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Copy number variation may be the most common form of structural genetic variation in the genome. Numerous studies have shown that gene copy number variation can correlate with phenotypic variation, where higher copy numbers correspond to increased expression of the protein and vice versa. Examples include some digestive enzyme genes, where variation in copy numbers and protein expression may be related to dietary differences. Increasing the expression of a digestive enzyme through higher gene copy numbers may thus be a potential mechanism for altering an organism’s digestive capabilities. I investigated copy number variation in genes coding for acidic mammalian chitinase, a chitinolytic digestive enzyme that may be used for the digestion of insect exoskeletons, in nonhuman primates with varying levels of insect consumption. I hypothesized that CHIA copy number correlates positively with level of insectivory, predicting higher copy numbers in more insectivorous primates. I assessed copy number variation with the QuantStudio 3D digital PCR platform, in a comparative sample of Old World and New World primate species (N = 10 species, one or two individuals each). Contrary to my prediction, no evidence of copy number variation was found and all species tested had two gene copies per diploid genome. These findings suggest that if acidic mammalian chitinase expression varies according to insect consumption in primates, it may be up- or downregulated through another mechanism. 

The rich diversity of morphology and behavior displayed across primate species provides an informative context in which to study the impact of genomic diversity on fundamental biological processes. Analysis of that diversity provides insight into long-standing questions in evolutionary and conservation biology and is urgent given severe threats these species are facing. Here, we present high-coverage whole-genome data from 233 primate species representing 86% of genera and all 16 families. This dataset was used, together with fossil calibration, to create a nuclear DNA phylogeny and to reassess evolutionary divergence times among primate clades. We found within-species genetic diversity across families and geographic regions to be associated with climate and sociality, but not with extinction risk. Furthermore, mutation rates differ across species, potentially influenced by effective population sizes. Lastly, we identified extensive recurrence of missense mutations previously thought to be human specific. This study will open a wide range of research avenues for future primate genomic research.