Meeting Abstract
Biological clocks and the rhythms they produce are fundamental to eukaryotic life, allowing organisms to anticipate change in the environment. While many physiological and behavioral life processes may change in direct response to external influence, most also change over time because of internal timekeeping mechanisms – biological clocks. Extensive research has defined the anatomical locations and molecular make-up of clocks in people and some lab animals, but we understand very little about the functional utility of clocks and rhythms in the natural world. This research aims to shed insight on these issues by examining clock operation in the Atlantic tarpon (Megalops atlanticus), one of the most sought-after game fish. Tarpon undergo ecological shifts as they mature from larvae to adults. These shifts are accompanied by significant alterations in photoreceptor cell type and distribution, making tarpon exceptional models for studying how retinal structure and function adjust to a changing light environment. Using immunofluorescence, we have determined that tarpon begin life with rod-dominated retinas, and then add cone photoreceptors at key life transitions. Furthermore, after the compliment of rod and cone cells have developed, photoreceptors begin to undergo daily changes in position within the retina according to time of day. The development of these retinomotor movements is part of a suite of changes we have identified in the tarpon retina that occur over the course of the day and over the course of the lifetime. These dramatic changes in retinal form and function support survival of these fish as they transition among habitats, and may support their survival in the face of anthropogenic disturbance that alters light quality, such as exposure to light at inappropriate times due to coastal development.
