The Developmental Biology of Hybrid Incompatibility

杂种不相容性的发育生物学

• 批准号: 1936674
• 负责人: Scott Rifkin
• 金额: $ 77.5万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-15 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1936674&HistoricalAwards=false
• 关键词: Developmental; Biology; Hybrid; Incompatibility

Nontechnical description of the project: Over the course of evolution, species often become divided into subgroups, and members of different subgroups may become unable to produce healthy offspring with each other. Instead, the offspring can be sick or sterile or even die before reaching adulthood. At that point, scientists consider these subgroups to be different species. When they die, their deaths result from mistakes made during development, and the goal of this project is to determine whether there are general rules that explain why these hybrid offspring die when and how they do. Perhaps these mistakes are idiosyncratic, with each individual dying in its own way. Perhaps hybrids between two species die in one way but hybrids between two others die in a different way. Or perhaps, within a group of related species, the same pattern of when and how hybrids die is repeated over and over because some parts and phases of development are more sensitive to disruption than others. To test which of these is the case, this project will use a group of related roundworms which look very similar but whose hybrid offspring tend to die as embryos. This investigation of species incompatibility will also form the basis for two hands-on science modules aligned with the California secondary school biology standards. In one students will test for themselves whether different species can mate, and in the other they will trap roundworms in the wild and use their DNA to identify the species or to discover that they are new to science.Technical description of the project: As species separate during evolution, incompatibilities at the genome level can accumulate and ratchet the process forward. These incompatibilities often play out during development and render hybrid offspring inviable or infertile. The developmental biology of this process is relatively little studied. Recent advances in microscopy have made it possible to quantitatively and comprehensively measure key aspects of development in real time in an increasing range of organisms. This capacity makes it possible to test hypotheses about the variability of the cellular processes that construct organisms, to compare these both within and between species, and to dissect exactly what is disrupted when development goes wrong. Through a combination of systematic crosses, high-resolution 4D microscopy of developing embryos, and targeted measurements of gene expression, this project will test three primary hypotheses about the developmental biology of hybrid inviability using the Caenorhabditis roundworm genus as a model system. These nematodes are ideal for this kind of study because their normal development is stereotyped and repeatable, different species will often mate with each other even though their embryos die, and the genus includes at least two species pairs that are in the process of speciating and remain partially interfertile. The study will determine when and how hybrid embryos tend to die, where and when the first defects in development appear, whether these defects are caused by abnormal cell movement or by abnormal cell fate decisions, and whether these patterns are systematic across the genus or idiosyncratic for each embryo or species pair.Statement of Merit Review,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.

项目的非技术性描述：在进化过程中，物种经常被分成亚群，不同亚群的成员可能无法相互产生健康的后代。相反，后代可能生病或不育，甚至在成年前死亡。 在这一点上，科学家认为这些亚群是不同的物种。当它们死亡时，它们的死亡是由于发育过程中的错误造成的，这个项目的目标是确定是否有一般规则来解释为什么这些杂交后代在何时以及如何死亡。也许这些错误是特殊的，每个人都以自己的方式死去。也许两个物种之间的杂交种以一种方式死亡，但另外两个物种之间的杂交种以不同的方式死亡。 或者，在一组相关的物种中，杂交种何时以及如何死亡的相同模式会一次又一次地重复，因为发育的某些部分和阶段比其他部分和阶段更容易受到破坏。为了测试哪一种是这种情况，该项目将使用一组相关的蛔虫，它们看起来非常相似，但其杂交后代往往在胚胎中死亡。这种物种不相容性的调查也将形成两个动手科学模块与加州中学生物标准对齐的基础。在一个实验中，学生们将亲自测试不同物种是否可以交配;在另一个实验中，他们将在野外诱捕蛔虫，并利用它们的DNA来识别物种或发现它们是科学上的新物种。项目技术描述：随着物种在进化过程中的分离，基因组水平上的不相容性会积累并推动这一过程。这些不相容性通常在发育过程中发挥作用，使杂交后代不能存活或不育。这一过程的发育生物学研究相对较少。显微镜技术的最新进展使人们有可能在越来越多的生物体中以真实的时间定量和全面地测量发育的关键方面。这种能力使我们有可能检验关于构成生物体的细胞过程的变异性的假设，在物种内部和物种之间比较这些假设，并确切地剖析当发育出错时受到破坏的东西。通过系统杂交，发育胚胎的高分辨率4D显微镜和基因表达的有针对性的测量相结合，该项目将使用小杆线虫属作为模型系统来测试关于杂交不活力的发育生物学的三个主要假设。这些线虫是这种研究的理想对象，因为它们的正常发育是定型的和可重复的，不同的物种即使胚胎死亡也会经常相互交配，并且该属至少包括两个物种对，它们正在形成物种并保持部分可繁殖。该研究将确定杂交胚胎倾向于何时以及如何死亡，发育中的第一个缺陷出现在何处以及何时，这些缺陷是由异常细胞运动或异常细胞命运决定引起的，以及这些模式是否是跨属的系统性或每个胚胎或物种对的特异质。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估的支持。