Plant secondary metabolites and primate food choices: A meta‐analysis and future directions

The role of plant secondary metabolites (PSMs) in shaping the feeding decisions,
habitat suitability, and reproductive success of herbivorous mammals has been a
major theme in ecology for decades. Although primatologists were among the first to
test these ideas, studies of PSMs in the feeding ecology of non‐human primates have
lagged in recent years, leading to a recent call for primatologists to reconnect with
phytochemists to advance our understanding of the primate nutrition. To further this
case, we present a formal meta‐analysis of diet choice in response to PSMs based on
field studies on wild primates. Our analysis of 155 measurements of primate feeding
response to PSMs is drawn from 53 studies across 43 primate species which
focussed primarily on the effect of three classes of PSMs tannins, phenolics, and
alkaloids. We found a small but significant effect of PSMs on the diet choice of wild
primates, which was largely driven by the finding that colobine primates showed a
moderate aversion to condensed tannins. Conversely, there was no evidence that
PSMs had a significant deterrent effect on food choices of non‐colobine primates
when all were combined into a single group. Furthermore, within the colobine
primates, no other PSMs influenced feeding choices and we found no evidence that
foregut anatomy significantly affected food choice with respect to PSMs. We
suggest that methodological improvements related to experimental approaches and
the adoption of new techniques including metabolomics are needed to advance our
understanding of primate diet choice.