Exploring the diversity and distribution of crop wild relatives of cacao (Theobroma cacao L.) in Colombia

Crop wild relatives are important for agriculture because they contain high levels of genetic diversity and grow in a wide range of habitats and environments. Colombia has the largest number of cacao crop wild relatives in the world, including different species of the genus Theobroma and its sister genus Herrania. This paper investigates diversity and distribution of cacao crop wild relatives in Colombia using species occurrences extracted from museum and herbarium archives, fieldwork collections gathered on recently conducted expeditions and species distribution modelling. A total of 211 botanical collections comprising 174 samples of Theobroma species, and 37 samples of Herrania species were collected on expeditions to Caguán–Caquetá in the upper Amazon basin and La Victoria, in the Pacific region of central Choco. These collections represent 22 taxa of cacao crop wild relatives. On the Chocó expedition, we reported the highest richness and endemism, where seven taxa of Theobroma and three of Herrania were found within a radius of 10 km, which has never been recorded before. On the Amazon expedition, we found an abundance of wild populations of Theobroma cacao on the river banks. We estimated that 95% of the most suitable environments for wild cacao in Colombia are in unprotected areas. Our study reveals that species diversity and endemism of cacao crop wild relatives in Colombia is under sampled and distributional patterns are incomplete. Based on the findings of our study, we propose a conservation strategy that consists of further expeditions to collect herbarium and germplasm samples, and habitat protection of cacao crop wild relatives in Colombia.