Abstract

Aim: To reconstruct the spatiotemporal dynamics underlying the global distribution of palaemonine shrimps and to test how geographic origin, paleogeographic connectivity and larval developmental strategy shaped macroevolutionary dispersal patterns. Location: Global tropical and temperate coastal regions, emphasizing the Eastern Pacific, Indo-West Pacific and Atlantic basins. Taxon: Palaemoninae (Decapoda: Caridea), focusing on the most speciose genera, Palaemon and Macrobrachium. Methods: We inferred a densely sampled, fossil-calibrated phylogeny using three molecular markers (16S, 18S and H3) under a fossilized birth–death model. Continuous-space Bayesian models were used to estimate ancestral geographic locations, lineage-specific model-inferred dispersal rates and cumulative dispersal distances across a posterior sample of trees. Temporal, spatial and clade-level variation in dispersal dynamics was assessed using segmented regression, spatial generalized additive models and phylogenetic comparative tests. Results: The most recent common ancestor of Palaemoninae was consistently reconstructed in the Eastern Pacific during the Early Cretaceous (~125 Ma), providing little support for a primary Tethyan origin. Reconstructions reveal recurrent inter-basin dispersal, dominated by east-to-west Pacific expansions into Southeast Asia and Oceania and by trans-Atlantic exchanges linking the Neotropics and West Africa. Breakpoint analyses identified a broad concentration of dispersal-rate shifts near the Cretaceous–Paleogene boundary, whereas Neogene tectonic events showed little correspondence with rate changes. Despite contrasting larval developmental strategies, Palaemon and Macrobrachium did not differ significantly in cumulative dispersal distances or branch-specific model-inferred dispersal rates. Spatial models detected statistically significant but modest geographic structuring, with coastal regions acting as recurrent dispersal hotspots. Main Conclusions: Our results support an Eastern Pacific origin for palaemonine shrimps and highlight the central role of repeated long-distance dispersal in generating their pantropical distribution. Dispersal dynamics appear only weakly coupled to larval developmental mode and are better explained by ecological tolerance, historical connectivity and episodic opportunities for range expansion. By integrating fossil-calibrated phylogenies with continuous-space models, this study reveals dispersal pathways and rate heterogeneity that are difficult to detect using discrete-area approaches, while emphasizing the importance of cautious interpretation when projecting deep-time processes onto modern geographic frameworks.