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. |
QST–FST 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. |