Convergent evolution within a major rodent radiation

The repeated and independent evolution of convergent forms is one of the most remarkable patterns across the Tree of Life. Convergent morphologies, commonly associated with adaptive evolution, can evolve through multiple evolutionary pathways, whose full breadth is not yet well-understood. Moreover, most evidence for convergent evolution in mammals is qualitative and/or based on small taxonomic scales. Hystricomorpha is one of the major rodent radiations and represents an outstanding opportunity to investigate the extent of convergent evolution in shaping similar morphologies at a global scale. Despite its impressive ecomorphological disparity, the contribution of convergent evolution in shaping hystricomorph morphologies has never been assessed. Here, we quantify the degree of morphofunctional convergence of the skull of Hystricomorpha rodents using a combination of geometric morphometrics and comparative phylogenetic methods, discovering multiple instances of convergence in their craniomandibular complex morphology. Moreover, we show that convergent morphologies are associated with adaptations to specific ecological habits. For this, we gathered the largest morphological dataset for this clade, comprising 3,102 individuals from 189 species, covering the major diversity of the group. The Hystricomorpha skull convergently evolved primarily in subterranean and semiaquatic species, underscoring how unique evolutionary adaptations to those extreme conditions (relative to the ancestral habit) led to convergent morphologies. More broadly, our findings provide quantitative evidence for the prevalence of convergence across large taxonomic and geographic scales in the evolutionary history of mammals and highlight the importance of examining form-function relationships at a macroevolutionary scale.