Behavioral evidence of color vision in the Negligible Image Color Eye (NICE) copepod Diaptomus nevadensis

Thesis (M.A.)--Humboldt State University, Biology, 2008The following research addresses the question: does color vision occur in animals that can only see rudimentary images? Since the morphological and neurological requirements of color vision are minimal relative to those necessary for image formation, theoretically, color vision should be accessible to organisms with negligible ability to form images. I have designated and refer to such putative animals as Negligible Image Color Eye (NICE) animals. Despite the theoretical likelihood of NICE animals and the excellent potential they present as model systems for studying adaptive evolution of opsin, there is a striking dearth of wavelength-specific behavioral research on animals with negligible image-formation. And, behavioral evidence of color vision has not previously been established in an animal with negligible image-formation capacity.\ud I developed criteria for establishing behavioral evidence of color vision and designed behavioral experiments to determine whether the freshwater calanoid copepod Diaptomus nevadensis has the ability to distinguish wavelengths of light independent of intensity. In long-wavelength light the response is positive phototaxis; whereas, in short-wavelength light the response is positive geotaxis and a previously undescribed back-flip or ???donut??? behavior. The results are presented here as behavioral evidence of color vision. And, with methodological innovations such as the use of light emitting diodes (LEDs) as a light source, and varying the position of the light source relative to the study subject, evidence is provided that some behavior assumed to be negative phototaxis in previous wavelength-specific behavioral studies may actually be light-mediated positive geotaxis.Humboldt State University Department of Biological Sciences Master???s Student Grants;\ud Graduate Women in Science Sigma Delta Epsilon Fellowshi