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?
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 D(3) 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 D(3) 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 reflect a correlated response associated with less need for vitamin D photobiosynthesis and greater need for UV-B screening capacity as an adaptation to a more damaging UV-B environment. However, the possibility that adaptations for photobiosynthesis of vitamin D and for protection from skin damage could involve independent mechanisms needs investigation. Also, the ability to behaviorally regulate UV-B exposure, as shown for the panther chameleon, would benefit both species of Anolis and should be investigated.
Ferguson
Gary W
GW
Department of Biology, Texas Christian University, Fort Worth, 76129, USA. g.ferguson@ tcu.edu
Gehrmann
William H
WH
Karsten
Kristopher B
KB
Landwer
Allan J
AJ
Carman
Elliott N
EN
Chen
Tai C
TC
Holick
M F
MF
D000222:Adaptation, Physiological; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004032:Diet; D004307:Dose-Response Relationship, Radiation; D007076:Iguanas / Q000502:physiology*; D007563:Jamaica; D012867:Skin / Q000378:metabolism / Q000528:radiation effects; D013045:Species Specificity; D013472:Sunlight; D014466:Ultraviolet Rays; D014807:Vitamin D / Q000096:biosynthesis* / Q000378:metabolism
D014807:Vitamin D