Term
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Definition
| When the dominance coefficient is 0.5. The phenotype of the heterozygote is the sum of the phenotypic effects of each allele. Gives the maximum difference between marginal and average fitness across the entire range of genotype frequencies under random mating. |
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Term
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Definition
| A variant or alternative form of the DNA sequence at a given locus. It can be a single nucleotide site, or a microsatellite locus. Generally, a unique DNA sequence within a genomic region. |
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Term
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Definition
"Other"
A homozygous or heterozygous genotype composed of two alleles not inherited from a recent common ancestor. |
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Term
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Definition
| Sampled 200 individuals of Caenorhabditis elegans. Sequestered around 40,000 SNPs. In the sample, 47 had unique haplotypes, 50 had nearly identical haplotypes, and 97 had isotypes. |
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Term
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Definition
| Has a selfed mating system. Fixation index is 0.99 using allozyme method (Abbot and Gomes, 1989). |
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Term
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Definition
| Maintains frequencies of heterozygous genotypes. |
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Term
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Definition
Non-random mating
Mating patterns where individuals do not mate in proportion to their genotype frequencies in the population. Mating that is more or less frequent with respect to genotype or genetically based phenotype frequency than expected by random combination. Impacts expected genotype frequencies in a population. Includes positive and negative assortative mating. |
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Term
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Definition
| A homozygous genotype composed of two identical alleles that are inherited from a common ancestor. |
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Term
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Definition
| The average fitness of an entitty over all alleles and genotypes. |
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Term
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Definition
| A reduction in polymorphism caused by the combination of negative or purifying selection against deleterious mutatiosn that also leads to the loss of neutral alleles in gametic disequilibrium with the deleterious mutation. |
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Term
| Basic natural selection model |
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Definition
| Diploid individuals. One locus with two alleles. Obligate sexual reproduction. Generations do not ovelap. Mating is random. Mechanisms of natural selection are genotype-specific differences in survivorship that lead to variable genotype-specific growth rates. Fitness values are constants that do not vary with time, over space, or in the two sexes. Infinte population size so there is no genetic drift. No population structure. No gene flow. No mutation. |
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Term
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Definition
| Coined the term "coupling gametes". Punnett developed the Punnett square in 1905. |
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Term
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Definition
Binomial random variable
A variable representing a trial or sample that can have only two possible outcomes, such as zero or one. Coin flips are an example. |
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Term
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Definition
| A form of consanguineous mating. |
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Term
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Definition
| Requires a host to move geographically. Hosts have limited dispersal, causing population structure for the bacteria. |
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Term
| Breeding effective population size (Nbe) |
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Definition
| The number of individuals found in a genetic neighborhood defined by the variance in gamete dispersal. Suitable for populations where individuals may occur relatively uniformly over large areas. |
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Term
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Definition
| A nematode named after Sydney Brenner. It is little known to science. Closely related to C. elegans. It has the most molecular diversity of any eukaryote, with 14.1% polymorphic synonymous sites. Molecular diversity is 150 times greater than that of humans. |
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Term
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Definition
| A nematode that is central to research in molecular and cellular developmental biology. Almost all research has been conducted on a single strain. A globally distributed, free-living nematode that colonizes nutrient-rich human-associated habitats including compost heaps and rotting fruit. Reproduces primarily by hermaphroditic selfing. It has been shaped human interaction in recent history. Has very little population structure on a global scale; this may be caused by extended haplotypes. Population-level variation is shaped by selective sweeps. |
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Term
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Definition
| The upper bound of population growth in a logistic growth model. |
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Term
| Census population size (N) |
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Definition
| The number of individuals in a population. The head count size of a population. |
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Term
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Definition
| Suscribed to the idea of blending inheritance: offspring display phenotypes that are an intermediate combination of parental phenotypes. |
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Term
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Definition
Anas cyanoptera
A duck from South America with spatially heterogeneous selection. There are several populations on the coast and in the Andes. |
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Term
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Definition
Semi-dominance
Lack of dominance
The heterozygote is intermediate to phenotypes of both homozygotes.
h = 0.5 |
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Term
|
Definition
Dominance where one allele completely masks the phenotype of another allele so that the phenotype of a heterozygote is identical to a homozygote of the dominant allele.
h = 1 |
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Term
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Definition
| Mating between related individuals that can take the form of biparental inbreeding or sexual autogamy. Increases the probability that resulting progeny are homozygous compared to random mating. |
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Term
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Definition
Gametes where alleles on the same chromosome remain together. Term coined by Bateson and Punnett.
A1B1 and A2B2 |
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Term
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Definition
| Harmful or damaging consequences. |
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Term
|
Definition
Subpopulation
The largest area or collection of individuals where mating is, on average, random. Often applied to continuous populations. Closely connected with the concepts of breeding effective population size and genetic neighborhoods. A portion of the total population that experences limited gene flow from other parts of the total population so that its allele frequencies evolve independently to some degree. |
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Term
| Density-dependent selection |
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Definition
| A type of selection. Fitness of a genotype is a function of the population size. Absolute fitness of genotypes depends on rate of instantaneous growth (r), carrying capacity of the genotype (ki), and poulation size (N). If N equals ki, absolute fitness is one. If N is lesser than ki, absolute fitness is lesser than one. If N is greater than ki, absolute fitness is greater than one. |
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Term
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Definition
| Processes that always lead to the same outcome, given a set of initial conditions. |
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Term
|
Definition
| Species where individuals possess reproductive organs of one sex only. |
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Term
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Definition
| Parents undergo mating, random or inbreeding, to produce offspring which have selection, survival or viability, before they become parents. |
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Term
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Definition
| Have an outcrossed mating system. Breeds combined have a fixation index of 0.33, German shepherds 0.1, and mongrels 0.06, using allozyme method (Christensen et al, 1985). |
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Term
| Dominance coefficient (h) |
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Definition
| The relative fitness of the heterozygote. |
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Term
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Definition
| Increasing homozygosity increases the phenotypic expression of fully and partly recessive alleles with deleterious effects. Only homozygotes have deleterious recessive alleles. Purging of deleterious alleles is increasingly effective as the degree of recessiveness increases. Inbreeding depression is caused by the frequency of deleterious recessive alleles. |
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Term
|
Definition
| Where the expressed phenotype of one allele takes precedence over the expressed phenotype of another. The allele associated with the expressed phenotype is said to be dominant. Dominance is seen on a continuous scale that includes complete dominance, partial dominance, over-dominance, under-dominance, and codominance. |
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Term
| Effective population size (Ne) |
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Definition
| The size of an ideal Wright-Fisher population that maintains as much genetic variation or experiences as much genetec drift as an actual population regardless of census size. The total number of individuals that actually contribute gametes to the next generation. Take a real population, measure properties of that population, then find the size of a Wright-Fisher population with the same properties. |
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Term
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Definition
| Nonlinear phenotypic fitness interactions between alleles at two loci. Leads to fitness surfaces with curvature. |
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Term
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Definition
| An epiphytic benthic freshwater diatom. Can be terrestrial. |
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Term
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Definition
| A haplotype with a high frequency across a chromosome. Found in Caenorhabditis elegans. Includes large haplotype blocks. To find the expected frequencies, assume the high frequency allele is at a frequency of 0.99, and the low frequency allele is at 0.01. Expected frequencies depend on the number of loci. |
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Term
|
Definition
| The average difference between observed Hardy-Weinberg expected heterozygosity within each subpopulation due to non-random mating. The correlation between the states of two alleles in a genotype sampled at random from any subpopulation. The level of inbreeding within individuals relative to a randomly mating subpopulation. |
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Term
|
Definition
| The correlation between the states of two alleles in a genotype sampled at random from a single subpopulation given the possibility of non-random mating within populations and allele frequency divergence among populatoins. The level of inbreeding within individuals relative to a total population that randomly mates. |
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Term
|
Definition
| Has a different meaning for eukaryotes than for prokaryotes. In eukaryotes, the reduction in heterozygosity due to subpopulation divergence in allele frequency. The difference between the average expected heterozygosity of subpopulations and the expected heterozygosity of the total population. The probability that two alleles sampled from the total population are identical. Measures the fact that there is a difference between populations, due to lack of random mating between populations, causing overall inbreeding. The level of inbreeding within subpopulations relative to an entire total population that randomly mates. The larger the value, the greater the level of differentiation of allele frequencies. No migration in a population causes it to increase. The maximum value is one. |
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Term
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Definition
| Resolved the genetic basis of ABO blood groups in 1925. |
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Term
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Definition
| The inbreeding coefficient of this relationship is 1/16, or 0.0625. |
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Term
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Definition
Adaptive landscape
Adaptive topography
A 3D plot with frequency of A on the x axis, mean fitness on the y axis, and frequency of B on the z axis. Represents the range of natural selection. May be planar, or have curvature if there is epistasis. If there are two fitness peaks, fitness may not be maximized if the population evolves to the lower fitness peak. Linkage can have effect on the trajectory of allele frequencies. |
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Term
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Definition
| When an allele composes the entire sample, with a frequency of 1. The other allele will have loss. |
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Term
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Definition
| The proportion by which heterozygosity is reduced or increased relative to the heterozygosity in randomly mating populations with the same allele frequencies. |
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Term
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Definition
Tribolium castaneum
Has a (Ne/N) ratio of 0.81 - 1.02, and the ratio declined as population sizes increased. |
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Term
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Definition
| The establishment of a population by one or a few individuals, resulting in small effective population size in a newly founded population. |
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Term
| Frequency-dependent selection |
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Definition
| A type of selection. Fitness of a genotype is a function of frequencies of genotypes in a population. Includes negative and positive frequency-dependent selection. |
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Term
|
Definition
| The inbreeding coefficient of this relationship is 1/4, or 0.25. |
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Term
| Gametic disequilibrium parameter (D) |
|
Definition
Linkage disequilibrium parameter
The non-random association or combination of alleles at multiple loci in a sample of gametes or haplotypes. The difference between the product of coupling gamete frequencies and the product of repulsion gamete frequencies. If D is greater than zero, AB and ab haplotypes are over-represented. If D is lesser than zero, Ab and aB haplotypes are over-represented. If D is equal to zero, there is linkage equilibrium. |
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Term
|
Definition
|
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Term
|
Definition
| A unit of particulate inheritance. In contemporary usage it usually means an exon or series of exons, or a DNA sequence that codes for an RNA or protein. |
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Term
|
Definition
| The sum of expected frequencies of each possible homozygous genotype subtracted from one, or the sum of expected frequencies of heterozygotes. |
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Term
|
Definition
| The successful movement of alleles into populations through the movement of individuals or the movement of gametes. |
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Term
|
Definition
0 ≤ h ≤ 1
wAA = 1
wAa = 1 - hs
waa = 1 - s |
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Term
|
Definition
| A sharp but often transient reduction in the size of a population that increases allele frequency sampling error and has a disproportionate impact on the effective population size in later generations even if census size increases. |
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Term
|
Definition
| Random changes in allele frequency from one generation to the next in biological populations due to the finite samples of individuals, gametes, and ultimately alleles that contribute to the next generation. The amount of genetic drift increases as the size of the sample used to found the next generation decreases. |
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Term
|
Definition
| A term coined by Maynard Smith and Haigh. A change in the frequency of an allele due to an association with an allele with selection at another locus. Includes linkage to beneficial and deleterious alleles. Selection for beneficial alleles causes linked alleles to increase in frequency, to a value of 1. Selection against deleterious alleles causes linked alleles to decrease in frequency to a value of 0. Both processes lead to lower levels of polymorphism of neutral alleles. |
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Term
|
Definition
| An area or subunit of a population within which mating is random. Multiplied by the density of individuals to get the effective population size. |
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Term
|
Definition
| The set of alleles possessed by an individual at one locus; the genetic composition of an individual at one or many loci. Combinations of haplotypes. Includes AABB, AABb, AAbb, AaBB, AaBb, Aabb, aaBB, aaBb, and aabb. |
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Term
| Godfrey H. Hardy and Wilhelm Weinberg |
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Definition
| In 1908 worked independently to show that Mendelian heredity did not predict that alleles would disappear from populations. |
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Term
|
Definition
| An Augustinian monk. From 1856 to 1863, carried out experiments with peas that demonstrated the concept of particulate inheritance. Showed that phenotypes are determined by discrete units inherited intact and unchanged through generations. Hypothesis explained three common observations: phenotype is sometimes identical between parents and offspring, offspring phenotype can differ from parents, and "pure" phenotypes of earlier generations can skip generations and appear in later generations. At the time, there was no biological explanation, and his work was rediscovered in 1900. |
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Term
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Definition
| The average observed heterozygosity within each subpopulation. |
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Term
|
Definition
| The average expected heterozygosity of subpopulations assuming random mating within each subpopulation. |
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Term
|
Definition
| The expected heterozygosity of the total population assuming random mating within subpopulations and no divergence of allele frequencies among subpopulations. |
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Term
|
Definition
Hapoid genotypes
Should appear in frequencies proportional to the product of allele frequencies. Allelic states at two loci in a chromosome or gamete. May occur on separate chromosomes in a gamete. Includes AB, Ab, aB, and ab. |
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Term
|
Definition
| Natural selection due to differences in genotype viability. Frequency changes come about from death of individuals. |
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Term
|
Definition
| Used to estimate the effect of fluctuations in populations of the overall effective population size. Gives more weight to small values by virtue of summing the inverses of population size. |
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Term
|
Definition
| A type of selection. Fitness of a genotype is a function of the environment it occurs in, which may vary across space and/or time. |
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Term
|
Definition
Hybrid vigour
The increase in performance, survival, and ability to reproduce of individuals possessing heterozygous loci. Increase in the population average phenotype associated with increased heterozygosity. Beneficial consequences of increased heterozygosity. |
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Term
|
Definition
Overdominance for fitness
Balancing selection
A type of selection. Heterozygote genotypes have the highest fitness. Results in polymorphic equilibrium.
wAA = 1 - s
wAa = 1
waa = 1 - t |
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Term
| Heterozygote disadvantage |
|
Definition
Underdominance for fitness
Disruptive selection
A type of selection. Heterozygote genotypes have the lowest fitness. Results in monomorphic equilibrium.
wAA = 1
wAa = 1 - s
waa = 1 |
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Term
|
Definition
Homo sapiens
Have an outcrossed mating system. Fixation index is 0.0001 - 0.046 using pedigree method (Jorde, 1997). Across 40,000 SNPs all individuals in a sample of 200 would have a unique haplotype. |
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Term
| Identity by descent (IBD) |
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Definition
| Transmission from a common ancestor. Both alleles are descended from a common ancestral allele. Loci with identity by descent have a homozygous genotype. |
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Term
|
Definition
| Non-random mating. When mating involves individuals that are more closely related to each other than randomly chosen individuals from a population. Decreases the frequency of heterozygous genotypes, and increases the frequency of homozygous genotypes. Reduces the frequency of deleterious alleles, even when partially recessive, because they are exposed to fitness. Decreases the average fitness of a population, overall there is less potential to grow and it may go extinct. It can change equilibrium frequencies. |
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Term
| Inbreeding coefficient (f) |
|
Definition
Autozygosity
Coefficient of inbreeding
Inbreeding in the autozygosity sense. The probability that two alleles in a homozygous genotype are identical by descent. A way of expressing heterozygosity. |
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Term
|
Definition
| The reduction in performance, survival, and ability to reproduce of individuals possessing homozygous loci; decrease in population average phenotype associated with consanguineous mating that increases homozygosity. Abnormal phenotypes associated with consanguineous mating. |
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Term
| Inbreeding effective population size (Nie) |
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Definition
| The size of an ideal population that would show the same probability of allele copies being identical by descent as an actual population. |
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Term
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Definition
| Decreasing chances of mating or gene flow as the physical geographic distance between individuals or populations increases. Ubiquitous to natural populations. Causs local regions to approach fixation of allele frequencies. |
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Term
|
Definition
| Associated with the discredited hypothesis of inheritance of acquired characteristics. Argued that individuals contain "nervous fluid" that organs or features employed more frequently to attract more nervous fluid, causing the trait to become more developed in offspring. |
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Term
|
Definition
| From University of Vienna. In 1900, mixed blood from different people to study patterns of blood agglutination. Won the Nobel Prize for Medicine in 1930 for discovering human ABO blood groups. |
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Term
|
Definition
Rana pipiens
Has a (Ne/N) ratio of 0.1 - 1.0 |
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Term
|
Definition
| Co-inheritance of loci caused by physical location on the same chromosome. Broken down by recombination. |
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Term
| Linkage disequilibrium (LD) |
|
Definition
Haplotype frequencies that are not equal to what is expected with independent inheritance of alleles between loci. When two subpopulations with linkage equilibrium are combined into a single population, they can have linkage disequilibrium due to differences in allele frequencies; this may have happened in the Andersen et al paper.
pAB ≠ pApB |
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Term
|
Definition
Haplotype frequencies that are equal to what is expected with independent inheritance of alleles between loci. One allele at a locus has no effect on the state of the allele at the other locus. With independent assortment, frequencies of coupling and repulsion gametes are identical.
D = 0 |
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Term
|
Definition
| There is a species of lizard in which males have three morphs. The orange morph is aggressive and defends large territories. The blue morph is less aggressive and defends small territories. The yellow morph mimics females and can sneak into other males' territories to mate with females. They have negative frequency dependent selection, maintaining numbers of lizards of each morph. When orange is common, yellow has high relative fitness. When blue is common, orange has high relative fitness. When yellow is common, blue has high relative fitness. This is similar to the game rock-paper-scissors. |
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Term
|
Definition
plural: Loci
A "place" or location in the genome. In contemporary usage it is the most general reference to any sequence or genomic region, including non-coding regions. |
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Term
|
Definition
| A simple model where population growth has a carrying capacity. Depends on feedback between growth rate and population size. |
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Term
|
Definition
| When an allele is not in the sample at all, with a frequency of 0. The other allele will have fixation. |
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Term
|
Definition
| The frequency-weighted and allele-copy-weighted sum of the relative fitness values of genotypes that contain a specific allele; a special case of the average fitness for only those genotypes that contain a certain allele. The average fitness of an entity over all backgrounds in which that entitty occurs. It has a lower value with inbreeding. |
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Term
|
Definition
| A sequence of discrete random variables in which the probability distribution of states at time t + 1 depends only on the states at time t. A generation-by-generation prediction for the average behaviour of populations under genetic drift when there is an infinite number of replicate populations. Preducts the proportion of populations that have a given allelic state in each generation. Has the Markov property. |
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Term
|
Definition
| A property of a Markov chain. Probability of a given outcome in the next step or time interval depends only on the previous state and has no "memory" of states or events before the present time. Makes Markov chains a convenient model for genetic drift. |
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Term
|
Definition
| Coined the term "genetic hithhiking" in 1974. |
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Term
|
Definition
| When alleles at a locus have an advantage during segregation of homologous chromosomes. They are more likely to be found in gametes. |
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Term
|
Definition
| Preducts independent segregation of alleles at a single locus: two members of a gene pair (alleles) segregate separately into gametes so that half of the gametes carry one allele and the other half carry the other allele. |
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Term
|
Definition
| Predicts independent assortment of multiple loci: during gamete formation, the segregation of alleles of one gene is independent of the segregation of alleles in another gene. |
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Term
|
Definition
| An allele with a sequence that repeats. The allele is the number of repeats. |
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Term
|
Definition
| Partial self-fertilization in a population, where some matings are self-fertilizations and others are outcrossings. |
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Term
|
Definition
| An equilibrium with little or no genetic variation. Occurs with selection against recessive or dominant phenotype, and with heterozygote disadvantage. |
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Term
| Negative assortative mating |
|
Definition
Dis-assortative mating
Assortative mating where individuals with unlike genotypes or phenotypes tend to mate. |
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Term
| Negative frequency-dependent selection |
|
Definition
| Fitness of a genotype is a negative function of its frequency. With random mating, fitness of genotype i is 1 - sipi. Genotypes have higher fitness when they are rare. Maintains diversity in a population, as a genotype becomes common its fitness goes down. The graph has a negative slope, and allele frequencies shift towards a stable polymorphic equilibrium. |
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Term
|
Definition
| Once you've seen one nematode, you've seen thme all. They do not have much morphological variation. |
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Term
|
Definition
| When dN/dS is equal to one. There is no selection. Synonymous and nonsynonymous changes are neutral. A difference in rate of substitution is not expected. |
|
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Term
|
Definition
Pagrus auratus
Has a (Ne/N) ratio of (0.25 - 16.7) x 10-5. |
|
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Term
|
Definition
| A testable model of no effect. A prediction or expectation based on the simplest assumptions to predict outcomes. Often, null models make predictions based on purely random processes, random samples, or variables having no effect on an outcome. |
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Term
|
Definition
| When an inbreeding coefficient is negative. Occurs when the frequency of heterozygotes is greater than expected with random mating. |
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Term
|
Definition
| Mating between two separate individuals. |
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Term
|
Definition
| Dominance where the phenotype of the heterozygote is outside of the range of the homozygous phenotypes. |
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Term
|
Definition
| Inbreeding depression is the result of decrease in frequency of heterozygotes. Heterozygotes have advantage. All homozygotes have low fitness. No changes in inbreeding depression as long as heterozygosity is low. Inbreeding depression is caused by genotype frequencies in a population. |
|
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Term
|
Definition
|
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Term
|
Definition
"All mixed"
Random mating. A population where mating and movement of individuals is uniform throughout. It is unlikely to be true in a natural population. |
|
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Term
|
Definition
| The inbreeding coefficient of this relationship is 1/4, or 0.25. |
|
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Term
|
Definition
Incomplete dominance
Dominance where the masking effect is incomplete so that the phenotype of a heterozygote is intermediate to both homozygotes.
0.5 < h < 1 |
|
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Term
|
Definition
|
|
Term
|
Definition
Character
Trait
Morphological, biochemical, physiological, or behaviouaral attributes of an individual. |
|
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Term
|
Definition
| Has a selfed mating system. Fixation index is -0.37, using allozyme method (Brown, 1979). |
|
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Term
|
Definition
Balanced polymorphism
An equilibrium where both alleles are maintained in the population. There is no change in the frequency of A or a. Occurs with heterozygote advantage. |
|
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Term
|
Definition
| Heterogeneity in allele frequencies across a population caused by limited gene flow. The chance that two individuals mate depends on their location within the population. |
|
|
Term
| Positive assortative mating |
|
Definition
| Assortative mating where individuals with like genotypes or phenotypes tend to mate. |
|
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Term
| Positive frequency-dependent selection |
|
Definition
| The fitness of a genotype is a positive function of its frequency. There is no stable polymorphic equilibrium. The graph has a positive slope, and allele frequencies shift towards fixation or loss. |
|
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Term
|
Definition
| When dN/dS is greater than one. The protein is undergoing adaptive evolution. Nonsynonymous substitution changes the protein sequence, changing the phenotype, and changing fitness; it positively selects and generates adaptive evolution. A difference in rate of substitution is expected. |
|
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Term
|
Definition
| Reduction in the frequency of deleterious alleles by natural selection. Increases the frequency of alleles that do not have deleterious effects when homozygous, and average phenotype returns to the initial average before consanguineous mating. |
|
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Term
|
Definition
| When dN/dS is lesser than one. Synonymous substitutions do not change protein sequence, and phenotype is unchanged. Most likely there are no fitness effects. Nonsynonymous substitutions produce lower fitness. Difference in rate of substitution is expected. |
|
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Term
|
Definition
| Occurs when individuals mate independently of their genotype and relatedness. |
|
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Term
|
Definition
| The expressed phenotype of one allele is masked by the expressed phenotype of another allele. The allele associated with the concealed phenotype is said to be recessive. |
|
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Term
|
Definition
| Sister chromatids touch at random points during meiosis and exchange short segments in a process called crossing-over. Chances of recombination increase the further apart loci are. Has no detectable effect on homozygous genotypes, but does on heterozygous genotypes. |
|
|
Term
| Recombination factor (r, c) |
|
Definition
| The proportion of repulsion gametes produced by a double heterozygote genotype each generation. The probability that a recombination event will occur between two loci. A value of 0.5 indicates independent assortment. |
|
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Term
|
Definition
Sciaenops ocellatus
Has a (Ne/N) ratio of 0.001. |
|
|
Term
|
Definition
| The expected proportion of alleles between two individuals that are identical by descent; twice the autozygosity. Measures relatedness among individuals. |
|
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Term
|
Definition
Recombinant gametes
Gametes where alleles on the same chromosome seem repulsed be each other and pair with alleles on the opposite strand. Term coined by Thomas Hunt Morgan. |
|
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Term
|
Definition
| Helped produce the Wright-Fisher model in 1999. |
|
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Term
|
Definition
| The difference between the value found in a finite sample from a population and the true value in the population. |
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|
Term
| Selection against a dominant phenotype |
|
Definition
Results in monomorphic equilibrium
wAA = 1 - s
wAa = 1
waa = 1 |
|
|
Term
| Selection against a recessive phenotype |
|
Definition
Results in monomorphic equilibrium
wAA = 1
wAa = 1
waa = 1 - s |
|
|
Term
| Selection coefficient (s) |
|
Definition
| The difference between a relative fitness value and one. The lower the value, the slower the response to selection. |
|
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Term
|
Definition
Genetid draft
The reduction or elimination of polymorphism in a region of DNA sequence surrounding a site where beneficial mutation has increased in frequency due to positive natural selection. The reduction of polymorphism is a result of gametic disequilibrium between a beneficial mutation and a neighboring neutral site that has not been broken down by recombination. An indirect consequence of a natural selection. Genetic hitchhiking, with an association with a beneficial allele. |
|
|
Term
|
Definition
| An epipelic benthic freshwater diatom. Can be terrestrial. |
|
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Term
|
Definition
| Used data from spatial frequencies of blue and white flowers of Linathus parryae to develop expectations for populations experiencing isolation by distance. There is a patchwork spatial pattern of flower colour frequencies. Helped produce the Wright-Fisher model in 1931. Originally introduced the concept of effective population size. |
|
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Term
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Self-fertilizatoin
A form of consanguineous mating where an individual mates with itself. An extreme form of inbreeding. Many plants, and some animals including nematodes are hermaphrodites and are capable of this. |
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| A marine diatom. A small organism which can only be tracked using genetics. |
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Bulinus truncates
Have a selfed and outcrossed mating system. Fixation index is 0.6 - 1.0, using microsatellites method (Viard et al, 1997). |
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| Natural selection due to differences in fecundity of individuals. Frequency changes are within the progeny of each generation. |
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| The FST divided by the maximum FST. Used in Vanormelingen et al (2015). Used in situations where subpopulations do not share alleles, but the subpopulations are heterozygous. |
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| A process where individual outcomes are dictated by chance but the average of a large number of outcomes can be described as a probability distribution based on initial conditions. |
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| Estimates the number of subpopulations in a sample by finding sets of individuals whose genotype frequencies are close to Hardy-Weinberg expectatiosn. Once the subpopulations have been identified, the characteristic frequencies of alleles in the subpopulations are calculated. Then for each individual, its ancestry relative to the identified subpopulations is estimated. Ignores where individuals are from; groups are based on expected genotypes. Gives insight into how individuals are mating with other individuals. Can be a good estimate of a population. |
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Definition
| Coined the term "repulsion gamete". |
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| Transition probability (Pi→j) |
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Definition
| The probability that a population of one, starting out with zero, one, or two copies of an allele, ends up with one of these three states due to sampling error. |
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| The inbreeding coefficient of this relationship is 1/8, or 0.125. |
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| Dominance where the phenotype of the heterozygote is outside of the range of the homozygous phenotypes. |
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| An equilibrium point which is not robust to any change in allele frequency. A slight change in allele frequency results in frequencies changing to alternative stable equilibrium points of fixation or loss. Unlikely to persist in a finite population. |
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| Variance effective population size (Nve) |
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Definition
| The size of an ideal population that would show the same sampling variance in allele frequency as an actual population. |
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| Survival from zygote to adult. |
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| A form of natural selection where fitness is equivalent to the probability that individuals of given genotype survive to reproductive age but all surviving individuals have equal rates of reproduction. |
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| The appearance of a geographic barrier that resists gene flow among populations. |
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| Walter Sutton and Theodor Boveri |
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Definition
| Proposed the chromosome theory of heredity in 1902, based on evidence of microscopic observations of cell division. Bolstered Mendel's hypothesis of particulate inheritance. Observed cell division and saw discrete bodies that separated into sets at meiosis and mitosis. Hypothesized that these bodies contained hereditary material that was transmitted from parent to offspring. |
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Crocidura russula
Has a (Ne/N) ratio of 0.6. |
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| A simplified version of the biological life cycle where all sampling to found the next generation occurs from an infinite pool of gametes built from equal contributions of all individuals. This approximation is commonly employed to model genetic drift. Makes assumptions identical to those of Hardy-Weinberg, except popuilation is finite in size. Assumptions include discrete generations, equal numbers of males and females, constant population size, and no natural selection of gametes. Direction of changes in allele frequency is random. The magnitude of random fluctuations in allele frequencies from generation to generation increases as the population size decreases. Fixation or loss is the equilibrium state if there are no other processes acting to counteract genetic drift or reintroduce genetic variation. Genetic drift changes allele frequencies and thereby genotype frequencies. Thhe probability of eventual fixation of an allele is equal to its initial frequency. |
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