Doctoral Dissertation Improvement: A Behavioral and Genetic Study of Color Vision Polymorphism in Squirrel Monkeys

New York University, New York NY

Investigators

Abstract

The goal of this project is to investigate intraspecific variation in the color vision system of South American squirrel monkeys (Saimiri sciureus), a model taxon of New World primate (Platyrrhini). Unlike African and Asian primates, New World primates do not routinely possess trichromatic color vision. The genetic mechanisms that underlie the unique visual systems of most New World primate genera allow some females to possess trichromatic vision while other females (and all males) cannot visually differentiate red from green. It has been hypothesized that trichromatic individuals are better equipped to detect fruit against a green background, yet it has also been hypothesized that dichromatic individuals are more capable of detecting cryptic, camouflaged objects. This research project will evaluate these hypotheses by comparing behavioral data on foraging and predator avoidance collected on a wild population of squirrel monkeys with genetic data on the color vision status of all focal animals within the study population gleaned from genotyping their X-linked opsin alleles using DNA extracted from non-invasively collected fecal samples. Additionally, while collecting behavioral data, the investigators will further explore the significance of individual variation in color vision status through a series of experiments at feeding platforms that are designed to address the animals' use of color cues in solving foraging problems and detecting predators. This study represents one of the first comprehensive behavioral genetic studies undertaken with a wild population of primates. The intellectual merit of the project is that it will test, under wild conditions, several explicit hypotheses concerning the possible adaptive significance of trichromatic versus dichromatic color vision for solving foraging problems and for avoiding predation, with the aim of bringing the research community closer to an explanation as to why color vision polymorphism has been maintained over such a long period of time among most platyrrhine lineages. These data will also be used to better understand the molecular evolution of primate color vision. The broader impact of this study is that it will contribute to an ongoing long-term investigation on the comparative behavioral biology of sympatric Amazonian primates at the Tiputini Biodiversity Station in Ecuador run by co-PI Di Fiore and assist in efforts at protecting forested areas in the Amazon. Additionally, it will foster the professional development and graduate training of co-PI Montague, who will be instrumental in training other graduate students and undergraduates in New York University's Molecular Anthropology Laboratory, and it will provide for co-PI Montague's professional interaction with Ecuadorian and other international experts in tropical biology while in the field.