Final Exam Study Guide
Final Exam Study Guide Biology 110 002
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This 0 page Study Guide was uploaded by Kathleen Maris on Sunday December 6, 2015. The Study Guide belongs to Biology 110 002 at University of South Carolina - Columbia taught by Dr. Dhameja in Fall 2015. Since its upload, it has received 19 views. For similar materials see General Biology in Science at University of South Carolina - Columbia.
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Date Created: 12/06/15
Chapter 18 An Introduction to Ecology Ecology is the scientific study of the interactions between organisms and the environment 0 These interactions determine distribution of organisms and their abundance O Ecology reveals the richness of the biosphere which is the global ecosystem or the sum of all the planet s ecosystems O Ecologists work at levels ranging from individual organisms to the planet 0 Ecology provides the scientific understanding that underlies environmental issues Organismal ecology studies how an organism s structure physiology and behavior meet environmental challenges Population ecology focuses on factors affecting how many individuals of a species live in an area Community ecology deals with the whole arrays of interacting species in a community Ecosystem ecology emphasizes energy ow and chemical cycling among the various biotic living and abiotic nonliving components Landscape ecology deals with arrays of ecosystems and how they are arranged in a geographic region 0 A landscape is a mosaic of connected ecosystems Global ecology examines the in uence of energy and materials on organisms across the biosphere Concept 1 Ecology integrates all areas of biological research and informs environmental decision making O Ecology has a long history as a descriptive science 0 It is also a rigorous experimental science 0 Events that occur in ecological time affect life on the scale of evolutionary time 0 Rachel Carson is credited with starting the modern environmental movement with the publication of Silent Spring in 1962 Concept 2 Interactions between organisms and the environment limit the distribution of species 0 Ecologists consider multiple factors when attempting to explain the distribution of spec1es Why in EmailsHas Ka hasant tram an area i I39aa BF Arma inaacaaaitilsa 39 err inauf aiaznittime lls El nEa iapaiaai n 2 Habitat Ea lattiurl 1f liarlit b quot n 7 A D F39I39EIEllEIIIiEIII39Ii p l iti mi chemical dilatr39imtl n39i Mu quot B P W 39 quot39 Ewm39patitiun diaaaaaa Tamra J E a iiati iia tmfa H 11 Water Iimlit Ila IF Ell aliiiati Salliniitg I liah ibuti 39iquot 393 llirnititss 7 PH dil tfihmi Sail nutriarntai eta 39 ib 39Ta miparatura Physics Light latmm Eni atructuna Fira I39li39liziisturvaai ate 0 Dispersal is the movement of individuals away from centers of high population density or their area of origin I Dispersal contributes to the global distribution of organisms O Ecologists have long recognized global and regional patterns of distribution of organisms within the biosphere O Biogeography is a good starting point for understanding what limits geographic distribution of species Chapter 19 Community Ecology A biological community is an assembly of populations of various species living close enough for potential interaction Concept 1 The relationships between species in a community are called interspecific interactions Interspecific interactions can affect the survival and reproduction of each species and the effects classified as positive negative or no effect 0 O Interspeci c competition occurs when species compete for a scarce resource I Strong competition can lead to competitive exclusion the local elimination of a competing species I A species total use of biotic and abiotic resources is called the species ecological niche and can be thought of as an organism s ecological role I Resource partitioning is the differentiation of ecological niches enabling similar species to coeXist in a community 0 Predation refers to interaction where one species the predator kills and eats the other the prey I Some feeding adaptations of predators are claws teeth fangs stingers and poison I Behavioral defenses include hiding eeing forming herdsschools self defense alarm calls and some morphological and physiological defense adaptations 0 Cryptic coloration or camou age makes prey difficult to spot 0 Herbivory is an interaction in which an herbivore eats plants or algae I It has led to evolution of plant mechanical and Chemical defenses and adaptations by herbivores O Symbiosis is a relationship where two or more species live in direct and intimate contact with one another I Mutualism or mutualistic symbiosis is an interspecific interaction that benefits both species I A mutualism can be obligate where one species cannot survive without the other or facultative where both species can survive alone I Commensalism O is when one species benefits and the other is unaffected 0 Commensal interactions are hard to document in nature because any close association likely affects both species I Parasitism is when one organism the parasite derives nourishment from another organism the host which is harmed in the process I Parasites that live within the body of their host are called endoparasites parasites that live on the external surface of their host are called ectoparasites 0 Many parasites have a life cycle involving a number of hosts 0 Some parasites change the behavior of the host to increase their own fitness Concept 2 In general a few dominant and keystone species in a community exert strong control on that community s structure 0 Two fundamental features of community structure I Species diversity is the variety of organisms that make up the community I Trophic structure is the feeding relationships between organisms in a community 0 Food chains link trophic levels from producers to top carnivores uatnmary scumsumejrs Eamiuum 1 infai Eamniuum I emsumm ii Bamnimm Enuplamltt rn l Primary pmn lulz m Plant Fh npl mkmn A termite13 fraud chain A marine mid chain A food web is a branching food chain with complex trophic interactions 0 Species may play a role at more than one trophic level 0 Food webs can be simplified by isolating a portion of a community that interacts very little with the rest of the community Each food chain in a food web is usually only a few links long Two hypotheses attempt to eXplain food chain length 0 The energetic hypothesis suggests that length is limited by inefficient energy transfer 0 The dynamic stability hypothesis proposes that long food chains are less stable than short ones 0 Most data supports the energetic hypothesis 0 Certain species have a very large impact on community structure Such species are highly abundant or play a pivotal role in community dynamics I Dominant species are those that are most abundant or have the highest biomass 0 Biomass is the total mass of all individuals in a population 0 Dominant species exert powerful control over the occurrence and distribution of other species 0 One hypothesis suggests that dominant species are most competitive in eXploiting resources 0 Another hypothesis is that they are most successful at avoiding predators I Invasive species typically introduced to a new environment by humans often lack predators or disease I Keystone species exert strong control on a community by their ecological roles or niches 0 In contrast to dominant species they are not necessarily abundant in a community I Foundation species ecosystem engineers cause physical changes in the environment that affect community structure 0 Some foundation species act as facilitators that have positive effects on survival and reproduction of some other species in the community 0 The bottomup model of community organization proposes a unidirectional in uence from lower to higher trophic levels I In this case presence or absence of mineral nutrients determines community structure including abundance of primary producers O The topdown model also called the trophic cascade model proposes that control comes from the trophic level above I In this case predators control herbivores which in turn control primary producers 0 Long term experimental studies have shown that communities vary in their relative degree of bottom up and top down control Concept 3 Decades ago most ecologists favored the View that communities are in a state of equilibrium Recent evidence of change however has led to a nonequilibrium model which describes communities as constantly changing after disturbances O A disturbance is an event that changes a community removes organisms from it and alters resource availability 0 Fire is a significant disturbance in most terrestrial ecosystems O The intermediate disturbance hypothesis suggests that moderate levels of disturbance can foster greater diversity than either high or low levels of disturbances I High levels of disturbance exclude many slow growing species I Low levels of disturbance allow dominant species to exclude less competitive species 0 Ecological succession is the sequence of community and ecosystem changes after a disturbance I Primary succession occurs where no soil exists when succession begins I Secondary succession begins in an area where soil remains after a disturbance I Earlyarriving species and laterarriving species may be linked in one of three processes 0 Early arrivals may facilitate appearance of later species by making the environment favorable 0 Early arrivals may inhibit establishment of later species 0 Early arrivals may tolerate later species but have no impact on their establishment O Humans have the greatest impact on biological communities worldwide I Human disturbance to communities usually reduces species diversity I Humans also prevent some naturally occurring disturbances which can be important to community structure Concept 4 Biogeographic factors affect community biodiversity O Latitude and area are two key factors that affect a community s species diversity 0 Species richness generally declines along an equatorial polar gradient and is especially great in the tropics 0 Climate is likely the primary cause of the latitudinal gradient in biodiversity I Two main climatic factors correlated with biodiversity are solar energy and water availability They can be considered together by measuring a community s rate of evapotranspiration 0 Evapotranspiration is evaporation of water from soil plus transpiration of water from plants 0 The speciesarea curve quantifies the idea that all other factors being equal a larger geographic area has more species I Studies of species richness on the Galapagos Islands support the prediction that species richness increases with island size I A species area curve of North American breeding birds supports this idea Concept 5 Community ecology is useful for understanding universally affecting pathogen life cycles and controlling human disease and is needed to help study and combat these pathogens 0 Pathogens include disease causing microorganisms viruses viroids and prions O Pathogens can alter community structure quickly and extensively 0 Human activities transport pathogens around the world at unprecedented rates I The transfer of pathogens can be direct or through an intermediate species called a vector I Zoonotic pathogens have been transferred from animals to humans 0 Many of today s emerging human diseases are zoonotic 0 Avian u is a highly contagious virus from birds 0 Ecologists are studying the potential spread of the virus from Asia to North American through migrating of birds Chapter 20 Ecosystems An ecosystem consists of all the organisms living in a community as well as the abiotic factors with which they interact O Ecosystems range from a microcosm such as an aquarium to a large area such as a lake or forest O Regardless of an ecosystem s size its dynamics involve two main processes energy flow and chemical cycling I Energy ows through ecosystems while matter cycles within them 0 Ecologists study the transformations of energy and matter within a system Concept 1 The laws of physics and chemistry govern energy ow and chemical cycling in ecosystems 0 The first law of thermodynamics states that energy cannot be created or destroyed only transformed I Energy enters an ecosystem as solar radiation is conserved and is lost from organisms as heat 0 The second law of thermodynamics states that every exchange of energy increases the entropy of the universe I Entropy is disorder randomness or chaos of molecules 0 In an ecosystem energy conversions are not completely efficient and some energy is always lost as heat 0 The law of conservation of mass states that matter cannot be created or destroyed I Chemical elements are continually recycled within ecosystems I In a forest ecosystem most nutrients enter as dust or solutes in rain and are carried away in water 0 Ecosystems are open systems absorbing energy and mass and releasing heat and waste products I Autotrophs build molecules themselves using photosynthesis or chemosynthesis as an energy source heterotrophs depend on the biosynthetic output of other organisms I Energy and nutrients pass from primary producers autotrophs to primary consumers herbivores to secondary consumers carnivores to tertiary consumers carnivores that feed on other carnivores I Detritivores or decomposers are consumers that derive their energy from detritus nonliving organic matter 0 Prokaryotes and fungi are important detritivores 0 Decomposition connects all trophic levels Concept 2 Energy and other limiting factors control primary production in ecosystems 0 Primary production in an ecosystem is the amount of light energy converted to chemical energy by autotrophs during a given time period I The amount of solar radiation reaching the Earth s surface limits photosynthetic output of ecosystems I Only a small fraction of solar energy actually strikes photosynthetic organisms and even less is of a usable wavelength 0 In marine and freshwater ecosystems both light and nutrients control primary production I Depth of light penetration affects primary production in an ocean or lake I Also lack of nutrients limits primary production in geographic regions of the ocean and lakes I These are limiting nutrients the nutrients that are needed for continued growth but are unavailable at times due to their finite quantity hence limiting marine production in their absence 0 Two such elements are nitrogen and phosphorous O In terrestrial ecosystems temperature and moisture affect primary production on a large scale along with soil nutrients I Actual evapotranspiration the water annually transpired by plants and evaporated from a landscape can represent the contrast between wet and dry climates 0 It is related to net primary production Concept 3 Energy transfer between trophic levels is typically only 10 efficient 0 Secondary production of an ecosystem is the amount of chemical energy in food converted to new biomass during a given period of time I Trophic efficiency is the percentage of production transferred from one trophic level to the next and it usually ranges from 5 to 20 I When a caterpillar feeds on a leaf only about one sixth of the leaf s energy is used for secondary production 0 Approximately 01 of chemical energy fixed by photosynthesis reaches a tertiary consumer I A pyramid of net production represents the loss of energy with each transfer in a food chain 1000000 I 10000 I 1000 I 100 I 10 Producer I Con 1 I Con 2 I Con 3 I Con 4 Concept 4 Biological and geochemical processes cycle nutrients between organic and inorganic parts of an ecosystem 0 Life depends on recycling chemical elements 0 Nutrient circuits in ecosystems involve biotic and abiotic components and are often called biogeochemical cycles 0 Gaseous carbon oxygen sulfur and nitrogen occur in the atmosphere and cycle globally 0 Less mobile elements such as phosphorous potassium and calcium cycle on a more local level 0 All elements cycle between organic and inorganic reservoirs rather between living organisms and the atmosphere 0 In the carbon cycle C02 is taken up and released through photosynthesis and respiration additionally volcanoes and the burning of fossil fuels contribute C02 to the atmosphere I Carbon based organic molecules are essential to all organisms I Carbon reservoirs include fossil fuels soils and sediments solutes in oceans plant and animal biomass and the atmosphere In the nitrogen cycle N2 is decomposed to NH4 by ammonification and the NH4 is decomposed to NO3 by nitrification Denitrification converts NO3 back to N2 I Nitrogen is a component of amino acids proteins and nucleic acids I The main reservoir of nitrogen is the atmosphere N2 I This nitrogen must be converted for uptake by plants via nitrogen xation by bacteria Detritivores play a key role in the general pattern of chemical cycling I Rates at which nutrients cycle in different ecosystems vary greatly mostly as a result of differing rates of decomposition I The rate of decomposition is controlled by temperature moisture and nutrient availability The Hubbard Brook Experimental Forest has been used to study nutrient cycling in a forest ecosystem since 1963 I The research team constructed a dam on the site to monitor loss of water and minerals I In one experiment the trees in one valley were cut down and the valley was sprayed with herbicides I Net losses of water and minerals were studied and found to be greater than in an undisturbed area I These results showed that vegetation strongly regulates nutrient cycling and how human activity can affect ecosystems I Concept 5 Human activities now dominate most chemical cycles on Earth 0 O 0 As the human population has grown our activities have disrupted the trophic structure energy ow and chemical cycling of many ecosystems In addition humans have added new materials some of them toxins to ecosystems I Agriculture removes from ecosystems nutrients that would ordinarily be cycled back into the soil Nitrogen is the main nutrient lost through agriculture 0 Industrially produced fertilizer is typically used to replace lost nitrogen but effects on an ecosystem can be harmful Critical load for a nutrient is the amount that plants can absorb without damaging the ecosystem I When excess nutrients are added to an ecosystem the critical load is exceeded I Remaining nutrients can contaminate groundwater as well as freshwater and marine ecosystems I Sewage runoff causes eutrophication which is excessive algal growth that can greatly harm freshwater ecosystems Acid precipitation is any kind of precipitation that has a pH less than 56 I Combustion of fossil fuels is the main cause I North American and European ecosystems downwind from industrial regions have been damaged by rain and snow containing nitric and sulfuric acid I Acid precipitation changes soil pH and causes leaching of calcium and other nutrient I Environmental regulations and new technologies have allowed many developed countries to reduce sulfur dioxide emissions Humans release many toxic chemicals into nature including synthetics previously unknown to nature I One reason toxins are harmful is that they become more concentrated in successive trophic levels 0 Biological magnification concentrates toxins at higher trophic levels where biomass is lower 0 Polychlorinated biphenyls and many pesticides such as DDT are subject to biological magnification in ecosystems I One pressing problem caused by human activities is the rising level of atmospheric carbon dioxide 0 C02 water vapor and other greenhouse gases re ect infrared radiation back toward Earth this is the greenhouse effect 0 This effect is important for keeping Earth s surface at a habitable temperature 0 Due to the burning of fossil fuels and other human activities the concentration of atmospheric COz has been steadily increasing 0 Increased levels of atmospheric C02 are magnifying the greenhouse effect which could cause global warming and climatic change I Northern coniferous forests and tundra show the strongest effects of global warming I A warming trend would affect the geographic distribution of precipitation I Global warming can be slowed by reducing energy needs and converting to renewable sources of energy I Life on Earth is protected from damaging effects of UV radiation by a protective layer of ozone molecules in the atmosphere 0 Destruction of the atmospheric ozone results from chorine releasing pollutants produced by human activity 0 Ozone depletion can cause DNA damage resulting in the formation of a dangerous and lethal cancer 0 Satellite studies suggest that the ozone layer has been gradually thinning since 1975 0 Scientists first described an ozone hole over Antarctica in 1985 it has increased in size as ozone depletion has increased
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