Talk:Genetic erosion

Talk

Discussion for: Genetic erosion • View • Links • Related changes

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Page scope

Genetic erosion covers the loss of genetic diversity itself: what the term means at the levels of allele, variety and crop, how a loss is measured, the causes named for it, climate change among them, reports of lost cannabis varieties, including varieties said to have been lost to prohibition, losses from stored collections, and what surveys of cannabis have measured. How outside alleles enter a population belongs to Genetic contamination. Campaigns against the plant belong to Eradication. Storage and regrowing belong to Ex situ conservation and Gene bank. How diversity is measured and arranged in cannabis belongs to Genetic diversity and Gene pool. Definitions of a landrace belong to Landrace Cannabis.

Data verification

Record source conflicts, dating problems and sources not used here. Keep narrative content on the article.

Discussion

Sources

• Food and Agriculture Organization (2010), The Second Report on the State of the World's Plant Genetic Resources for Food and Agriculture, section 1.3; van de Wouw and colleagues (2010), Plant Genetic Resources 8: 1–15, and Theoretical and Applied Genetics 120: 1241–1252; Hammer and colleagues (1996), Genetic Resources and Crop Evolution 43: 329–336; Khoury and colleagues (2022), New Phytologist 233: 84–118: the term and its measurement in crops.
• Mercer and Perales (2010), Evolutionary Applications 3: 480–493; Halpin-McCormick and colleagues (2025), PLOS ONE 20: e0306007: climate change.
• Clarke and Merlin (2016), Critical Reviews in Plant Sciences 35: 293–327; McPartland and Small (2020), PhytoKeys 144: 81–112; Small and Marcus (2002), in Trends in New Crops and New Uses; Welling and colleagues (2016), Frontiers in Plant Science 7: 1113: reports of loss in cannabis.
• Chouvy and Afsahi (2014), International Journal of Drug Policy 25: 416–423; Afsahi and Darwich (2016), International Journal of Drug Policy 31: 190–198; Bachir and colleagues (2022), Cannabis and Cannabinoid Research 7: 603–615; Benkirane and colleagues (2024), Genetic Resources and Crop Evolution 71: 2037–2051; Chouvy (2024), International Journal of Drug Policy 129: 104479: Morocco.
• Soorni and colleagues (2017), Sawler and colleagues (2015), Dufresnes and colleagues (2017), Lynch and colleagues (2025): diversity surveys.

Varieties and alleles

The sources use "lost" and "extinct" of varieties and landraces. Most of them give no measurement of alleles. The article keeps these apart because the Food and Agriculture Organization and van de Wouw and colleagues distinguish the levels, and because Todesco and colleagues note that the pure genome of a lineage can end while its alleles and traits survive in hybrids. Clarke and Merlin's own sentence on North American hemp leaves the "feral offspring" alive. How much of the old cultivars those plants carry is not settled by Clarke and Merlin or by Aina and colleagues.

Whether a fall has been measured in cannabis

Benkirane, Soorni, Sawler, Dufresnes and Lynch and their colleagues compare populations, accessions or varieties with one another. None of these works compares a population with the same population at an earlier date. Bachir and colleagues propose herbarium sampling for Morocco. This is a statement about these works.

Benkirane and colleagues find the local Moroccan population more diverse than the cultivar Critical at six markers. That is a comparison of two populations. It does not show that the local population has kept the diversity it had before the hybrids.

Prohibition as a cause

"Varieties lost to prohibition" is a claim, and the sources that make it differ in what they mean. Welling and colleagues and Small and Marcus write above all of collections. Watson and Clarke, as quoted by Clarke and Merlin, list suppression and eradication with other causes. McPartland and Small explain the threat to Central and South Asian landraces by hybridisation and do not mention eradication. ACE Seeds gives prohibition first among its reasons; that is a seller's statement of its reasons for its own work.

Chouvy and Afsahi's remark on forced eradication concerns one campaign in one region. Their 2013 estimate of the hybrids' spread is, in their word, a "guesstimate" from what they saw in the fields. Afsahi and Darwich make their point about Lebanon and Morocco in a sentence.

Small's collections and the reply from the Department of Agriculture are Small and Marcus's own account. Welling and colleagues, citing it, write of collections "confiscated, or in some instances reported to have been destroyed". The Geneva collection has since been built up: 581 accessions in 2024 (see Effective population size).

Hammer and colleagues' percentages

The figures of 72.4 and 72.8 per cent are the share of landraces no longer found in cultivation when two collecting missions are compared. They measure the disappearance of named local forms from two areas, and they rest on what the missions collected.

The Afghan claim

McPartland and Small's word "disappearing" for Afghani landraces rests on Casano (2005), a doctoral thesis on the agronomy of hemp at the University of Palermo.

Climate model

Halpin-McCormick and colleagues' occurrences come from iNaturalist photographs, filtered to plants judged wild or escaped and to longitudes above zero. The model describes where the plant could grow; it does not model landrace fields, irrigation or farmers' choices. Soil properties are absent from the future projections. The percentages are averages across scenarios and dates.

Names

Beldia is Benkirane and colleagues' word for the local Moroccan population. The article otherwise calls the plant kif, the name in Kif. Chouvy and Afsahi record the name beldiya among those growers came to use once hybrids were planted beside it.