The life cycles of parasitic worms, from macroevolutionary patterns to the genetics of adaptation

寄生虫的生命周期，从宏观进化模式到适应遗传学

• 批准号: 408202975
• 负责人: Dr. Daniel Benesh
• 金额: --
• 依托单位: Institut für Fischereiökologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/408202975?language=en
• 关键词: life; cycles; parasitic; worms; macroevolutionary

Many parasites have complex life cycles in which they infect multiple hosts in succession before reproducing. These life cycles are perplexing, because they seem risky. As the number of consecutive hosts in a life cycle increases, so does the risk of not making it to the next host and thus not completing the cycle. Additionally, such parasites must adapt to different host physiologies, immune systems, and often thermal regimes (e.g. when moving from cold- to warm-blooded hosts). What are the offsetting benefits that explain the evolution and persistence of complex life cycles in multiple parasite taxa? And what genetic changes enable such a life style? To address these questions, I propose two complementary kinds of projects: (i) cross-species comparative analyses and (ii) genomic and transcriptomic comparisons. I have compiled a comprehensive database of parasitic worm life cycles that includes nearly 1000 species. I will use this database to test hypotheses about life cycle evolution, such as whether complex life cycle parasites grow larger or infect a wider variety of hosts. These analyses will identify key differences between simple- and complex-cycle parasites. I then propose exploring how such differences are manifested in parasite genomes. I will use existing datasets to look for shared genomic features in independent lineages, like gene family expansions or increases in alternative splicing, that would be indicative of general solutions to the problems posed by complex life cycles. I also describe transcriptomic experiments assessing when and to what extent parasite stages in different hosts are genetically ‘decoupled’, i.e. whether genetic changes affecting a stage in one host have correlated effects on stages in other hosts. By combining phenotypic, genomic, and transcriptomic approaches, I hope to reveal both why (the costs and benefits) and how (the genetic mechanisms of adaptation) complex life cycles have evolved.

许多寄生虫具有复杂的生命周期，在繁殖之前，它们连续感染了多个宿主。这些生命周期令人困惑，因为它们似乎有风险。随着生命周期中连续的宿主数量的增加，不进入下一个主机而无法完成周期的风险也会增加。此外，此类寄生虫必须适应不同的宿主生理，免疫系统和通常的热度状态（例如，从冷血宿主到温水时）。解释多个寄生虫分类单元中复杂生命周期的演变和持久性的抵消好处是什么？什么遗传变化使这种生活方式变化？为了解决这些问题，我提出了两个完整的项目：（i）跨物种比较分析以及（ii）基因组和转录组比较。我编制了一个寄生虫生命周期的综合数据库，其中包括将近1000个，我将使用此数据库来测试有关生命周期进化的假设，例如复杂的生命周期寄生虫是生长更大还是感染了各种各样的宿主。这些分析将确定简单周期和复杂周期寄生虫之间的关键差异。然后，我建议探索如何在寄生虫基因组中表现出这种差异。我将使用现有数据集在独立谱系中寻找共享的基因组特征，例如基因家族扩展或替代剪接的增加，这将表明对复杂生命周期针对的问题的一般解决方案。我还描述了转录组实验评估不同宿主的寄生虫阶段的何时何种程度，在遗传上是“解耦”的，即遗传变化是否影响一个宿主的阶段，对其他宿主的阶段具有相关作用。通过结合表型，基因组和转录组方法，我希望揭示原因（成本和收益）以及（适应性的遗传机制）复杂生命周期的发展。