The gene pool is all the alleles present in a population, at all loci. A large, diverse gene pool holds many versions of each gene; a narrow one holds few. Breeders can only select from what is there.
In practice
The evidence suggests the commercial cannabis gene pool is narrowing. Large chemical datasets show commercial products cluster into a few chemotype and terpene groups (Smith et al. 2022). Landraces in source regions have been mixed with imported hybrids. Popular lines are crossed again and again with similar material, and one cut can travel under many names, so the number of truly different genotypes behind the market is smaller than the number of names suggests.
Patents on plants, traits and methods add another pressure: they can restrict how some material is used. The facts are public records; the concern is the effect on the commons.
The response is preservation: keeping landraces, heirlooms, old cuts and males alive, documenting them, and sharing them openly.
Don't confuse with
- Germplasm: the physical seeds, plants and tissue.
- Genome: the DNA of one individual; a gene pool spans many.
- Number of strains: names are not genetic diversity.
Myth check
"Everything tastes the same now" has evidence behind it; see why everything tastes the same.
An allele is one version of a gene; a diploid cannabis plant carries two alleles at each locus, one from each parent, which may be the same or different.A gene is a stretch of DNA that carries the instructions for one functional product, usually a protein such as an enzyme, and is the basic unit of inheritance.Terpenes are volatile hydrocarbon compounds built from five-carbon isoprene units; in cannabis they are made in the trichome heads and are a major part of aroma and flavour.A landrace is a traditional, locally adapted cannabis population kept by farmers in one region over many generations, with its own type and plenty of internal variation.A hybrid is the offspring of two genetically different parents; almost all modern cannabis is hybrid, built from crosses between landrace-derived and other lines.The genotype is the set of alleles a plant actually carries, either at one locus or across its whole genome, as opposed to the traits you can see.An heirloom is a seed line kept and passed down by growers for decades, usually outside its region of origin, preserving an older type rather than a recent hybrid.Germplasm is living genetic material (seeds, pollen, tissue or plants) kept for breeding, research or conservation, representing the genetic diversity of a crop.A genetic bottleneck is a sharp drop in the number of breeding plants, after which the population carries only a fraction of its former genetic diversity.Genetic drift is random change in allele frequencies between generations of a seed population, strongest in small populations; clones do not drift this way.The founder effect is the loss of genetic diversity when a new population is started from a few individuals, so it carries only a sample of the source population's alleles.
