The hypothesis of adaptive radiation in evolutionary biology: hard facts about a hazy concept

Adaptive radiation is one of the most emblematic concepts in evolutionary biology. However, the current lack of a consensual definition and the diversity of methods used to assess the extent and speed of adaptive radiation indicate the need for a reappraisal of this research field. In order to depict how adaptive radiations have been studied in recent years, we performed a scientometric assessment of 765 articles published between 2003 and 2012 in five journals known to serve a broad audience. From each study, we extracted and analyzed data relative to the taxon and geographical area investigated and to the methodological setup, and we categorized its outcomes and conclusions. This scientometry-oriented work allowed us to identify and discuss trends relative to the way research about adaptive radiations was carried out during the 10-year period starting in 2003. We then provided some recommendations for how to conduct a reliable study of a suspected adaptive radiation. The associated database resulting from our study will be a valuable source of information for biologists as they design a study or put their results in perspective. Our work may also inspire a critical assessment of the relevance of this pivotal concept in evolutionary biology.