207679567 | the smallest unit that evolves | population (not individuals) | 0 | |
207679568 | microevolution | the change in allele frequencies of a population | 1 | |
210651924 | What was missing in Darwin's explanations? | an understanding of inheritance that could explain how chance variations arise in a population while also accounting for the precise transmission of these variations from parents to offspring | 2 | |
210651925 | Mendel's laws of inheritance were originally believed to be | at odds with Darwin's theory of natural selection | 3 | |
210651926 | What did Darwin believe regarding traits? | he believed in quantitative characters, those characteristics in a population that vary along a continuum (i.e. fur length and speed at which an animal can flee from a predator) | 4 | |
210651927 | What was Mendel's point of view regarding traits? | he recognized only discrete "either-or" traits as heritable | 5 | |
210651928 | population genetics | emphasizes the extensive genetic variation within a populations and recognizes im[importance of quantitative characters | 6 | |
210651929 | quantitative characters | A heritable feature in a population that varies continuously as a result of environmental influences and the additive effect of two or more genes (polygenic inheritance). | 7 | |
210651930 | modern synthesis | (1940s) integrates ideas and discoveries from different fields like paleontology, taxonomy, biogeography, population genetics. | 8 | |
210651931 | architects of modern synthesis | Theodosius Dobzhansky (1900-1975), Sewall Wright (1889-1998), Ernst Mayr (1904-), Gaylord Simpson (1902-1984), G. Ledyard Stebbins (1906-2000) | 9 | |
210651932 | 3 emphasis of modern synthesis | 1. importance of populations as the units of evolution 2. the central role of natural selection as the most important mechanism of evolution 3. the idea of gradualism to explain how large changes can evolve as an accumulation of small changes occurring over long periods of time | 10 | |
210651933 | population | localized group of individuals belonging to the same species | 11 | |
210651934 | species | a group of populations whose individuals have the potential to interbreed and produce fertile offspring in nature | 12 | |
210651935 | individuals are more likely to breed with | members of their own population rather then members of a different population | 13 | |
210651936 | individuals near a population center are on average more closely related to | one another than to members of other populations | 14 | |
210651937 | gene pool | the total aggregate of genes in a population at any one time. consists of all alleles at all gene loci in all individuals of a population | 15 | |
210651938 | homozygous | two identical alleles for a given character | 16 | |
210651939 | heterozygous | two different alleles for a given character | 17 | |
210651940 | If all members of a population are homozygous for the same allele, that allele is | fixed in the gene pool | 18 | |
210651941 | Hardy-Weinberg Theorem | states that the frequencies of alleles and genotypes in a population's gene pool remain constant over the generations unless acted upon by agents other than Mendelian segregation and recombination of alleles | 19 | |
210651942 | Hardy-Weinberg Equilibrium | condition that occurs when the frequency of alleles in a particular gene pool remain constant over time | 20 | |
210651943 | Hardy-Weinberg Equation | (p squared) + 2pq + (q squared) = 1, where (p squared) = frequency of RR genotype, 2pq = frequency of Rr plus rR genotype, and (q squared) = frequency of rr genotype | 21 | |
210651944 | connection between Hardy-Weinberg, Mendel, and Darwin | Natural selection requires genetic variation, and the Hardy-Weinberg theorem explains how Mendelian inheritance preserves genetic variation from one generation to the next | 22 | |
210651945 | Assumptions of Hardy-Weinberg Theorem | 1. Very large population size (small population can cause genetic drift) 2. No migration (gene flow) 3. No net mutations (alter gene pool by changing one allele into another) 4. Random mating 6. No natural selection (differential survival and reproductive success of genotypes will alter their frequencies) | 23 | |
210651946 | Genetic drift | the chance fluctuation in the gene pool, can cause genotype frequencies to change over time | 24 | |
210651947 | gene flow | the transfer of alleles between populations due to movement of individuals or gametes, can increase the frequency of any genotype that is in high frequency among immigrants | 25 | |
210660701 | if the frequencies of alleles or genotypes deviate from values predicted by Hardy-Weinberg equation it is usually because.. | the population is evolving | 26 | |
210660702 | evolution at the population level | evolution is a generation-to-generation change in a population's frequencies of alleles | 27 | |
210660703 | main factors that cause microevolution (alter the allele frequencies in a population) | genetic drift, natural selection, gene flow, mutation. Genetic drift and natural selection are the most important | 28 | |
210660704 | Natural selection always has a | positive effect on the population (the others can have positive, negative, or neutral effect) | 29 | |
210660705 | what are two situations that can shrink a population down to a small enough size where genetic drift becomes a problem? | bottleneck effect and founder effect | 30 | |
210660706 | Bottleneck effect | disasters such as earthquakes, floods, droughts, and fires reduce the size of a population drastically, and the new population may not be representative of the original population. Often times by change certain alleles become over represented while others become under represented , and still some alleles may be eliminated all together. reduces overall genetic variability in a population | 31 | |
210660707 | Founder effect | when a few individuals from a larger population colonize in an isolated island, lake, or other new habitat. results in genetic drift. usually accounts for high frequency of certain inherited disorders | 32 | |
210660708 | natural selection | differential success in reproduction among individuals in a population. accumulates favorable genotype in a population | 33 | |
210660709 | mutation | change in an organism's nucleotide sequence in DNA, rare | 34 | |
210660710 | both quantitative and discrete characters contribute to | variation within a population | 35 | |
210660711 | most heritable variation consists of | quantitative characters that vary along a continuum within a population, usually indicates polygenic inheritance | 36 | |
210660712 | polygenic inheritance | combined effect of two or more genes on a single phenotypic character, | 37 | |
210660713 | discrete characters | can be classified on an either or basis, usually because they are determined by a single gene locus with different alleles that affect distinct phenotypes | 38 | |
210660714 | morphs | the different forms when two or more forms of a discrete character are represented in a population | 39 | |
210660715 | polymorphic | a population is said to be polymorphic for a characters if two or more distinct morphs are each represented in high enough frequencies to be readily noticeable | 40 | |
210660716 | gene diversity | genetic variation at level of whole genes | 41 | |
210660717 | nucleotide diversity | genetic variation at the molecular level | 42 | |
210660718 | geographic variation | differences in gene pools between populations or subgroups of populations | 43 | |
210660719 | cline | a type of geographic variation, a graded change in some trait along a geographic axis | 44 | |
210660720 | new alleles originate only by | mutation | 45 | |
210660721 | where do mutations have to occur in order to produce gametes that can be passed along to offspring? | cell lines | 46 | |
210660722 | to what do members of a sexually reproducing population owe nearly all their genetic differences to? | the unique recombinations of existing alleles each individual receives from the gene pool | 47 | |
210660723 | how is variation preserved? | diploidy and balanced polymorphism | 48 | |
210660724 | diploidy | hides genetic variation from selection in the form of recessive alleles in heterozygotes | 49 | |
210660725 | balanced polymorphism | the ability of natural selection to maintain stable frequencies of two or more phenotypic forms in a population | 50 | |
210660726 | heterozygote advantage | if individuals who are heterozygous at a particular locus have greater survivorship and reproductive success than any homozygote, then two or more alleles will be maintained at the locus by natural selection | 51 | |
210660727 | neutral variation | confers no selective advantage for some individuals over others (fingerprints), frequencies not affected by natural selection | 52 | |
210660728 | frequency-dependent selection | the survival and reproduction of any one morph declines if that phenotypic form becomes too common in a population | 53 | |
210660729 | only a fraction of the extensive variation in a gene pool | significantly affects organisms | 54 | |
210660730 | Darwinian fitness | the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals | 55 | |
210660731 | relative fitness | the contribution of a genotype to the next generation compared to the contributions of alternative genotypes for the same locus | 56 | |
210660732 | the relative fitness of an allele depends on | the entire genetic context in which it works | 57 | |
210660733 | three selection trends | directional selection, diversifying selection, stabilizing selection | 58 | |
210660734 | directional selection | most common during periods of environmental change or when members of a population migrate to some new habitat with different environmental conditions. Shifts the frequency curve for variations in some phenotypic character in one direction or the other by favoring what are initially relatively rare individuals that deviate from the average for that character | 59 | |
210660735 | diversifying selection | occurs when the environmental conditions are varied in a way that favors individuals on both extremes of a phenotypic range over intermediate phenotypes | 60 | |
210660736 | stabilizing selection | acts against extreme phenotypes and favors the more common intermediate variants. reduces variation and maintains that status quo for a particular phenotypic character | 61 | |
210660737 | advantage of sex | the processes of meiosis and fertilization generate the genetic variation upon which natural selection can act as an agent of adaptation. | 62 | |
210660738 | sexual dimorphism | A special case of polymorphism based on the distinction between the secondary sex characteristics of males and females. | 63 | |
210660739 | intrasexual selection | A direct competition among individuals of one sex (usually the males in vertebrates) for mates of the opposite sex. | 64 | |
210660740 | intersexual selection | Selection whereby individuals of one sex (usually females) are choosy in selecting their mates from individuals of the other sex; also called mate choice. | 65 | |
210660741 | four reasons why natural selection cannot fashion perfect organisms | 1. Evolution is limited by historical constraints 2. Adaptations are often compromises 3. Not all evolution is adaptive 4. Selection can only edit existing variations | 66 |
Chapter 23: The Evolution of Populations Flashcards
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