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Ecology Definitions (Lectures 1 - 24)

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Western University
Biology 2483A
Hugh Henry

ECOLOGY DEFINITIONS (LECTURES 1 – 24)  ABIOTIC – physical or non-living environment  ABSOLUTE POPULATION SIZE – the actual number of individuals in a population  ABUNDANCE – number of individuals in a species that are found in a given area  ACCLIMATIZATION – organism’s adjustment of its physiology, morphology, or behavior to lessen the effect of an environmental change and minimize the associated stress  ACIDITY – measure of ability of a solution to behave as an acid, compound that releases protons  ACID NEUTRALIZNG CAPACITY – ability of chemical environment to counteract acidity, usually associated with with concentrations of base cations, including Ca2+, Mg2+, and K+  ADAPTATION – physiological, morphological or behavioral trait with an underlying genetic basis that enhances the survival and reproduction of its bearers in their environment  ADAPTIVE EVOLUTION – process of evolutionary change in which traits that confer survival or reproductive advantages tend to increase in frequency in a population over time  ADAPTIVE RADIATION – event in which a group of organism gives rise to many new species that expand into new habitats or new ecological roles in a short time  AEROSOLS – solid or liquid particles suspended in the atmosphere  AGE STRUCTURE – proportion of the population in each age class  ALBEDO – amount of solar radiation reflected by a surface  ALKALINITY – measure of the ability of a solution to behave as a base, a compound that takes up protons  ALLEE EFFECT – decrease in the population growth rate as the population density decreases  ALLELE – one of two or more forms of a gene that result in the production of different versions of the protein that the gene encodes  ALLOCHTHONOUS – produced outside the ecosystem  ALLOMETRY – differential growth of body parts that results in a change of shape or proportion with size  ALPHA DIVERSITY – species diversity at local or community scale  ALTERNATION OF GENERATIONS – complex life cycle, in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte  ALTERNATIVE STABLE STATES – different community development scenarios that are possible at the same location under similar environmental conditions  ANISOGAMY – production of two types of gametes of different sizes  ANTHROPOGENIC – relating to or caused by humans and their activities  APOSEMATIC COLORATION – (warning coloration) bright coloration usually displayed by animal with effective chemical defenses  ARBUSCULAR MYCORRHIZAE – mycorrihizae in which the fungal partner grows into the soil, extending some distance away from the plant root, and also grows between some root cells while penetrating others  ASSIMILATION EFFICIENCY – proportion of ingested food that is assimilated by an organism  ATMOSPHERIC DEPOSITION – movement of particulate and dissolved matter from the atmosphere to Earth’s surface by gravity or precipitation  ATMOSPHERIC PRESSURE – pressure exerted on a surface due to the mass of the atmosphere above it  AUTOCHTHONOUS – produced within the ecosystem  AUTOTROPH – organism that converts energy from sunlight or from inorganic chemical compounds in the environment into chemical energy  AVOIDANCE – a response to stressful environmental conditions that lessens their effect through some behavior or physiological activity that minimizes an organism’s exposure to stress  BENTHIC ZONE – bottom of a body of water including the surface and shallow subsurface layers of sediment  BETA DIVERSITY – change in species number and composition, or turnover of species, as one moves from one community to another  BIOACCUMULATION – progressive increase in the concentration of a substance in an organism's body over its lifetime  BIODIVERSITY – diversity of important ecological entities that span multiple spatial scales, from genes to species to communities  BIOMAGNIFICATION – progressive increase in the tissue concentrations of a substance in animals at successively higher trophic levels that results as animals at each trophic level consume prey with higher concentrations of the substance due to bioaccumulation  BIOME – large-scale terrestrial biological community shaped by the regional climate, soil and disturbance patterns where it is found  BIOSPHERE – the highest level of biological organization, consisting of all living organisms on Earth + the environments in which they live  BIOTIC – living components of an environment  BIOTIC RESISTANCE – interactions of the native species in a community with non-native species that exclude or slow the growth of those non-native species  BOTTOM-UP CONTROL – limitation of abundance of population by nutrient supply or availability of food  BOUNDARY LAYER – zone close to a surface where a flow of fluid, usually air, encounters resistance and becomes turbulent  BUFFER ZONE – portion of nature reserve surrounding a core natural area where controls on land use are less stringent than in the core natural area, yet land uses are at least partially compatible with many species' resource requirements  C3 PHOTOSYNTHETIC PATHWAY – biochemical pathway involving the uptake of CO by th2 enzyme ribulose 1,5 bisphosphate carboxylase/oxygenase (rubisco) and synthesis of sugars by the Calvin cycle  C4 PHOTOSYNTHETIC PATHWAY – biochemical pathway involving the daytime uptake of CO by the2enzyme phosphoenol pyruvate carboxylase (PEPcase) in mesophyll cells; the carbon is then transferred as a four-carbon acid to the bundle sheath cells, where CO 2s released to the Calvin cycle for sugar synthesis  CALVIN CYCLE – biochemical pathway used by photosynthetic organisms to fix carbon and synthesize sugars  CARBON NEUTRAL – fuels that produce an amount of CO when2burned that is equal to or less than the amount taken up by the plants from which they are made  CARRYING CAPACITY – max population size that can be supported indefinitely by the environment (K in logistic equation)  CATCHMENT – area in a terrestrial ecosystem that is drained by a single stream; a common unit of study in terrestrial ecosystem studies; also called a watershed  CATION EXCHANGE CAPACITY – soil’s ability to hold nutrient cations such as Ca2+, K+, and Mg2+ and exchange them with the soil solution, determined by the clay content of the soil  CHEATER – in a mutualism, individuals that increase offspring production by overexploiting their mutualistic partner  CHARACTER DISPLACEMENT – process in which competition causes phenotypes of competing species to evolve to become more different over time, thereby causing species to become more different where they live together than where they live apart  CHEMICAL WEATHERING – chemical breakdown of soil minerals leading to the release of soluble forms of nutrients and other elements  CLAY – fine soil particles (<2 μm) that have a semicrystalline structure and weak negative charges on their surfaces that can hold onto cations and exchange them with the soil solution  CLIMATE – long-term description of weather, based on averages and variation measured over decades  CLIMATE CHANGE – directional change in climate over a period of three decades or longer  CLINE – pattern of gradual change in a characteristic of an organism over a geographic region  CLUMPED DISPERSION – dispersion pattern in which individuals are grouped together  COARSE-FILTER – of or referring to an approach to conservation biology that focuses on habitats, landscapes and ecosystems  COEVOLUTION – evolution of two interacting species, each in response to selection pressure imposed by the other  COHORT LIFE TABLE – life table in which the fate of a group of individuals born during the same time period (cohort) is followed from birth to death  COMMENSALISM – interaction between two species in which individuals of one species benefit while individuals of the other species do not benefit and are not harmed  COMMUNITY – group of interacting species that occur together at the same place and time  COMPENSATION – adaptive growth response of plants to herbivory in which removal of plant tissue stimulates the plant to produce new tissues  COMPETITION – interaction between individuals of two species in which each is harmed by their shared use of a resource that limits their ability to grow, survive or reproduce (-/- relationship)  COMPETITION COEFFICIENT – constant used in the Lotka-Volterra competition model to describe the extent to which an individual of one competing species decreases the per capita growth rate of the other species  COMPETITIVE EXCLUSION PRINCIPLE – two species that use a limiting resource in the same way cannot coexist  COMPETITVE NETWORKS – sets of competitive interactions involving multiple species in which every species negatively interacts with every other species thus promoting species coexistence  COMPETITIVE PLANTS – in Grime’s triangular model, plants that are superior competitors under conditions of low stress and low disturbance  COMPLEX LIFE CYCLE – at least two distinct stages that differ in their habitat, physiology or morphology  COMPLEMENTARITY HYPOTHESIS – hypothesis proposing that as the species richness of a community increases, there is a linear increase in the positive effects of those species on community function  CONDUCTION – transfer of heat through the exchange of kinetic energy between molecules due to temperature gradient  CONSUMER – organism that obtains its energy by eating other organisms  CONSUMPTION EFFICIENCY – proportion of the biomass available in an ecosystem that is ingested  CONTINENTAL CLIMATE – climate typical of terrestrial areas in the middle of large continental land masses at high latitudes, characterized by high variation in seasonal temperatures  CONTINENTAL DRIFT – slow movement of tectonic plates (sections of Earth’s crust) across Earth’s surface  CONTROLLED EXPERIMENT – standard scientific approach in which an experimental group (that has the factor being tested) is compared with a control group (that lacks the factor being tested)  CONVECTION – transfer of heat through exchange of air/water molecules as they move from one area to another  CONVERGENCE – evolution of similar growth forms among distantly related species in response to similar selection pressures  COOPERATIVE BREEDING – behavioral pattern in which young animals postpone breeding and instead help their parents raise offspring  CORE NATURAL AREA – portion of nature reserve where the conservation of biodiversity and ecological integrity takes precedence over other values or uses  CORIOLIS EFFECT – apparent deflection of air/water currents when viewed from a rotating reference such as Earth’s surface  CRASSULACEAN ACID METABOLISM (CAM) – photosynthetic pathway in which CO is fixed 2nd stored as an organic acid at night, and then released to the Calvin cycle during the day  CRYPSIS – defense against predators in which prey species have a shape or coloration that provides camouflage and allows them to avoid detection  DAMPED OSCILLATIONS – pattern of population fluctuations where the extent to which the population rises and falls in abundance gradually become smaller over time  DECOMPOSITION – physical/chemical breakdown of detritus by detritivores, leading to the release of nutrients as simple, soluble organic and inorganic compounds that can be taken up by other organisms  DELAYED DENSITY DEPENDENCE – delays in the effect of population density on population size that can contribute to population fluctuations  DEMOGRAPHIC STOCHASTICITY – chance events associated with whether individuals survive or reproduce  DENSITY-DEPENDENT – factor that causes birth rates, death rates, or dispersal rates to change as the density of the population changes  DENSITY-INDEPENDENT – factor whose effects on birth and death rates are independent of population density  DESERTIFICATION – degradation of formerly productive land in arid regions resulting in loss of plant cover and acceleration of soil erosion  DETRITUS – freshly dead or partially decomposed remains of organisms  DIRECT DEVELOPMENT – simple life cycle that goes directly from fertilized egg to juvenile without passing through a free-living larval stage  DIRECT INTERACTIONS – interactions between two species, including competition, exploitation, and positive interactions  DIRECTIONAL SELECTION – selection that favors individuals with one extreme of a heritable phenotypic trait  DISPERSAL – movement of organisms or propagules from their birthplace  DISPERSAL LIMITATION – situation in which a species’ limited capacity for dispersal prevents it from reaching areas of suitable habitat  DISRUPTIVE SELECTION – selection that favors individuals with a phenotype at either extreme over those with an intermediate phenotype  DISTRIBUTION – geographic area where individuals of a species are present  DISTURBANCE – abiotic event that kills/damages some individuals and creates opportunities for other individuals to grow/reproduce  DOMINANT SPECIES – species that has large, community-wide effects by virtue of its size or abundance, its strong competitive ability, or its provision of habitat or food for other species, also called a foundation species  DORMANCY – state in which little or no metabolic activity occurs  DOUBLING TIME (td) – number of years it takes a population to double in size  DRIVER AND PASSENGER HYPOTHESIS – hypothesis proposing that the strengths of the effects of species' ecological functions on their communities vary dramatically, such that "driver" species have a large effect on community function, while "passenger" species have a minimal effect  DYNAMIC EQUILIBRIUM MODEL – elaboration of intermediate disturbance hypothesis proposing that species diversity is maximized when the level of disturbance and the rate of competitive displacement are roughly equivalent  ECOLOGICAL FOOTPRINT – total area of productive ecosystems required to support a population  ECOLOGICAL NICHE – physical/biological conditions that a species needs to grow, survive and reproduce  ECOLOGY – scientific study of interactions between organisms and their environment  ECOSYSTEM – all organisms in a given area as well as the physical environment in which they live  ECOSYSTEM ENGINEER – species that influences its community by creating, modifying, or maintaining physical habitat for itself and other species  ECTOMYCORRHIZAE – mycorrhizae in which the fungal partner typically grows between plant root cells and forms a mantle around the exterior of the root  ECTOPARASITE – parasite that lives on the surface of another organism  ECOTYPE – population with adaptations to unique local environmental conditions  ECOTHERM – animal that regulates its body temperature primarily through energy exchange with its external environment  EDGE EFFECTS – abiotic and biotic changes that are associated with an abrupt habitat boundary such as that created by habitat fragmentation  EL NINO SOUTHERN OSCILLATION – oscillation of pressure cells and sea surface temperatures in the equatorial Pacific Ocean causing widespread climate variation and changes in upwelling currents  ENDOPARASITE – parasite that lives inside the body of its host organism  ENDOSPERM – nutrient-rich material in a seed that sustains the developing embryo and often the young seedling  ENDOTHERM – animal that regulates its body temperature primarily through internal metabolic heat generation  ENVIRONMENTAL STOCHASTICITY – erratic or unpredictable changes in the environment  EPILIMNION – warm surface layer of water in a lake, lying above the thermocline, that forms during the summer in some lakes of temperate and polar regions  EQUILIBRIUM THEORY OF ISLAND BIOGEOGRAPHY – theory proposing that the number of species on an island or in an island- like habitat results from a dynamic balance between immigration rates and extinction rates  EUTROPHIC – nutrient-rich, characterized by high primary production  EUTROPHICATION – change in the nutrient status of an ecosystem from nutrient-poor to nutrient-rich; such changes occur naturally in some lakes due to the accumulation of sediments, but they may also be caused by nutrient inputs that result from human activities  EVAPOTRANSPIRATION – sum of water loss through evaporation and transpiration  EVOLUTION – change in allele frequencies in a population over time; descent with modification, process by which organisms gradually accumulate differences from their ancestors  EXPLOITATION COMPETITION – interaction in which species compete indirectly through their mutual effects on the availability of a shared resource  EXPONENTIAL GROWTH – change in size of population of species with continuous reproduction by a constant proportion at each instant in time  EXPONENTIAL POPULATION GROWTH RATE (r) – constant proportion by which a population of a species with continuous reproduction changes in size at each instant in time; also called the intrinsic rate of increase  EXTINCTION VORTEX – pattern in which small population that drops below a certain size may decrease even further in size, perhaps spiraling toward extinction  FECUNDITY – average number of offspring produced by a female while she is of age x (denoted Fx in a life table)  FERRELL CELL – large-scale, three-dimensional pattern of atmospheric circulation in each hemisphere, located at mid-latitudes between the Hadley and polar cells  FINE-FILTER – approach to conservation biology that focuses on genes, populations, and species  FITNESS – genetic contribution of organism’s descendants to future generations  FIXATION – uptake of the gaseous form of a compound, including CO 2n photosynthesis and N2 in nitrogen fixation, by organisms for use in metabolic functions; with respect to the genetic composition of a population, an allele frequency of 100%  FLAGSHIP SPECIES – charismatic species that may emphasized in conservation efforts because it helps to garner public support for a conservation project  FOCAL SPECIES – one of a group of species selected as a priority for conservation efforts, chosen because its ecological requirements differ from those of other species in the group, thereby helping to ensure that as many different species as possible receive protection  FUNCTIONAL GROUP – subset of a community that includes species that function in similar ways, but do not necessarily use the same resources  GAMMA DIVERSITY – species diversity at the regional scale  GENE FLOW – transfer of alleles from one population to another via the movement of individuals or gametes  GENE-FOR-GENE INTERACTION – specific defensive response that makes particular plant genotypes resistant to particular parasite genotypes  GENET – genetic individual, resulting from a single fertilization event; in organisms that can reproduce asexually, a genet may consist of multiple, genetically identical parts, each of which has the potential to function as an independent physiological unit  GENETIC DRIFT – process in which chance events determine which alleles are passed from one generation to the next, thereby causing allele frequencies to fluctuate randomly over time; the effects of genetic drift are most pronounced in small populations  GENOTYPE – genetic makeup of an individual  GEOGRAPHIC RANGE – entire geographic region over which a species is found  GEOMETRIC GROWTH – change in the size of a population of a species with discrete reproduction by a constant proportion from one discrete time period to the next  GEOMETRIC POPULATION GROWTH RATE (λ) – constant proportion by which a population of a species with discrete reproduction changes in size from one discrete time period to the next; also called the finite rate of increase  GRAIN – size of the smallest homogeneous unit of study (such as a pixel in a digital image), which determines the resolution at which a landscape is observed; together with extent, grain characterizes the scale at which a landscape is studied  GRAVITATIONAL POTENTIAL – energy associated with gravity  GREENHOUSE EFFECT – warming of Earth by gases in the atmosphere that absorb and reradiate infrared energy emitted by Earth’s surface  GREENHOUSE GASES – atmospheric gases that absorb and reradiate the infrared radiation emitted by Earth's surface, including water vapor (H2O), carbon dioxide (C2 ), methane (CH4), and nitrous oxide2(N O)  GROSS PRIMARY PRODUCTION (GPP) – amount of energy that autotrophs capture by photosynthesis and chemosynthesis per unit time  GUILD – subset of a community that includes species that use the same resources, whether or not they are taxonomically related  HABITAT CORRIDOR – relatively narrow patch that connects blocks of habitat and often facilitates the movement of species between those blocks  HABITAT DEGRADATION – anthropogenic change that reduces the quality of habitat for many, but not all, species  HABITAT FRAGMENTATION – breaking up of once continuous habitat into a complex pattern of spatially isolated habitat patches amid a matrix of human-dominated landscape  HABITAT LOSS – complete conversion of an ecosystem to another use by human activities  HABITAT MUTUALISM – mutualism in which one partner provides the other with shelter, a place to live, or favorable habitat  HADLEY CELL – large-scale, three-dimensional pattern of atmospheric circulation in each hemisphere in which air is uplifted at the equator and subsides at about 30° N and S  HEAT CAPACITY – amount of energy required to raise the temperature of a substance  HETEROTROPH – organism that obtains energy by consuming energy-rich organic compounds from the other organisms  HIBERNATION – torpor lasting several weeks during the winter; a strategy that is possible only for
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