Facultative Oviposition of Eastern Newt (Notophthalmus viridescens) in Response to Water Reduction of Aquatic Habitats

Plastic responses by amphibian larvae to various pond hydroperiods have received much theoretical and empirical attention. In contrast few studies examined maternal plasticity in oviposition in response to different hydroperiods. Using the Eastern Newts as a model, we tested a hypothesis that mothers respond to water reduction of aquatic habitats and alter life history traits such as timing of oviposition, clutch size, and egg size. Alternatively, females may entirely forgo oviposition if aquatic habitats are unsuited for larval survival, in which case we predicted greater body-mass gain of females that forgo oviposition. We daily monitored oviposition of 20 females for 38 d, 10 in constant water treatment and 10 in water reduction treatment. Six females deposited a total of 265 eggs in the constant water treatment whereas only one female deposited 17 eggs in the water reduction treatment, suggesting females facultatively altered oviposition behavior in response to water reduction. Contrary to the prediction, oviposited females gained significantly more body mass, suggesting those females that skipped oviposition stopped vitellogenesis during the experiment; whereas, oviposited females still contained yolk-laden ova at the end of the experiment. We could not test maternal plasticity in timing of oviposition, egg size, and clutch size because only one female from the water reduction treatment deposited eggs. The present study demonstrates that the Eastern Newt is a potentially useful model to further explore maternal plasticity in amphibians