Notable paper: Macho GA, Lee-Thorp JA. (2014). Niche Partitioning in Sympatric Gorilla and Pan from Cameroon: Implications for Life History Strategies and for Reconstructing the Evolution of Hominin Life History. PLoS ONE 9(7): e102794. doi:10.1371/journal.pone.0102794
Synopsis: Even though chimpanzees and gorillas eat an overlapping range of foods, both almost entirely dependent on C3 plants, they have slightly different ratios of stable isotopes of carbon and nitrogen. Macho and Lee-Thorp show that the gorilla and chimpanzee populations that coexisted in the late 1920s in Cameroon can be clearly distinguished in their carbon-13 content. Additionally, from infants to adults the two species have different trajectories of nitrogen-15 content, likely reflecting different weaning strategies.
Important because: A very close study of the local resources may enable finer distinctions about diet preferences from stable isotope data than have been made so far for early hominins and prehistoric humans. In this case, the subtle differences in carbon-13 content between different C3 plant species, or between leaves and fruits within a plant, have left a mark on the chimpanzees and gorillas. The authors suspect that the gorillas were feeding in more closed-canopy context, not only eating different foods than chimpanzees but actively using different space.
Interesting… The data here come from hair samples taken from museum specimens collected by Major Percy Powell-Cotton, wild-shot between 1927 and 1935. It is a case where museum collections show the potential for interesting research – in this case hair samples taken non-invasively from the field may prove useful for the same kind of analyses.