The ecology and evolution of the model species Xenopus laevis

The African clawed frog Xenopus laevis has been a cornerstone of experimental biology for over a century, but its value as a model organism extends far beyond embryology. In this integrative review, we synthesize how the natural history and systematics of X. laevis underpin its power to address fundamental questions in evolution and ecology. We highlight three areas where the study of X. laevis has been especially transformative. First, as a relatively recent vertebrate allopolyploid, it provides a rare opportunity to investigate the evolutionary consequences of whole-genome duplication, including sub-genome asymmetry, biased gene loss, and the evolutionary roles of transposable elements in reshaping gene regulation. Second, X. laevis has emerged as a premier system for studying the early stages and rapid turnover of sex-determination mechanisms, yielding insights from the dm-w locus and the surprising diversity of sex-determining regions across Xenopus species. Third, global escapes and releases have produced replicated invasive populations across continents, creating natural experiments to test adaptation, niche shifts, rapid evolution of dispersal traits, and the hypothesized advantages of polyploidy in invasions. We conclude by outlining key open questions, especially how polyploid genomes generate adaptive potential, how sub-genome evolution varies among Xenopus lineages, and how integrating field ecology with modern genomics can further establish this classic laboratory organism as a powerful model in evolutionary biology.