Dissertation Research: Using Genealogical Portraits of Speciation to Understand Diversity Patterns

富马 9801284 拟议中的研究使用分子分析来深入了解相对较近的地质历史中的物种起源，以及气候重大变化的生物后果。 北美西部的山脉为高海拔物种构成了一个不寻常的空中岛屿群岛。 与之密切相关的物种，包括黑蝗以及其他动物和植物，占据了不同的山脉和山峰，这种模式表明最近的进化多样化。 人们经常认为，这些物种起源于大约1万年前结束的更新世冰川时期的隔离和殖民。然而，目前尚不确定哪些地区仍然没有冰，或者在冰期和间冰期交替期间，草原等栖息地是如何分布的。 因此，生物体占据不同山脉并分化成不同物种的确切历史是非常不确定的。 例如，随着冰川的消退，物种可能从南部的避难所逐渐迁移到更多的北方地区。 或者，祖先物种可能在低海拔地区持续存在，并产生了新的物种，因为当气候变暖时，它们的栖息地仅限于孤立的山顶。 这项拟议中的研究使用Melanoplus蚱蜢来更全面地确定西部山区生物多样性起源的历史。 不同山脉的种群和物种之间的DNA序列比较可以提供分歧的日期，从而检验许多物种在更新世冰川期间或之后形成的假设。 从DNA序列重建物种之间的进化关系，将被用来确定物种是通过分裂还是通过逐步向北殖民形成的。这项研究将为进化辐射提供为数不多的全面观点之一。 利用现代系统发育技术和种群遗传模型，它将测试有关物种形成的假设，从而提供对多样性起源的见解。 它将揭示过去气候变化如何影响生物的分布和多样性-这些信息可能有助于预测未来全球气候变化的影响。

Futuyma 9801284 The proposed research uses molecular analyses to gain insight into the origin of species in the relatively recent geological past, and into the biological consequences of major changes in climate. The mountains of western North America constitute an unusual archipelago of sky islands for high-altitude species. Closely related species, including Melanoplus grasshoppers as well as other animals and plants, occupy different mountain ranges and peaks, in a pattern that suggests recent evolutionary diversification. It as often been suggested that such species originated by isolation and colonization during the Pleistocene glaciations that ended about 10,000 years ago. However, it is not certain which regions remained free of ice, or how habitats such as grasslands were distributed during the alternating glacial and interglacial periods. Thus the exact history by which organisms came to occupy different mountain ranges and differentiated into distinct species is very uncertain. For instance, species may have colonized progressively more northern areas from southern refuges as the glaciers retreated. Alternatively, ancestral species may have persisted at low altitudes, and have given rise to new species, as their habitats became restricted to isolated mountaintops when the climate became warmer. The proposed research uses Melanoplus grasshoppers to determine more fully the history by which biodiversity has originated in the western mountains. Comparisons of DNA sequences among populations and species from different mountain ranges can provide dates for divergence, and thus test the hypothesis that many species formed during or since the Pleistocene glaciations. Evolutionary relationships among species as reconstructed from DNA sequences, will be used to determine whether species formed by fragmentation or by progressive northward colonization. This research will provide one of the few comprehensive views of an evolutionary radiation. Using modern phylogenetic techniques and population genetic models, it will test hypotheses about species formation, and thus provide insights into the origin of diversity. And it will cast light on how past changes in climate have affected the distribution and diversity of organisms - information that may help to predict effects of future global changes in climate.