The flyingfishes (Teleostei: Exocoetidae) are a family of 53 epipelagic marine species distributed throughout tropical and subtropical surface waters. They form a key mid-trophic link between zooplankton and predators, and have evolved special adaptations to survive in the open ocean. However, little is known about their basic evolutionary history and ecology. Here, I apply a multidisciplinary approach to better understand the evolution and ecology of flyingfishes. I propose the first species-level phylogenetic hypothesis for the group, based on nuclear and mtDNA sequences, and show that the most speciose genus (Cheilopogon) is paraphyletic. Gliding evolved progressively from two- to four-wing strategies, and habitat preference is correlated with species range size. I also analyzed patterns of genetic diversity within the most abundant genus, Exocoetus, and found no evidence of cryptic species. Instead, I found that this genus likely consists of three genetically distinct species (in contrast to the five currently recognized) and two indistinct species that diverged very recently. Population genetic analysis of Exocoetus volitans (266 samples from 97 localities) indicates a single, circum-tropical population that is well connected; yet the Isthmus of Panama and an Equatorial barrier limit gene flow. Finally, I investigated species abundance, richness, diversity, and distributions within the eastern tropical Pacific Ocean (11,125 specimens). My results provide critical updates on species distributions and habitat preferences. Predictive modeling indicates that sea surface temperature is important for defining flyingfish habitat. This thesis addresses central issues concerning both evolution and ecology in the epipelagic zone, and highlights the need for better understanding remote marine regions and organisms.

The flyingfishes (Teleostei: Exocoetidae) are a family of 53 epipelagic marine species distributed throughout tropical and subtropical surface waters. They form a key mid-trophic link between zooplankton and predators, and have evolved special adaptations to survive in the open ocean. However, little is known about their basic evolutionary history and ecology. Here, I apply a multidisciplinary approach to better understand the evolution and ecology of flyingfishes. I propose the first species-level phylogenetic hypothesis for the group, based on nuclear and mtDNA sequences, and show that the most speciose genus (Cheilopogon) is paraphyletic. Gliding evolved progressively from two- to four-wing strategies, and habitat preference is correlated with species range size. I also analyzed patterns of genetic diversity within the most abundant genus, Exocoetus, and found no evidence of cryptic species. Instead, I found that this genus likely consists of three genetically distinct species (in contrast to the five currently recognized) and two indistinct species that diverged very recently. Population genetic analysis of Exocoetus volitans (266 samples from 97 localities) indicates a single, circum-tropical population that is well connected; yet the Isthmus of Panama and an Equatorial barrier limit gene flow. Finally, I investigated species abundance, richness, diversity, and distributions within the eastern tropical Pacific Ocean (11,125 specimens). My results provide critical updates on species distributions and habitat preferences. Predictive modeling indicates that sea surface temperature is important for defining flyingfish habitat. This thesis addresses central issues concerning both evolution and ecology in the epipelagic zone, and highlights the need for better understanding remote marine regions and organisms.