Ultraviolet Exposure and Vitamin D Synthesis in a Sun‐Dwelling and a Shade‐Dwelling Species of Anolis: Are There Adaptations for Lower Ultraviolet B and Dietary Vitamin D3 Availability in the Shade?

Abstract We compared the natural ultraviolet B (UV‐B) exposure, dietary vitamin D, and skin‐generated vitamin D synthesis for adult males of two species of Jamaican anoles. The more shade‐tolerant and thermal‐conforming Anolis lineotopus merope, rarely exposed to full sun, experienced less UV‐B irradiation in its shady environment than the more heliophilic and thermophilic Anolis sagrei, which frequently basked in full sun during the morning hours (0800–1100 hours). Both species obtained detectable levels of vitamin D3 in their diet, but the heliophilic A. sagrei obtained more. To compensate for less availability of UV‐B and dietary vitamin D, the skin of A. lineotopus merope seems to have acquired a greater sensitivity than that of A. sagrei regarding UV‐B‐induced vitamin D3 photobiosynthesis. We assessed this by observing a greater conversion of provitamin D to photoproducts in skin exposed to UV‐B from a sunlamp. The reduced skin sensitivity of A. sagrei regarding vitamin D photobiosynthesis may reflec...