Evolution of research on global amphibian declines

Abstract

In the late 1980s, the scientific community became aware of severe, enigmatic amphibian population declines. These declines triggered a wave of research focused on quantifying their extent and identifying key drivers. We used text-analysis techniques, including topic modeling and geoparsing, to examine the evolution of research focused on amphibian declines. We sought to provide an example of scientific inquiry in action, from the initial recognition and quantification of the phenomenon to identifying drivers and understanding mechanisms of amphibian decline. We delineated research topics, tracked spatiotemporal trends from 1985 to 2024, and extracted the number of publications per topic. Early research focused on evaluating the veracity of declines and was followed by investigations of potential drivers (in particular, UVB radiation, pollution, and habitat fragmentation and loss). After the amphibian chytrid fungus ( Batrachochytrium dendrobatidis ) was identified in the late 1990s, research emphasis shifted toward disease. Subsequently, disease-focused research became increasingly specialized, the primary topics of which were susceptibility, resistance and tolerance, and mitigation. Most recently, extinction risk and climate change became increasingly prominent topics, reflecting emerging threats to amphibians. Regions with high amphibian biodiversity and observed declines (e.g., Central and South America) were underrepresented in the literature, and research was strongly biased toward North America, Australia, and Europe. We uncovered a clear disconnect between the amphibian decline literature and the development of effective management and conservation actions. To address this gap, we suggest an increased emphasis on the application of existing knowledge to drive meaningful conservation outcomes and prioritization of new research on ongoing and emerging threats.