Une vue multidimensionnelle de la spéciation : relier la micro et la macroévolution

In the marine realm, the increasing concentration of species toward the Indo-Australian Archipelago (IAA) has been extensively studied, and numerous hypotheses have been proposed to explain this pronounced longitudinal diversity gradient. Numerous historical and evolutionary hypotheses have been proposed to explain the origin of this longitudinal gradient in marine diversity. A consensus has emerged that these hypotheses are not mutually exclusive, as the IAA has successively served as a center of accumulation, origination, and survival through geological time. Although significant progress has been made in recent years in understanding the origin of the longitudinal gradient in tropical marine fish diversity, several questions remain unexplored. For example, recent studies suggest that complex, resource-rich ecosystems such as coral reefs may promote the emergence of novel species and the evolution of traits by providing ecological opportunities. Conversely, other studies propose that diversity dependence and ecological saturation may limit species richness by constraining both diversification and trait evolution In this study, we address these questions using a global dataset on tropical reef fish distribution, combined with species traits (body size, trophic level, and maximum depth range), and a super phylogeny of Actinopterygii. Our study stands out by looking at the most species-rich vertebrate assemblage on Earth (nearly 6,000 tropical reef fishes) while accounting for multiple potential drivers of spatial patterns of species richness, with a special emphasis on the influence of recent speciation and trait evolution. We estimated assemblage-level speciation rates across the world’s tropical marine ecoregions using tip speciation rates inferred from complementary approaches. Similarly, we estimated assemblage-level trait evolution rates for the three traits considered using the TR statistic, a derived metric of the DR statistic for quantitative traits (body size, maximum depth and trophic level). We employed a causal statistical approach that allowed us to simultaneously account for the potential influence of biotic and abiotic factors on recent speciation and trait evolution rates, and ultimately, on species richness. Our results did not reveal a bull’s-eye’s pattern of recent speciation and trait evolution rates centered on the IAA, as found for species richness. The Caribbean region in the Atlantic, while being four fold species poor compared to the IAA, displayed the greatest rates of recent speciation. Compared to the IAA, the Caribbean also concentrated species with greater rates of recent body size evolution. Last, whatever the biogeographic realms considered (Indo-Pacific, Atlantic, Tropical Eastern Pacific), our findings suggest that diversity-dependence mechanisms may have played an important role in shaping trait evolution related to the trophic level of tropical reef fishes.

Oct 20, 2025 12:00 AM — Oct 24, 2030 12:00 AM