Adaptation of Visual Pigments to the Aquatic Environment

A central theme of John Lythgoe’s book “The Ecology of Vision” (Lythgoe, 1979) was that of adaptation: the matching between an organism’s phenotype and its natural environment. In “The Ecology of Vision”, numerous adaptations of animal visual systems were identified, covering diverse aspects of life related to vision including ocular anatomy, visual physiology, biochemistry, behaviour, diet and life style. In this process various striking correlations between the ecology of different species and aspects of their visual systems were described. One of the strongest themes of the book is that of the matching of photoreceptor spectral sensitivities to the visual environment, a theme that was illustrated by numerous examples giving many insights into the evolutionary pressures on visual systems. Indeed, much of “The Ecology of Vision” is concerned with the way in which evolution has driven different species to have the diverse spectral sensitivities that they have today. Nevertheless, the future of the ecology of vision lies in understanding visual adaptations by studies that explicitly identify the selective pressures acting on visual systems.