Ecology Introduction

Ecology Introduction - Biology 307: Ecology

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Unformatted text preview: Biology 307: Ecology http://mason.gmu.edu/~lrockwoo/newecologyfrontpage.html For Power Points, Lab and Lecture syllabi For and other information go to: http://courses.gmu.edu Purchase the text, lab manual and iclicker Purchase at the bookstore at iClicker Go to iclicker.com to register your iclicker Google ‘iclicker registration” Ecology Ecology Dedicated to an understanding of the Dedicated relationships between organisms and their environment. their Ecology is often the center of public Ecology center policy disputes: policy 1. 1. Decline of Decline fisheries worldwide. worldwide. -Two kinds of -Two rockfish. rockfish. 2. Collapse of Chesapeake Bay oyster, blue 2. crab and fish populations. crab 3. 3. 4. Collapse of human Collapse societies due to deforestation and other abuses of the environment (Haiti, Easter Island, Mayans). Mayans). Flooding and Flooding droughts as a result of destruction of wetlands and montane forests. montane 5. Connected with this are the “dead zones” in the Gulf of Mexico due to pesticide and fertilizer run off along the Mississippi River. Before the oil spill in 2010! Ecology The dead zone is caused by nutrient enrichment from the Mississippi River, particularly nitrogen and phosphorous. Watersheds within the Mississippi River Basin drain much of the United States, from Montana to Pennsylvania and extending southward along the Mississippi River. Most of the nitrogen input comes from major farming states in the Mississippi River Valley. Ecology Nitrogen and phosphorous enter the river through upstream runoff of fertilizers, soil erosion, animal wastes and sewage. With increased nitrogen and phosphorus input, algae growth is no longer limited. Consequently, algal blooms develop, followed thereafter by massive die offs. The dissolved oxygen is depleted, resulting in deaths of commercial and non-commercial animal life. 6. 6. Fire, Fire, logging and forest health. health. 7. 7. Global climate change resulting from Global deforestation and greenhouse gas emissions. 8. 8. The introduction of exotic species The resulting in the disruption of both natural and human dominated ecosystems and the spread of diseases (West Nile Virus). the Specific Goals of Biology 307 Specific 1. Develop an appreciation for the modern scope of scientific inquiry in ecology. scope 2. Become familiar with the variety of ways Become that organisms interact with both the physical and the biological environment. physical Specific Goals of Biology 307 Specific 3. Develop an Develop understanding of the differences in the structure and function of different types of ecosystems (aquatic versus terrestrial, tropical versus temperate versus boreal). versus Marsh at Mason Neck Specific Goals of Biology 307 Specific 4. Become familiar with mathematical Become models, especially those dealing with population dynamics. population 80 00 Deterministic growth using arithmetic mean (1.05) Stochastic growth with low variance (0.02) Stochastic growth with high variance (0.08) "Most Likely" stochastic growth uising the geometric mean (1.04) 70 00 60 00 50 00 40 00 30 00 20 00 10 00 0 0 10 20 30 40 50 Time 60 70 80 90 1 00 Specific Goals of Biology 307 Specific 5. Learn techniques of data analysis as well Learn as methods for presenting scientific information in appropriate figures and tables. tables. 0.35 0.3 Probability 0.25 0.2 0.15 0.1 0.05 0 0 1 2 3 4 5 6 7 Number of female individuals in the next generation Figure 1.7. Stochastic growth in a population of three females based on the parameters of Table 1.7 Specific Goals of Biology 307 Specific 6. Become proficient in writing a scientific Become paper. This course fulfills the faculty senate mandated “writing intensive” requirement in the biology major. requirement 7. Learn techniques for data gathering in Learn the field. the Specific Goals of Biology 307 Specific 8. Develop an Develop understanding of applied ecology and environmental issues facing the world today. world May Apples in Spring Specific Goals of Biology 307 Specific 9. Develop an Develop appreciation for the natural world natural through direct experience with local ecosystems. local Grassland at Grassland Banshee Reeks in Loudoun County Loudoun What is Ecology? What 1. The study of the relationships between The organisms and their environment. organisms 2. The study of the interactions (both with The the physical environment and other organisms) that determine the distribution and abundance of a species. distribution Ernst Haeckel: German Zoologist in 1870 Ernst “By Ecology we mean the body of knowledge By Ecology concerning the economy of nature—the investigation of the total relations of the animal both to its organic and to its inorganic environment; above all, its friendly and inimical relation with those animals and plants with which it comes directly or indirectly into contact in a word, ecology is the study of all the complex interrelationships referred to by Darwin as the conditions of the struggle for existence.” existence.” What is the Environment? What 1. 2. The sum total of all physical and biological factors influencing a particular organism. The external physical and biological factors that influence growth, survivorship, development and reproduction of organisms. What is the Environment? What Physical environment = Abiotic factors Physical Abiotic Climate, soil, nutrients, etc. What is the Environment? What Biological environment = Biotic factors Biological Biotic Competitors, predators, parasites, diseases, Competitors, etc. etc. What is the Environment? What Habitat = a place where organisms live and the environmental factors found there and General Principles of Ecology General 1. Ecological systems function according to Ecological the laws of thermodynamics (Ecosystems). (Ecosystems). 2. The physical environment exerts a The controlling influence on the productivity of ecological systems (Ecosystems). of General Principles of Ecology General 3. The structure and dynamics of ecological The communities are regulated by population processes (Populations). processes 4. Over generations, organisms respond to Over change in the environment through evolution within populations (Evolution). evolution Sample Quiz: Question One Sample Which of the following is a general Which principle of ecology? principle A. A. B. C. D. Populations tend to grow linearly. Community ecology concerns populations of Community many species. many Ecological systems function according to the Ecological laws of thermodynamics. laws The first definition of ecology was articulated The by Darwin. by Laws of Thermodynamics Laws First Law: Energy can neither be created First nor destroyed but may change form. nor Important transformations include: 1. 2. Electromagnetic energy to chemical energy Electromagnetic (photosynthesis) and to heat energy (climate). (climate). Chemical energy to kinetic energy (energy Chemical of motion) and to heat energy. of Laws of Thermodynamics Laws Second Law: In each energetic transformation, potential energy is reduced, as some energy is lost to the system as heat; or system or Entropy increases in a closed system. Laws of Thermodynamics Laws The second law The says that energetic transformations are always less than 100% efficient. 100% Laws of Thermodynamics Laws Ecosystems do not degrade over time, in Ecosystems spite of the fact that they use energy, because they are not closed systems. not Without a constant input of energy, Without ecosystems would degrade and life would perish. perish. Laws of Thermodynamics Laws Applying the Second Law of Applying Thermodynamics to energy flow in ecosystems tells us that the transfer of ecosystems energy from one trophic (energy) level (plants to herbivores, for example) to another always involves a dissipation of dissipation energy. energy. Laws of Thermodynamics Laws The second law places a limit on the The number of trophic levels in an ecosystem. number Levels of Organization in Ecology Levels Units of study: Units 1. Individual organisms (adaptations to their 1. Individual environment) environment) 2. Populations 3. Communities 4. Ecosystems Levels of Organization in Ecology Levels 1. Population = A group of interbreeding individuals of the same species found in the same place at the same time (sympatric). (sympatric). Levels of Organization in Ecology Levels 2. Species = A group of actually or potentially interbreeding individuals that potentially are reproductively isolated from all other kinds of organisms (more later). kinds Levels of Organization in Ecology Levels 3. Community = the assemblage of plants, animals, microbes or other organisms living in the same habitat, and that interact and affect one another. interact Levels of Organization in Ecology Levels 4. Ecosystem = An environmental unit consisting of biotic and abiotic components related through exchanges of energy and nutrients. of The emphasis in ecosystem ecology is on The the movement of energy and nutrients within ecosystems. within Levels of Organization in Ecology Levels 5. Metapopulation = assemblages of populations or individualsof a particular species within a large spatial scale, with spatial with the long-term survival of the species or population depending on a shifting balance between local population extinctions and colonizations in the extinctions colonizations patchwork of a fragmented landscape. patchwork Metapopulation Metapopulation In a metapopulation, local populations in all habitat patches are assumed to undergo extinction but all can receive immigrants from other populations. Patches Connected by Immigration and Emigration Plant Hopper Movie Levels of Organization in Ecology Levels Metapopulation Metapopulation theory is of particular importance to conservation biology in which species are thought to undergo regular local extinctions. extinctions. Levels of Organization in Ecology Levels Trophic (Energy) Levels 1. Producers (autotrophs) Can be Photosynthetic or Photosynthetic Chemosynthetic Chemosynthetic organisms organisms Local Primary Production Based on Photosynthesis Levels of Organization in Ecology Levels 2. Heterotrophs A. Consumers: Organisms Organisms that consume other living organisms (herbivores, predators, etc.) predators, Levels of Organization in Ecology Levels B. Decomposers: Organisms that consume non-living non-living organic material (many fungi, bacteria, earthworms, flesh flies etc.) flies Levels of Organization in Ecology Levels A. Consumers are defined more directly by their functional roles. roles. Herbivores: animals animals that feed directly on producers (e.g. grasshoppers, wildebeest). wildebeest). Levels of Organization in Ecology Levels B. Primary Carnivores: animals that feed on herbivores (e.g. spiders, snakes, crocodiles). crocodiles). Levels of Organization in Ecology Levels C. Secondary Carnivores: animals that animals feed on primary carnivores (e.g. birds such as chickadees that feed on insects). such D. Tertiary Carnivores: animals that feed animals on secondary carnivores (e.g. hawks). on Trophic Pyramids Trophic Food chains or food Food webs. webs. Based on trophic Based relationships. relationships. Limited number of Limited trophic links due to Laws of Thermodynamics. Thermodynamics. Trophic Pyramids Trophic Declining energy in higher trophic levels, Declining produces the “Trophic Pyramid”. produces Rule of Thumb: approximately 10% of Rule energy transferred to next trophic level. energy Trophic Pyramids Trophic Energy lost from one trophic level to the next Energy is due to: is 1. Not all organisms are consumed. Not organisms consumed 2. Not all parts of organisms are consumed. Not parts consumed Trophic Pyramids Trophic 3. Not all energy consumed is assimilated. Not consumed assimilated 4. Most energy assimilated is lost to Most assimilated respiration (2nd Law of Thermodynamics). respiration 5. Energy from points 1-3 goes to the Energy decomposer food chain. decomposer Trophic Pyramids Trophic Food Food webs (and ecosystems) work in unknown and unexpected ways: unknown Ecosystems are unpredictable. “The law of unintended consequences.” Robert Merton (1970s): Complex systems create Robert unanticipated or undesirable outcomes. unanticipated Lake Victoria and the Nile Perch Lake Victoria is the world's second largest freshwater lake by surface area and is the largest lake in Africa. It is surrounded by Uganda, Tanzania and Kenya It has dried out three times; it last dried out 17,300 years ago, and it refilled beginning about 14,700 years ago. Lake Victoria and the Nile Perch Before 1954, Lake Victoria's ecology was characterized by enormous biodiversity. It was inhabited by over 500 species of fish, 90% of which were cichlids belonging to the genus Haplochromis. Lake Victoria and the Nile Perch In the late 1950s the Nile Perch Lates In niloticus was introduced as a “sport fish” niloticus into Lake Victoria because the British colonial fishermen had driven the most popular local fish to near extinction. popular Lake Victoria and the Nile Perch Lake Victoria and the Nile Perch Results of this introduction: 1. Extinction or near extinction of many Extinction native endemic fish species. About half of the 400 species of Tilapia are now extinct. extinct. Lake Victoria and the Nile Perch 2. Loss of phytoplankton eating fish Loss species. species. 3. Great increase in algae (“blooms”) Followed by: Lake Victoria and the Nile Perch 4. Die off of algae; decomposition of algae; Die anoxia for much of the lake. anoxia 5. Further die off of fish from lack of Further oxygen. oxygen. Lake Victoria and the Nile Perch 6. Proliferation of snails due to loss of snail Proliferation eating fish. eating Lake Victoria and the Nile Perch 7. Spread of snail borne diseases among Spread the people (Schistosomyosis). the Lake Victoria and the Nile Perch 8. Necessity of wood fires to smoke the Nile Necessity Perch. Native fish could be air dried. Perch. 9. Cutting of forest around lake to provide Cutting wood for fire. Lake Victoria and the Nile Perch 10. 11. 12. Erosion of land around lake due to tree Erosion removal. removal. Pollution and sedimentation of lake. Pollution Further loss of fish species. Further Lake Victoria and the Nile Perch Nevertheless, it has now become a major Nevertheless, export from several countries surrounding Lake Victoria. Lake But the Nile Perch itself showing evidence But of being over fished and its populations are declining. are Export of Nile Perch Export Kenya Uganda Tanzania Landings 104,000 120,000 159,000 Exports in fillets 16,493 18,000 13,500 Export Value (million USD) 49.0 53.5 37.9 Food webs work in unknown and unexpected ways! unexpected Nature is constantly changing and Nature ecosystem change is not necessarily “unnatural.” What is unnatural and problematic is the What accelerated rate of change caused by rate human interventions and disturbances. human Sample Quiz: Question Two The Nile Perch is: A. a native fish in Lake Victoria. B. can be preserved by air drying. C. was introduced as a sport fish. D. was introduced in order to control schistosomyosis. Questions? ...
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This note was uploaded on 01/23/2012 for the course BIOL/EVPP 307 taught by Professor Crerar during the Summer '11 term at George Mason.

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