Dissertation Research: The Role of Selection in Diversifi- cation of Herbivorous Insects: An Analysis of Mechanism

物种增殖必须通过进化 生殖隔离。 然而，很少有研究 进化辐射探索了 生物学创新可能促进物种形成。 的 相对少数食草动物的高繁殖率 昆虫分类群表明，草食动物代表了一种 创新促进辐射。 寄主植物 此外，专业化可能会促进 生殖隔离，作为寄主植物：1）是斑块状的 分布，产生地理隔离，2） 施加强大的选择压力，产生适应性 发散 学生将研究 食叶甲虫属。 三个地理上隔离的N. Bebbianae，两个共享同一宿主的生物，将成为焦点 微观进化研究 生殖程度 同寄主种群对表现出的隔离 将与不同主机对进行比较， 各种潜在的隔离成分。 不同宿主之间观察到的隔离度更高 人口将支持这一假设， 物种形成是由选择驱动的，而不是随机的。 遗传漂变。 基于DNA序列的系统发育研究 将被执行，并用于推断主机关联 古老的蕨类植物

Species proliferation must occur through the evolution of reproductive isolation. However, few studies of evolutionary radiation explore the mechanisms by which biological innovations may facilitate speciation. The high diversities of the relatively few herbivorous insect taxa suggest that herbivory represents an innovation fostering radiation. Host-plant specialization, furthermore, may plausibly promote reproductive isolation, as host plants: 1) are patchily distributed, yielding geographic isolation, and 2) exert strong selection pressures, yielding adaptive divergence. The student will investigate speciation in the leaf-feeding beetle genus Neochlamisus. Three geographically isolated populations of N. bebbianae, two sharing the same host, will be the focus of microevolutionary study. The degree of reproductive isolation exhibited by the same-host population pair will be compared to that for a different-host pair for a variety of potential components of isolation. Greater observed isolation between the different-host populations would support the hypothesis that speciation is driven by selection rather than by random genetic drift. A DNA sequence-based phylogenetic study will be performed and use to infer host-associations of ancestral ferns.