Extreme climate refugia: a case study of wild relatives of cacao (Theobroma cacao) in Colombia

Identification of global climate refugia for biodiversity relies mainly on long term climate cycles data. However, information on short term contemporary refugia of climate extremes for native genetic resources of agriculture such as crop wild relatives in tropical regions is limited. Understanding the threats of current extreme climate is a valuable strategy for the mitigation of global changes. The main objective is to identify extreme climate refugia of crop wild relatives of cacao (Theobroma cacao) in Colombia (South America) based on a contemporary climate dataset of 30 years (1980–2010), and secondly, to assess threats caused by deforestation in the Amazon region. We found that only one-third of the most climatically suitable habitat remained stable, comparing current average climate of 30 years against extreme climates of the same period, and therefore considered those areas the best candidates for current extreme climate refugia of wild cacao in the country. Small changes (1.0%) in extreme precipitation, in just 30 years, showed a decrease of suitable habitat on 70.2% of the habitat for wild cacao in the centre of origin in the Colombia Amazon, and 80.8% in the Pacific region, which is the most important area of wild cacao endemism in the world. In addition, we estimated that at the current rate of deforestation in the Amazon region (0.7% annually), the areas with the most climatically stable climate, or refugia, for wild cacao could be reduced by half in the next 50 years. Considering the importance of cacao as a crop worldwide, the identification of refugia for conservation of wild cacao genetic resources is a necessary step towards mitigating climate impacts on agriculture.