Population genetics

POPULATION GENETICS : the study of the distribution of genes in populations and of how genes and genotype frequencies are maintained or changed

admixture mapping : A strategy for mapping loci for complex traits that differ in prevalence between 2 populations that have recently admixed with each other.

deme / genetic population : a population of very similar organisms interbreeding in nature and occupying a circumscribed area

Hardy-Weinberg law : the proportions of the 3 genotypes determined by 2 alleles (A and a) occurring with a frequency of p and q, respectively, in a randomly mating population will remain constant from one generation to the next: AA = p², Aa = 2pq, aa = q². Mutation, selection, non-random mating, migration, and genetic drift can disturb this equilibrium

population structure : organization of a population into sub-populations as a consequence of factors such as finite population size and geographical subdivision.
founder population : a group of individuals that establishes a new population
assortative mating : nonrandom choice of matesbased on phenotypic characteristics such as geographical proximity, skin colour, height or religion.
genetic drift : fluctuations of allele frequencies over time due to chance alone
local positive selection : a type of natural selection in which favoured variants increase in frequency in a localized geographical region.
convergent evolution : a process in which traits evolve to a similar state in two or more genetically distinct populations, typically as an adaptive response.
balancing selection : a selection regime that results in the maintenance of two or more alleles at a single locus in a population
CEPH Human Diversity Panel : a resource of 1,064 cultured lymphoblastoid cell lines from individuals in 51 different world populations that are banked at the Foundation Jean Dausset (CEPH) in Paris, France.
penetrance : the proportion of individuals with a specific genotype who manifest this genotype at the phenotype level.
generation : a class composed of all individuals removed by the same number of successive ancestors from a common predecessor, or occupying positions on the same level in a genealogic chart.

parental generation (P₁) : the generation with which a particular genetic study is begun
first filial generation (F₁) : all of the offspring produced by the mating of two individuals, as in a hybrid cross
second filial generation (F₂) : all of the offspring produced by the mating of two individuals of the first filial generation
third generation (F₃)
fourth generation (F₄)

doubled haploids (DH) : a progeny of doubled haploids derived from a heterozygous or F₁ individual can serve as a mapping population. Making a DH is faster than RIL; DHs have a better resolution than a F₂ progeny (no heterozygousity); DHs can be maintained infinitely
backcross introgression lines (BIL)
intermated recombinant inbreds (IRI) : just another structure of a mapping population like F₂, BC, RIL, NIL. The intermating of F₂ individuals result in new recombination events. Therefore, IRI populations have improved genetic resolution^ref
near isogenic lines (NIL): homozygous line, produced by recurrent selection, which only heterozygous and different from the recurrent parent with respect to a locus of interest. Young N.D., D. Zamir, M.W. Ganal and S.D. Tanksley (1988) Use of isogenic lines and simultaneous probing to identify DNA markers tightly linked to the Tm-2a gene in tomato. Genetics 120:579-585.
recombinant inbred lines (RIL) : an F₄ population derived from a F₂ by single seed descent (SSD). The consequence of infinite selfing is a doubling of the recombination frequency; a immortalization of the population and the exclusion of dominance variance due to heterozygosity^ref.
races :

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