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Testing the niche differentiation hypothesis in wild capuchin monkeys with polymorphic color vision

Citation

DePasquale, Allegra et al. (2021), Testing the niche differentiation hypothesis in wild capuchin monkeys with polymorphic color vision, Dryad, Dataset, https://doi.org/10.5061/dryad.g1jwstqq4

Abstract

The polymorphic color vision system of most North, Central, and South American monkeys is a textbook case of balancing selection, yet the mechanism behind it is poorly understood. Previous work has established task-specific foraging advantages to different color vision phenotypes: dichromats (red-green colorblind) are more efficient foraging for invertebrates, while trichromats (color “normal” relative to humans) are more efficient foraging for “reddish” ripe fruit, suggesting that niche differentiation may underlie the maintenance of color vision variation. We explore a prediction of the niche differentiation hypothesis by asking whether dichromatic and trichromatic capuchin monkeys (Cebus imitator) diverge in their foraging activity budget, specifically testing whether dichromats forage more frequently for invertebrates and trichromats forage more frequently for “reddish” ripe fruit. To assess this, we analyze a large dataset of behavioral scan samples (n = 21,984) from 48 wild adult female capuchins of known color vision genotype, dominance rank and reproductive status, together with models of food conspicuity. We find no significant differences between dichromats and trichromats in the frequency of scans spent foraging for different food types but do find that nursing females forage less overall than cycling females. Our results suggest that the potential for color vision-based niche differentiation in foraging time may be curtailed by the energetic requirements of reproduction, behavioral synchrony caused by group-living, and/or individual preferences. While niche differentiation in activity budgets by color vision type is not apparent, fine-scale niche differentiation may be occurring. This research enhances our understanding of the evolutionary processes maintaining sensory polymorphisms.

Methods

The data here represent behavioral scan samples collected from 2007-2018 on 48 adult female white-faced capuchins in Sector Santa Rosa, Costa Rica. Detailed data collection methodology can be found in our corresponding manuscript of the same name.