Light environment interacts with visual displays in a species-specific manner in multimodal signaling wolf spiders

Light availability is highly variable, yet predictable, over various
timescales and the light environment is expected to play an important role
in the evolution of visual signals. Courtship displays within the wolf
spider genus Schizocosa always involve the use of substrate borne
vibrations, however, there is substantial variation between species in the
use of visual displays. We assessed the impact of light intensity on the
courtship of four species of Schizocosa that vary in their use of visual
signals during courtship. To examine the effects of the light environment
on mating success and courtship effort in each species, we ran behavioral
trials at three light intensities (bright, dim and dark). We also examined
each species’ circadian activity patterns. We found multiple effects of
the light environment and these varied between species. Circadian activity
patterns also differed between species and sexes. Our results suggest that
dim-light might favor more conspicuous visual displays, while less
conspicuous displays might be favored in bright light conditions.
Additionally, we found evidence for light-dependent changes in selection
on male traits, illustrating that short-term changes in light intensity
have the potential for strong effects on the dynamics of sexual selection.