NEELEY, E.F.; BARBER, P.H.; ROSENTHAL, G.G.; Boston University; Boston University; Boston University: Adaptive response of color patterns in the Labroidei to environmental parameters: a comparative approach

The diversity of colorful patterns in tropical reef fishes has piqued the interest of naturalists for centuries. While much research has been devoted to studying color by quantifying spectral properties of these signals, the spatial arrangement of pattern elements is also likely to encode important species identity and reproductive status information. Transmission and reception of such visual signals are dependent upon environmental conditions. The Caribbean is characterized by clear water and bright, visually heterogeneous coral reefs, while the eastern Pacific is more turbid and has darker, visually homogeneous rocky reefs. We have used this comparative system to track evolutionary trends in the spatial qualities of reef fish color patterns in wrasses and parrotfish (Pisces: Labroidei), a speciose group characterized by diverse color patterns and a distribution across the Isthmus of Panama. Data from 16S, 12S, and CO1 mitochondrial gene regions and published molecular and morphological phylogenies were combined to generate a species-level supertree. Color pattern parameters from both terminal- and initial-phase individuals of each species were mapped to the tree and independent contrasts and concentrated changes tests were calculated to assess environmental tuning of visual signal components. Eastern Pacific species tend to have larger, simpler patterns with fewer elements while their Caribbean relatives have finer, more complex patterns. These data suggest that greater scattering and attenuation of light in the eastern Pacific may have selected for coarser, simpler patterns less susceptible to distortion in the visual environment. This type of comparative analysis is essential for understanding the evolution and communicative function of color patterns in reef fishes.