DISSERTATION RESEARCH: Avian contact zones and phylogeographic breaks in northern Amazonia: unveiling the outcome of secondary contact in closely related pairs of taxa

亚马逊流域具有高度的生物多样性，是研究地理因素对物种多样化影响的理想区域。众所周知，亚马孙大河是将遗传上截然不同的鸟类（物种对或不同亚种）隔离开来的屏障。然而，河流在源头不再充当屏障，在那里，许多成对的鸟类在其他地方相遇。本研究的目的是利用90对鸟类物种或亚种，探索河流作为基因流动障碍（系统地理断裂）和河流源头作为交汇点（接触带）的作用。本研究将以羽毛特征和分子数据为重点，开创一种比较多物种的方法来研究亚马逊偏远地区的鸟类分布和物种相互作用。本研究将解决进化生物学中长期存在的问题，包括物理和生态屏障在接触带地理位置中的作用，河流作为历史和当代鸟类物种障碍的作用（“河流屏障”假说），以及遗传独特性与两个种群在接触时杂交可能性之间的关系。该项目依赖于美国、巴西和委内瑞拉机构之间的密切合作。在亚马逊地区进行实地考察的包括巴西学生和助理，他们被介绍到以博物馆为基础的生物多样性研究。这个项目很可能导致与南美科学家的长期合作。了解物理障碍如何阻止基因流动将有助于理解大规模人为分裂对自然种群的影响。

The Amazon basin has high biodiversity and is an ideal region in which to examine geographic influences on species diversification. Large Amazonian rivers are known to act as barriers that separate genetically distinct populations of related birds (species pairs or different subspecies). Rivers, however, cease to act as barriers in their headwaters, where many pairs of otherwise divided populations of birds come into contact. The aim of this study is to explore both the role of rivers as barriers to gene flow (phylogeographic breaks) and the rivers' headwaters as meeting points (contact zones) using 90 pairs of species or subspecies of birds. This research will pioneer a comparative multi-species approach to study bird distributions and species interactions in remote regions of the Amazon, focusing on plumage characters and molecular data. This study will address long-standing questions in evolutionary biology, including the role of physical and ecological barriers in the geographic location of contact zones, the role of rivers as historical and contemporary barriers to bird species (the "Riverine Barrier" hypothesis), and the relationship between genetic distinctness and the likelihood that two populations will interbreed when in contact.This project relies on close cooperation between American, Brazilian, and Venezuelan institutions. Fieldwork in Amazonia included Brazilian students and assistants, who were introduced to museum-based studies of biodiversity. This project is likely to lead to long-term collaborations with South American scientists. Understanding how physical barriers prevent gene flow will help understand the consequences of large-scale human-created fragmentation on natural populations.