Visual communication 3/3/11 Lecture #11 Visual communication 3/3/11

Most diverse invertebrates are insects Live in many different habitats Under ground Cave Aquatic Forest Field Live in different light conditions Diurnal to nocturnal

Insect visual pigments Opsin protein bound to the chromophore Insects have two chromophores A1 11-cis retinal vitamin A1 carotene A3 11-cis 3-hydroxyretinal xanthophylls In combination with same opsin, each chromophore makes a visual pigment which absorb at slightly different wavelengths

Compound eye = many ommatidia http://www.daviddarling.info/images/compound_eye_detail.jpg We’ll talk about the optics starting next week. For now lets focus on the visual pigments. Visual pigments are in rhabdoms

Photoreceptors Ciliary Microvillar Rod Cone Octopus Insect There show the similarities and differences between vertebrate and invertebrate photoreceptors. Both increase the amount of cell membrane which is full of visual pigment. Bradbury and Vehrencamp “Animal Communication” figure 9.2 Rod Cone Octopus Insect

Rhabdoms Each visual cell has a microvillar part The microvilli of all the visual cells project into the center to make the rhabdom The microvilli are like bristles on a toothbrush

Rhabdoms The microvilli contain the visual pigment Absorption of light excites the visual cells

Bee ommatidium UV B G This shows the bee visual pigments and how the rhabdoms are arranged so that all wavelengths will be detected and so compared at once.

Spaethe and Briscoe 2005 Fig 4 showing UV gene expression which varies in different ommatidium being either 0 (double head arro) 1 (single arrow) or two rhabdoms

Bees have compound eyes and ocelli Ocelli gather light and are thought not to produce images. Lens sits right on top of receptor cells see, Cornwell 1955. He quotes others that say the image distance is 5 times behind the retina not at the retina. Ocelli are used for navigation and also contain UV opsins

Drosophila eyes WT cinnabar sepia white 800 ommatidia per eye

Drosophila ommatidium There are 8 rhabdomeres that make up rhabdom 6 are around center 2 in center - one on top of the other Cells are numbered R1-6 R7, R8 http://scienceblogs.com/pharyngula/upload/2006/03/ommatidium.jpg

Drosophila visual pigments http://scien.stanford.edu/class/psych221/projects/05/granlund/BrittPlot.png Pigments are numbered Rh1-Rh6

Visual pigment arrangements Light The six outer rhabdomeres (R1-R6) surround the two inner ones. Inner ones are one on top of other, R7 and R8 The same visual pigment is in R1-R6 Rh1 - green R1-R6 used for motion detection L means cells project to lamina M cells project to medula where color is likely processed

Drosophila visual pigment Rh1 is in most of rhabdomeres (R1-6) http://scien.stanford.edu/class/psych221/projects/05/granlund/BrittPlot.png

Two combinations for R7/R8 cells From Wernet…Desplan 2003 “Homothorax switches function of Drosophila photoreceptors from color to polarized light sensors

Visual pigment combinations in R7/R8 http://scien.stanford.edu/class/psych221/projects/05/granlund/BrittPlot.png There are two combinations of pigments. You can have 1) Rh3 in R7 and Rh5 in R8 This is the pale combination Or 2) Rh4 in R7 and Rh6 in R8. This is the yellow combination Note: Rh2 is in the ocelli

Rh2 is expressed only in ocelli Rh2 is in the ocelli

Rh2 is expressed in ocelli http://www.dgrc.kit.ac.jp/~jdd/bodyparts/head_dorsal.html

R7/R8 cells are used for color vision Wernet 2002 R1-R6 cover entire retina. Project to lamina (L, part of optic lobe). R7 and R8 project to medula 30% 70%

What spectral ranges are being compared? http://scien.stanford.edu/class/psych221/projects/05/granlund/BrittPlot.png Pale: UV vs blue Yellow: UV vs green/yellow - see next slide for immuno of this combo

Individual ommatidia - stained for opsin Rh1 / R1-R6 Rh4 / R7 Rh6 / R8 Rh4 is UV pigment; Rh6 is green/yellow sensitive pigment

Light polarization http://www.nikon.co.jp/main/eng/feelnikon/discovery/light/chap04/img/sec01_p06.jpg Orientation of oscillation of photon’s electric field

Can analyze polarization with polarizers http://www.molecularexpressions.com/optics/lightandcolor/images/polarizationfigure1.jpg

Polarization Single polarizer lets through light polarized in one direction

Polarization Add a second polarizer at 90 degrees to 1st

Black and white What does it mean when something is white? What does it mean when something is black?

Light sources Sun, flashlight - not polarized Laser - partially polarized

Reflection can cause polarization http://jolisfukyu.tokai-sc.jaea.go.jp/fukyu/tayu/ACT05E/img/05IMG/05_11.jpg S = senkrecht = perpendicular P = in plane of incidence We will call these perpendicular and parallel Light can be polarized in the plane (p-polarized) or perpendiculat to the plane (s-polarized)

Reflection can cause polarization http://jolisfukyu.tokai-sc.jaea.go.jp/fukyu/tayu/ACT05E/img/05IMG/05_11.jpg S = senkrecht = perpendicular P = in plane of incidence We will call these perpendicular and parallel s-polarization (R ) is reflected more than p-polarization (R||)

Reflected light n nair=1 i This applies to normal incidence

Transmitted light is refracted (Snell’s law) nair=1 i

Two polarization planes reflect differently http://jolisfukyu.tokai-sc.jaea.go.jp/fukyu/tayu/ACT05E/img/05IMG/05_11.jpg S = senkrecht = perpendicular P = in plane of incidence We will call these perpendicular and parallel s-polarization (R ) is reflected more than p-polarization (R||)

Fresnel equations to calculate reflectance of either polarization http://www.physics.ucok.edu/wwilson/Courses/PHY4264/lab/Lab7_Fresnel.pdf Note - any incident polarization can be expressed as a sum of different amounts of parallel and perp polarization i What happens to light that is not reflected?

Reflectance - light polarized perpendicular to plane is reflected more This calculation was done for air / glass interface. Depends on angle of incidence

Brewster’s angle is incident angle at which reflected light becomes totally polarized This calculation was done for air / glass interface.

Reflectance - both polarizations approach same reflectance at normal incidence (=0)

Simple equation works for unpolarized light at <45° Unpolarized light is average of both polarizations.

At large angles, reflectance goes to 1 for both polarizations

Light reflecting from surface is polarized http://polarization.com/sky/sky.html Light is coming towards us and bounces off water. The light polarized in this plane is not reflected very much. Light polarized perpendicular to this plane (going left right in the picture) is reflected most. If the polarizer passes horizontal light (as on left) light goes through. If blocks horizontal and passes vertical polarized light (of which there isn’t any) there is no reflection and can see into water.

Polarization off surfaces Reflectance from gray matt surface is pretty much independent of polarization - matt surface scatters light more than reflects. Reflectance from water is mostly in the horizontal direction. That light is blocked if polarizer is || polarizer Fig 2.8

Light from the sun is unpolarized http://micro.magnet.fsu.edu/primer/lightandcolor/polarizedlightintro.html Each photon has polarization - but group of them have random polarizations

Sun light gets polarized Bradbury and Vehrencamp Animal Communication Chapter 7

Polarized light patterns in sky

Polarized light patterns in sky

Polarized light field in sky

Animals can use these sky patterns Insects (bees) and fish Uses Navigation and local orientation Time of day Migration

Drosophila - Three kinds of ommatidia UV Wernet et al 2002 Pale Yellow

Dorsal rim area (DRA) is sensitive to polarized light - rh3 pigment Note how the microvilli (the toothbrush bristles) are all aligned in the same direction. This makes all of these cells sensitive to the same polarization of light. Red line separated DRA cells (above) which have large center cell and non-DRA (below) which have smaller central cell. Can see one or two DRA cells at top. Wernet et al 2002 Note rh3 in both

Bristles of rhabdomere can further orient visual pigment in membrane The lines are meant to be the 11-cis retinal molecules. They absorb light best when light is polarized along their axis.

Bristles of rhabdomere can further orient visual pigment in membrane

Cells in dorsal rim area will preferentially detect polarized light Wernet 2002

Polarized light patterns in sky Bee’s orientation will determine DRA receptor absorption

Polarized light patterns in sky

Polarized light field in sky

Polarization detection The polarization field in the sky. The small yellow circle is the sun. The lines show the direction of the light polarization with longer lines showing more polarization. The ommatidia in the dorsal rim area which are specialized to have two perpendicular kinds of rhabdoms to detect alternate polarizations. Polarization response of the neuron wired to the dorsal rim area ommatidia. Labhart 2002, field crickets

Why should polarization sensitive receptors work in UV Rayleigh scattering Air particles << wavelength of light 10 nm << 500 nm Scattered intensity Wavelength of light is similar in size to particles: air

Why should polarization sensitive receptors work in UV? Light scattering depends on wavelength http://www.croydonastro.org.uk/img1.gif

Rayleigh scattering 1/4

Rayleigh scattering 1/4 UV

So to a bee, the sky is…

So to a bee, the sky is UV

Inverts are “usually” trichromatic Drosophila

Many insects are trichromatic - UV, blue and green pigments Briscoe and Chittka 2001 Many insects are trichromatic - UV, blue and green pigments Papilio xuthus - swallowtail butterfly Notonecta - backswimmers Sympetrum rubicundulum - dragonfly Shape is just spectral class Drosophila melanogaster - fruit fly Gryllus - crickets Libellula needhami - dragonfly circle - UV square blue Panorpa cognata - scorpion fly Locusta migratoria - locusts Hemicordulia - dragonfly Triangle - green; open red Apis mellifera - honey bee Periplaneta americana - cockroach Odonata - dragonflies Photuris are species of fire fly Ascalaphus macaronius - owl fly 1=11-cis retinal 3=11-cis 3-hydroxyretinal

All have UV pigments UV blue green red Present not recorded Papilio xuthus - swallowtail butterfly Notonecta - backswimmers Sympetrum rubicundulum - dragonfly Drosophila melanogaster - fruit fly Gryllus - crickets Libellula needhami - dragonfly Panorpa cognata - scorpion fly Locusta migratoria - locusts Hemicordulia - dragonfly Apis mellifera - honey bee Periplaneta americana - cockroach Odonata - dragonflies Photuris are species of fire fly Ascalaphus macaronius - owl fly UV green blue red

Few dichromats - not correlated with lifestyle Present not recorded Owlfly diurnal Cock roach nocturnal Papilio xuthus - swallowtail butterfly Notonecta - backswimmers Sympetrum rubicundulum - dragonfly Drosophila melanogaster - fruit fly Gryllus - crickets Libellula needhami - dragonfly Panorpa cognata - scorpion fly Locusta migratoria - locusts Hemicordulia - dragonfly Apis mellifera - honey bee Periplaneta americana - cockroach Odonata - dragonflies Photuris are species of fire fly Ascalaphus macaronius - owl fly UV green blue red

A few have red or far red pigments Present not recorded Papilio xuthus - swallowtail butterfly Notonecta - backswimmers Sympetrum rubicundulum - dragonfly Drosophila melanogaster - fruit fly Gryllus - crickets Libellula needhami - dragonfly Panorpa cognata - scorpion fly Locusta migratoria - locusts Hemicordulia - dragonfly Apis mellifera - honey bee Periplaneta americana - cockroach Odonata - dragonflies Photuris are species of fire fly Ascalaphus macaronius - owl fly UV green blue red

Butterflies have 8 rhabdomers like Drosophila 6 on outside are green sensitive Two stacked rhabdomers These can be blue/blue blue / uv uv/uv But 9th cell below

Variation in long wavelength sensitivity of butterflies This is due to sequence changes in the long wavelength opsin gene

Evolution of red sensitivity in Lepidoptera A, alpine C, crepuscular D, desert N, nocturnal TF, trop forest TL temperate lowlands GFV generalist flower visitor SFV specialist flower visitor GCF general carbohydrate forager SP specialist predator We can map onto the phylogeny which species have these long wavelength pigments. These pigments have evolved multiple times. They do not seem to correlate with habitat or foraging styles. Both nocturnal species with red sensitivity (Spodoptera) and diurnal species without (M. stellaturum) both moths. Lose several time within butterflies.

What is relationship of flower color with pollinator? Bee Butterfly Bird Nocturnal moth

Hypotheses