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SUMMARY:The evolution of color vision in Heliconius butterflies. - Adriana
  Briscoe (University of California at Irvine)
DTSTART:20180529T120000Z
DTEND:20180529T130000Z
UID:TALK105898@talks.cam.ac.uk
CONTACT:Professor Chris Jiggins
DESCRIPTION:Numerous animal lineages have expanded and diversified the ops
 in-based photoreceptors in their eyes underlying color vision behavior. Ho
 wever\, the selective pressures giving rise to new photoreceptors and thei
 r spectral tuning remain mostly obscure. Previously\, we identified a viol
 et receptor (UV2) that is the result of a UV opsin gene duplication specif
 ic to Heliconius butterflies. At the same time the violet receptor evolved
 \, Heliconius evolved UV-yellow coloration on their wings\, due to the pig
 ment 3-hydroxykynurenine (3-OHK) and the nanostructure architecture of the
  scale cells. In order to better understand the selective pressures giving
  rise to the violet receptor\, we characterized opsin expression patterns 
 using immunostaining (14 species) and RNA-Seq (18 species)\, and reconstru
 cted evolutionary histories of visual traits in five major lineages within
  Heliconius and one species from the genus Eueides. Opsin expression patte
 rns are hyperdiverse within Heliconius. We identified six unique retinal m
 osaics and three distinct forms of sexual dimorphism based on ommatidial t
 ypes within the genus Heliconius. Additionally\, phylogenetic analysis rev
 ealed independent losses of opsin expression\, pseudogenization events\, a
 nd relaxation of selection on UVRh2 in one lineage. Despite this diversity
 \, the newly evolved violet receptor is retained across most species and s
 exes surveyed. Discriminability modeling of behaviorally preferred 3-OHK y
 ellow wing coloration suggests that the violet receptor may facilitate Hel
 iconius color vision in the context of conspecific recognition. Our observ
 ations give insights into the selective pressures underlying the origins o
 f new visual receptors.
LOCATION:Main Lecture Theatre\, Department of Zoology\, Downing Street\, C
 ambridge CB2 3EJ
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