Molecular evolution models. Strategy used to test for accelerated rates of evolution along branches leading to male-baised aphid slimfast paralogs. Tree topology is identical to the phylogeny in Figure 1. Each branch was assigned a ω category as indicated. The models tested are outlined below the phylogeny. The null model (one ratio) assumed equal ω across all branches. The first alternative model (two ratios) assumed one ω ratio for branches outside the aphid-specific slimfast expansion and a different ω ratio for branches within the expansion. The second alternative model (three ratios) assumed an additional, collective ω ratio for the branches leading to the three male-biased paralogs, and third alternative model (five ratios) assumed a distinct ω for each branch leading to a male-biased paralog or clade.
Duncan et al. BMC Evolutionary Biology 2011 11:253 doi:10.1186/1471-2148-11-253