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Chapter 18 An Introduction to Ecology and the Biosphere PowerPoint® Lectures for Campbell Essential Biology, Fourth Edition – Eric Simon, Jane Reece, and Jean Dickey Campbell Essential Biology with Physiology, Third Edition – Eric Simon, Jane Reece, and Jean Dickey Lectures by Chris C. Romero, updated by Edward J. Zalisko © 2010 Pearson Education, Inc. Biology and Society: Penguins and Polar Bears in Peril • The scientific debate is over. • The great majority of scientists now agree that the global climate is changing. • Average global temperatures have risen 0.8°C (about 1.4°F) over the past century, mostly over the last 30 years. © 2010 Pearson Education, Inc. AN OVERVIEW OF ECOLOGY • Ecology is the scientific study of the interactions between organisms and their environments. © 2010 Pearson Education, Inc. • Humans have always had an interest in other organisms and their environments. • Extraordinary insight can be gained from a discovery-based approach of – Watching nature – Recording its structure and processes © 2010 Pearson Education, Inc. A Hierarchy of Interactions • Many different factors can potentially affect an organism’s interaction with the environment. – Biotic factors are – All of the organisms in the area – The living component of the environment – Abiotic factors – Are the environment’s nonliving component – Include chemical and physical factors, such as temperature, light, water, minerals, and air © 2010 Pearson Education, Inc. • The biosphere is the global ecosystem, the sum of all the planet’s ecosystems or all of life and where it lives. © 2010 Pearson Education, Inc. Energy Source • All organisms require a usable source of energy to live. • Solar energy from sunlight – Is captured by chlorophyll during the process of photosynthesis – Powers most ecosystems © 2010 Pearson Education, Inc. Chlorophyll levels around the world. GREEN = HIGH LEVELS DARKER COLORS = LOW LEVELS Figure 18.5 Temperature • Temperature affects metabolism. – Few organisms can maintain a sufficiently active metabolism at temperatures close to 0ºC. – Temperatures above 45ºC destroy the enzymes of most organisms. © 2010 Pearson Education, Inc. Water • Water is essential to all life. • For terrestrial organisms, the main water problem is drying out. • Aquatic organisms – Are surrounded by water – Face problems of water balance if their own solute concentration does not match that of their surroundings © 2010 Pearson Education, Inc. Animal cell H2O H2O H 2O Normal Lysing H 2O Flaccid (wilts) (a) Isotonic solution Shriveled Plasma membrane Plant cell H 2O H2O H 2O Turgid (b) Hypotonic solution H 2O Shriveled (c) Hypertonic solution Figure 5.14 Nutrients • The distribution and abundance of plants is often determined by the – Availability of nitrogen and phosphorus – The structure, pH, and nutrient content of the soil © 2010 Pearson Education, Inc. Other Aquatic Factors • Aquatic but not terrestrial ecosystems are more limited by – The levels of dissolved oxygen and salinity – Currents – Tides © 2010 Pearson Education, Inc. Other Terrestrial Factors • Terrestrial but not aquatic ecosystems are more limited by – Wind – Storms – Fire © 2010 Pearson Education, Inc. Key Number of lizard species =0 = 1–5 = 6–10 = 11–15 = 16–20 = 20+ Figure 18.10 Anatomical Responses • Many organisms respond to environmental challenges with some type of change in – Body shape – Structure • Reversible change, such as a heavier fur coat in response to cold, is an example of acclimation. © 2010 Pearson Education, Inc. Figure 18.11 Behavioral Responses • In contrast to plants, most animals can respond to an unfavorable change in the environment by moving to a new location. – Ectotherms may shuttle between sun and shade. – Migratory birds travel great distances in response to changing seasons. – Humans have an especially rich range of behavioral responses. © 2010 Pearson Education, Inc. BIOMES • A biome is – A major terrestrial or aquatic life zone – Characterized by – Vegetation type in terrestrial biomes – The physical environment in aquatic biomes © 2010 Pearson Education, Inc. • Aquatic biomes – Occupy roughly 75% of Earth’s surface – Are determined by their – Salinity (what is the salinity of the worlds oceans?) – Other physical factors © 2010 Pearson Education, Inc. • Freshwater biomes – Typically have a salt concentration of less than 1% – Include lakes, streams, rivers, and wetlands • Marine biomes – Typically have a salt concentration around 3% – Include oceans, intertidal zones, coral reefs, and estuaries © 2010 Pearson Education, Inc. Freshwater Biomes • Freshwater biomes – Cover less than 1% of Earth – Contain a mere 0.01% of its water – Harbor about 6% of all described species – Are used for drinking water, crop irrigation, sanitation, and industry © 2010 Pearson Education, Inc. Photic zone Benthic realm Aphotic zone Figure 18.15 Wetlands • A wetland is a transitional biome between an aquatic ecosystem and a terrestrial one. • Wetlands – Support the growth of aquatic plants – Are among the richest of biomes in terms of species diversity © 2010 Pearson Education, Inc. Figure 18.18 Marine Biomes • Marine biomes are diverse, ranging from vivid coral reefs to perpetually dark realms in the deepest regions. © 2010 Pearson Education, Inc. High tide Low tide Pelagic realm (open water) Sea star (to 33 cm) Oarweed (to 2 m) Brain coral (to 1.8 m) PhytoZooplankton plankton Intertidal Continental zone shelf Sponges (1 cm–1 m) Turtle (60–180 cm) Blue shark (to 2 m) Photic zone 200 m Sperm whale (10–20 cm) Sea pen (to 45 cm) Benthic realm (seafloor from continental shelf to deep-sea bottom) Man-of-war (to 50 m long) Octopus (to 10 m) Sea spider (1–90 cm) Brittle star (to 60 cm) Glass Rat-tail fish (to 80 cm) Hatchet fish (2–60 cm) Gulper eel (to 180 cm) Anglerfish (45 cm–2 m) sponge Sea cucumber Tripod fish (to 30 cm) (to 1.8 m) (to 40 cm) “Twilight” Aphotic zone 1,000– 4,000 m No light 6,000– 10,000 m Figure 18.19 • Estuaries – Are a transition area between a river and the ocean – Have a saltiness ranging from nearly that of fresh water to that of the ocean – Are among the most productive areas on Earth © 2010 Pearson Education, Inc. Figure 18.22 • Estuaries are threatened by – Landfills – Nutrient pollution – Contamination by pathogens or toxic chemicals – Alteration of freshwater inflow – The introduction of non-native species © 2010 Pearson Education, Inc. How Climate Affects Terrestrial Biome Distribution • Terrestrial biomes are primarily determined by – Temperature – Rainfall • Earth’s global climate patterns are largely the result of – The input of radiant energy from the sun – The planet’s movement in space © 2010 Pearson Education, Inc. North Pole 60º N Low angle of incoming sunlight 30º N Tropic of Cancer Sunlight strikes most directly 0º (equator) Tropic of Capricorn 30º S Low angle of incoming sunlight Atmosphere 60º S South Pole Figure 18.23 • Heated by the direct rays of the sun, air at the equator rises, then cools forming clouds, and drops rain. • This largely explains why rain forests are concentrated in the tropics, the region from the Tropic of Cancer to the Tropic of Capricorn. © 2010 Pearson Education, Inc. Descending dry air absorbs moisture Ascending moist air Trade winds releases Trade winds moisture Descending dry air absorbs moisture Doldrums 0º Temperate zone Tropics Temperate zone Figure 18.24 • Climate is also affected by – Proximity to large bodies of water – The presence of landforms such as mountain ranges © 2010 Pearson Education, Inc. Terrestrial Biomes • Terrestrial ecosystems are grouped into biomes primarily on the basis of their vegetation type. © 2010 Pearson Education, Inc. 30º N Tropic of Cancer Equator Tropic of Capricorn 30º S Key Tropical forest Savanna Desert Chaparral Temperate grassland Temperate broadleaf forest Coniferous forest Arctic tundra High mountains (coniferous forest and alpine tundra) Polar ice Figure 18.27 Desert • Deserts – Are the driest of all biomes – May be very hot or very cold © 2010 Pearson Education, Inc. Figure 18.31 Precipitation Temperature Descending dry air absorbs moisture Ascending moist air Trade winds releases Trade winds moisture Descending dry air absorbs moisture Doldrums 0º Temperate zone © 2010 Pearson Education, Inc. Tropics Temperate zone Figure 18.24 Temperate Broadleaf Forest • Temperate broadleaf forest – Occurs throughout midlatitudes where there is sufficient moisture to support the growth of large trees – Includes dense stands of deciduous trees in the Northern Hemisphere © 2010 Pearson Education, Inc. Figure 18.34 Precipitation Temperature Coniferous Forest • Coniferous forests – Are dominated by cone-bearing evergreen trees – Include the northern coniferous forest, or taiga, the largest terrestrial biome on Earth © 2010 Pearson Education, Inc. Figure 18.35 Precipitation Temperature Polar Ice • Polar ice covers the land at high latitudes north of the arctic tundra in the northern hemisphere and Antarctica in the southern hemisphere. • Only a small portion of these land masses is free of ice or snow, even during the summer. © 2010 Pearson Education, Inc. Figure 18.37 Precipitation Temperature The Water Cycle • All parts of the biosphere are linked by the global water cycle. • Human activities that affect the global water cycle include – Destruction of forests – Pumping large amounts of groundwater to the surface for irrigation © 2010 Pearson Education, Inc. Solar heat Water vapor over the sea Precipitation over the sea Net movement of water vapor by wind Evaporation from the sea Water vapor over the land Precipitation over the land Evaporation and transpiration Oceans Flow of water from land to sea Surface water and groundwater Figure 18.38 Human Impact on Biomes • Sustainability is the goal of developing, managing, and conserving Earth’s resources in ways that meet the needs of people today without compromising the ability of future generations to meet their needs. © 2010 Pearson Education, Inc. Satellite photos of a small area in Brazil show how thoroughly a landscape can be altered in a short amount of time. 1975 2001 Figure 18.39 Every year, more and more forested land is cleared for agriculture. Figure 18.40 Fresh Water • The impact of human activities on freshwater ecosystems may pose an even greater threat to life on Earth—including ourselves—than the damage to terrestrial ecosystems. © 2010 Pearson Education, Inc. GLOBAL CLIMATE CHANGE • Global climate patterns are changing because of rising concentration in the atmosphere of – Carbon dioxide (CO2) – Some other gases © 2010 Pearson Education, Inc. The Greenhouse Effect and Global Warming • Greenhouse gases – Include CO2, water vapor, and methane – Are transparent to solar radiation – Absorb or reflect heat – Contribute to increases in global temperatures © 2010 Pearson Education, Inc. Some heat energy escapes into space Sunlight Atmosphere Radiant heat trapped by greenhouse gases Figure 18.43 The Accumulation of Greenhouse Gases • The vast majority of scientists are confident that human activities have caused the rising concentrations of greenhouse gases. © 2010 Pearson Education, Inc. Carbon dioxide (CO2) (ppm) 400 350 300 250 0 500 1000 1500 2000 Year Figure 18.45 • Overall, the uptake of CO2 by photosynthesis roughly equals the release of CO2 by cellular respiration. © 2010 Pearson Education, Inc. Atmosphere Photosynthesis Respiration Combustion of fossil fuel Ocean Figure 18.46 Effects of Climate Change on Ecosystems • In many plants and animals, life cycle events are triggered by – Warming temperatures – Day length © 2010 Pearson Education, Inc. • As global temperatures warm, and day length remains steady, natural interactions may become out of sync. – Plants may bloom before pollinators have emerged. – Eggs may hatch before dependable food sources are available. © 2010 Pearson Education, Inc. Looking to Our Future • Emissions of greenhouse gases are accelerating. • From 2000–2005 global CO2 emissions increased four times faster than in the preceding 10-year span. © 2010 Pearson Education, Inc. • The amount of greenhouse gas emitted as the result of the actions of a single individual is that person’s carbon footprint. • We can reduce our carbon footprints by – Reducing our use of energy – Driving less – Recycling © 2010 Pearson Education, Inc. • In addition, eating locally grown fresh foods may lower the greenhouse gas emissions that result from food processing and transportation. © 2010 Pearson Education, Inc.