Document Type

Article

Publication Date

2010

Abstract

Amphibian declines have been well documented throughout the world. Several studies have examined whether UV radiation from the sun is a possible contributing cause to declining populations. In Southern California, two closely related species of treefrogs, Pseudacris hypochondriaca and Pseudacris cadaverina, coexist in many perennial streams. P. hypochondriaca is primarily nocturnal while P. cadaverina is known to bask in direct sunlight. The purpose of the study is to determine how the two different species of frogs will react under different types of light emitted by a portable flashlight. The light was emitting either UV radiation or visible light, or was turned off as it was slowly brought toward the frog. When the frog jumped from its resting position, the light was held stationary and the distance from the light to the original frog perch was recorded. Our results suggest that both species are more sensitive to the UV light than to the light that was turned off or the visible light. Frogs jumped much sooner when presented with UV even the light was farther away from them. There appeared to be no differences in the sensitivity of the two species to the UV light. Our results suggest that both species of treefrogs are sensitive to UV. This sensitivity may be due in part to the large levels of UV that reach streams after wildfires. Wildfires are a natural part of these ecosystems and the removal of tree canopy by wildfire may create periodic strong selection on riparian animals to avoid increased levels of UV radiation.

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