title: Three spectrally distinct photoreceptors in diurnal and nocturnal Australian ants.
abstract: Ants are thought to be special among Hymenopterans in having only dichromatic colour vision based on two spectrally distinct photoreceptors. Many ants are highly visual animals, however, and use vision extensively for navigation. We show here that two congeneric day- and night-active Australian ants have three spectrally distinct photoreceptor types, potentially supporting trichromatic colour vision. Electroretinogram recordings show the presence of three spectral sensitivities with peaks (λmax) at 370, 450 and 550 nm in the night-active Myrmecia vindex and peaks at 370, 470 and 510 nm in the day-active Myrmecia croslandi. Intracellular electrophysiology on individual photoreceptors confirmed that the night-active M. vindex has three spectral sensitivities with peaks (λmax) at 370, 430 and 550 nm. A large number of the intracellular recordings in the night-active M. vindex show unusually broad-band spectral sensitivities, suggesting that photoreceptors may be coupled. Spectral measurements at different temporal frequencies revealed that the ultraviolet receptors are comparatively slow. We discuss the adaptive significance and the probability of trichromacy in Myrmecia ants in the context of dim light vision and visual navigation.
authors.affiliation: School of Animal Biology and UWA Oceans Institute (M092), The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia yuri.ogawa@uwa.edu.au.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Ogawa
authors.affiliation: School of Animal Biology and UWA Oceans Institute (M092), The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia.
authors.forename: Marcin
authors.initials: M
authors.lastname: Falkowski
authors.affiliation: Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia.
authors.forename: Ajay
authors.initials: A
authors.lastname: Narendra
authors.affiliation: Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia.
authors.forename: Jochen
authors.initials: J
authors.lastname: Zeil
authors.affiliation: School of Animal Biology and UWA Oceans Institute (M092), The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia.
authors.forename: Jan M
authors.initials: JM
authors.lastname: Hemmi
mesh_terms: D000818:Animals; D001000:Ants / Q000502:physiology*; D001315:Australia; D002940:Circadian Rhythm; D055253:Color Vision; D004596:Electroretinography; D017956:Photoreceptor Cells, Invertebrate / Q000502:physiology*; D065854:Spatial Navigation
keywords: ants; colour vision; navigation; photoreceptors; spectral sensitivity