Population Bottleneck

Population bottleneck is not a terpene, but rather a genetic phenomenon relevant to cannabis breeding programs. It describes a reduction in genetic diversity when a breeding population passes through a period of severely limited size, founder count, or selection intensity. In cannabis cultivation and preservation, bottlenecks occur when breeders work with small seed lots, make extremely selective crosses, or stabilize lines through repeated inbreeding. Understanding bottleneck effects is critical for maintaining vigor, disease resistance, and trait stability across generations. Breeders working to preserve heirloom or rare strains must actively manage population size and genetic sampling to avoid unintended loss of allelic diversity.

Cannabis breeders intentionally navigate population bottlenecks during line-fixing and IBL (inbred line) development, accepting short-term diversity loss for trait stabilization. However, uncontrolled bottlenecks—caused by seed scarcity, culling errors, or limited founder material—can fix deleterious mutations, reduce vigor, or narrow cannabinoid/terpene expression in ways that degrade breeding st