Fig. 1From: Evolution of the avian β-defensin and cathelicidin genesPhylogenetic tree showing evolutionary relationships between 53 examined bird species. The tree was generated via webserver http://birdtree.org/ [38]. Branch length indicates evolutionary time; numbers besides the nodes are estimated divergence time (million years before present). The number of genes detected to have undergone episodic diversifying selection over total number of annotated genes in each species is shown to the right of the species nameBack to article page