| Recent studies have shown that the avian order Caprimulgiformes includes eight families: the owlet-nightjars (Aegothelidae), the nightjars (Caprimulgidae), the potoos (Nyctibiidae), the frogmouths (Podargidae), the monotypic oilbird (Steatornithidae) and the three families traditionally placed in the order Apodiformes: the swifts (Apodidae), the tree-swifts (Hemiprocnidae) and the hummingbirds (Trochilidae). In this study, a total-evidence approach was utilized to address the relationships of these families. A phylogenetic analysis of a combined dataset of 134 skeletal morphological characters, 14 nuclear loci (exons and introns) and a presence/absence indel matrix, with a taxon sampling of all eight families as well as 16 outgroup taxa provided a better resolved phylogeny for the group than obtained by previous studies. New relationships include the placement of the frogmouths (Podargidae) as the sistergroup to a clade containing the owlet-nightjars (Aegothelidae) and the three "apodiform" families. Both morphological and molecular data supported the sister-relationship of the nightjars (Caprimulgidae) and the potoos (Nyctibiidae).;A phylogeny for the three New World radiations of nightjars (Caprimulgidae) was produced from a four-loci molecular dataset. The taxon sampling was the densest of any phylogenetic study of the group, not only were all but three New World nightjar species sampled, but also 78 of 101 recognized subspecies. This provided an opportunity to address species- and intraspecific-level relationships. The taxonomic modifications resulting from the phylogeny included a reduction in the number of genera for the three radiations, from 14 to 10, and nine subspecies were elevated to full phylogenetic species status resulting in an increase in total species numbers from 89 to 98 for the family.;The modified phylogeny of the New World nightjars was utilized to investigate temporal patterns of diversification, historical biogeography and evolution of habitat choice and migratory behavior. The three New World radiations are for the most part temporally congruent but they show highly independent histories of spatial and ecological diversification that have resulted in divergent patterns of extant species distributions as well as ecology, impacted by multiple independent vicariant events, long-distance dispersal and habitat shifts. |
