Insights from publicly available data for Cannabis sativa L.

Abstract

Cannabis sativa L. (Cannabaceae) is an annual flowering herb of Eurasian origin that has been associated with humans for thousands of years. Multiple independent domestications occurred with different events leading to use as food, fiber, and medicine, with human intervention likely accelerating a division in the genus with varietals broadly known today as either hemp-type or drug-type. In chapter one of this work, publicly available sequence data was used to assess genome wide diversity and population relationships across seven independently developed datasets. Phylogenetic analysis was conducted, with data sources providing a unique sampling of Cannabis varieties, with landrace and modern cultivars represented. Population structure was evident based on use type and there was evidence of extensive hybridization across the datasets. In a subset of landrace individuals where geographic origin was known, population separation was observed between varieties collected from Northern India in the Hindu Kush Mountains and Myanmar. The use of publicly available data provides an initial impression of the complexity within the Cannabis genus and adds to our understanding of the genetics underlying evolutionary history and population stratification, which will be critical for future crop improvement for any potential human use. In chapter two, species distribution of Cannabis was examined. Human-mediated associations with Cannabis have influenced its distribution, often leading to introduction into new habitats around the world; however, changing environmental conditions and climatic fluctuations have also contributed to the distribution of the species and where it is cultivated. Here we explore likely shifts in distribution that Cannabis may have undergone during the eras of paleoclimate, current climate, and future projected climate. We found that in the deep past large changes in suitable distribution likely occurred for Cannabis, associated with range expansions as well as constrictions as the extent of suitable climate changed. This contrasts with likely shifts in distribution predicted from future models which project a loss of broad climate suitability by 2050 and 2070. Changing habitat range has large implications for the outdoor cultivation of Cannabis. Using this approach, we can gain an understanding of how favorable niches have expanded and contracted through time and how this may influence present day and future cultivation.