Section A06 - Week 10 Filled

Section A06 - Week 10 Filled - WEEK 10 Dan's Section BIEB...

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WEEK 10 Dan’s Section – BIEB 166 – Dr. Nieh Wed. 5 – 5:50 PM @ CSB 004 OH: Wed 3 – 4 PM @ York 3010 A Lecture 22: Visual Signal Transmission and Reception I. Conspicuousness A) Ambient light (A) – Amount and type of light in the environment B) Reflectance (R) – Properties of the signaler’s surface C) Background (B) – Contrast from the background 1. Optimal signal hue: Specific coloration depending on A, R, and B (know chart) II. Exploiting background A) Brightness contrast – Dark environments, use white and vice versa B) Hue contrast – Color signals should contrast from background C) Pattern contrast – To camouflage or outline striking features 1. Shape enhancement – Eyes like to fill in gaps; make outlines Ex) Hooded Meganser, Monarch Butterfly 2. Shape concealment – disruptive coloration conceals major body parts Ex) Frog, fish D) Movement contrast – Blend in with the environment temporally III. Transfer functions A) V = direct light from sun, results in glare B) Transmission: Reflectance from one source upon sender Q R : Reflectance from ambient light upon sender Q B : Reflectance from ambient light upon background IV. Reception A) Phototransduction – photon strikes and conforms cis -retinal to trans -retinal attached to opsin B) Photoreceptors have stacks of pigments which increase the chance of photon hitting receptor V. Eye evolution A) Pigment cup – Patch of skin becomes sensitive to light and becomes a photoreceptor 1. Can detect light from dark, but cannot form an image Ex) Flatworm, limpet B) Camera lens eye 1. Pigment cup forms an invagination to make a pinhole eye a) Bending of light forms a focused image b) Problems i. Smaller hole = clearer image ii. Diffraction sets a limit on the resolving power
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Section A06 - Week 10 Filled - WEEK 10 Dan's Section BIEB...

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