ORIGINAL ARTICLE doi:10.1111/evo.12562 The impact of shifts in marine biodiversity hotspots on patterns of range evolution: Evidence from the Holocentridae (squirrelfishes and soldierfishes) Alex Dornburg, 1,2 Jon Moore, 3,4 Jeremy M. Beaulieu, 5 Ron I. Eytan, 1 and Thomas J. Near 1 1 Department of Ecology and Evolutionary Biology and Peabody Museum of Natural History, Yale University, New Haven, Connecticut 2 E-mail: alex.dornburg@yale.edu 3 Wilkes Honors College, Florida Atlantic University, Jupiter, Florida 4 Harbor Branch Oceanographic Institution, Florida Atlantic University, Fort Pierce, Florida 5 National Institute of Mathematical and Biological Synthesis, University of Tennessee, Knoxville, Tennessee Received October 1, 2013 Accepted October 27, 2014 One of the most striking biodiversity patterns is the uneven distribution of marine species richness, with species diversity in the Indo-Australian Archipelago (IAA) exceeding all other areas. However, the IAA formed fairly recently, and marine biodiversity hotspots have shifted across nearly half the globe since the Paleogene. Understanding how lineages have responded to shifting biodiversity hotspots represents a necessary historic perspective on the formation and maintenance of global marine biodiversity. Such evolutionary inferences are often challenged by a lack of fossil evidence that provide insights into historic patterns of abundance and diversity. The greatest diversity of squirrelfishes and soldierfishes (Holocentridae) is in the IAA, yet these fishes also represent some of the most numerous fossil taxa in deposits of the former West Tethyan biodiversity hotspot. We reconstruct the pattern of holocentrid range evolution using time-calibrated phylogenies that include most living species and several fossil lineages, demonstrating the importance of including fossil species as terminal taxa in ancestral area reconstructions. Holocentrids exhibit increased range fragmentation following the West Tethyan hotspot collapse. However, rather than originating within the emerging IAA hotspot, the IAA has acted as a reservoir for holocentrid diversity that originated in adjacent regions over deep evolutionary time scales. KEY WORDS: Ancestral range reconstruction, biodiversity hotspot, biogeography, coral reef fish, fossil, West Tethys. Hotspots of biodiversity are among the most striking bio- geographic patterns. These areas are characterized by a large concentration of species per unit of area, a disproportionately high number of endemic species, and high levels of extinction vulnerability (Myers et al. 2000). Given their unusual diversity patterns, understanding how biodiversity originates and is Data associated with this manuscript: All sequence data is deposited on genbank, dryad, and the associated morphological character matrix is also available as a supplemental data file. maintained within hotspots is not only of high importance for conservation efforts (e.g., Mace et al. 2003; Forest et al. 2007), but also for understanding the evolutionary mechanisms that result in the uneven patterns of species richness across the Tree of Life (Cowman and Bellwood 2011). In the marine realm, studies of the macroevolutionary dynamics that underlie hotspots have tended to focus on the Indo-Australian Archipelago (IAA), as this area contains the world’s highest diversity of corals and coral reef associated organisms (Veron 1995; Briggs 1999; Hoeksema 2007; Lohman et al. 2011). In contrast with terrestrial hotspots, the high 1 C  2014 The Author(s). Evolution C  2014 The Society for the Study of Evolution. Evolution 00-0: 1–16