Data from: Thyroid hormone tinkering elicits integrated phenotypic changes potentially explaining rapid adaptation of color vision in cichlid fish

Vision is critical for most vertebrates, including fish. One challenge
that aquatic habitats pose is the high variability in spectral properties
depending on depth, turbidity and composition of the water body. By
altering opsin gene expression and chromophore usage, cichlid fish
modulate visual sensitivities to maximize sensory input from the available
light in their respective habitat. Thyroid hormone (TH) has been proposed
to play a role in governing adaptive diversification in visual sensitivity
in Nicaraguan Midas cichlids, which evolved in less than ~3,100
generations. As suggested by indirect measurements of TH levels (i.e.,
expression of deiodinases), populations adapted to short wavelength light
in clear lakes have lower TH levels than ones inhabiting turbid lakes
enriched in long-wavelength light. We experimentally manipulated TH levels
by exposing two-week-old Midas cichlids to exogenous TH or a TH-inhibitor
and measured opsin gene expression and chromophore usage (via cyp27c1
expression). Whereas exogenous TH induces long-wavelength sensitivity by
changing opsin gene expression and chromophore usage in a concerted
manner, TH-inhibited fish exhibit a visual phenotype with sensitivities
shifted to shorter-wavelengths. Tinkering with TH levels in eyes results
in concerted phenotypic changes that can provide a rapid mechanism of
adaptation to novel light environments. --