A review of leucism in South American primates: new reports, considerations on their geographic distribution, and implications for conservation

Leucism is a hereditary genetic trait characterized by total or partial body hypopigmentation. This condition has been described across several taxa but is rarely observed in mammals. The environmental factors influencing the distribution of leucism and their impacts on the survival and fitness of individuals are still poorly understood. We present reports retrieved from peer-reviewed articles and fieldwork studies, according to the adaptive relevance of this condition in each species and the potential influence of environments under leucism. The reported number of leucistic primates has recently been increasing, likely due to citizen science and the widespread use of smartphones. We identified 23 records of leucistic primates, from at least eight different species and hybrids, related especially to forested biomes of South America. Given its contribution to understanding the ecology of these variations, we highlight the importance of a collaborative effort between the scientific community and the general public to report new cases of polymorphic phenotypes discovered in nature. Also, information on exact geographic coordinates is essential for the reports to be scientifically relevant. Our database can serve as a baseline for better understanding the spatial patterns of leucism in Neotropical primates and to comprehend the evolutionary ecology of genetically controlled polymorphic phenotypes and their persistence in wild populations.