Fig. 2.

The number of full-length CR1s varies significantly across the diversity of birds sampled. Minimum, maximum, and mean number of full-length CR1 copies identified in each order of birds, and the number of species surveyed in each order. Largest differences are noticeable between sister clades such as parrots (Psittaciformes) and perching birds (Passeriformes), and landfowl (Galliformes) and waterfowl (Anseriformes). The double helix represents a putative hard polytomy at the root of Neoaves (Suh 2016). Orders bolded contain at least one intact and potentially active CR1 copy and those highlighted are the orders examined in detail. For coordinates of full-length CR1s within genomes, see supplementary data 1, Supplementary Material online. Tree adapted from Mitchell et al. (2014) and Suh (2016).