Morphological variation and ultraviolet radiation defenses in Helisoma trivolvis: implications for potential plasticity in tolerance
Norford, Ariek Barakat
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Ultraviolet radiation (UVR; 290-400 nm) is a source of environmental stress for all organisms exposed to the sun. In response to this threat, organisms may develop defenses on a population level over a short temporal scale through phenotypic plasticity. Previous studies have found plasticity in the morphological traits of length as related to shell growth, shell thickness, and pigmentation, all of which influence the tolerance of freshwater snails to UVR. This study quantifies inter-population variation in UVR tolerance of Helisoma trivolvis (Planorbidae) as it relates to length, shell thickness, and pigmentation. For each of the five populations, 40 individuals were exposed to 9.72 kJ/m2 of radiation over 12 hours on a phototron. Mortality within five days and length, crushing resistance as a proxy for shell thickness, and lightness/darkness pigmentation were quantified for each individual. The populations varied in mortality, length, shell thickness, and pigmentation. None of these morphological characteristics predicted mortality though, except for length for one population, indicating that another variable or a combination of these variables influences variation in UVR tolerance.
Franklin and Marshall College Archives, Undergraduate Honors Thesis 2018
- F&M Theses Collection