Collaborative Research: Evolution and Development of Retinal Organization in Primates

Harvard University, Cambridge MA

Investigators

Abstract

We know very little how evolution produces new species adapted to particular ecological niches. This project is to study two closely related species, one diurnal and the other nocturnal. The nocturnal animal has more rods for night vision, fewer cones, a bigger eye and a different eye conformation than the diurnal one. How many and what kind of genetic changes produce this constellation of differences? We hypothesize that a relatively simple change, an alteration of when maximal cell proliferation occurs to favor rods over cones in the nocturnal species, is the essential genetic change, and the rest of the alterations in eye conformation are "epigenetic" as eye growth patterns fall under the control of rods. To test this, we bring the together the expertise of three laboratories. The Finlay lab at Cornell University has developed the quantitative techniques for comparing the developmental schedules and morphologies of different animals; the Cepko lab at Harvard Medical School has pioneered studies of cell proliferation and differentiation of the eye; the Silveira lab of the Federal University of Para, Amazonia, Brazil has produced the fundamental descriptions of the visual systems of these species. We will investigate the development of the retina and the eye in both species, looking at the expression of developmental control genes, regulators of the cell cycle, and markers of cell type to see exactly what has changed between the two. At the heart of the project lies the question whether genes, over evolutionary time, have produced coordinated patterns in response to repeatedly encountered challenges like the shift from diurnal to nocturnal living. As a multi-institutional international collaboration, this project has special features. The universities of the north of Brazil struggle economically, so this project provides a link for the researchers and students of Amazonia to new technologies, research resources and ideas. All of the students, North American and Brazilian, benefit from the exposure to different educational systems and expectations; we plan to provide more formal means for student exchange in the near future. Financial support for the animal center is also very important: in addition to its role as a research facility and breeding colony, the center serves as a cachement center for animals confiscated by poachers and those endangered by natural or man-made ecological challenges.