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Ecology
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Ecology

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  1. Ecology

  2. Part 1 of 5The Biosphere: An Introduction to Earth's Diverse Environments

  3. A Mysterious Giant of the Deep • Ecology is the scientific study of the interactions of organisms with their environment • The ocean is Earth’s largest and least explored ecosystem • Recent explorations of the deep sea have brought previously unknown species to light, such as this “mystery squid”

  4. Scientists have found seafloor life whose ultimate energy source is not sunlight, but energy that comes from the interior of the planet • This energy is emitted from hydrothermal vents near the edges of Earth’s crustal plates

  5. Many animals thrive in the extreme environment around hydrothermal vents • Tube worms were unknown to science until hydrothermal vents were explored • They live on energy extracted from chemicals by bacteria

  6. Ecologists study how organisms interact with their environment at several levels • Ecologists study environmental interactions at the organism, population, community, and ecosystem levels • These clams that live near an ocean vent constitute a population

  7. Ecosystem interactions involve living (biotic) communities and nonliving (abiotic) components • Abiotic components include energy, nutrients, gases, and water • Organisms are affected by their environment • But their presence and activities often change the environment they inhabit

  8. THE BIOSPHERE The biosphere is the total of all of Earth's ecosystems • The global ecosystem is called the biosphere • It is the sum of all the Earth's ecosystems • The biosphere is the most complex level in ecology

  9. except for energy obtained from the sun and heat lost to space • Patchiness characterizes the biosphere • Patchiness occurs in the distribution of deserts, grasslands, forests, and lakes • Each habitat has a unique community of species • The biosphere is self-contained

  10. Connection: Environmental problems reveal the limits of the biosphere • Human activities affect all parts of the biosphere • One example is the widespread use of chemicals

  11. Disturbances such as fires, hurricanes, and volcanic eruptions are also abiotic factors

  12. Physical and chemical factors influence life in the biosphere • The most important abiotic factors that determine the biosphere's structure and dynamics include • solar energy • water • temperature

  13. Organisms are adapted to abiotic and biotic factors by natural selection • The presence and success of a species in a particular place depends upon its ability to adapt • Natural selection adapts organisms to abiotic and biotic factors • Biotic factors include predation and competition

  14. Regional climate influences the distribution of biological communities • Climate often determines the distribution of communities • Earth's global climate patterns are largely determined by the input of solar energy and the planet's movement in space

  15. This is a result of the variation in solar radiation at different latitudes • Most climatic variations are due to the uneven heating of Earth's surface North Pole 60º N Low angle ofincoming sunlight 30º N Tropic ofCancer Sunlight directlyoverhead 0º (equator) Tropic ofCapricorn 30º S Low angle ofincoming sunlight 60º S Atmosphere South Pole

  16. AQUATIC BIOMES Oceans occupy most of Earth's surface • Oceans cover about 75% of the Earth's surface • Light and the availability of nutrients are the major factors that shape aquatic communities

  17. The saltiness of estuaries ranges from less than 1% to 3% • They provide nursery areas for oysters, crabs, and many fishes • They are often bordered by extensive coastal wetlands • Estuaries are productive areas where rivers meet the ocean

  18. The intertidal zone is the wetland at the edge of an estuary or ocean, where water meets land • Salt marshes, sand and rocky beaches, and tide pools are part of the intertidal zone • It is often flooded by high tides and then left dry during low tides

  19. Abiotic conditions dictate the kinds of communities that ocean zones can support Intertidal zone Continental zone Photiczone Pelagiczone Benthiczone(seafloor) Aphoticzone

  20. It supports highly motile animals such as fishes, squids, and marine mammals • Phytoplankton and zooplankton drift in the pelagic zone • The benthic zone is the ocean bottom • It supports a variety of organisms based upon water depth and light penetration • The pelagic zone is the open ocean

  21. The photic zone is the portion of the ocean into which light penetrates • Photosynthesis occurs here • The aphotic zone is a vast, dark region of the ocean • It is the most extensive part of the biosphere • Although there is no light, a diverse and dense population inhabits this zone

  22. They support a huge diversity of invertebrates and fishes • Coral reefs are easily degraded by • pollution • native and introduced predators • human souvenir hunters • Coral reefs are found in warm tropical waters above the continental shelf

  23. Freshwater biomes include lakes, ponds, rivers, streams, and wetlands • Lake and pond communities are shaped by • light • temperature • the availability of nutrients and dissolved oxygen

  24. A river environment changes greatly between its source and its mouth • Temperature, nutrients, currents, and water clarity vary at different points

  25. Wetlands are among the richest biomes in terms of species diversity

  26. TERRESTRIAL BIOMES Terrestrial biomes reflect regional variations in climate • Climatic differences, mainly temperature and rainfall, shape the major biomes that cover Earth's land surface • Biomes tend to grade into each other • Within each biome there is local variation • This gives vegetation a patchy, rather than uniform, appearance

  27. Major terrestrial biomes 30º N Equator 30º S Tropical forest Polar and high-mountain ice Temperate deciduous forest Savanna Chaparral Coniferous forest Desert Temperate grassland Tundra (arctic and alpine)

  28. Tropical forests cluster near the equator • Several types of tropical forests occur in the warm, moist belt along the equator

  29. The tropical rain forest is the most diverse ecosystem on Earth • Large-scale human destruction of tropical rain forests continues to endanger many species • It may also alter world climate

  30. Savannas are grasslands with scattered trees • Drier, tropical areas and some nontropical areas are characterized by the savanna

  31. Deserts are defined by their dryness • Deserts are the driest of all terrestrial biomes • They are characterized by low and unpredictable rainfall • Desertification is a significant environmental problem • the rapid depletion of plant life and the loss of topsoil at desert boundaries and in semiarid regions, usually caused by a combination of drought and the overexploitation of grasses and other vegetation by people.

  32. Spiny shrubs dominate the chaparral • The chaparral biome is a shrubland with cool, rainy winters and dry, hot summers • Chaparral vegetation is adapted to periodic fires

  33. Temperate grasslands include the North American prairie • Temperate grasslands are found in the interiors of the continents, where winters are cold • Drought, fires, and grazing animals prevent trees from growing • Farms have replaced most of North America's temperate grasslands

  34. Deciduous trees dominate temperate forests • Temperate deciduous forests grow where there is sufficient moisture to support the growth of large trees • Nearly all of the original deciduous forests in North America have been drastically altered by agriculture and urban development

  35. Coniferous forests are often dominated by a few species of trees • The northern coniferous forest, or taiga, is the largest terrestrial biome on Earth

  36. The taiga is characterized by long, cold winters and short, wet summers • Coastal coniferous forests of the Pacific Northwest are actually temperate rain forests

  37. Long, bitter-cold winters characterize the tundra • The arctic tundra lies between the taiga and the permanently frozen polar regions • It is a treeless biome characterized by extreme cold, wind, and permafrost • Permafrost is continuously frozen subsoil

  38. Part 2 of 5Population Dynamics

  39. The Spread of Shakespeare's Starlings • In the 1800s and early 1900s, introducing foreign species of animals and plants to North America was a popular, unregulated activity • In 1890, a group of Shakespeare enthusiasts released about 120 starlings in New York's Central Park • It was part of a project to bring to America every bird species mentioned in Shakespeare’s works

  40. Today, the starling range extends from Mexico to Alaska • Their population is estimated at well over 100 million Current 1955 Current 1955 1945 1935 1925 1945 1905 1915 1925 1935 1925 1935

  41. Starlings are omnivorous, aggressive, and tenacious • They cause destruction and often replace native bird species • Attempts to eradicate starlings have been unsuccessful • Over 5 million starlings have been counted in a single roost

  42. The starling population in North America has some features in common with the global human population • Both are expanding and are virtually uncontrolled • Both are harming other species • Population ecology is concerned with changes in population size and the factors that regulate populations over time

  43. Populations are defined in several ways • Ecologists define a population as a single-species group of individuals that use common resources and are regulated by the same environmental factors • Individuals in a population have a high likelihood of interacting and breeding with one another • Researchers must define a population by geographic boundaries appropriate to the questions being asked

  44. POPULATION STRUCTURE AND DYNAMICS Density and dispersion patterns are important population variables • Population density is the number of individuals in a given area or volume • It is sometimes possible to count all the individuals in a population • More often, density is estimated by sampling

  45. One useful sampling technique for estimating population density is the mark-recapture method Total population = No. animals in 1st sample X Total no. animals in 2nd sample No. marked animals in 2nd sample

  46. The dispersion pattern of a population refers to the way individuals are spaced within their area • Clumped • Uniform • Random

  47. Clumped dispersion is a pattern in which individuals are aggregated in patches • This is the most common dispersion pattern in nature • It often results from an unequal distribution of resources in the environment

  48. A uniform pattern of dispersion often results from interactions among individuals of a population • Territorial behavior and competition for water are examples of such interactions

  49. Random dispersion is characterized by individuals in a population spaced in a patternless, unpredictable way • Example: clams living in a mudflat • Environmental conditions and social interactions make random dispersion rare

  50. Idealized models help us understand population growth • Idealized models describe two kinds of population growth • exponential growth • logistic growth