Amphibians’ response to the lunar synodic cycle—a review of current knowledge, recommendations, and implications for conservation

Although there is growing concern that amphibian populations are declining globally, much of the supporting evidence is either anecdotal or derived from short-term studies at small geographical scales. This raises questions not only about the difficulty of detecting temporal trends in populations which are notoriously variable, but also about the validity of inferring global trends from local or regional studies. Here we use data from 936 populations to assess large-scale temporal and spatial variations in amphibian population trends. On a global scale, our results indicate relatively rapid declines from the late 1950s/early 1960s to the late 1960s, followed by a reduced rate of decline to the present. Amphibian population trends during the 1960s were negative in western Europe (including the United Kingdom) and North America, but only the latter populations showed declines from the 1970s to the late 1990s. These results suggest that while large-scale trends show considerable geographical and temporal variability, amphibian populations are in fact declining--and that this decline has been happening for several decades.

The temporal pattern of breeding in populations is often characterized by a pronounced temporal clustering of births, flowering or seed set. It has long been suspected that this phenomenon is not caused by climatic seasonality alone but that reproductive synchrony represents a strategy that individuals adopt to maximize reproductive success. The classical hypotheses predicting an adaptive advantage of reproductive synchrony incorporate both sociobiological and ecological explanations. However, new theoretical and empirical analyses have shown that the predicted advantage of reproductive synchrony depends on the ecological setting in which populations reproduce, and processes earlier thought to be responsible only for synchrony may under some ecological conditions lead to asynchronous reproduction being the best strategy. Copyright © 1990. Published by Elsevier Ltd.