Conducting assisted evolution in a threatened coral species for promoting more resilient reef ecosystems in the face of climate change

珊瑚礁是生物多样性的储存库，对维持健康的生态系统至关重要。然而，由于与气候变化有关的持续有害的人为影响和自然事件，人们担心，环境变化的强度和复杂性正在压倒珊瑚适应和生存的内在能力。作为增加珊瑚弹性和促进珊瑚礁生态系统长期生存的可能解决方案，我提出了一项研究，利用人类辅助进化和选择性育种来加速自然发生的进化过程，以提高关键的耐受性性状。使用弹性基因型进行种内杂交是一种快速产生甚至更稳健的基因型的方法，因为有性生殖可以将多个有益等位基因联合收割机组合到单个基因组中，因此更快地产生更适合的基因型。此外，利用有性繁殖的珊瑚提供了获得数百万繁殖体的机会，从而增加了实验测试的可能性，以估计对适应气候变化至关重要的特征的遗传性，并产生大量可用于恢复工作的个体。具体而言，我建议进行第一次实验调查的选择性繁殖的受威胁的和生态上重要的珊瑚物种，鹿角珊瑚，以测试的假设，交叉温度和疾病的弹性基因型可以产生后代，更强大的耐热性和抗病性在当前和/或预计的环境条件下。随着时间的推移，我将测量一系列生理反应作为适应性的代表，并从这些数据中确定耐热性和疾病恢复力的遗传性，这对于评估适应潜力至关重要。我还将比较差异基因表达在环境和压力条件下随着时间的推移，以确定有助于珊瑚弹性的分子途径。然后，我将进行适应性测定，以测试pH耐受性的权衡，因为对性状的选择可能会导致其他性状的负面适应性后果。随着海洋酸化加剧导致海水pH值降低，pH耐受性也是需要考虑的一个重要特性。最后，我将选择一系列健壮的基因型进行田间试验，并将它们放置在同一个离岸苗圃中，在那里饲养亲本基因型，以原位监测它们随时间的生长和存活。这项研究的结果将产生深远的影响，因为遗传力和基因表达分析的数据将有助于基础科学研究，因为大多数珊瑚物种的性状遗传力在很大程度上是未知的。此外，如果选择性繁殖被证明是成功的，这种方法可能适用于其他物种和地区，并最终有助于推进全球珊瑚恢复战略。

Coral reefs serve as reservoirs of biodiversity and are essential for the maintenance of healthy ecosystems. However, as a result of continued detrimental anthropogenic effects and natural events linked to climate change, it is feared that the intensity and complexity of environmental changes are overwhelming the intrinsic ability of corals to adapt and survive. As a possible solution for increasing coral resiliency and for promoting the long-term survival of reef ecosystems, I am proposing a study for using human-assisted evolution and selective breeding to accelerate naturally-occurring evolutionary processes in order to enhance key tolerance traits. Performing intraspecific crosses using resilient genotypes is one method for rapidly generating even more robust genotypes because sexual reproduction can combine multiple beneficial alleles into a single genome and therefore generate fitter genotypes faster. Moreover, utilizing sexually-reproducing corals offers access to millions of propagules, thereby increasing the potential for experimental testing, for estimating the heritability of traits crucial for adaptation to climate change, and for producing large numbers of individuals that can be reared for restoration efforts. Specifically, I am proposing to perform the first experimental investigation of selective breeding in a threatened and ecologically-important coral species, Acropora cervicornis, in order to test the hypothesis that crossing temperature and disease resilient genotypes can generate offspring that are more robust in terms of thermotolerance and disease resistance under current and/or projected environmental conditions. I will measure, over time, a suite of physiological responses as proxies for fitness and from these data determine the heritability of thermotolerance and disease resilience, which is crucial for evaluating adaptive potential. I will also compare differential gene expression during ambient and stressful conditions over time in order to identify the molecular pathways contributing to coral resilience. Then I will conduct fitness assays to test for trade-offs to pH tolerance, as selection on trait(s) can lead to negative fitness consequences for other traits. With increasing ocean acidification resulting in lower seawater pH values, pH tolerance is also an important trait to consider. Finally, I will select a range of robust genotypes for conducting field trials and place them in the same offshore nursery where the parental genotypes are housed to monitor, in-situ, their growth and survival over time. The results of this study will have far-reaching implications as the data from the heritability and gene expression analyses will be useful for basic sciences research since trait heritabilities are largely unknown for most coral species. Additionally, if selective breeding proves successful, this method may be adapted to other species and regions and ultimately help to advance coral restoration strategies worldwide.