Ecological Research ranges from adaptations of organisms to dynamic ecosystems

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1 AP Bio Ecology Chapter 50 Ecology is the study of the interactions between organisms and the environment. Ecological Research ranges from adaptations of organisms to dynamic ecosystems Ecology can be divided into 4 levels of study. Organismal ecology: is concerned with the behavioral, physiological and morphological ways in which individual organisms meet challenges posed by their abiotic environment. Populations: is the next level of organization, population is a group of individuals of the same species living in a particular geographical area. A community: which consists of all organisms that inhabit a particular area Ecosystem: includes all the abiotic factors in addition to the community of species that exist in a certain area. Ecology provides a scientific context for evaluating environmental issues Much of our current environmental awareness had its beginnings with Rachel Carson s 1962 book Silent Spring which pointed out the use of pesticides such as DDT were causing populations to decline. Today acid rain, localized famine aggravated by land misuse and population growth, the poisoning of soil and streams with toxic waste, and the growing list of species extinct or endangered because of habitat destruction are just a few problems that threaten the home we share with millions of other life forms. Abiotic factors of the biosphere Temperature Water The biosphere is the sum of all the planets ecosystems, or all of life and where it lives. Major abiotic factors: Temperature, water, sunlight, wind, rocks and soil. Most organisms ultimately get there energy from sunlight, and must tolerate the ranges of temperature, humidity, salinity, and light in there environment. Temperature is an important factor in the distribution of organisms because of the effects on biological processes and the inability to regulate body temperature precisely. For example cells may rupture if the water they contain freezes at temperatures below 0C and most proteins will denature if temperature rises above 45C. The actual internal temperature of an organism is affected by heat exchange with its environment. Endotherms are the exception, but even endotherms function best with in certain environmental temperature ranges that vary from species to species Water is essential to life, but its availability varies dramatically among habitats. Freshwater and marine organisms live submerged in an aquatic environment, but face problems with osmolarity. Organisms in terrestrial environments encounter a nearly constant threat of desiccation, and their environment has been shaped by the requirements for obtaining and conserving adequate supplies of water. The unique properties of water have effects on organisms an their environments (cohesive/adhesive, high specific heat, etc) Sunlight Wind Rocks and Minerals Sunlight provides the energy that drives nearly all ecosystems, although plants and other photosynthetic organisms are the only ones to use the sunlight directly. Light is also important to the development and behavior of the many plants and animals that are sensitive to photoperiod, the realtive lengths of daytime and nighttime. Photoperiod is a more reliable indicator then temperature for cueing seasonal events, such flowering or migration. Wind amplifies the effect of environmental temperature on organisms by increasing heat loss due to evaporation and convection. It also increases water loss in organisms due to the increased rate of evaporation. Wind can also inhibit the growth of limbs on trees on the windward side. Rocks and soil: The physical structure, ph, and mineral composition of rocks and soil limit the distribution of plants and other animals that feed on them. In streams and rivers the composition of the substrate can affect water chemistry, which in turn influences the resident plants and animals. In marine environments the structure of substrates in the intertidal zone on the sea floors determines the types of organisms that can attach or burrow in those habitats. 1

2 Continued Biome vs. Ecosystem EC Periodic Disturbances: Catastrophic disturbances such as fire, hurricanes, tornadoes, and volcanic eruptions can devastate biological communities. After the disturbance the area is repopulated by the survivors, but the structure of the community is changes during the rebound. Some periodic disturbances such as volcanic eruptions, are so infrequent and unpredictable that organisms have no evolutionary adaptations to them. Fire on the other hand recurs frequently in some communities and some communities require fire to maintain them. Biome: refers to the major types of ecosystems. Ecosystem: includes all the biotic and abiotic factors in a given area. Biosphere: The global ecosystem. It is the sum of all the planet s ecosystems, it includes the atmosphere and below ground caves. I contain a large amount of H2O I am considered mesotrophic There are slot sizes fishermen have to abide by before they take fish from me. I have a lot of Stizostedion vitreum vitreum in me. I was in the news paper a lot last spring and summer I am the fifth largest of my kind in MN Native Americans can fish me year around with few restrictions Aquatic Biomes occupy the largest part of biosphere Ecologists distinguish between fresh water biomes and marine biomes. The evaporation of seawater provides most of the planets precipitation. Marine algae and photosynthetic bacteria supply a substantial portion of the worlds oxygen. Aquatic Biomes Lakes: Oligotrophic, Eutrophic, Mesotrophic Rivers and Streams Ponds Wetlands Estuaries Marine biomes: Intertidal zones, coral reefs, benthos, and abyssal zones. Vertical Stratification of Aquatic Biomes Lakes Many aquatic biomes exhibit vertical stratification of physical and chemical variables. Light is absorbed by both the water itself and the microorganisms in it. Photic Zone- where light is sufficient for photosynthesis. Aphotic Zone- Where little light penetrates. At the bottom of all aquatic biomes a substrate called the benthic zone, made up of sand and organic and inorganic sediments. Occupied by organisms collectively called benthos, there main food source is called detritus. Fresh Water Biomes Continued Two types of fresh water biomes; standing bodies of water which include lakes and ponds, and moving bodies of water which include rivers and streams. littoral zone: the shallow waters close to the shore rooted and floating aquatic plants flourish here. limnetic zone: The well-lit, open surface, farther from shore occupied by a variety of phytoplankton consisting of algae, cyanobacteria. These organisms photosynthesize and reproduce at a high rate during the spring and summer. Zooplankton, mostly rotifers and small crustaceans, graze on the photoplankton. The zooplankton are then consumed by small fish, which in turn are eaten by larger fish, semi aquatic snakes, turtles and fish eating birds. Most of the small organisms are short lived and their remains sink into a deep aphotic region called the profundal zone, and down to the benthic zone. Microbes in the profundal zone and benthic zone use oxygen for cellular respiration as they decompose the detritus. Lakes are often classified according to there production of organic matter. 2

3 Classification of lakes Turn over Oligotrophic lakes are deep and nutrient poor, the photoplankton in the limnetic zone are not very productive. Eutrophic lakes, in contrast are usually shallower and their nutrient concentration is usually high. As a result photoplankton are very productive and thw waters a re frequently murky. Mesotrophic lakes are in the middle of Oligotrophic and Eutrophic. Over long periods of time oligtrophic lakes become Eutrophic lakes. Streams and river are bodies of water moving in one direction constantly. A stratum of rapid temperature change called a thermocline separates a more uniformly warm upper layer from a more uniformly lower cold layer in lakes and oceans. Terrestrial Biomes Based mainly on regional variations in climate. Tropical forests Savanna Desert Chaparral Temperate Grasslands Tundra Climate and the Distribution of Organisms The abiotic factors just described have a direct effect on the biology of organisms. Four factors: Temperature, water, light, and wind are the major components of the climate. Biome refers to major types of ecosystems found in a given area. USE AP CD AND FIGURE OUT THE DIFFERENT BIOMES Global Climate Patterns Earth s global climate patterns are largely determined by the input of solar energy and the planets movement through space. The planet is tilted on its axis by 23.5 degrees relative to its plane of orbit around the sun, its tilt causes seasonal variation in the intensity of solar radiation. The angle of solar radiation changes from day to day as Earth revolves around the sun. Only the tropic receives sunlight from directly overhead. As a result, the tropics experience the greatest annual input and least seasonal variation in solar radiation of any region on Earth. 3

4 Local and Seasonal Effects on Climate. Ocean currents effect climates along coasts of continents by heating or cooling overlying air masses, which may then pass across the land. Evaporation from the ocean is greater then the land, which is why areas near the coast are generally moister. Oceans and large bodies of water generally moderate the climates of the nearby terrestrial environments on a daily bases. Mountains also have a major effect on the climate. In the Northern hemisphere south side slopes receive more sunlight and therefore are warmer and drier. Deserts commonly occur on the leeward side of a mountain. 4

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