Elevational differences in trait response to UV-B radiation by long-toed salamander populations
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Amphibian species capable of optimizing trait response to environmental stressors may develop complex strategies for defending against rapid environmental change. Trait responses may differ between populations, particularly if stressor strength varies across spatial or temporal gradients. Ultraviolet-B (UV-B) radiation is one such stressor that poses a significant threat to amphibian species. We examined the ability of long-toed salamanders (Ambystoma macrodactylum) at high- and low-elevation breeding sites to cooperatively employ behavioral and physiological trait responses to mediate UV-B damage. We performed a microhabitat survey to examine differences in oviposition behavior and UV-B conditions among breeding populations at high- (n = 3; >1,500 m) and low-elevation (n = 3; <100 m) sites. We found significant differences in oviposition behavior across populations, with females at high-elevation sites selecting oviposition substrates in UV-B protected microhabitats. We also collected eggs (n = 633) from each of the breeding sites for analysis of photolyase activity, a photoreactivating enzyme that repairs UV-B damage to the DNA, using a photoproduct immunoassay. Our results revealed no significant differences in photolyase activity between long-toed salamander populations at high and low elevations. For high-elevation salamander populations, relatively low physiological repair capabilities in embryos appear to be buffered by extensive behavioral modifications to reduce UV-B exposure and standardize developmental temperatures. This study provides valuable insight into environmental stress responses via the assessment of multiple traits in allowing sensitive species to persist in rapidly changing landscapes.
KeywordsAmphibian Photolyase Oviposition Behavior Ultraviolet radiation
We would like to thank the John Hays Laboratory in the Department of Environmental and Molecular Toxicology at Oregon State University for their extensive assistance in the laboratory analysis portion of this project. We thank L. Ganio, K. Dugger, and J. Van Sickle for assistance with statistical analyses and the Willamette Valley National Wildlife Refuge Complex and US Forest Service for site access. We thank D.T. Thurman and S.K. McMurrain for their invaluable contributions. This study was funded by scholarship stipends from The Society for Northwestern Vertebrate Biology, Oregon State University Department of Fisheries and Wildlife, and Oregon State University College of Agricultural Sciences. Animals were collected under Oregon Department of Fisheries and Wildlife Scientific Taking Permit no. 078-10, US Fish and Wildlife Service Special Use Permit no. 13590-11-02, E.E. Wilson Management Area Special Use Permit no. 1513, and Oregon State University Animal Care and Use Protocol no. 3978.
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