CAREER: Colonizing Land Via the Estuarine Route: Ontogeny of Osmoregulation and Settlement Behaviors in Three Brackish Water Fiddler Crabs

职业生涯：通过河口路线殖民土地：三种微咸水蟹渗透调节和定居行为的个体发育-南卡罗来纳大学雷纳·J·布罗迪大学陆地殖民是动物生活史上最重要的进化事件之一。虽然脊椎动物是陆地动物群的显眼成员，但最多产和最多样化的陆地动物实际上是从海洋祖先进化而来的无脊椎动物。海洋无脊椎动物定居面临的首要挑战之一是需要修改幼虫阶段，以便它们在接近成年陆地栖息地的地方进行招募。幼虫的定居行为必须改变，幼虫必须进化出耐受陆地上遇到的生理压力的能力。在完全陆地动物中，这些早期生命阶段在陆地上发育，在具有保护性的卵膜内或在成年父母体内。这项研究将研究处于陆地入侵中间阶段的淡水招潮蟹Uca minax幼虫行为和生理的变化。为了检验这些变化，Uca minax将与两个较少的陆生近亲Uca pugilator和Uca pugnax进行比较。这三个物种都在沿海海域经历幼虫发育。使用分子遗传技术，这些蟹类将被追踪，从它们离开沿海开放水域进入南卡罗来纳州北部入海口，直到它们作为幼体加入成年种群。这将解开幼蟹是直接定居在成年栖息地，随着它们的发育和成长逐渐迁入，还是在整个河口随机定居，在不适合它们的地区灭绝的谜团。一旦定居模式建立，幼虫对不同盐度环境中成虫气味线索的反应将在实验室进行研究。与其他两个物种不同的行为反应可能有助于解释它是如何入侵成体淡水和陆地栖息地的。为了确定幼体是否在生理上适应低盐度条件，将幼虫和幼体在一系列盐度(对淡水的海洋强度)中的存活率与来自巴西的远亲物种--打斗鱼、普格纳克斯和乌鲁瓜伊斯的存活率进行比较。还将评估在这些盐度下的渗透调节能力(控制内部盐浓度的能力)。通过这种方式，将有可能探索伴随着陆地入侵而发生的发育中渗透调节变化的进化。除了产生进化见解外，这项研究还将具有生态和教育影响。招潮蟹是东南部河口的主要参与者，在那里它们是鸟类和鱼类的重要猎物，并改变它们洞穴和觅食地区的地形和物种组成。更详细地了解幼蟹的扩散模式、行为和生理，将有助于对河口的监测。这项工作的教育效益将来自于大力提高有色人种参与生物研究的水平。为此，将从南卡罗来纳大学和附近历史上的黑人学院和大学招募有色人种研究生和本科生，以协助拟议的研究。此外，本科生和研究生将把科学工作的方方面面转化为K-12学生的动手活动，在当地小学生的帮助下，这些活动将被开发成一个关于海洋和陆地无脊椎动物的网站。

CAREER: Colonizing land via the estuarine route: ontogeny of osmoregulation and settlement behaviors in three brackish water fiddler crabsRenae J. BrodieUniversity of South CarolinaThe colonization of land is one of the most significant evolutionary events in the history of animal life. While vertebrates are conspicuous members of terrestrial faunas, the most prolific and diverse land animals are actually invertebrates that have evolved from marine ancestors. One of the first challenges faced by colonizing marine invertebrates is the need to modify larval stages so they recruit near adult terrestrial habitats. Larval settlement behaviors must change and larvae must evolve the capability to tolerate physiological stresses that they encounter on land. In completely terrestrial animals, these early life stages develop on land within protective egg membranes or inside the adult parent. This study will examine changes in larval behavior and physiology in Uca minax, a freshwater fiddler crab that is at an intermediate stage of land invasion.To examine these changes, U. minax will be compared to two less terrestrial relatives, Uca pugilator and Uca pugnax. All three species undergo larval development in coastal marine waters. Using molecular genetic techniques, these fiddler crab species will be tracked from when they leave open coastal waters and enter South Carolina's north inlet estuary, until they join adult populations as juveniles. This will resolve the mystery of whether young crabs settle directly into adult habitats, move in gradually as they develop and grow, or settle randomly throughout the estuary, dying out in areas that are not suitable for them. Once patterns of settlement are established, larval responses to adult odor cues in different salinity environments will be investigated in the lab. A different suite of behavioral responses by U. minax compared to the other two species may help to explain how it invades adult freshwater and terrestrial habitats.To determine if young U. minax are physiologically adapted to survive low-salinity conditions, survivorship of larval and juvenile U. minax in a series of salinities (ocean-strength to freshwater) will be compared to that of U. pugilator, U. pugnax and U. uruguayensis, a distantly-related species from Brazil. Osmoregulatory ability (ability to control internal salt concentrations) at these salinities will also be assessed. In this way, it will be possible to explore the evolution of osmoregulatory changes in development that accompany the invasion of land in fiddler crabs.In addition to yielding evolutionary insights, this study will have ecological and educational impacts. Fiddler crabs are dominant players in southeastern estuaries, where they are important prey for birds and fishes, and modify landscape topography and species composition in areas where they burrow and feed. A more detailed understanding of the dispersal patterns, behavior and physiology of young fiddler crabs will facilitate the monitoring of estuaries. The educational benefits of this work will come from a strong effort to increase the level of participation of people of color in biological research. To this end, graduate and undergraduate students of color will be recruited from the University of South Carolina and nearby Historically Black Colleges and Universities to assist in the proposed research. Also, undergraduate and graduate students will turn aspects of the scientific work into hands-on activities for K-12 students that will be developed for a Web site about marine and terrestrial invertebrates with the assistance of local elementary-school children.