Term Definition
Adaptation A trait that increases the ability of a population or an organism to survive in its environment.
Allelic richness (AR) A measurement of the number of alleles per locus with rarefaction adjusting for differences in sample sizes.
Balancing selection A process in which more than one allele is maintained at a locus at a frequency higher than expected by chance. Balancing selection can come about due to overdominance (heterozygote advantage) or frequency-dependent selection.
Broad-sense heritability (H2) The ratio of total genetic variance to total phenotypic variance within a population.
Common garden experiment A traditional experiment in which genotypes from different populations (provenances) are grown under a common environment to test the relative contribution of genetic and environmental variation on a given phenotypic trait.
Conservation genetics A branch of (population) genetics aimed to reduce the risk of population and species extinctions and to design strategies for their preservation or restoration.
Conservation genomics The use of genome-scale data with the same aims of conservation genetics, i.e., ensuring the viability of populations and the biodiversity of living organisms.
FST The probability of identity by descent (ibd; describing the pair of homologous DNA sequences [for simplicity, alleles] carried by the gametes that produced it from a recent ancestor) resulting from population subdivision (independent of inbreeding within subdivisions); FST measures the probability of ibd of alleles within subpopulations relative to the total population.
GST The proportion of total genetic diversity found among populations averaged over all polymorphic loci; it is regarded as a multiallelic variant of Wright’s FST (1951).
Gene diversity (He) Hardy-Weinberg expected heterozygosity both at monomorphic and polymorphic loci. The probability that an individual will be heterozygous at a given locus, based on allele frequencies at that locus.
Gene flow The movement of alleles from one population to another population, which for plants is achieved by the transport of pollen and seeds by wind, water, or animals.
Genetic drift A change in allele frequencies in a population over time resulting from a random sampling of gametes (i.e., error) to produce zygotes in the next generation and from chance variation in individuals’ survival and/or reproductive success. Thus, it results in nonadaptive evolution.
Genetic markers Any type of neutral (see below) genetic information (e.g., allozymes, amplified fragment length polymorphism, inter-simple sequence repeats, microsatellites, DNA sequences [e.g., single nucleotide polymorphisms, SNPs] that can be used to identify differences between individuals, populations, and/or species.
Isolation by distance A process by which geographically restricted gene flow results in a genetic differentiation being an increasing function of geographic distance.
Linkage disequilibrium A state in which genes are combined in a dependent manner (i.e., linkage). It arises when genotypes at one locus within a population are non-randomly distributed with respect to genotypes at another locus.
Local adaptation A situation in which resident genotypes have a relatively higher fitness in their local environments than in other environments.
Narrow-sense heritability (h2) The ratio of additive genetic variance to the phenotypic variance in a trait within a population.
Neutral Molecular markers that do not affect fitness, i.e., individuals with different genotypes A1A1 vs. A1A2 have the same fitness.
Non-additive genetic variation Results from interactions between an allele at the same locus (dominance) or at different loci (epistasis).
Percentage of polymorphic loci (%P) A measure used to quantify genetic diversity.
QST The proportion of total additive genetic variance that is due to among-population differences in a quantitative trait.
QSTFST comparison experiment The comparison of the degree of genetic differentiation in quantitative traits (QST) with that in neutral molecular markers (FST). This comparison allows the identification of a trait divergence caused by natural selection, as opposed to genetic drift.
Reciprocal transplant experiment A traditional experimental approach in which living organisms from two different environments are reciprocally grown in their respective environments. If the phenotype of the transplanted individuals does not converge towards that of individuals in receiving population would be evidence for the strong genetic basis of the focal trait. The opposite outcome would be evidence for plasticity in determining the trait value.
Translocation The deliberate (human-mediated) transfer of plants (entire plants, seeds, or propagules) from an ex-situ collection or a natural population to a new location, usually in the wild.