Selection experiments and sequencing to identify mechanisms of thermal adaptation in a splash pool copepod

耐热性是一个重要的特征，因为它影响到一个物种的生存环境，以及它是否能在变暖的气候中生存。不同物种的耐热性各不相同，但人们对使一些动物和植物比其他动物和植物更耐热的基因差异知之甚少。本研究将使用小型海洋甲壳类动物加利福尼亚虎甲作为实验模型，研究导致耐热性增加的遗传变化。研究人员将进行一系列的进化实验，他们将在实验室中人为地选择Tigriopus的耐热性。在实验结束时，他们将对实验种群的基因组进行测序，以检查哪些基因变化导致了更强的耐热性。然后，他们将把这些基因变化与北方和南方Tigriopus种群之间的差异进行比较，这两个种群在耐热性上自然不同，以测试同样的变化是否导致了实验室和自然界中耐热性的增加。这项研究将有助于更好地理解为什么一些物种比其他物种更耐热，从而提高预测哪些物种更容易受到气候变化影响的能力。对导致更强耐热性的基因变化的了解也可以用于水产养殖和保护育种计划，以确定特定物种的哪些菌株最有可能适应变暖。热耐受性性状决定了生物在不同环境中的丰度和分布，并决定了生物对气候变化的反应。然而，大多数物种的热耐受性变化机制尚不清楚。泼溅池桡足动物加利福尼亚虎爪在不同种群中表现出不同的耐热特性，并且很容易在实验室中杂交和饲养。因此，它是研究温度适应机制的一个很好的模型。研究人员将进行三个选择实验，每个实验针对不同Tigriopus种群的热性能的不同方面：(a)致死上限，(B)热极限的可塑性，(C)热最佳。他们将把这些实验与生理测量、转录组分析和全基因组重测序结合起来，以确定热适应各个方面的潜在机制。最后，他们将把实验室实验结果与分布在北美和南美平行温度梯度上的两种Tigriopus物种的种群重测序数据进行比较。该项目的研究结果将提供该物种温度适应的遗传和生理基础的综合图谱，并揭示一些关键问题，包括基因调控与蛋白质编码变化在种群间生理差异中的作用、参与温度适应的基因组比例、热宽度增加的进化所带来的成本和权衡。以及适应平行环境梯度的可重复性。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

Heat tolerance is an important trait, because it influences where a species can live, and whether it will survive in a warming climate. Heat tolerance varies among species, but little is understood about the genetic differences that make some animals and plants more heat tolerant than others. This research will use the small marine crustacean, Tigriopus californicus, as an experimental model to investigate the genetic changes lead to increased heat tolerance. The researchers will conduct a series of evolution experiments, where they will artificially select for increased heat tolerance in Tigriopus in the laboratory. At the end of the experiments they will sequence the genomes of the experimental populations to examine which genetic changes led to greater heat tolerance. Then they will compare these genetic changes to differences among northern and southern populations of Tigriopus, which naturally differ in their heat tolerance, to test whether the same changes are responsible for increased heat tolerance in the lab and in nature. This research will contribute a greater understanding of why some species are more heat tolerant than others, leading to an improved ability to predict which species will be more vulnerable to climate change. An understanding of the genetic changes that lead to greater heat tolerance could also be used in aquaculture and in conservation breeding programs, to identify which strains of a given species are the most likely to be resilient to warming.Thermal tolerance traits govern the abundance and distribution of organisms across environments and shape organismal responses to climate change. However, mechanisms determining variation in thermal tolerance are poorly understood for most species. The splash pool copepod Tigriopus californicus exhibits divergent thermal tolerance traits across populations, and is easily crossed and reared in the lab. As a result, it is an excellent model for examining mechanisms of temperature adaptation. The researchers will perform three selection experiments, each targeting a different aspect of thermal performance that differs among Tigriopus populations: (A) upper lethal limits, (B) plasticity of thermal limits, and (C) thermal optima. They will combine these experiments with physiological measurements, transcriptome profiling, and whole-genome resequencing to identify mechanisms underlying each aspect of thermal adaptation. Finally, they will compare results of laboratory experiments to population resequencing data for two Tigriopus species distributed over parallel temperature gradients in North and South America. Results of this project will provide a comprehensive map of the genetic and physiological bases of temperature adaptation in this species, and shed light on key questions, including the role of gene regulation vs. protein coding changes in physiological divergence among populations, the proportion of the genome involved in temperature adaptation, the costs and trade-offs imposed by the evolution of increased thermal breadth, and the repeatability of adaptation across parallel environmental gradients.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.