Big Wyoming Sagebrush Screens UV Radiation More Effectively at Higher Altitudes
Location
CSU Ballroom
Start Date
9-4-2012 10:00 AM
End Date
9-4-2012 11:30 AM
Student's Major
Biological Sciences
Student's College
Science, Engineering and Technology
Mentor's Name
Christopher Ruhland
Mentor's Department
Biological Sciences
Mentor's College
Science, Engineering and Technology
Second Mentor's Name
John Krenz
Second Mentor's Department
Biological Sciences
Second Mentor's College
Science, Engineering and Technology
Description
The flux of biologically-effective ultraviolet radiation (UV; 280-400nm) reaching the Earth’s surface diminishes at lower elevations which may cause physiological and morphological phenotypic differences within plant populations. We examined epidermal UV- screening effectiveness in Artemisia tridentata ssp. wyomingensis (Big Wyoming Sagebrush) along an 800 m elevation gradient in central Wyoming with a pulse amplitude modulated UV fluorometer. Epidermal transmittance of UV increased at lower elevations; adaxial UV-transmittance values ranged from 10.2% (low elevation) to 2.3% (high elevation). To provide a proximate explanation for this relationship, we collected plants from across the gradient and estimated the concentration of bulk-soluble UV-absorbing compounds (spectrophotometry; λ=300 and 365 nm) and the density of adaxial leaf hairs (epifluorescence microscopy). Concentrations of UV-absorbing compounds increased with elevation and ranged from 0.64 to 2.25 A300 cm-2 and 0.43 to 1.35 A365 cm-2. Trichome density also increased from a mean of 14,400 cm-2 at low elevation to a mean of 22,500 cm-2 at high elevation. Because the distance along the elevation gradient was only 18 km, gene flow likely prevents ecotypic differentiation; the ultimate cause of the cline in screening effectiveness is likely the evolution of phenotypic plasticity in both biochemical and anatomical properties of leaves in response to UV stimuli.
Big Wyoming Sagebrush Screens UV Radiation More Effectively at Higher Altitudes
CSU Ballroom
The flux of biologically-effective ultraviolet radiation (UV; 280-400nm) reaching the Earth’s surface diminishes at lower elevations which may cause physiological and morphological phenotypic differences within plant populations. We examined epidermal UV- screening effectiveness in Artemisia tridentata ssp. wyomingensis (Big Wyoming Sagebrush) along an 800 m elevation gradient in central Wyoming with a pulse amplitude modulated UV fluorometer. Epidermal transmittance of UV increased at lower elevations; adaxial UV-transmittance values ranged from 10.2% (low elevation) to 2.3% (high elevation). To provide a proximate explanation for this relationship, we collected plants from across the gradient and estimated the concentration of bulk-soluble UV-absorbing compounds (spectrophotometry; λ=300 and 365 nm) and the density of adaxial leaf hairs (epifluorescence microscopy). Concentrations of UV-absorbing compounds increased with elevation and ranged from 0.64 to 2.25 A300 cm-2 and 0.43 to 1.35 A365 cm-2. Trichome density also increased from a mean of 14,400 cm-2 at low elevation to a mean of 22,500 cm-2 at high elevation. Because the distance along the elevation gradient was only 18 km, gene flow likely prevents ecotypic differentiation; the ultimate cause of the cline in screening effectiveness is likely the evolution of phenotypic plasticity in both biochemical and anatomical properties of leaves in response to UV stimuli.
Recommended Citation
Dyslin, Michael. "Big Wyoming Sagebrush Screens UV Radiation More Effectively at Higher Altitudes." Undergraduate Research Symposium, Mankato, MN, April 9, 2012.
https://cornerstone.lib.mnsu.edu/urs/2012/poster-session-A/8
