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Brian Dalton – Postdoc in the Vision Group

A smiling person is sitting on a bench with the text Fisher's only.

Exploring nature in coastal California is how I spent much of the first half of my life, in particular trying to convince fish that my creations of fur and feathers were actually insects or baitfish. Through my love of fish and the environments where they lived, biology became a sort of hobby, and later my course of study at Occidental College in Los Angeles.

I have become fascinated by the different ways animals have evolved to visually detect information about their environments. In my PhD I worked with Tom Cronin and Karen Carleton on vision and coloration in African cichlid fishes at the University of Maryland (UMBC and College Park). I discovered that the cichlid Metriaclima zebra mixes different pairs of opsins in retinal regions that view distinct backgrounds. These visual pigment mixtures tune retinal sensitivity to the color of the corresponding background. I also found that the location as well as the relative proportion of opsins in the retina can be influenced by the light environment during development. Finally, I used color space models to compare cichlid colors and backgrounds as seen by cichlid eyes. Male colors were typically more conspicuous than female colors, consistent with the selective forces thought to act on each sex. However, in some species female colors were conspicuous, raising questions about their role in communication.

During my doctoral studies I became interested in polarized light. Naturally, I was excited to do a postdoc with Rachel Muheim at Lund University studying polarization sensitivity in zebra finches. There is good evidence that birds use patterns of polarized light in the sky to calibrate their magnetic compass. However, the mechanism of avian polarized light sensitivity is unknown, and attempts to demonstrate this sensitivity have met with mixed success. I am using a behavioral assay, with cues similar to those used in compass calibration, to characterize zebra finch sensitivity to polarized light. Future plans include localizing putative polarized light photopigments in the zebra finch retina.

mars 14, 2014

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