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186 Cards in this Set
- Front
- Back
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The known evolutionary mechanisms include:
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mutation, gene flow, genetic drift, nonrandom mating, and selection
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Mutation
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any change in the nucleotide sequences of an organism’s DNA
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Long-horned cattle have greater difficulty moving through heavily forested areas compared with cattle that have short or no horns, but long-horned cattle are better able to defend their young against predators. This contrast is an example of...
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a trade-off
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population bottleneck:
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A period during which only a few individuals of a normally large population survive.
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The contribution of a genotype or phenotype to the genetic composition of subsequent generations, relative to the contribution of other genotypes or phenotypes.
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Fitness
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STABILIZING SELECTION
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Selection against the extreme phenotypes in a population, so that the intermediate types are favored.
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Directional Selection
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Selection in which phenotypes at one extreme of the population distribution are favored.
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The long horns of Texas Longhorn cattle are an example of a trait that has evolved through...
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directional selection
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Disruptive Selection
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Selection in which phenotypes at both extremes of the population distribution are favored.
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The fitness of a genotype is a function of the...
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average rates of survival and reproduction of individuals with that genotype.
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Frequency Dependent Selection
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Selection that changes in intensity with the proportion of individuals in a population having the trait.
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Trade-Off
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The relationship between the fitness benefits conferred by an adaptation and the fitness costs it imposes. For an adaptation to be favored by natural selection, the benefits must exceed the costs.
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Genetic drift affects small populations more than large ones. Why?
A) Genetic drift drives the extinction of many species. B) Random changes in allele frequencies from one generation to the next can produce large changes in allele frequencies over time, allowing harmful alleles to increase in frequency. C) Genetic drift in fact affects larger populations more than smaller ones. D) Genetic drift drives the movement of many species worldwide causing populations size to reduce even further. E) Genetic drift affects all populations equally. |
B.) Random changes in allele frequencies from one generation to the next can produce large changes in allele frequencies over time, allowing harmful alleles to increase in frequency.
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Allele frequencies measure the _______ of a Mendelian population, whereas _______ show(s) how it is distributed among its members.
A) genetic structure; genotype frequencies B) polymorphisms; genotype frequencies C) genetic variation; genotype frequencies D) genotype frequencies; genetic structure E) genotype frequencies; genetic variation |
C.) genetic variation; genotype frequencies
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Artificial selection for certain traits in Brassica oleracea (European wild mustard)
A) generated new species. B) generated plants with identical genetic makeup. C) gave rise to plants that are quite different in appearance due to the introduction of foreign DNA. D) gave rise to plants that are quite different in appearance by virtue of the genetic variation inherent in the mustard plant. E) is less rapid than natural selection. |
D) gave rise to plants that are quite different in appearance by virtue of the genetic variation inherent in the mustard plant
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Deviations from the Hardy–Weinberg equilibrium in populations
A) are very rare. B) suggest that mechanisms exist in nature that can change the frequency of alleles. C) are evidence for evolution. D) can help in the identification of the mechanisms of evolution. E) b, c, and d |
E.) b, c and d
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The frequency of one allele of a monomorphic locus (A and a) in a population is known. Assume Hardy–Weinberg conditions hold true. Which of the following statements is false?
A) The frequency of heterozygotes is given by (p + q)/N, where N is the number of individuals in the population. B) There is sufficient information given to calculate the frequency of heterozygotes (Aa). C) The frequency of a is given by 1 – p. D) The frequency of A is given by 1 – q. E) The frequency of a is dependent of that of A. |
A) The frequency of heterozygotes is given by (p + q)/N, where N is the number of individuals in the population.
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Which of the following phenomena is not an evolutionary mechanism?
A) Mutation B) Gene flow C) Genetic drift D) Random mating E) Natural selection |
D.) random mating
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Which of the following statements about biological evolution is false?
A) Species change over time. B) Natural selection produces changes in species. C) Individuals in a population evolve. D) An adaptation may be defined as a phenotypic characteristic that allows an organism to adjust to its environment. E) Most populations are genetically diverse. |
C) Individuals in a population evolve
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Genotype frequencies may be altered by
A) genetic drift. B) the founder effect. C) gene flow. D) nonrandom mating. E) All of the above |
E.) all of the above
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Which of the following agents of evolution adapts populations to their environments?
A) Mutation B) Natural selection C) Nonrandom mating D) Gene flow E) Genetic drift |
B.) Natural Selection
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The frequency of A alleles is 0.2. The frequency of heterozygotes for this allele is
A) 0.8. B) 0.4. C) 0.16. D) 0.32. E) 0.08. |
D.) 0.32
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The origin of genetic variation is
A) mutation. B) gene flow. C) genetic drift. D) natural selection. E) nonrandom mating. |
A.) mutation
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Natural selection
A) works directly on the genotype of an organism. B) always favors average individuals in a population. C) acts on the phenotype of an organism. D) is unrelated to reproduction of an organism. E) is influenced by the number of offspring. |
C) acts on the phenotype of an organism.
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Genetic variation is
A) favored by variation in the environment. B) maintained in subpopulations of the same species. C) generated by recombination. D) disfavored by frequency-dependent selection. E) a, b, and c |
E) a, b, and c
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Evolution may be constrained by
A) sexual dimorphism. B) genetic diversity. C) environmental variation. D) developmental processes. E) neutral alleles. |
D) developmental processes.
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A neutral allele
A) is affected by natural selection. B) can lead to a discernable phenotype. C) can accumulate in populations. D) cannot be detected at the molecular level. E) Both a and c |
C) can accumulate in populations
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_______ selection operates if individuals within a population with the smallest and largest body sizes have fewer offspring than those of average body size.
A) Stabilizing B) Destabilizing C) Sexual D) Directional E) Disruptive |
A) Stabilizing
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Mutations
A) are any change in an organism's DNA. B) occur at high frequencies. C) are not inherited. D) maintain and generate genetic diversity. E) Both a and d |
E) Both a and d
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The Hardy–Weinberg equilibrium is not applicable under which of the following conditions?
A) Random mating B) Large population size C) No gene flow D) Asexual reproduction E) No mutations |
D) Asexual reproduction
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Sexual recombination
A) increases the overall reproductive rate. B) can result in the elimination of harmful mutations. C) decreases the variety of genetic combinations. D) changes the frequency of alleles in a population. E) has no influence on evolution. |
B) can result in the elimination of harmful mutations.
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The frequency of alleles for a given monomorphic locus (A and a) in two subpopulations of the same species
A) is necessarily the same in both populations. B) can vary from p + q = 1. C) is N = NAA + NAa + Naa (where N is the number of individuals in the populations) in both populations. D) is always lower for the heterozygote. E) is always lower for the homozygotes. |
C) is N = NAA + NAa + Naa (where N is the number of individuals in the populations) in both populations
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What is the formula for calculating the Hardy-Weinberg Law
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p and q represent frequency of each allele at a gene locus;
N = total number of individuals in population 2NAA = number of homozygous AA individuals in population NAa = number of heterozygous individuals in the population 2Naa = number of homozygous aa individuals in population |
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Hardy-Weinberg Equilibrium
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The sum of the alleles is one: p + q = 1
Square both sides of the equation: (p + q)2 = 1 Result: p2 + 2pq + q2 = 1 |
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Estivation
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A state of dormancy and hypometabolism that occurs during the summer; usually a means of surviving drought and/or intense heat.
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Diapause
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period of developmental or reproductive arrest, entered in response to day length, that enables an organism to better survive.
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Biome
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A major division of the ecological communities of Earth, characterized primarily by distinctive vegetation. A given biogeographic region contains many different biomes.
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Biotic Interchange
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The dispersal of species from two different biotas into the region they had not previously inhabited, as when two formerly separated land masses fuse.
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A parsimonious interpretation of a distribution pattern is one that...
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requires the smallest total number of undocumented vicariant plus dispersal events.
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Rain shadows form on the _______ of mountains and result in _______ rainfall there.
A) windward side; more B) windward side; less C) leeward side; more D) leeward side; less E) peaks; more |
D) leeward side; less
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The tundra biome is found
A) at high latitudes and in high mountains. B) at low latitudes and in high mountains. C) near the equator and in the lowlands. D) near the Arctic circle. E) at sea level. |
A) at high latitudes and in high mountains
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A(n) _______ is a terrestrial environment defined by the growth forms of its plants.
A) ecosystem B) Forest C) Biome D) Tundra E) Chaparral |
C) Biome
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How can biogeographers determine the roles of vicariance and dispersal when reconstructing the evolutionary history of a particular distribution?
A) By studying area phylogenies B) By applying the parsimony principle C) By understanding the geologic events of the area D) Both a and b E) All of the above |
E) All of the abov
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3 basic dispersion patterns:
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clumped, regular and random
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clumped dispersion
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pattern occurs when the presence of one individual at any point in space increases the probability of others being near that point.
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regular dispersion
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pattern occurs when the presence of one individual at any point in space reduces the probability of others being near that point.
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random dispersion
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pattern occurs when there is an equal probability of an individual occupying any point in space.
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intraspecific competition
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Competition among members of the same species.
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iteroparous
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Reproducing multiple times in a lifetime.
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semelparous
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Reproducing only once in a lifetime.
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density dependent regulation factors (3)
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food supply, pathogens, predators
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Net primary production is:
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the total amount of primary producer biomass available for consumption by heterotrophs.
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On average, only about ____ percent of the energy of one trophic level is transferred the next
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10
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Reasons that energy is lost from one trophic level to another:
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Heat loss, biomass availability, indegestability
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interspecific competition
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Competition between members of two or more species.
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Alpha Diversity
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diversity within a single community or habitat
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Beta Diversity
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between-habitat diversity, a measure of the change in species composition from one community or habitat to another.
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Gamma Diversity
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the regional diversity found over a range of communities or habitats in a geographic region.
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Sorenson’s index
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Mathematical formula that measures beta diversity.
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Shannon diversity index:
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A formula for quantifying diversity that takes both species richness and species evenness into account; based on a mathematical expression of the certainty with which the next item sampled in a series can be predicted.
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Climax Community
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The final stage of succession; a community that is capable of perpetuating itself under local climatic and soil conditions and persists for a relatively long time.
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Organisms that are most likely to tolerate harsh conditions are found during
A) early primary succession. B) late primary succession. C) secondary succession. D) early climax stage. E) late climax stage. |
A) early primary succession.
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In the equation for net primary production, would you ever expect R to be zero?
A) Yes, but only when the system is at equilibrium. B) Yes, but only when the system is out of equilibrium. C) No, unless the system is at equilibrium. D) No, unless the system is out of equilibrium E) No, because there would be no life if R was zero. |
E) No, because there would be no life if R was zero.
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Heterotrophic succession
A) is a type of succession in which the energy reserves become depleted and there is no mechanism to restore them. B) is a type of succession in which there are no energy reserves at the onset and they are produced over time as colonization takes place. C) is commensalism. D) All of the above E) None of the above |
A) is a type of succession in which the energy reserves become depleted and there is no mechanism to restore them.
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Which of the following is not an example of succession?
A) A pond changing to a meadow B) The self-perpetuation of a climax community C) Shrubs filling in a forest gap D) The recolonization of Mount St. Helens after its eruption E) A forest being clear-cut |
B) The self-perpetuation of a climax community
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Although the consequences of various kinds of disturbances are highly variable, their results conform to a general pattern. This general pattern is called
A) succession. B) general disturbance. C) disaster equilibrium. D) general equilibrium. E) intermediate equilibrium. |
A) succession.
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The Shannon Index is a mathematical expression used to measure diversity that takes both species richness and species evenness into account. A higher H value
A) indicates a higher certainty about species composition and greater diversity. B) indicates a lower certainty about species composition and less diversity. C) indicates a lower certainty about species composition and greater diversity. D) indicates a higher certainty about species composition and less diversity. E) None of the above |
C) indicates a lower certainty about species composition and greater diversity.
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Which of the following hypotheses is not related to the latitudinal diversity gradient?
A) The time hypothesis B) The trophic hypothesis C) The spatial heterogeneity hypothesis D) The specialization hypothesis E) The predation hypothesis |
B) The trophic hypothesis
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the physical environment can be divided into four interacting compartments:
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the atmosphere, the oceans, fresh waters, and land.
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The atmosphere is made up of these gases...
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78.08% nitrogen gas (N2), 20.95% oxygen gas (O2), 1% water vapor, 0.93% argon, and 0.03% carbon dioxide (CO2). It also contains traces of hydrogen gas, neon, helium, krypton, xenon, ozone, and methane.
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troposphere
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The lowest atmospheric zone, reaching upward from the Earth’s surface approximately 10–17 km. Zone in which virtually all water vapor is located
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stratosphere
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The upper part of Earth’s atmosphere, above the troposphere; extends from approximately 18 kilometers upward to approximately 50 kilometers above the surface
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Greenhouse gases
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Carbon dioxide, methane, water vapor: Gases in the atmosphere, such as carbon dioxide and methane, that are transparent to sunlight, but trap heat radiating from Earth’s surface, causing heat to build up at Earth’s surface.
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more water is evaporated from the ocean surface than is returned to them as precipitation
True or False? |
True
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The ozone layer is found in the
A) stratosphere and absorbs many biologically damaging short-wavelength radiation. B) stratosphere and absorbs many biologically damaging long-wavelength radiation. C) troposphere and absorbs many biologically damaging short-wavelength radiation. D) troposphere and absorbs many biologically damaging long-wavelength radiation. E) between the stratosphere and the troposphere. |
A) stratosphere and absorbs many biologically damaging short-wavelength radiation.
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Which of the following is an example in which the energy is/was not derived from solar radiation?
A) Oil. B) Hydrothermal vents. C) Tornados D) Natural gas E) All of the above |
B) Hydrothermal vents.
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Environmental writers introduced the idea of "natural capital" in the 1940s and it was in 1970 that ecosystems were first said to provide people with a variety of "goods and services." The "goods" include all of the following except
A) food. B) clean air and water. C) fuel. D) pollination. E) fiber. |
D) pollination.
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All of the following human activities have modified energy flow except
A) conversion of forests to grasslands. B) urban development. C) conversion of tundras to rain forests. D) increasing use of fossil fuels. E) increasing agriculture. |
C) conversion of tundras to rain forests.
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The most important driver of change in ecosystems has been changes in _______ as natural ecosystems have been converted to other, more intensive uses.
A) carbon dioxide levels. B) land use C) global warming D) human population growth E) pollution of waterways. |
B) land use
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Less than half of the CO2 released to the atmosphere via human activities remains in the atmosphere. The rest may be found
A) dissolved in the oceans. B) stored on land. C) above the stratosphere. D) Both a and b E) None of the above |
D) Both a and b
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Which of the following statements about the water cycle is false?
A) There is a net movement of water vapor from oceans to terrestrial environments. B) Precipitation exceeds evaporation on land. C) Most of the water that evaporates from oceans is returned by run-off from land. D) Transpiration makes a significant contribution to evaporative water loss from terrestrial ecosystems. E) Evaporation exceeds precipitation over the seas. |
C) Most of the water that evaporates from oceans is returned by run-off from land.
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The role of decomposers in the nitrogen cycle is to
A) fix N2 into ammonium. B) release ammonium and other inorganic nitrogen compounds from organic compounds, thus returning nitrogen to the soil. C) denitrify ammonium, thus returning N2 to the atmosphere. D) convert ammonium to nitrate, which can then be absorbed by plants. E) incorporate nitrogen into amino acids and organic compounds. |
B) release ammonium and other inorganic nitrogen compounds from organic compounds, thus returning nitrogen to the soil.
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How will global climates and ecosystems change in response to the rapid carbon dioxide enrichment by human activities?
A) Global warming B) Increased outbreaks of disease C) Increase of land mass D) Increased size of the polar ice caps E) Both a and b |
E) Both a and b
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How can knowledge of evolutionary theory assist in understanding viruses and help in developing vaccines?
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by being able to measure the rate of new mutations rising, observing the spread of genetic variations and seeing the effects of genetic change.
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What are the two meanings of adaptation?
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1. The processes by which characteristics that appear to be useful to the bearer evolve. (evolutionary mechanisms)
2.) the characteristics themselves (phenotype) |
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What are the major elements of Darwin's theory of evolution?
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1. Species are not immutable: they change over time
2. Divergent species share a common ancestor 3. The mechanism that produces changes in species is Natural Selection.` |
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How does population genetics help us better understand the process of natural selection?
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by explaining patterns and organization of genetic variation, the origin and maintenance of genetic variation and understanding the mechanisms that cause changes in allele frequencies in populations.
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allele frequency
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The relative proportion of a particular allele in a specific population.
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What is the Hardy-Weinberg equilibrium and how does it relate to our understanding of populations?
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It describes a model in which allele frequencies do not change across generations and genotype frequencies can be predicted from allele frequencies. The principles of Hardy–Weinberg equilibrium apply only to sexually reproducing organisms.
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Conditions of Hardy-Weinberg theory:
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- Mating is random - Population size is infinite - There is NO gene flow (movement of individuals in or out of pop) - There is NO mutation - Selection does not affect the survival of specific genotypes.
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What happens if a population violates the five underlying assumptions of the Hardy-Weinberg?
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If we violate assumptions, then we can have predictable effects on the outcomes of allele or genotype frequencies
Therefore, we can determine which factors (or lack of assumptions) are effecting our populations |
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What is the role of mutation?
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Mutations are the material upon which natural selection acts. Evolution is a two sided coin. Once side is mutation, and the other side is natural selection.
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What is the role of gene flow?
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Transfer of genes from one population to another of the same species, as by migration or the dispersal of seeds and pollen.
Which may also result in the addition of new genetic variants to the established gene pool of a particular species or population. |
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What is the role of genetic drift?
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Genetic drift affects the genetic makeup of the population but, unlike natural selection, through an entirely random process. So although genetic drift is a mechanism of evolution, it doesn’t work to produce adaptations.
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What is the role of non-random mating in the evolution process?
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The result of nonrandom mating is that some individuals have more opportunity to mate than others and thus produce more offspring.
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What is the significance of measuring the fitness as a measure of reproductive rates in terms of evolutionary change?
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- Stabilizing selection preserves the average characteristics of a population by favoring average individuals.
- Directional selection changes the characteristics of a population by favoring individuals that vary in one direction from the mean of the population. - Disruptive selection changes the characteristics of a population by favoring individuals that vary in both directions from the mean of the population. |
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How may sexual selection influence fitness and the evolution of populations?
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sexual selection may favor traits that enhance an individual’s chances of reproduction but reduce its chances of survival. For example, females may be more likely to see or hear males with a given trait (and thus be more likely to mate with those males), even though the favored trait may also increase the chances that the male will be seen or heard by a predator.
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What are the differences between intra- and inter- sexual selection? Examples?
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- To compete for access to mates (intrasexual selection), This gives rise to males most often having secondary sexual equipment such as antlers that are used in competing for females.
- Bearers more attractive to members of the opposite sex (intersexual selection). such as bright colors, long tails, and elaborate courtship displays in males of many species. |
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What is the effect of sexual recombination on variation, and thus the evolutionary process?
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In sexually reproducing populations, sexual recombination is far more important than mutation on a generation–to–generation time scale in producing the variations that make adaptation possible. Nearly all phenotypic variations based on genetic differences result from recombinational shuffling of the existing alleles in the gene pool. A population contains a vast number of possible mating combinations, and fertilization brings together the gametes of individuals with different genetic backgrounds. Sexual reproduction reshuffles alleles into fresh combinations every generation.
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What are the disadvantages of sex?
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- Recombination breaks up adaptive combinations of genes.
- Sex reduces the rate at which females pass genes on to their offspring. - Dividing offspring into separate genders greatly reduces the overall reproductive rate. |
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Describe frequency dependent selection and heterozygote advantage.
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occurs when the fitness of a phenotype is dependent on its frequency relative to other phenotypes in a given population. For example in prey switching, rare morphs of prey are actually fitter due to predators concentrating on the more frequent morphs.
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Describe the heterozygote advantage.
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an individual who is heterozygous at a particular gene locus has a greater fitness than a homozygous individual.
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How may geographic distribution affect the genetic structure of populations? Give examples.
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Populations often vary genetically because they are subjected to different selective pressures in different environments. Some individuals of the white clover (Trifolium repens) produce the poisonous chemical cyanide. However, clover plants that produce cyanide are more likely to be killed by frost, because freezing damages cell membranes and releases cyanide into the plant’s own tissues.
In European populations of Trifolium repens, the frequency of cyanide-producing individuals increases gradually from north to south and from east to west |
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Give Some examples of constraints on evolution.
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- developmental constraints on evolution are paramount because all evolutionary innovations are modifications of previously existing structures.
- trade-offs, many traits that are adaptive in one context may be maladaptive in another. - |
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What defines the environment?
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Whatever surrounds and interacts with or otherwise affects a population, organism, or cell. May be external or internal.
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Differentiate between biotic and abiotic factors. Give examples.
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Biotic = Alive
Abiotic = physical and chemical Examples: Biotic: the organisms themselves as well as such items as predation, competition for food resources, and symbiotic relationships. Abiotic: sunlight, temperature, wind patterns, and precipitation |
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Why do scientists study ecology?
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Ecology provides explanations of the perceptible, palpable world. The need for sound science in making decisions about our own interactions with the environment is another important reason for studying ecology. An understanding of ecology greatly improves our ability to grow food sustainably; to manage pests and diseases safely and effectively; and to deal with natural disasters such as floods and fires.
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How does variation in solar energy on the Earth's surface affect climate?
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Solar energy is the major determinant of climates.
- High lat: sun at angle, distributed over larger area, thus less intense. - At Equator: sun perpendicular, more intense - when coming in at angle, goes through more atmosphere, which absorbs more engergy, thus poles are colder - Because of tilt, higher lats receive greater variation in day length and angle |
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How does variation in solar energy create the major wind belts?
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Air masses moving toward the equator from the north and south veer to become the northeast and southeast trade winds, respectively. Air masses moving away from the equator also veer, becoming the westerly winds that prevail at mid-latitudes
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How are patterns of ocean circulation related to wind belts?
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Solar energy heats the atmosphere and powers the wind, which in turn, through frictional drag, moves the water it blows over. As these currents move toward the poles, the water veers right in the Northern Hemisphere and left in the Southern Hemisphere, just as the winds do.
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Tundra
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Arctic, high elevations, all latitudes. Underlain by permafrost, short summers
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Boreal Forest (Taiga)
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latitudes below Arctic tundra, elevations below alpine tundra. Winters are long and cold; summers are short and warm. Cone bearing forests
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Temperate Deciduous Forest
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eastern North America, eastern Asia, and Europe, temps fluctuate dramatically between winter and summer,
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Temperate Grasslands
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relatively dry for much of year, hot summers, cold winters, well suited for growing crops
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Hot Desert vs Cold Desert
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Hot: driest region, centered around lats 30°N and 30°S, Examples are center of Australia and middle Sahara in Africa.
Cold: dry regions at mid– to high latitudes, in the rain shadows of mountain ranges. Seasonal changes in temperature are great. |
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Chaparral
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western sides of continents at mid-latitudes (around 40°) where cool ocean currents flow offshore, winters cool and wet, summers warm and dry. Mediterranean
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Thorn Forests/tropical savanna
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lats below hot deserts of Africa, South America, and Australia. Little or no rain falls in winter, but rainfall may be heavy during summer.
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Tropical Deciduous Forest
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As the length of the rainy season increases toward the Equator, the tropical deciduous forest biome replaces thorn forest. mountain range in the extreme southwestern US
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Tropical Evergreen Forests
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rainforest, Equatorial regions, tons of rain, dry season lasts no longer than 2 or 3 months
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What is biogeography and what ecological, geologic and historical factors help determine distribution of species?
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the scientific study of the patterns of distribution of populations, species, and ecological communities across Earth. Factors: past glaciation, land bridges, deep ocean channels, and mountain ranges. oceans, mountains, deserts, and other barriers restrict the dispersal of organisms from one region to another
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What are endemic species. Any endemic species to Florida?
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Found only in a certain region.
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What are the underlying principles described by island biogeography? How do these affect species numbers on islands?
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islands close to source area should have higher number of species than islands further from the source area, larger islands should have more species than smaller islands. Immigration curve and extinction curve
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Explain how a vicariant event may affect species composition and evolution on continents.
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divides species into 2 discontinuous populations, Differences in distribution patterns among taxonomic groups may indicate that they responded differently to the same vicariant events, that they diverged at different times, or that they had very different dispersal histories.
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What environmental factors affect the distribution of species in marine environments? Freshwater environments?
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Water temperature, salinity, and food supply all vary spatially. Changes in water temperature can be barriers to dispersal . depth determines how much light is available to sustain the photosynthetic organisms. Coastal zone, littoral zone, benthic zone, pelagic zone, abyssal zone. Freshwater: littoral and pelagic.
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Coastal zone
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shoreline to continental shelf, phytoplankton, coral reefs
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Littoral Zone
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near shoreline, affected by waves, sea grasses, algae, invertebrates, intertidal organisms
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Pelagic Zone
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Open Ocean, larger free-swimming vertebrate and invertebrate species.
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Benthic Zone
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ocean floor, sessile animals such as sponges, bryozoans, ribbon worms, and brachiopods
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Abyssal plain
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deep ocean bottom, subsist on decaying organic matter that sinks down from the photic zone
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Photic zone
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depth of water reached by enough sunlight to support photosynthesis
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What are typical population variables or parameters are studied by ecologists? What are some techniques used to measure these?
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ecologists need to count the individuals in a given area, determine their ages, and calculate the rates at which individuals enter and leave the population.
Counting, monitoring populations, tag and release |
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What are the basic variables in teh equation to calculate population size?
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Over any given interval of time, the number of individuals in a population increases by the number of individuals added to the population by birth and immigration and decreases by the number of individuals lost from the population by death and emigration.
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What are life tables used for?
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keeping track of demographic events (births, deaths, immigration, and emigration) in populations and determining the rate (number per unit of time) at which they occur.
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How can fishing pressure alter the life history traits of a population? How can natural predation affect life history traits?
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The haddock population has rebounded enough to support a fishery because commercial fishing of that species ceased and was restarted only after the population had recovered. In contrast, managers reduced fishing pressure on cod only slowly, and the cod population has failed to increase.
These Central American toads were introduced to control cane beetles attacking Australian sugarcane fields. But Australian cane beetles stay high on the upper stalks of the plants; the toads could not reach that high, and thus had no effect on the beetle population. |
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How does knowing age distribution of a population help ecologists understand population changes?
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the distribution of individuals across all age groups—has a profound effect on population growth because reproductive capacity varies with age. Populations with a large proportion of young individuals have a greater potential to grow than populations dominated by individuals that are beyond their peak reproductive years.
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Contrast exponential growth and logistic growth. Under what type of situations might each growth occur?
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Logistic: growth that slows steadily as the entity approaches its maximum size. Pop needs to be well below carrying capacity.
Exponential: growth which is a geometric function of the size of the growing entity: the larger the entity, the faster it grows. Pop skewed toward younger age classes. |
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What ecological factors determine carrying capacity. How does carrying capacity affect population growth?
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Food availability, water, environmental conditions, and space.
When all are in supply, growth can be exponential |
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Contrast Density-Dependent and Density-Independent factors. Give examples.
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Dependent: Food supply (pop increase, deplete food, more deaths), Predation (predators capture more, prey pop goes down), Pathogens (spread more easily in dense pop). Biotic
Independent: period of extreme cold, hurricane, natural disasters, abiotic |
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What four factors strongly influence population density? How does each affect variation in population density?
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- Species that use abundant resources generally reach higher population densities than species that use scarce resources.
- Species with small body sizes generally reach higher population densities than species with large body sizes - Complex social organization may facilitate high population densities. - Some newly introduced species reach high population densities. |
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What are meta populations and how are they affected by habitat patchiness? How are habitat patchiness and gene flow related to extinction?
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The larger population to which subpopulations belong. Each subpopulation has a probability of “birth” (colonization of its habitat patch) and “death” (extinction in that patch). random fluctuations in numbers of individuals are more likely to cause the extinction of a subpopulation than of the entire metapopulation.
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How can our understanding of biogeography help in our understanding of metapopulations? How can this be applied to conserving species survival?
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In any metapopulation, connections between patches, known as corridors, play a critical role in facilitating dispersal to maintain subpopulations.
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what information do ecologists require in order to successfully manage populations?
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Knowing the life history strategy of a species can be helpful in managing populations of commercial value. Rockfish: Larvae from eggs with larger oil droplets, produced by larger females, grow faster and survive better than do larvae from eggs with smaller oil droplets.
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How does human population growth affect the environment?
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Larvae from eggs with larger oil droplets, produced by larger females, grow faster and survive better than do larvae from eggs with smaller oil droplets.
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What were the different conclusions of the Clement's and Gleason views of communities?
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Henry Gleason (1926) described communities were loose assemblages of species,
with each one distributed individualistically according to its unique interactions with the physical environment. (do not move as a unit community) |
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What are the general trophic levels of an ecosystem?
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Producer: green plants, photosynthetic protists
Primary Consumer: termites, grasshoppers, dine on producers Secondary Consumer: herbivores, spiders, warblers, frog, copepods Tertiary Consumer: carnivores, tuna, falcon, orca Decomposer: |
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What are the main differences between a food chain and food web? Which is more realistic?
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A food chain depicts the linear sequence of who eats whom in a given community; food chains are interwoven in a food web . Food webs are more realistic, because energy doesn't just flow up, it flows in multiple directions.
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Energy and biomass pyramids are valuable in comparing the trophic levels of different ecosystems. What do they depict and what are the differences btwn energy and biomass pyramids?
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patterns of energy flow through trophic levels in different communities and (B) the amount of biomass present at the different trophic levels. Biomass can go up or down, energy only goes up. different environments can produce different biomass (ocean phytoplankton example)
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Species Interaction: Neutralism
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two species interact, but don't affect each other
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Species interaction: parasitism
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product of one organism has a negative effect on another organism
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Circumstance when herbivores are considered parasites? Predator?
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The elimination of grazing increased the abundance of trees
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Species Interaction: Amensalism
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one species is harmed other is unaffected, predation
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Species Interaction: Commensalism
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benefits one organism and the other organism is neither benefited nor harmed
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Species Interaction: Mutualism
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interaction between two or more species, where species derive a mutual benefit
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Describe what is meant by "bottom-up control" and "top down control" of population cycles. Examples
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bottom-up control, states that it is the nutrient supply to the primary producers that ultimately controls how ecosystems function. top-down control, states that predation and grazing by higher trophic levels on lower trophic levels ultimately controls ecosystem function. For example, if you have an increase in predators, that increase will result in fewer grazers,
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How can predators affect the populations of their prey?
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think of the wolves in yellowstone
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What are some examples of adaptations of prey organisms to predation pressure?
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toxic hairs and bristles, cryptic
coloration, camouflage shape, deceptive markings as fake eyes, chemical defenses as in skunk, mimicry of harmful food item, resistance to infection by parasites |
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Describe general differences between Batesian and Mullerian mimicry. How do the models and mimics of each type differ?
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Batesian - nontoxic resembles toxic
Mullerian - a number of aposematic species converge on a common color pattern |
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How can parasites affect their host population?
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increase pop: coevolve together, selection can favor diversity of host genotypes, host-parasite trade offse
decrease pop: |
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Describe the differences between interference and exploitation competition. Give examples.
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Exploitation occurs when a limiting resource is available to all competitors and the outcome of competition depends on the relative efficiency with which the competitors use up the resource.
Interference occurs when a competitor interferes with another competitor’s access to a limiting resource. |
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Explain how competitive exclusion might occur btwn two competing species. Give example.
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If one species can prevent all members of another species from utilizing a resource, the inferior competitor may go locally extinct
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Example of amensalism
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when sheep or cattle make trails in grass that they trample on, and without realizing, they are killing the grass.
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Example of mutualism
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clown fish and sea anenomes
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Describe a trophic cascade
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The progression over successively lower trophic levels of the indirect effects of a predator. The elimination of grazing increased the abundance of trees, which in turn increased the number of beetles by providing more food and habitat, which in turn increased the number of lizards, which feed preferentially on beetles.
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ecosystem engineer
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Organisms that build structures that alter existing habitats or create new habitats. Beaver
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Keystone species
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influence both the species richness and the number of trophic levels in a community. ochre sea star
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What is the effect of disturbance on communities?
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Disturbances may remove some species from a community, but may open up space and resources for other species. A community’s history of disturbance may explain patterns of species diversity that would otherwise be puzzling. log carried by waves may crush algae, hurricanes, forest fires, and volcanic eruptions
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Contrast Primary and Secondary succession.
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Primary: Succession that begins in an area initially devoid of life, glaciers, volcanic activity, and in some cases, floods.
Secondary: Succession after a disturbance that did not eliminate all the organisms, forested land that had been cleared for agriculture is abandoned |
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Describe the intermediate disturbance hypothesis.
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species richness is greatest at intermediate
levels of disturbance |
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Why do mountainous regions tend to have greater species richness compared to flatter regions?
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more of these areas are protected.
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What is meant by the statement, "Earth is a closed system with respect to matter but open with respect to energy?"
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Each of the elements that is vital for life exists on Earth in a closed loop of cyclical changes. From a systems point of view, Earth is essentially a closed system with respect to matter. The functioning of our planet relies on a constant input of energy from the sun. This energy leaves Earth in the form of heat flowing to outer space. From a systems point of view, Earth is an open system with respect to energy.
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Why is Earth so unusual, compared to other planets we know about?
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lithospheric plates that move continuously, a moderate surface temperature, a large quantity of liquid water on its surface, and a tremendous diversity of living organisms,
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What are the four compartments of the physical environment? How might they interact?
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the atmosphere, the oceans, fresh waters, and land.
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What is the role of greenhouse gases in the atmosphere?
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they are transparent to sunlight, but trap heat radiating from Earth’s surface back toward space.
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Contrast gross and net primary productivity.
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Gross: rate at which all the primary producers in a particular community turn solar energy into stored chemical energy via photosynthesis.
Net: rate at which energy is incorporated into the primary producers’ bodies through growth and reproduction. |
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What are biogeochemical cycles and how do they facilitate change between the different compartments on earth?
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Movement of inorganic elements such as nitrogen, photosphorus, and carbon through living organisms and the physical environment.
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Describe the hydrologic cycle and how water moves between compartments.
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The hydrologic cycle operates because more water is evaporated from the ocean surface than is returned to them as precipitation. Water also evaporates from soils, from lakes and rivers, and from the leaves of plants (by transpiration), but the total amount evaporated from those surfaces is less than the amount that falls on them as precipitation. The excess terrestrial precipitation eventually returns to the oceans via streams, coastal runoff, and groundwater flows
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How does fire affect nutrient cycling?
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Some nutrients, such as nitrogen, are easily vaporized by fire. They are discharged to the atmosphere in smoke or carried into groundwater by rain falling on burned ground.
Fires also release large amounts of carbon into the atmosphere. |
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Describe the carbon cycle. How are bacteria involved? How is eutrophication involved?
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Carbon atmosphere is incorporated into organic molecules by photosynthesis in the cells of autotrophs. heterotrophic organisms get their carbon by consuming autotrophs. Most carbon stored as organic in soils, biological process: removing it from the atmosphere during photosynthesis and returning it to the atmosphere through metabolism
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What are some of the predicted effects of increasing atmospheric CO2 adn global climate change?
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increase annual temps, cause droughts, increase precipitation in coastal, melt ice caps, sea levels rise
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Describe the nitrogen cycle.
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Nitrogen-fixing bacteria are often found as symbiotic associates in the root nodules of plants such as legumes. Other microorganisms carry out denitrification, the principal process that removes nitrogen from the biosphere and returns it to the atmosphere as N2. industrial production of inexpensive artificial fertilizers has had some unanticipated effects on the nitrogen cycle.
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Describe the sulfur cycle.
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Most of Earth’s sulfur supply is locked up in rocks on land and as sulfate salts in deep-sea sediments. ultimately, this sulfur is returned to the atmosphere via microbial decomposition. The combustion of fossil fuels releases sulfur in the form of SO2 and nitrogen in the form of nitrogen dioxide (NO2) into the atmosphere, where they react with water molecules to form sulfuric acid (H2SO4) and nitric acid (HNO3).
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Describe the phosphorous cycle.
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key component of DNA, RNA, and ATP. lacks a gaseous component, present in the form of phosphate salts in rocks and deep-sea sediments. Phosphorus cycling takes millions of years because the processes of sedimentary rock formation, uplift, and weathering all take a long time. In contrast, phosphorus often cycles rapidly among organisms, and it is often a limiting factor for their growth, particularly for plants.
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What are some other micronutrients important in ecosystems?
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Iron: in most aerobic organisms play a central role in detoxifying environmental poisons, rely upon iron for their catalytic activity.
Cobalt: bacteria that fix atmospheric nitrogen require coenzymes Iodine: essential component of the hormone thyroxine, which governs many metabolic processes... lead to goiter Selenium: component of several important mammalian enzymes |
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What services do ecosystems provide to humans?
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flood control, soil stabilization, pollination, and climate regulation.
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What goods do ecosystems provide humans?
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food, clean water, clean air, fiber, building materials, and fuel
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How have humans impacted ecosystem services and biogeochemical cycles?
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Humans have increasingly altered Earth’s ecosystems to increase their capacity to provide us with goods such as food, fresh water, timber, fiber, and fuel.
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