Term
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Definition
| Geologist and influencer of Darwin. Advocated gradualism in geology -- that present phenomena would lead to geologic change gradually over time (as opposed to catastrophism) |
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Term
| Two main problems with Darwinian natural selection |
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Definition
*Origin / characterization of variation on which selection hinges, and
*Assumption of Blending inheritance |
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Term
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Definition
| Large, discontinuous variations |
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Term
| Provisional Hypothesis of Pangenesis |
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Definition
Darwin's hypothesis of 1868:
Each part of an organism "throws off" gemmules of their contents, which make it to reproductive apparatus and are passed onto subsequent generation.
Environmentally-affected parts of organisms would pass that info to the offspring, which contribute to the hereditary composition of the offspring. |
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Term
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Definition
"Darwin's Bulldog" - big advocate.
Felt that Darwin was too gradualistic, and burdened his hypothesis with a focus on the most minor variations. Questioned why there was an incomplete fossil record, and few very intermediate forms living.
Natura non facit saltum |
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Term
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Definition
"Nature does not make jumps"
Continuous vs. discreet variation as the fodder for natural selection |
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Term
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Definition
Advocate of Darwin's who challenges his provisional hypothesis of Pangenesis.
Also challenges Darwin on gradualism vs. discontinuity of evolution.
Emphasized stability of sports and principle of regression--actively sought to quantify inheretance from parents to offspring, foreshadowing heritability of traits. Regressed traits of sons on fathers. Sought universal units of regression/transmission of traits (i.e. 2/3, 3/5, ...) |
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Definition
| Belief in evolution / inheretence proceeding more or less continuosly. Held by Thomas Huxley, Pearson, Galton, Weldon |
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Definition
| One (such as William Bateson) hypothesizing that evolution proceeds in discontinuous jerks |
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Term
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Definition
Principle of homotypes -
variation within individual is less than that between races.
Undifferentiated like organs have some degree of resemblance. |
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Term
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Definition
| Around rediscovery of Mendel, emphasizes that mutations are the driver, source of discontinuity in evolutionary process. |
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Term
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Definition
| A tendency to revert to evolutionarily previous phenotypes -- or display traits thought to have gone from previous generations |
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Term
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Definition
| "Converted" to Mendelism on the basis of his work with Drosophila |
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Term
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Definition
Genetic similarities that are obscured by dominance, epistatic effects.
For example, the function of A in two individuals may vary based upon A's interaction with other genes. |
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Term
Fisher's
"Fundamental Theorem of Natural Selection" |
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Definition
The effectiveness of selection depends
upon the total heritable variation
in the population at the time |
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Term
Wright's
Path Coefficient |
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Definition
Ratio of the variability of an effect
when all causes are kept constant except the one in question (the variability of which is kept unchanged),
to the total variability |
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Term
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Definition
| Scoring a number of individuals for a trait; genotyping only a subset of individuals. Perhaps those with extreme phenotypes. |
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Term
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Definition
| Increase design power by asexually replicating a particular genotype (like in Daphnia) |
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Term
| Recombinant Inbred Lines (RIL) |
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Definition
| Lines produced by selfing/repeated sibling mating, that have essentially no within-line genetic variance. |
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Term
| Randomly Amplified Polymorphic DNA (RAPDs) |
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Definition
| sending random primers out into genome, that may stick and amplify specific region between primer-site loci. Use this region as a marker. |
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Term
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Definition
| Generally, when one sex between a hybrid cross is inviable, it is the one with two different sex chromosomes |
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Term
| Dobzhansky-Muller Model of Speciation |
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Definition
| Speciation occurs through epistasis - with isolated populations fixing alleles within pops that are mutually incompatible between populations |
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Term
| Bulked Segregant Analysis (BSA) |
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Definition
| Individuals are pooled into groups based on trait value. Marker alleles in LD with QTL alleles will have non-random distribution across bulks |
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Term
| Nearly Isogenic Lines (NIL) |
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Definition
Inbred lines containing one or more DNA regions from a donor parent, in otherwise standard background.
Earliest obtained were done by backcrossing many times - essentially introgressing a fragment (random or QTL-selected) into parental genotype. |
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Term
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Definition
| In a backcross design where something is introgressed into a parental line, the 'drag' of linked, undesirable genes with the desired marker |
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Term
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Definition
| Student of Morgan's, defined evolution as the changing of allele frequencies within population. Spread idea of mutations in gene regions being major targets of natural selection. "Nothing in biology makes sense but in the light of evolution." |
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Term
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Definition
| British biologist, creator of field of Ecological Genetics. Along with Fisher was a big advocate of natural selection (as opposed to drift) causing evolutionary change. |
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Definition
| Evolutionary Biologist, advocate of small steps in evolutionary change, and that natural selection was the driving force. Major player in the Modern Synthesis. |
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Term
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Definition
| By crossing two inbred lines, create LD by loci that differ between the lines. This creates associations between marker loci and linked segregating QTLs. |
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Term
| F2 Cross Design Advantages |
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Definition
| F2s generate 3 genotypes at each marker locus, allowing estimation of dominance in detected QTLs |
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Term
| Advanced Intercross Lines (AILs) |
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Definition
| QTL designs utilizing F3+. |
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Term
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Definition
| Dist'n of trait values is considered separately for each marker locus |
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Term
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Definition
| Trait values are compared for each pair of adjacent marker loci |
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Term
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Definition
A method for n multiple statistical comparisons, stating that for an overall significance level of y across all comparisons, each individual test be based upon a significance level of
a = 1 - (1 - y)^(1/n), roughly y/n |
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Term
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Definition
| QTL Phenotypes (given mean, variance) are randomly assigned to genotypes as a Fisher's exact test basis of comparison for association of genotypes to phenotypic values |
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Term
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Definition
| Evolutionary response to environmental change by natural selection -- causes increased proportion of individuals with environmentally-induced adaptive phenotype |
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Term
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Definition
| Evolutionary response to environmental change that causes canalization, especially leading to appearance of individuals with an adaptive trait in the absence of original environmental stimulus |
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Term
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Definition
| Evolved resistance to environmental or genetic perturbation |
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Term
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Definition
| A genome-mapping function/model that takes multiple recombination events (but not interference) into account while linking markers. |
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Term
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Definition
| A marker interval contains a single QTL, while flanking intervals are free of QTLs |
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Term
| Kosambi's Mapping Function |
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Definition
| A mapping function, building upon Haldane's, that incorporates multiple crossings over AND interference. |
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Term
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Definition
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Term
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Definition
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Term
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Definition
| recombination frequency (per Lynch & Walsh) |
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Term
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Definition
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Term
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Definition
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Term
| Likelihood-Ratio statistic |
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Definition
| Tests whether QTL is linked to the marker under consideration. |
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Term
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Definition
Some F2 individuals showing more extreme character values than seen in either parental line.
Reason(s): Nonadditive gene action.
OR, parents fixed for sets of alleles with counteracting effects (+/- x -/+) |
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Term
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Definition
| Maize cytogeneticist, among first to visualize crossing over of chromosomes during meiosis. She related this to linkage, producing the maize linkage map. Demonstrated the role of centromere, telomere. Later discovered transposition, demonstrated gene expression. |
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Definition
| Japanese geneticist and creator of Neutral Theory of Evolution. Combined population genetics of modern synthesis with emerging molecular data, variance in which did not seem directly tied to selected phenotypes. Drift displaces selection as main driver of evolution. |
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Definition
| Kimura's student in the Neutral work; developed a slightly-deleterious model, then a more general nearly-neutral theory of evolution |
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Term
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Definition
| Botanist interested in the generation of new ecological species via hybridization mechanisms. Works in sunflowers. Cool study of the F1s of a hybridization being particularly well-suited for that hybrid range. |
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Term
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Definition
| Contemporary of Darwin's; also published evolutionary hypothesis in 1858. Inclined toward 'fringe' transmutational species ideas all his life. Wallace a bit less 'Malthusian', saw mechanism of evolution more species adapting to fit environment than competing. |
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Term
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Definition
Statistician and evolutionary biologist, sought to reconcile Mendel, Darwin.
He applied differential equations and maximum likelihood models to genotype distributions within populations, and
ML to estimate linkage.
Very additive in consideration of different alleles, viewed variance as largest in larger populations. Natural selection direct function of Additive variation |
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Term
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Definition
| American geneticist. Began path analysis and chief developer of genetic drift, F-statistics, inbreeding coefficients. Advocate of drift as a main evolutionary driver. Interested in epistasis, 'networks' (precursory) of interacting genes. Emphasized role of small populations in evolution. Big role introducing quantitative genetics into breeding. |
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Term
| John Burdon Sanderson Haldane |
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Definition
| British geneticist, developed linkage and crossing-over with greater resolution. Impressed by the mathematical effects of selection working over generations, sought to further quantify consequences of selection. |
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Term
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Definition
| Describes phenotypic value of a given genotype across a range of environments |
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Term
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Definition
| An adaptation of a particular individual relative to it's population, peers |
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Term
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Definition
| Any adaptation changing biota - can refer to shifts in ecological dominance, or status of an entire taxa. Not necessarily correspondent to Organic adaptation. |
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Term
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Definition
| (Simpson) View that life is indistinguishable from naturalistic processes. |
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Term
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Definition
| Life is a unique, "vital" element that is fundamentally different from non-life |
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Term
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Definition
| Encompassed by vitalism, but includes life building to some final goal. Teleological in nature. |
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Term
| "Classical" Hypothesis of Evolutionary Genetics |
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Definition
| Polymorphic alleles are exceedingly rare. In the case of mutation, the overwhelming majority are bad - soon swamped out. If beneficial, new allele is soon driven to fixation. Almost no standing polymorphism. |
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Term
| "Balance" Hypothesis of Evolutionary Genetics |
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Definition
| Many polymorphic loci exist, with 2+ alleles at a given locus quite common. Nearly everything is heterozygous. |
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Term
| Recognition Species Concept |
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Definition
| A species is a set of organisms that recognize each other as potential mates |
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Term
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Definition
| A set of organisms that look similar-yet distinct from other organisms-is a species |
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Term
| Phylogenetic Species Concept |
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Definition
| A species is the smallest set of organisms sharing a common ancestor and can be distinguished from other such sets |
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Term
| Biological Species Concept |
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Definition
| Species are members of populations that actually or potentially interbreed. Similar appearance not necessary. |
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Term
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Definition
| Members that share the same ecological resources and interbreed are a species |
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Term
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Definition
| Members drawing off of a common gene pool (through interbreeding) are a species |
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Term
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Definition
| German-American taxonomist who essentially founded speciation, was key in developing biological species concept. Considered alloparty/parapatry as hugely important; critical of overly-mathematical theories of evolution as "beanbag" genetics. Distinguished between proximate/ultimate causes in adaptation. |
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Term
| Complex Segregation Analysis (CSA) |
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Definition
| Extension of Mixture Models which incorporates pedigree information, to likelihood-ratio test different models of genetic transmission (single major gene, polygene w/ no major gene, etc.) |
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Term
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Definition
| mapping genetic factors that contribute to transcriptional variation by monitoring genotypes, expression data (esp. in the context of a cross) |
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Term
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Definition
| trans-regulatory eQTLs whose influence seems to be induced by environmental conditions |
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Term
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Definition
| Tests for mixing of two or more normals, as you'd expect if phenotype dist'ns were normal about each genotype AA, Aa, aa |
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Term
| Maximum Likelihood Estimation |
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Definition
| Calculates the most likely parameters of a density function (distribution), given z data observations from that function. |
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Term
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Definition
| Cannot resolve a heterozygote |
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Term
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Definition
| Can see both alleles of a heterozygote |
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Term
| Likelihood Ratio (LR) tests |
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Definition
| In tests for major genes, determines whether a full model of normals gives significantly better fit than a subset of that model |
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Term
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Definition
Say you have line ABC and line abc. Cross them.
F1 is heterozygous AaBbCc. Backcross into ABC. Recombinant aC
progeny scored for trait, knowing they are EITHER abC or aBC |
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Term
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Definition
| Chromosomes which do not undergo crossing-over; great for constructing genetic lines |
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Term
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Definition
| Statistical test, distinguishing between DNA sequence evolving randomly (neutrally), and sequence evolving non-randomly due to (selection, expansion/contraction, ...) |
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Term
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Definition
| The pattern of genetic variation and covariation for a set of traits. Most useful definition has been variances/covariances between parents and offspring, enabling us to predict response to selection. |
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Term
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Definition
| (Additive) Genetic Variance / Phenotypic Variance |
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Term
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Definition
| A phenotypic feature resulting from the Bauplan of an organism, or some other adaptive constraint. |
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Term
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Definition
| Shift in function of something during evolution |
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Term
| Antagonistic Pleiotropy Hypothesis |
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Definition
| Negative Correlations among Life History characteristics may constrain evolution and maintain genetic variation |
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Term
| Linkage Disequilibrium (LD) Mapping |
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Definition
| Utilizing high-LD populations (small, recent expansion, etc.) to map markers to one-gene presence/absence traits associatively. |
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Term
| Transmission/Disequilibrium Test (TDT) |
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Definition
| Compare number of times a marker allele is transmitted vs. non-transmitted from heterozygote parents to affected offspring. The null expectation is zero; offers a test statistic. |
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Term
| Tinbergen's Four Questions |
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Definition
1. Causation
2. Function
3. Ontogeny
4. Phylogeny |
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Term
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Definition
Population mutation rate;
Θ = 4*Ne*µ.
(µ -> per generation mutation rate) |
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Term
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Definition
Per generation neutral mutation rate:
Θ = 4*Ne*µ.
(Θ -> Population mutation rate) |
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Term
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Definition
Nucleotide diversity;
The average number of nucleotide differences between homologous sequences of DNA taken from two random individuals in a population.
The equilibrium state of Population mutation rate Θ. |
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Term
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Definition
| d = (average # SNP differences between homologous sequences in each pair of individuals) - (total number of polymorphic sites) |
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Term
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Definition
A Negative Tajima's D signifies an excess of low frequency polymorphisms relative to expectation, indicating population size expansion (e.g., after a bottleneck or a selective sweep) and/or purifying selection.
A Positive Tajima's D signifies low levels of both low and high frequency polymorphisms, indicating a decrease in population size and/or balancing selection. |
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Term
τ
(Mendelian transmission probability) |
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Definition
The probability for transmission of a given allele S.
τ1 - SS parent
τ2 - Ss parent
τ3 - ss parent
This parameter becomes very important for detecting if putative transmitted locus is acting in Mendelian fashion. |
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