Molecular Evolution of Anthocyanin Pathway Genes in Morning Glories (Ipomoea)

大多数分子进化研究只考察单个基因，而不考虑它们与其他基因的相互作用。然而，大多数基因并不是孤立地发挥作用，而是与许多其他基因相互作用，这些基因可能会相互影响彼此的进化。该项目的一个目标是确定这种相互作用是否以及如何实际上导致基因进化速度的可预测变化。具体地说，将研究牵牛花(Ipomoea属)花青素色素途径的基因，以确定观察到的进化速率差异是否由于选择限制的差异(即该途径下游的基因是否因为影响较少的性状而较少受到净化自然选择的影响)。该项目的第二个目标是通过确定表型差异的分子基础，开始检查调节基因和结构基因在物种间适应差异中的相对重要性。这个项目的长期目标是检查大量的物种，它们的颜色模式已经偏离整个花冠肢体和喉部的假定祖先类型的基于氰化物的蓝色/紫色色素沉着。对于每个物种，将确定结构和调控基因对差异的相对贡献。然而，目前的目标更加有限：描述导致两个物种产生白色花朵的遗传变化的特征，这两个物种分别是I.alba和I.最初，调查将集中在这两个物种上，以证明拟议方法的可行性。

Most investigations of molecular evolution examine single genes, without respect to their interactions with other genes. However, most genes do not act in isolation, but interact with many other genes, which are likely to influence each other's evolution. One goal of this project is to determine whether and how such interactions actually cause predictable variation among genes in their rates of evolution. Specifically, genes of the anthocyanin pigment pathway in morning glories (genus Ipomoea) will be examined to determine whether observed evolutionary rate variation is due to differences in selective constraint (i.e. whether genes downstream in the pathway are less subject to purifying natural selection because they influence fewer characters). A second goal of this project is to begin examining the relative importance of regulatory and structural genes in adaptive divergence between species by determining the molecular basis of phenotypic divergence. The long-term goal of this project is to examine a large number of species whose color pattern has diverged from the presumed ancestral type of cyanidin-based blue/purple pigmentation throughout the corolla limb and throat. For each species the relative contribution of structural and regulatory genes to divergence will be determined. However, the current objective is more limited: to characterize the genetic changes that have resulted in the production of white flowers by two species, I. alba and I. igualensis. Initially, investigation will concentrate on these two species to demonstrate the feasibility of the proposed approach.