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Table 2 Intensity of purifying selection (1-f) and levels of adaptive evolution (α)

From: Molecular adaptation in flowering and symbiotic recognition pathways: insights from patterns of polymorphism in the legume Medicago truncatula

Model name and description f α ΔAIC wAIC
M0: Strict selective neutrality 1 0 321 ~ 0
M1: Homogeneous purifying selection + No adaptive evolution 0.13 0 2.16 0.06
M2: Purifying selection with variable intensity + No adaptive evolution f1 = 0.11 f2 = 0.17 f3 = 0.08 0 1.16 0.16
M3 Homogeneous purifying selection + homogeneous levels of adaptive evolution 0.11 0.36 0.79 0.24
M4 Purifying selection with variable intensity + homogeneous levels of adaptive evolution f 1 = 0.10 f 2 = 0.14 f 3 = 0.07 0.35 0 0.52
M5: Purifying selection with variable intensity + varying levels of adaptive evolution f1 = 0.09 f2 = 0.14 f3 = 0.09 α1 = 0.4 α2 = 0.37 α3 = -0.04 3.48 0.02
Model average (over M0 to M5) f 1 = 0.08 f 2 = 0.11 f 3 = 0.06 α 1 = 0.28 α 2 = 0.028 α 3 = 0.027 N/A N/A
  1. 1-f quantifies the intensity of purifying selection through the fraction of new amino acid changing mutation under strong purifying selection. α is the fraction of divergence attributable to adaptive evolution (driven by positive selection on amino acid changing mutations).
  2. The best model (M4) is highlighted in bold and all differences in AIC among models ΔAIC) are computed relative to M4. WAIC are the statistical weights of each model in the model averaging procedure we used.
  3. Subscripts in f1, f2, f3, α1, α2, α3 refer to the gene fragment categories. 1: control fragments, 2: flowering gene fragments, 3: symbiotic gene fragments. N/A: not applicable.