Amphibian responses to anthropogenic and natural stressors

Abstract

In my dissertation, I asked the following questions: 1) what is the length of time that induced tolerance is retained and are there trade-offs to inducing increased tolerance, 2) what factors (i.e., frequency of exposure, timing of exposure) influence the induction and retention of induced tolerance to contaminants, 3) how do populations with no previous history of contaminant exposure induce adaptive responses to contaminants, and 4) how do aquatic communities respond to combinations of anthropogenic and natural stressors?

Human modifications of natural ecosystems can expose organisms to novel stressors. For instance, the use of agrochemicals and road deicers has led to the ubiquitous contamination of ecosystems and, in many cases, the evolution of increased tolerance. The evolution of increased tolerance to anthropogenic contaminants has historically been attributed to the natural selection on beneficial constitutive traits over many generations. Recently, however, researchers have discovered that increased tolerance to contaminants can be induced in a single generation following a sublethal exposure to the contaminant. Given that agrochemicals were developed relatively recently (in evolutionary time), it is surprising that organisms are able to induce adaptive responses without having any previous history of exposure. Moreover, it is not well understood how species respond to novel contaminants under more natural conditions.