Intergroup variation in oestrogenic plant consumption by black-and-white colobus monkeys

Abstract

Endocrine-active phytochemicals (EAPs) are a potentially important component of the tropical plant foods of many primate species due to their interactions with hormones and potential effects on reproduction and behavior. If EAPs, such as phytoestrogens, do significantly affect primate biology in their natural environment, then variation in exposure to these chemicals should relate to variation in physiological or behavioral outcomes. Therefore, we quantified the diet of eight black-and-white colobus monkey groups (Colobus guereza) living in Kibale National Park, Uganda, for one year and analyzed their plant foods for estrogenic activity using transient transfection assays. The percent of diet from these estrogenic plant items varied across groups from 1.24% (± SD 1.65) to 5.85% (± SD 4.51), however this variation was not statistically significant given seasonal variation within the same group. Additionally, grooming was not correlated with phytoestrogen consumption, except for in one group. This lack of an effect was likely due to the low levels of consumption of estrogenic plants compared to previous studies that did document a grooming effect. Examining intergroup variation in other primate species that consume a greater quantity of EAPs in their diet will provide further insight into physiological and behavioral effects of consumption on primate ecology.