Environmental factors driving Macrobrachium species richness on a global scale

Context Understanding the processes that influence species diversity and distribution is a central goal in ecology. Aims This study investigated the global distribution of freshwater shrimps in the genus Macrobrachium and evaluated the environmental and historical factors driving their species richness across biogeographic realms. Methods We analysed predictive models composed of multiple environmental predictors across biogeographic regions, testing which hypothesis (temperature–speciation, water–energy and habitat heterogeneity) or a combination of hypotheses best explains species richness. Key results Our analyses showed that the highest Macrobrachium species richness occurs in the Neotropic and Indo-Malay realms. The best model varied among regions, reflecting regional differences and the historical influences: Afrotropic and Australasia shared similar models, as did Neotropical and Palearctic regions. Indo-Malay exhibited a distinct model, with variations in the most influential variables according to local conditions. Conclusion These findings suggest that combined environmental and historical factors are key predictors of Macrobrachium species richness. Implications This study underscores the importance of integrating environmental and historical factors when assessing species richness patterns and offers a scientific basis for conservation strategies. It highlights the need to consider current environmental changes when protecting biodiversity hotspots and the diversity of Macrobrachium across freshwater ecosystems.