We performed artificial selection on the visual system in guppies (Poecilia reticulata), using the optomotor reaction threshold as the selection criterion. Two lines were selected for increased sensitivity to blue light, two were selected for increased sensitivity to red light, and two were unselected controls. There was significant response to selection in all four selected lines and significant heritability for sensitivity. An examination of the spectral sensitivity function showed that the form of the response differed between the red and blue lines and among the red lines. Such divergence is likely because there are many different mechanisms allowing response to selection for spectral sensitivity. Diverse mechanisms allow a divergent response by different populations to the same selective pressures. Such a mechanism can promote diversity in vision and visual signals, and any multicomponent system where different components can respond to the same selective regime.

This paper describes an experimental study of gamma radiation effects in low-density arrays of vertically aligned carbon nanotubes. These arrays are characterized by excellent anti-reflective and absorbing properties for wavelengths from UV to IR which makes them an interesting option for stray light control in optical space applications. Gamma irradiation equivalent to an estimated surface life-time exposition in geostationary orbit does not affect the reflectivity of the structures. First high-energy proton irradiation studies indicate that the reflectivity of the carbon nanotubes forests remains unchanged.