The origin of biogeographic segregation in the copper shark (Carcharhinus brachyurus): an integrative reconstruction based on neontological and paleontological data

Nowadays, the copper shark Carcharhinus brachyurus Günther, 1870 displays an antitropical, disjunct distribution in marginal-marine environments of both the hemispheres. Differing from other species of Carcharhinus, C. brachyurus inhabits temperate rather than tropical coastal waters, and its dispersal abilities are strongly conditioned by the presence of habitats suitable as nursery grounds. Here we analyze, through well-defined geological timeslices, the global fossil record of C. brachyurus in order to identify the main biogeographic dynamics that led to the present-day biogeographic segregation pattern of this requiem shark species. By integrating a thorough review of the paleontological literature with the results of recent phylogeographic analyses on extant copper shark populations, our study provides a first integrated reconstruction of the historical distributional patterns of this shark species that allows for proposing the identification of some dispersal trajectories as well as of a number of key events in the paleobiogeographic history of C. brachyurus. Our research supports the notion that the present-day distributional pattern of C. brachyurus is the product of historical biogeographic processes and events that might be traced back to an early Miocene East Pacific-central West Atlantic center of origin and likely reflect major changes in the global ocean system (including the closure of major seaways and the emergence of new oceanic circulation patterns).