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88 Cards in this Set
- Front
- Back
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Population-genetic definition of evolution
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change in allele or gamete frequency in the gene pool. Fates of alternative forms of genes over space and time in a population
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evolutionary forces in population
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factors or processes that can change the frequency of an allele in the gene pool
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genetic drift
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random change of allele frequency
--finite population size --smaller the population, the larger the effect |
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Ideal population
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-constant size
--even sex ratio --nonoverlapping generations --mating random --no selection --fecundity Poisson distributed (have on avg 2 offspring) |
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effective population number (Ne)
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size of an ideal population whose rate of (random genetic drift) equals that of the real population
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inbreeding effective size
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accumulation of identity by descent
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variance effective size
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change of allele frequency
--if small, then large changes of allele frequency occur by gen. drift |
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bottleneck effect
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a large population had one or more generations of small size in the past
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founder effect
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bottleneck coincides with a new geographic settlement
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neutral alleles
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natural selection is not invoked to explain evolutionary change
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muew
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mutation rate to neutral allele
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UEP (unit evolutionary period)
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time needed for 1 % amino acid sequence divergence between homologous proteins
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functional density of proteins
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proportion of AA that perform specific functions (substrate recognition, active site for catalysis, ligand binding, allosteric shift)
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metapopulation
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large population subdivided geographically into many local demes
--most matins occur w/in a local population, but sometimes individuals mate outside their local deme |
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m
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fraction of a population that migrates to another one before mating
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gene flow
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movement of genes between demes
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Fst
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what portion of allelic diversity in gene pools consists of differences between the local demes as opposed to being variation w/in the local demes
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isolation by distance
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--haplotypes have geographic distribution
--younger haplotypes have smaller geographic distribution located w/in the ranges of their ancestral haplotypes --explains geographic genetic differentiation among human pops |
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geographic range expansion
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younger haplotypes can have geographic distributions well outside the ranges of ancestral haplotypes
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Fisher's fundamental theorem of NS
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rate of increase in fitness of a population at any time equals its additive genetic variance in fitness at that time
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selective equilibrium (selective peak)
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no additive variance in fitness
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evolution by shifting balance
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interaction between NS, genetic drift and gene flow in a metapopulation causing it to explore adaptive peaks
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adjacent 1
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homologous centromeres segregate to opposite poles
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chromatid interference
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level determines fraction of double crossovers that are 2-strand, 3-strand, and 4-strand doubles
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coalescence
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analytical reversal of the history of DNA replication
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dn=d0(1-2m)^n
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gene flow among demes keeps their gene pools similar
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expressivity
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degree to which phenotype is altered in affected individuals
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fitness
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the most inclusive sufficient parameter used in Fisher's mathematical model of NS
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gradualism
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part of the intellectual heritage of Lyell's uniformitarianism
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habitat fragmentation
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increases loss of alleles by genetic drift in local populations
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homology
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the most important concept of comparative biology, defined using Darwin's theory of common descent
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metapopulation
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a large population subdivided into multiple demes connected by gene flow
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multigene family
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groups of genes of related sequence descended from a common ancestor
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phylogenetic species concept
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a single lineage of ancestor-descendant populations diagnosably and evolutionarily distinct from other such lineages
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pyrin
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haplotype trees analyzed using dn/ds show that human genetic diseases are caused by mutational reversal of ancient selectively-driven changes
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sister chromatids
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adhere to one another in prophase 1
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viability
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an environment-dependent component of fitness
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Mendel's first law (seg)
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Each trait is controlled by particulate factors that occur in pairs. During gamete formation, the members of a pair separate from one another so that each gamete receives only one. The double number is restored upon fertilization
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Mendel's 2nd law (Indep. Ass.)
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The segregation of each gene pair during gamete formation is independent of all others
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isolation by distance
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ancestral haplotypes have the largest geographic distributions and haplotypes derived from them are located within the ancestor's geographic boundaries
--correlation btwn Fst and geographic distance |
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low Fst
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gene pools of different glades are very similar to each other
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allelic diversity
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subject to analysis of variance using parameters Hs, Ht, Fst
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Barr Bodies
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#=number X chromosomes-1
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Beta-Hemoglobin C & S alleles
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frequencies negatively correlated in African malarial regions
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dn/ds=1
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molecular evolution explained by mutation and genetic drift alone
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HIV
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evolves by natural selection for different cell tropisms sequentially
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isolation by distance
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strength of gene flow among populations is inversely proportional to their geographic separation
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pleiotropy
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production of seemingly unrelated phenotypes by a single allele
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p(WAA-W)+q(WAa-W)
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average excess for fitness of allele A
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selective peak
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allele frequencies at which heritable variance in fitness is absent
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W
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sufficient parameter subsuming multiple variables in quantitative genetic models of NS
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X-linked locus
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average coalescence time of haplotypes is 3N; reflects gene flow by both females and males
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Fisher's fundamental theorem of NS
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Rate of increase in fitness of any population at any time equals its additive genetic variance in fitness at that time
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SNP
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site in aligned haplotype sequences for which 2 alternative bases exist in a pop
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correlation coeffecient
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standardized covariance that ranged from -1 to 1
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shifting balance
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interaction between genetic drift and NS in a metapopulation that allows the metapopulation to move from one selective peak to a higher one
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evolution as such
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life has a long history of ongoing change
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common descent
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all living forms share common ancestry. Also accept "history of life forms a branching tree or phylogeny"
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mult. of species
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new species are formed from older one by geographic isolation and divergence of populations
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gradualism
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accumulation of small, quantitative phenotypic changes in populations lead to qualitative change over evolutionary time
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NS
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differential survival and reproduction of varying organisms causes populations to accumulate favorable variants and to discard less favorable ones. Favorable variants are thsoe that give their possessors more effective use of resources for survival/reproduction
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allelic diversity
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its variance is expressed as Hardy-Weinberg expected heterozygosity even if not heterozygous individuals occur in male
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anticipation
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increase in severity of disorder from one generation to the next
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balanced polymorphism
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a polymorphic selective equilibrium
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epistatic variance
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nonadditive genetic variance revealed in measured-genotype studies of variation at the ApoE and LDLR loci analyzed together but not individually
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fitness
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NS destroys heritable variance in this phenotype
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functional density
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a critical parameter for explaining why rates of neutral evolution differ among proteins
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HIV
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molecular evolution occurs about one million times faster than for human nuclear genes
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N
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expected number of generations for coalescence of autosomal haplotypes
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1/2N
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rate of loss of alleles by genetic drift for an autosomal locus
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postmeiotic segregation
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failure of mismatch repair
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1st degree sex determination
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determination of sex of gonad
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pseudolinkage
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apparent linkage due to death of zygotes not receiving alleles together
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reductional division
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meiosis I
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Y-chromosomal haplotypes
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reveal male-specific gene flow from Yemeni to Lemba populations
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(A=.89,S=0.11) &C=1
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two alternative selective equilibria for variation at the hemoglobin locus in malarial regions of Africa
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branch migration
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changes amount hybrid DNA present
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diplotene
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when chiasmata become visible
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dn/ds
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permits evaluating the role of NS in the evolutionary history of a protein-coding gene
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euchromatin
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decondenses in interphase
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haplotype tree scan
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used to identify which of many base substitutions at a locus might be casually related to variation of a quantitative phenotype
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hemizygous
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genes in deleted region in deficiency heterozygote
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homogametic
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male in butterflies
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pachytene
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when crossing over occurs
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polytene chromosomes
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source of data on gene orders used to construct a haplotype tree of Drosophila and D pseudoobscura
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shared derived character
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a criterion for recognizing homology in phylogenetic analysis
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shifting balance
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described evolutionary change occuring by interactions among NS, genetic drift, and migration w/in a species
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sufficient parameter
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illustrated by fitness in Fisher's genetical theory of NS
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