title: Spectral sensitivities of photoreceptors and their role in colour discrimination in the green-backed firecrown hummingbird (Sephanoides sephaniodes).
abstract: We studied the photopic spectral sensitivity in the green-backed firecrown, Sephanoides sephaniodes, a South American hummingbird, and its possible ecological relationship with preferred flowers and body colouration. Avian colour vision is in general tetrachromatic with at least four types of cones, which vary in sensitivity from the near ultraviolet (UV) to the red wavelength range. Hummingbirds represent an important family of birds, yet little is known about their eye sensitivity, especially about the role of photoreceptors and their oil droplet complements. The photopic electroretinogram shows a main sensitivity peak at 560 nm and a secondary peak in the UV, and may be explained by the presence of four single cones (lambda max at approximately 370, 440, 508 and 560 nm), and a double cone (lambda max at 560 nm) screened by oil droplets. The flowers preferred by the firecrown are those in which the red-green wavelength region predominates and have higher contrast than other flowers. The crown plumage of males is highly iridescent in the red wavelength range (peak at 650 nm) and UV; when plotted in a high-dimensional tetrachromatic space, it falls in a "red + UV" purple hue line, suggesting a potential significant communication signal for sexual differentiation.
authors.affiliation: Centro de Neurociencia de Valparaiso, Facultad de Ciencias, Universidad de Valparaíso, P.O. Box 5030, Valparaíso, Chile.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Herrera
authors.forename: Juan Cristóbal
authors.initials: JC
authors.lastname: Zagal
authors.forename: Marcelo
authors.initials: M
authors.lastname: Diaz
authors.forename: Maria José
authors.initials: MJ
authors.lastname: Fernández
authors.forename: Alex
authors.initials: A
authors.lastname: Vielma
authors.forename: Michel
authors.initials: M
authors.lastname: Cure
authors.forename: Jaime
authors.initials: J
authors.lastname: Martinez
authors.forename: Francisco
authors.initials: F
authors.lastname: Bozinovic
authors.forename: Adrián G
authors.initials: AG
authors.lastname: Palacios
mesh_terms: D000818:Animals; D001717:Birds / Q000033:anatomy & histology / Q000502:physiology*; D003116:Color; D055253:Color Vision / Q000502:physiology* / Q000528:radiation effects; D004596:Electroretinography; D005241:Feathers / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology / Q000528:radiation effects; D005260:Female; D035264:Flowers / Q000502:physiology; D008027:Light; D055537:Light Signal Transduction / Q000502:physiology* / Q000528:radiation effects; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009821:Oils / Q000378:metabolism; D010775:Photic Stimulation; D020419:Photoreceptor Cells, Vertebrate / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects; D010858:Pigmentation / Q000502:physiology; D012160:Retina / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects; D012726:Sexual Behavior, Animal / Q000502:physiology; D013045:Species Specificity; D014466:Ultraviolet Rays
chemical_list: D009821:Oils