Global phylogeography of hyperdiverse lanternfishes indicates sympatric speciation in the deep sea

Lanternfishes (Myctophidae) are one of the most species-rich families of mid-water fishes. They inhabit the mesopelagic zone, where physical barriers to dispersal and gene flow are permeable. Thus, modes of speciation that rely exclusively on geographical separation are potentially of less importance than those that rely more prominently on evolution of assortative mating through divergent habitat use and/or sexual signals, including visual signals from bioluminescent light organs. Here we used phylogenetic, ecological and morphological data to investigate the roles of geography, habitat use and lateral photophores in lanternfish speciation.