Barrier et al. 2001. Accelerated regulatory gene evolution in an adaptive radiation. PNAS. 98: 10208–10213.
1. In 1975, Mary-Claire King and Allan Wilson suggested that in some lineages evolutionary change at regulatory genes may be more important than evolutionary change at structural genes. Discuss their hypothesis and how it relates to 1) the comparisons among the different genes and 2) the patterns of morphological evolution described in Barrier et al.
2. Describe how comparing rates of synonymous and non-synonymous substitutions can provide insights into patterns of natural selection, and how that approach informs the analyses of Barrier et al.
3. How many copies of the two regulatory genes are found in Hawaiian silversword species? Discuss the evolutionary significance of this change in copy number compared to their mainland ancestors, including the significance of the expression patterns illustrated in Figure 1.
4. Barrier et al. did not find an increase in neutral substitution rates in the Hawaiian species compared to their mainland ancestors. Explain the significance of this pattern in the context of the Ka/Ks differences seen between Hawaiian and mainland species.