Gasterosteus, Anolis, Mus, and more: the changing roles of vertebrate models in evolution and behaviour

Background: The choice of model systems is important for research and researchers, and has been studied in the biomedical literature but not with regard to evolution and behaviour. Neither have changes in the use of the threespine stickleback, Gasterosteus aculeatus, as a model been examined quantitatively. Questions: What are the major vertebrate model systems in evolutionary biology and animal behaviour. How have they changed over the last 25 years, and how has work on the threespine stickleback model evolved in this period? Data: We collected publication rates from the Web of Science for candidate model organisms for three periods over the last 25 years. As a complement to this analysis, we conducted a more focused and inductive analysis on Gasterosteus, concerning which fields have used this model, by analysing the keywords co-occurring with 'Gasterosteus'. To elucidate emerging trends involving stickleback, we analysed word frequencies in the abstracts of the current conference and of manuscripts in the stickleback special issues of Evolutionary Ecology Research, Volume 20. Results: For evolutionary biology, traditional biomedical models have declined in importance over the last 25 years whereas non-biomedical comparative models have shown the opposite trend. Patterns for behaviour are more complex, with some natural systems increasing in usage and newer biomedical models, such as Danio, replacing previously important ones. Salmonids proved unexpectedly important for both evolution and behaviour and Drosophila appeared in more publications than any vertebrate. Overall, model systems were stable or declining in usage, a pattern also reported in the biomedical literature. Our keyword analysis for Gasterosteus suggests that the stickleback has evolved as a model. At first it was used mainly in behaviour but now it is also being used extensively to study evolution as well as to address concerns over human-induced environmental changes, and to investigate other new topics. Abstracts from the conference and the special issues illustrate the diversity of stickleback research, including emphases on variation in phenotypes between habitats and between sexes and the evolutionary and ecological processes that lead to these differences, as well as on genome-level questions, interactions with parasites, and eco-evolutionary dynamics.