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Figure 3 | BMC Evolutionary Biology

Figure 3

From: Parallel reduction in expression, but no loss of functional constraint, in two opsin paralogs within cave populations of Gammarus minus (Crustacea: Amphipoda)

Figure 3

Tree topology and dN/dS ratio ( ω ) branch parameters used in ML tests of selective constraint. A maximum likelihood analysis of codon-based models (PAML) was employed to test for possible differences in selective constraint among cave and surface populations. The dN/dS ratio in ancestral lineages is ω0, the dN/dS ratio in surface lineages is ω1, and the dN/dS ratio in cave lineages is ω2. Under the one-ratio model there are no differences in selective constraint and ω0 = ω1 = ω2. Under the two-ratio model the ancestral and surface lineages have the same dN/dS ratio whereas the cave lineages have a unique dN/dS ratio such that ω0 = ω1 ≠ ω2. The three-ratio model allows for three unique dN/dS ratios in the ancestral, surface, and cave lineages such that ω0 ≠ ω1 ≠ ω2. See Table 2 for parameter estimates and likelihood ratio test results.

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BMC Ecology and Evolution

ISSN: 2730-7182

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