bio 260 exam 1

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air is composed of what78% N2 21% O2 .1% othergreenhouse effectkeeps earth warm. only molecules that have at least three atoms can absorb and reemit radiationwhy summer and winter?temporal changes in climate are due to earths tilt. solar radiation strikes earth in varying intensities bc the tiltglobal atmospheric circulationwarm air is less dense and can hold more moisture than cool air. surface warmed by the sun gives off infrared radiation and warms the air above it, and this varies by latitude. warm air rises (because it's less dense), expands, then cools, and water vapor condenses to form clouds. this is why tropics receive greatest amount of precipitationGlobal atmospheric circulation cellsHadley cell. Heating leads to uplift of air, creating large band of low atmospheric pressure. Air hits stratosphere and is displaced toward the poles.prevailing windspatterns of air movement due to areas of high and low pressure caused by atmospheric circulationCoriolis effectWinds appear to be 'deflected' due to a force resulting from Earth's rotation which causes particles in motion to be deflectedbiomesBiomes vary with temperature and precipitation -Whittaker's biome-type classification. tropical rain forest, tropical savanna, desert, temperate grasslands, temperate shrubland, temperate deciduous forest, temperate evergreen forest, boreal forest, tundrafreshwater biological zonemain channel- organisms that swim Behenic zone- invertebrates that consume detrius hyporheic zone- substrate around stream, small inevertebratesglaciationEarth is characterized by periods when glaciers are at their largest extent (glacial maxima) and periods of warming with glacial melting (interglacialperiods). These glacial-interglacial cycles occur at regular frequencies.what causes glacial cyclesRegular changes in the shape of Earth's orbit and the tilt of its axis—Milankovitch cycles. The intensity of solar radiation reaching Earth changes, accentuating seasonal variation and resulting in climatic changestressenvironmental change results in decreased rates of physiological processes, lowering the potential for survival, growth, or reproduction.acclimatizationshort-term, reversible adjustment to stress. like increased cold tolerance of a single individualadaptationlong-term, genetic response of a population that increases ecological success. is a characteristic of an organism that improves its ability to survive and reproduce within its environmentsolar radiationsunlightinfrared radiationrom surrounding objects and emission of IR to environmentconductiontransfer of energy from warmer to cooler molecules (hot sand, cold bench).convectionheat energy is carried by moving water or air (wind).why is generating heat an advantage?Mammals and birds can maintain constant internal temperatures near the optimum for metabolic functions under a wide range of external temperatures. These animals can extend their geographic range. They can be active longer.endothermsRely primarily on internal heat generation—mostly birds and mammals.ectothermsRegulate body temperature through energy exchange with the external environment (thermoregulate primarily via behavior) -they do generate some metabolic heat, but can't increase it. generally have a greater tolerance for variation in body temperature than endothermsbody size and heatHeat exchange with the environment depends on the surface area-to-volume ratio of the body. A high surface area allows greater heat exchange, but makes it harder to maintain internal temperature. The coat of small mammals simply cannot be thick enough to provide adequate insulation in cold conditions.Bergmanns ruleis an ecogeographic rule that states that within a broadly distributed taxonomic clade, individuals of populations or species found in colder environments should be a larger size than individuals of populations or species found in warmer regions. Larger animals have relatively lower surface to volume ratios, allowing them to conserve more warmth than smaller bodied individuals in a given climate. Because winters are colder at higher latitudes, a larger body size would result in greater heat conservation per unit volume than a smaller body size.autotrophsAssimilate energy from sunlight or from inorganic compounds (don't contain C-H bond) -converted into chemical energy stored in the bonds of organic molecules.HeterotrophObtain their energy by consuming organic compounds from other organisms (detritovores, parasites and herbivores, predators).evolutionchange in allele frequencies(proportions) in a population over time.allelesdifferent forms of the same genegenotypegenetic makeup of an individualphenotypeobservable characteristics that a re determined by genotype by environment interactionhistory of evolutionCharles Darwin. Natural historian on the HMS Beagle (1831-1836). Collected organisms and made observations. Galapagos island. bird beaks.artificial selectionVariation occurs among individuals within a population. People have used this natural variation to express or exaggerate traits. characters selected by humans withthe goal of creating a kind of organismwith particular traitsnatural selectionnatural factors and the struggle for existence could naturally do whatartificial selection doesdistinctionnatural selection is different from artificial selection in that there is no end goal, only selection acting on those individuals present and breeding at a particular timerequirements for evolutionVariation -Individuals that form a population of a species are not identical Inheritance -Some variation among individuals is heritable Struggle for existence -Many more offspring are born than can survive in an environment Differential survival and reproduction -Individuals vary in the number of descendants they leave behindpopulationSubset of individuals of one species that occupies a particular geographic area. Group of interacting individuals of the same species living in a particular area.four mechanisms of evolutionmutation gene flow genetic drift selectionmutationleads to new alleles in a population, changing allele frequencies. a change in DNA (e.g. copying errors during cell division, mechanical damage, exposure to chemicals) By changing the material that makes up a gene, mutations lead to new alleles!gene flowcan introduce new alleles into a population or affect allele frequencies. Alleles move between populations via movement of individuals or gametes. adds genetic diversitygenetic driftleads to changes in allele frequencies due to chance events. occurs when chance events determine which alleles are passed to the next generation. can have significant impact on small populations. 1.Because some alleles are lost, genetic variation of the population is reduced (less ability to respond to environmental change). 2.Frequency of harmful alleles can increasenatural selectionchanges allele frequencies in a population over time due to differential survival and reproduction among individuals within a population. a process through which individuals with certain characteristics survive and reproduce at a higher rate because of those characteristics.directional selectionndividuals at one phenotypic extreme (e.g., large size) are favored.stabilizing selectionIndividuals with an intermediate phenotype are favored.disruptive selectionIndividuals at both phenotypic extremes are favored.fitnessthe average number of viable offspring produced by an individual relative to the number produced by other individualssexual selectionis selection because of preference by one sex for certain characteristics in individuals of the other sex. preference by one sex for certain characteristics in individuals of the other sex. can be in conflict between natural selection -can be harmful to individual's survivalspeciationone species split into two. it is due to gradual accumulation of small genetic changes --equivalent to saying that macroevolution is simply a lot of microevolutionallopatric speciationgeographic isolation of populations generates new speciessympatric speciationspeciation occurs in non-isolated populations (same geographic areas)life historyis a record of events and behaviors relating to its growth, development, reproduction, and survival.G.E. HutchinsonFather of modern ecology. formalized the niche concept as n-dimensional hypervolumeskutchnest predation was driving latitudinal variation in clutch size fewer trips to nest = less opportunity to be spotted by predatorslackFood availability was driving latitudinal variation in clutch size Summer insect emergence in temperate areas Long summer days in temperate areaswhich hypothesis was better supportedSkutch'snest predator hypothesis is better supported. Even though birds on Santa Cruz have more food available, they are taking significantly fewer trips and laying fewer eggs. Birds on Catalina are making significantly more trips, likely due to fewer allocate energy or resources to one function at the expense of anotherphenotypic plasticitythe ability of one genotype to produce different phenotypes in different environmentsannualsgenerations lives one yearperennialsgenerations live multiple years- age structured populationsemelparoussingle reproductive episode before deathiteroparousRepeated reproduction throughout lifetimeconditionsabiotic factors of environment that are experienced but cannot be consumed. Temperature, relative humidity, pH, salinityresourcesbiotic and abiotic components of an environment that an organism consumes. Water, mineral nutrients (macro-, micronutrients), food, spaceniche conceptdescribing and organisms "place" in the environmentecological nicheThe limits for all important environmental features (conditions and resources) within which individuals of a species can survive, grow, and reproduce.fundamental nichethe limits for all important environmental features (conditions and resources) within which individuals of a species can survive, grow, and reproducerealized nicheThe portion of the fundamental niche occupied by a speciesdispersalthe spread of individuals away from each other, (often parents or siblings) leaving some behindmigrationthe movement of individuals (or populations) from one region to another, usually leaving none behinddispersal limitationcan prevent species from reaching areas of suitable habitat (affecting distributions).individualA single organism, of a specific speciescommunitya group or association of populations of two or more different species occupying the same geographical area at the same timeecosystema biological community of interacting organisms and their physical environment.