Dissertation Research: The Mechanism of Selection at the Mpi Polymorphism in Semibalanus balanoides

Rand 9801563以前的工作表明，自然选择在决定潮间带橡子藤壶中负责碳水化合物代谢的关键酶的两个不同遗传变体的分布方面非常重要。携带一种酶的甘露糖磷酸异构酶(MPI)的藤壶在较热的高潮间带有较高的存活率，而具有另一种MPI变种的藤壶在较良性的地点如低潮间带和海藻下有较高的存活率。拟议的实验将在流动的海水水箱中检查不同酶变种的藤壶在受控条件下的存活率。温度、干燥度和甘露糖的利用率将在析因设计中进行处理。已经在野外岩板上定居的藤壶将被带到实验室，并允许在不同的条件组合下生长。实验处理前后MPI酶变体的比例将提供关于自然选择对这种酶的作用的明确信息，该酶调节饮食甘露糖(从海藻)转化为细胞能量的关键步骤。这项研究将涉及异质环境在维持自然种群遗传变异中的作用。

Rand 9801563 Previous work has shown that natural selection is important in determining the distribution of two different genetic variants of a key enzyme responsible for carbohydrate metabolism in the intertidal acorn barnacle, Semibalanus balanoides. Barnacles with one enzyme variant of mannose phosphate isomerase (Mpi) exhibit higher survivorship in hotter, high-intertidal sites, while barnacles with the other Mpi variant have higher survivorship at more benign sites such as the low intertidal and under seaweeds. The proposed experiments will examine the survivorship of barnacles with different enzyme variants under controlled conditions in a flowing sea water tank. Temperature, desiccation, and the availability of mannose will be manipulated in a factorial design. Barnacles that have settled onto rock slabs in the wild will be brought into the lab and allowed to grow under different combinations of conditions. The proportions of Mpi enzyme variants before and after experimental treatments will provide explicit information about the action of natural selection on this enzyme that regulates a key step in the conversion of dietary mannose (from marine algae) into cellular energy. The research will bear on the role of heterogeneous environments in the maintenance of genetic variation in natural populations.