Fig. 7. Effects of oil droplet filtering on the theoretical capture area of
Anolis cristatellus visual pigments. The solid curves were obtained
by multiplying smoothed, normalized visual pigment spectra by the associated
smoothed, normalized oil droplet transmission spectra. The dotted lines are
the smoothed visual pigment spectra. The numbers are the calculated capture
areas under the filtered visual pigment spectra obtained by integration and
expressed as a percentage of the unfiltered pigment capture area. The effect
of the oil droplets on the long-wavelength-sensitive and
medium-wavelength-sensitive (MWS) cones is to reduce short-wavelength
absorbance while reducing overall absorbance by 17% and 5%, respectively. In
these cases, there is no change in the absorbance maximum. However, the
position of the oil droplet cut-off of the MWS cone reduces the capture area
to 29% of that of the unfiltered pigment and moves the absorbance peak from
443 to 525 nm. This also produces a much steeper short-wavelength cut-off,
which could improve color discrimination in an opponent processing system (see
text).
