The Evolution of Placentas in the Poeciliid Fishes: An Empirical Study of the Evolution of Complexity

大卫·雷兹尼克和迈克尔·盖多蒂 胎盘是一个复杂的器官，它是许多适应性的复合体，必须很好地整合以实现适当的功能。 大卫·雷兹尼克和迈克尔·盖多蒂将研究鱼科中胎盘的进化。 他们将根据DNA序列和形态学建立一个“家谱”，以确定胎盘是否在不同的分支上独立进化，并确定有或没有胎盘的物种群体。 这些鱼类中有30种是密切相关的，并且具有不同形式的母体供应，这些实验将测试胎盘进化的最新理论的预测。 在《物种起源》一书中，达尔文在《物种起源》中加入了一个名为“理论上的困难”的章节，考虑了自然选择进化理论面临的最严重挑战。 一个是复杂器官的起源：进化似乎不可能同时整合许多特征。 他提出，如果每一步都代表一种适应，那么复杂性可以通过小步进化。 这些鱼提供了一个检验达尔文理论的机会。 该研究还将为学生提供多学科培训，与生物学的几个领域相关，并提出进化的案例研究。

David Reznick + Michael Ghedotti DEB-0416085 + 0415633 AbstractThe Evolution of Placentas in the Poeciliid Fishes: An Empirical Study of the Evolution of ComplexityThe placenta is a complex organ that is a composite of many adaptations that must be well integrated for proper function. David Reznick and Michael Ghedotti will study the evolution of the placenta in the fish family Poeciliidae. They will develop a "family tree", based on DNA sequence and morphology, to determine if the placenta evolved independently on different branches and to define groups of species that do or do not have the placenta. Experiments on 30 species of those fish that are closely related and have different forms of maternal provisioning will test the predictions of a recent theory for the evolution of the placenta. Working together, the biologists will provide insights to refine the theory, while theoreticians will provide insights to suggest new lines of experimental inquiry.In the Origin of Species, Darwin included a chapter entitled "Difficulties on Theory", considering the most serious challenges to the theory of evolution by natural selection. One was the origin of complex organs: it seemed improbable that evolution could integrate many traits at once. He proposed that complexity could evolve by small steps if each represented an adaptation. These fish provide an opportunity to test Darwin's proposition. The research will also offer multidisciplinary training for students, be relevant to several fields of biology, and present a case study in evolution.