58 Cards in this Set
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Evolution
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change in allele frequency from one generation to the next in a population
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Microevolution
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Small scale changes within a population over time, underlying processes, direct observation
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Macroevolution
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Large scale changes that lead to speciation or higher level diversification, large scale patterns in nature
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Vestigial Traits
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useless or rudimentary structures with a function in a closely related species, can be considered a type of homology
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Pseudogenes
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a gene that is homologous to another gene in an allied species but lacks function, usually the result of a mutation that stops transcription
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Fossil Record
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any trace of an organism that lived in the past which gest preserved
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Law of Succession
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the observation that fossil types are succeeded, in the same geographic area, by similar fossil or living species
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Transitional Forms
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fossilized organisms that share traits of ancestral and modern species
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Homology
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similarity between species that results from inheritance of traits from a common ancestor
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Catastophism
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the view that most or all landforms are the product of catastrophic events
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Uniformitarianism
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the assumption that processes identical to those at work today are responsible for events that occurred in the past
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Lamarckian inheritance
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the idea that an organism can pass on characteristics that it acquired during its lifetime to its offspring
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Gradualness
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evolution occurs in small steps and within a population
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Heredity
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the passing on of physical or mental characteristics genetically from one generation to another
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Pangenesis Theory
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all body parts contribute genetic material to sex cells
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Germ Plasm Theory
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only gonads contribute genetic material to sex cells
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Blending Inheritance
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the hypothesis that heritable factors blend to produce a phenotype and are passed on to offspring in this blending form
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Gene
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a sequence of DNA
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Locus
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the position that the gene occupies on a chromosome
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Allele
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the alternative forms of a single gene
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Homozygous
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same allele on both chromosomes
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Heterozygous
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different alleles on each chromosome
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Genotype
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genetic constitution of an individual
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Phenotype
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expression of the genotype in a particular environment
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Dominant Allele
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always expressed
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Recessive Allele
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need both alleles to be recessive to be expressed
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Codominance
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both alleles in the gene pair are expressed
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Segregation
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during meiosis alternate alleles of a single gene go to two different gametes
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Independent Assortment
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random assortment of allele
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Linkage
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occurs when two or more genes are on the same chromosome and can't be independently assorted, will always appear together and can't have one without the other
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Meiosis
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process of cell division resulting in gametes
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Gametes
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sex cells
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Diploid
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2n
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Haploid
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n
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Discrete Variation
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the trait is either present or its not
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Continuous Variation
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trait follows along a numerical continuum, example: height
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Biometricians
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biostatistics
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Epistasis
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the interaction of two genes, one may block the other
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Modern Synthesis
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unites Mendelian genetics with the theory of evolution by natural selection
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Heterozygosity
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the number of heterozygotes
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Allelic Diversity
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diversity of alleles
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Allele Frequency
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how often an allele appears in a population
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Genotype Frequency
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how often a genotype appears in a population
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Hardy-Weinberg Equilibrium
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a situation in which allele and genotype frequencies in an ideal population do not change from one generation to the next, because th population experiences no selection, no mutation, no migration, no genetic drift, and random mating
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Heritability
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the fraction of the total phenotypic variation in a population that is caused by genetic differences among individuals
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Selection Differential
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the difference between the mean phenotype of the selected individuals and the mean phenotype of the entire population
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Response to Selection
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the difference between the mean phenotype of the offspring of the selected individuals in a population and the mean phenotype of the offspring of all the individuals
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Fisher's Fundamental Theorem of Natural Selection
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the rate of change in a trait (and in average fitness) is proportional to the amount of genetic variation for that trait
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Directional Selection
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individuals at one extreme of a trait distribution have the highest fitness
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Stabilizing Selection
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individuals with intermediate trait value have highest fitness
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Heterozygote Superiority (Overdominance)
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a situation in which heterozygotes at a particular locus tend to have higher fitness than homozygotes
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Balancing Selection
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two alleles are maintained at a stable equilibrium because the heterozygote is more fit than either of the homozygotes
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Disruptive Selection
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individuals at both extremes of a trait have highest fitness
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Heterozygote Inferiority (Underdominance)
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a situation in which heterozygotes at a particular locus tend to have lower fitness than homozygotes
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Frequency Dependent Selection
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occurs when an individual's fitness depends on the frequency of its phenotype in the population, typically occurs when a phenotype has higher fitness when it is rare and lower fitness when it is common
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Mutation-Selection Balance
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an equilibrium in the frequency of an allele that occurs because new copies of the allele are created by mutation at exactly the same rate that old copies of the allele are eliminated by natural selection
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Migration
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the movement of alleles from one population to another, via the movement of individuals or transport of gametes by wind, water or pollinators
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Selection Coefficient
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a variable used in population genetics to represent the difference in fitness between one genotype and another
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BZ 220:Final Exam