Phylogenetic diversifications linked to the morphological traits and global phylogeographic pattern of closed pouch fishes in Syngnathidae

<p>Syngnathids, distinguished by their unique morphology and male pregnancy, serve as flagship species in global dispersal and colonization studies. There is high morphological variation among Syngnathidae, but the relationship between their morphology and phylogeographic patterns still requires further investigation. Here, we analyzed the mitochondrial genomes of 48 species in Syngnathidae to clarify their phylogenetic relationships and divergence times. The relationship between morphological traits and phylogeographic patterns has been revealed based on reconstructing the ancestral status of seahorses, pipehorses, pipefishes, and seadragons. We show that <i>Hippocampus</i> and <i>Syngnathus</i> species with enclosed brood pouches are likely associated with higher biodiversity and broader distribution. Moreover, by comparing the worldwide dispersal and biogeographic patterns of pipefishes and seahorses, our results indicate that they have distinct origin centres but colonized globally, which might be influenced by the ocean currents and historical climatic shifts during the Miocene.</p>