seasonal turnover Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Microclimate • Microclimate is determined by fine-scale differences in the environment that affect light and wind patterns – Ex: Forested areas create a shade microclimate that experiences less extremes in temperature than the open areas. – Ex: A log creates a microclimate for salamanders and insects, protecting them from changes in temperature Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Long-Term Climate Change • Global climate change will profoundly affect the biosphere • One way to predict future global climate change is to study previous changes • As glaciers began retreating 16,000 years ago, tree distribution patterns changed • As climate changes, species that have difficulty dispersing may have smaller ranges or could become extinct Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-14 Current range Predicted range Overlap (a) 4.5ºC warming over next century (b) 6.5ºC warming over next century Concept 52.3: Aquatic biomes are diverse and dynamic systems that cover most of Earth • Biomes are the major ecological associations that occupy broad geographic regions of land or water • Varying combinations of biotic and abiotic factors determine the nature of biomes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • Aquatic biomes account for the largest part of the biosphere in terms of area • They can contain fresh water (less than 1% salt)or salt water (marine; 3% salt) • Oceans cover about 75% of Earth’s surface and have an enormous impact on the biosphere – Evaporation from oceans provides most of the world’s rainfall – Effect climate and wind patterns – Photosynthetic marine algae and bacteria supply oxygen and consume carbon dioxide Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-15 30ºN Tropic of Cancer Equator Tropic of Capricorn 30ºS Lakes Coral reefs Rivers Oceanic pelagic and benthic zones Estuaries Intertidal zones Fig. 52-16 Many aquatic biomes are stratified into zones or layers defined by light penetration, temperature, and depth Intertidal zone Oceanic zone Neritic zone Littoral zone Limnetic zone 0 Photic zone 200 m Continental shelf Benthic zone Photic zone Benthic zone Pelagic zone Pelagic zone Aphotic zone 2,000–6,000 m Abyssal zone (a) Zonation in a lake (b) Marine zonation Aphotic zone • The upper photic zone has sufficient light for photosynthesis while the lower aphotic zone receives little light • The organic and inorganic sediment at the bottom of all aquatic zones is called the benthic zone • The communities of organisms in the benthic zone are collectively called the benthos • Detritus, dead organic matter, falls from the productive surface water and is an important source of food • The most extensive part of the ocean is the abyssal zone with a depth of 2,000 to 6,000 m Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • In oceans and most lakes, a temperature boundary called the thermocline separates the warm upper layer from the cold deeper water • Many lakes undergo a semiannual mixing of their waters called turnover • Turnover mixes oxygenated water from the surface with nutrient-rich water from the bottom. It happens in spring and fall Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-17-5 Winter Summer Spring 2º 4º 4º 4º 4ºC 0º 4º 4º Autumn 20º 18º 8º 6º 5º 4ºC 4º 4º 4º 4ºC Thermocline 22º 4º 4º 4º 4º 4ºC 4º Aquatic Biomes • Major aquatic biomes can be characterized by their physical environment, chemical environment, geological features, photosynthetic organisms, and heterotrophs Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Lakes • Oligotrophic lakes are nutrient-poor and generally oxygen-rich • Eutrophic lakes are nutrient-rich and often depleted of oxygen if ice covered in winter Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-18a An oligotrophic lake in Grand Teton National Park, Wyoming A eutrophic lake in the Okavango Delta, Botswana Wetlands • A wetland is a habitat that is inundated by water at least some of the time and that supports plants adapted to watersaturated soil • Wetlands can develop in shallow basins, along flooded river banks, or on the coasts of large lakes and seas • Wetlands are among the most productive biomes on earth and are home to diverse invertebrates and birds Okefenokee National Wetland Reserve in Georgia Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Streams and Rivers • The most prominent physical characteristic of streams and rivers is current – Headwater streams: cold, clear, swift, oxygen rich, rocky bottom – Downstream: warm, turbid, slow, less oxygen, more organic material, silty bottom • A diversity of fishes and invertebrates inhabit unpolluted rivers and streams • Damming and flood control impair natural functioning of stream and river ecosystems Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-18d A headwater stream in the Great Smoky Mountains The Mississippi River far from its headwaters Estuaries • An estuary is a transition area between river and sea • Salinity varies with the rise and fall of the tides • Estuaries are nutrient rich and highly productive • An abundant supply of food attracts marine invertebrates and fish An estuary in a low coastal plain of Georgia Video: Flapping Geese Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Intertidal Zones • An intertidal zone is periodically submerged and exposed by the tides • Intertidal organisms are challenged by variations in temperature and salinity and by the mechanical forces of wave action • Many animals of rocky intertidal environments have structural adaptations that enable them to attach to the hard substrate Rocky intertidal zone on the Oregon coast Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Oceanic Pelagic Zone • The oceanic pelagic biome is a vast realm of open blue water, constantly mixed by wind-driven oceanic currents • This biome covers approximately 70% of Earth’s surface • Phytoplankton and zooplankton are the dominant organisms in this biome; also found are free-swimming animals Open ocean off the island of Hawaii Video: Shark Eating a Seal Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Coral Reefs • Coral reefs are formed from the calcium carbonate skeletons of corals (phylum Cnidaria) • Corals require a solid substrate for attachment • Unicellular algae live within the tissues of the corals and form a mutualistic relationship that provides the corals with organic molecules A coral reef in the Red Sea Video: Coral Reef Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Video: Clownfish and Anemone Marine Benthic Zone • The marine benthic zone consists of the seafloor below the surface waters of the coastal, or neritic, zone and the offshore pelagic zone • Organisms in the very deep benthic, or abyssal, zone are adapted to continuous cold and extremely high water pressure • Unique assemblages of organisms are associated with deep-sea hydrothermal vents of volcanic origin on mid-oceanic ridges; here the autotrophs are chemoautotrophic prokaryotes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings A deep-sea hydrothermal vent community Concept 52.4: The structure and distribution of terrestrial biomes are controlled by climate and disturbance • Climate is very important in determining why terrestrial biomes are found in certain areas – Latitudinal patterns of climate create latitudinal patterns of biome distribution • Biome patterns can then be modified by disturbance such as a storm, fire, or human activity Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-19 Tropical forest Savanna Desert 30ºN Tropic of Cancer Equator Tropic of Capricorn 30ºS Chaparral Temperate grassland Temperate broadleaf forest Northern coniferous forest Tundra High mountains Polar ice Climate and Terrestrial Biomes • Climate has a great impact on the distribution of organisms • This can be illustrated with a climograph, a plot of the temperature and precipitation in a region • Biomes are affected not just by average temperature and precipitation, but also by the pattern of temperature and precipitation through the year – Ex: Some areas may receive the same average amount of rainfall but it can occur regularly in one and in wet and dry seasons in another. Therefore, different organisms will be found in each. – Ex: Type of bedrock and nutrients in soil may also be a factor. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 52-20 Annual mean temperature (ºC) Desert Temperate grassland Tropical forest 30 Temperate broadleaf forest 15 Northern coniferous forest 0 Arctic and alpine tundra –15 0 100 200 400 300 Annual mean precipitation (cm) General Features of Terrestrial Biomes and the Role of Disturbance • Terrestrial biomes are often named for major physical or climatic factors and for vegetation • Terrestrial biomes usually grade into each other, without sharp boundaries • The area of intergradation, called an ecotone, may be wide or narrow Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • Vertical layering is an important feature of terrestrial biomes, and in a forest it might consist of an upper canopy, low-tree layer, shrub understory, ground layer of herbaceous plants, forest floor, and root layer • Layering of vegetation in all biomes provides diverse habitats for animals • Biomes are dynamic and usually exhibit extensive patchiness (several different communities represented in any particular area). This is usually the result of a disturbance occurring that opens up some part of the biome for new organisms. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Terrestrial Biomes • Terrestrial biomes can be characterized by distribution, precipitation, temperature, plants, and animals Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Tropical Forest • Tropical rain forests: constant rainfall tropical dry forests: seasonal rainfall • Vertically layered and competition for light is intense • Home to millions of animal species, including an estimated 5–30 million still undescribed species of insects, spiders, and other arthropods Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings A tropical rainforest in Borneo. Desert • Low precipitation (less than 30 cm per year); deserts may be hot or cold • Plants are adapted for heat and desiccation tolerance, water storage, and reduced leaf surface area • Common desert animals include snakes and lizards, scorpions, ants, beetles, migratory and resident birds, and seed-eating rodents; many are nocturnal Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings A desert in the southwestern United States Savanna • Savanna precipitation and temperature are seasonal • Grasses and forbs make up most of the ground cover. Plants are adapted to fire and drought. • Common inhabitants include insects and mammals such as wildebeests, zebras, lions, and hyenas A savanna in Kenya Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Chaparral • Chaparral climate is highly seasonal, with cool and rainy winters and hot dry summers • The chaparral is dominated by shrubs, small trees, grasses, and herbs; many plants are adapted to fire and drought • Animals include amphibians, birds and other reptiles, insects, small mammals and browsing mammals An area of chaparral in California Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Temperate Grassland • Temperate grasslands are found on many continents • Winters are cold and dry, while summers are wet and hot • The dominant plants, grasses and forbs, are adapted to droughts and fire • Native mammals include large grazers and small burrowers Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Sheyenne National Grassland in North Dakota Northern Coniferous Forest • The northern coniferous forest, or taiga, extends across northern North America and Eurasia and is the largest terrestrial biome on Earth • Winters are cold and long while summers may be hot • The conical shape of conifers prevents too much snow from accumulating and breaking their branches • Animals include migratory and resident birds, and large mammals Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Rocky Mountain National Park in Colorado Temperate Broadleaf Forest • Winters are cool, while summers are hot and humid; significant precipitation falls year round as rain and snow • A mature temperate broadleaf forest has vertical layers dominated by deciduous trees in the Northern Hemisphere and evergreen eucalyptus in Australia • Mammals, birds, and insects make use of all vertical layers in the forest • In the Northern Hemisphere, many mammals hibernate in the winter Great Smoky Mountains National Park in North Carolina Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Tundra • Tundra covers expansive areas of the Arctic; alpine tundra exists on high mountaintops at all latitudes • Winters are long and cold while summers are relatively cool; precipitation varies • Permafrost, a permanently frozen layer of soil, prevents water infiltration • Vegetation is herbaceous (mosses, grasses, forbs, dwarf shrubs and trees, and lichen) and supports birds, grazers, and their predators Denali National Park, Alaska, in autumn Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings You should now be able to: 1. Distinguish among the following types of ecology: organismal, population, community, ecosystem, and landscape 2. Explain how dispersal may contribute to a species’ distribution 3. Distinguish between the following pairs of terms: potential and actual range, biotic and abiotic factors, macroclimate and microclimate patterns 4. Explain how a body of water or mountain range might affect regional climatic conditions 5. Define the following terms: photic zone, aphotic zone, benthic zone, abyssal zone, thermal stratification, thermocline, seasonal turnover, climograph, disturbance 6. List and describe the characteristics of the major aquatic biomes 7. List and describe the characteristics of the major terrestrial biomes 8. Compare the vertical layering of a forest and grassland Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings