Hybridization is the main cause of extinction and biodiversity loss in Cannabis.
Here’s an important and freely available ecological study by Judith Rhymer and Daniel Simberloff, Extinction by Hybridization and Introgression. A key focus of the paper is loss of biodiversity by hybridization within a single species, as now threatens the future of Cannabis.
For a brief overview, see the new blog post: Extinction by Hybridization.
For a recent general discussion of hybridization and extinction, which covers ‘genetic swamping‘, see this talk by renowned professor of botany and plant evolutionary genomics, Loren Rieseberg: