Meeting Abstract
Adaptive variation in color reflects a suite of organismal specific traits and behaviors, ranging from warning signaling to thermoregulation. However, how this variation is partitioned within the spectrum of solar radiation (300-2500nm) and why, remains unknown. The near-infrared reflectance (NIR) spectrum (700-2500nm) compromises 55% of all solar irradiance, yet spectral reflectance is rarely measured outside of the UV or visible spectra. Furthermore, extensive animal insensitivity to near-infrared wavelengths, makes this spectrum an ideal candidate for understanding the role spectral reflectance plays in ectotherm thermal physiology. The NIR spectrum may be less constrained by selection for warning signaling, camouflage, and sexual signaling, and may instead largely reflect thermoregulatory requirements. Our work examines the relationship between NIR, visible spectral reflectance, and thermoregulation, in a clade of Epipedobates poison frogs exhibiting a diverse range of color variation and thermal habitat regimes. We measured spectral reflectance of cryptic and conspicuous species throughout western Ecuador across elevational and temperature gradients in both the visible and NIR spectra (400-1100nm), and measured critical thermal maxima & minima (CTmax & CTmin), desiccation rate, and body temperature of each individual. Our results show statistically significant differences between total reflectance in the NIR spectrum and the visible spectrum, indicating the possibility of different selective pressures on each spectrum, and emphasizing the need to consider multiple spectra when studying adaptive variation in color. Furthermore, we found inter-populational variation in CTmax, CTmin, desiccation rate, and body temperature that may illuminate NIR’s role in thermoregulation.
