A MULTI-GENE ESTIMATE OF HIGHER-LEVEL PHYLOGENETIC RELATIONSHIPS AMONG NIGHTJARS (AVES: CAPRIMULGIDAE)

The higher-level phylogenetic relationships of the nightjars and nighthawks (Caprimulgidae) have been challenging for traditional systematics due to their cryptic plumage and conservative morphology. We explored these relationships by combining two previously published molecular datasets with new data to generate a complete matrix (7,104 bp) of evolutionarily disparate sequence elements from four genes for 36 taxa. We analyzed each of the genes separately for base composition heterogeneity and heterozygosity. We analyzed the concatenated matrix in a likelihood framework using seven different partitioning schemes. As the number of subsets in a given partitioning scheme increased, tree length and likelihood score also increased; however, the branching topology was little affected by increasingly complex partitioning schemes. Our best maximum likelihood tree has increased bootstrap support at 13 of 30 ingroup nodes compared with previous analyses, a result likely due to doubling the length of the sequence data. Coalescent-based species tree inference produced a tree congruent with all strongly supported nodes in the maximum likelihood tree. This topology agrees with previous molecular studies in identifying three small, early branching Old World genera (Eurostopodus, Lyncornis, and Gactornis) and four more speciose terminal clades, representing the New World nighthawks (genus Chordeiles) and three nightjar radiations centered in South America, Central America and the Old World, respectively. Increased node support across the tree reinforces a historical scenario with origins in the region surrounding the Indian Ocean, followed by diversification in the New World and subsequent recolonization and radiation in the Old World. Future work on this group should incorporate additional members of the genera Lyncornis and Eurostopodus, to determine which is the basal lineage of Caprimulgidae.