NSFDEB-NERC: The origin of reproductive parasitism in the Amazon Molly

这个项目将通过探索一个明显的生殖悖论来研究复杂的特征是如何进化的。绝大多数物种有两种性别，而且双方都需要繁殖。但一种生殖模式，即雌核发育，似乎结合了一种看似不可能的特征组合。在这种模式下，卵子必须由不同物种的雄性受精，但雄性提供的基因不会整合到后代中，因此产生的后代在基因上与他们的母亲相同。这种繁殖模式需要进化出几个重要的进化变化：排斥父亲的DNA，失去雄性，以及形成二倍体卵子。在单个进化步骤中发生大规模转变是极不可能的，但这是主流的解释。在拟议的项目中，研究人员将通过复制导致亚马逊莫利鱼起源的进化路径，形成一个合成的雌核发育物种。数学模型将指导跨越现有物种及其杂交物种的实验。这项研究还将通过研讨会和培训机会向公众提供多名年轻科学家的机会。这项研究将通过两个现有物种的杂交，人工形成一个雌核发育物种，确定从一个物种到另一个物种最可能的进化路径。现有的物种来自德克萨斯州和墨西哥，新物种是自然杂交事件的结果。为了追溯这一物种的进化，研究小组将使用包括微分方程式和蒙特卡洛模拟在内的几种数学技术来模拟一组独特特征进化的最可能途径，包括单性、未减少卵子的形成和克隆。目前的想法假设，所有这些变化都发生在一个进化步骤中，但这似乎不太可能。在模型的指导下，将在实验室进行大规模杂交实验，以实际形成雌核发育物种。这项实验将包括有性鱼类的杂交，产生的F1个体之间的杂交，以及回交。每一个独特的杂交都将进一步从基因组、基因和形态上进行表征。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project will examine how complex traits evolve by exploring an apparent reproductive paradox. The vast majority of species have two sexes and both are needed to reproduce. But one mode of reproduction, gynogenesis, seems to combine a seemingly impossible combination of traits. In this mode, eggs have to be fertilized by males of a different species, but the genes provided by males are not incorporated into the offspring so that the resulting offspring are genetically identical to their mothers. This reproductive mode requires the evolution of several important evolutionary changes: rejection of the father's DNA, the loss of males, and the formation of diploid eggs. Large transitions in a single evolutionary step is highly unlikely, but this is the prevailing explanation. In the proposed project, the researchers will form a synthetic gynogenetic species by replicating the evolutionary pathway that led to the origin of the fish, the Amazon molly. Mathematical models will guide experiments that cross existing species and their hybrids. This research also will provide outreach to the public via workshops and training opportunities for multiple young scientists.The research will artificially form a gynogenetic species through hybridization of two existing species, determining the most likely evolutionary pathway from one to the other. The existing species are from Texas and Mexico, and the new species resulted from a natural hybridization event. To retrace the evolution of this species, the research team will use several mathematical techniques, including differential equations and Monte-Carlo simulations to model the most likely pathway for the evolution of a unique set of traits, including unisexuality, formation of unreduced eggs, and clonality. Current thinking hypothesizes that all of these changes happened in one evolutionary step, but this seems unlikely. Guided by the models, a large-scale crossing experiment will be conducted to actually form a gynogenetic species in the laboratory. This experiment will involve crossing sexual fishes, the resulting F1 individuals amongst each other, and backcrosses. Every unique cross will further be characterized genomically, genetically, and morphologically.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.