Understanding how species may respond to climate change is of paramount importance. Species that occupy highly heterogenous environments, such as intertidal zone estuarine habitats, provide an ideal test case for examining phenotypic and genomic adaptations to different environmental conditions, which may influence their response to rapidly shifting climatic conditions. The California coast is projected to experience changes in both temperature and salinity, which currently vary seasonally and latitudinally. Using comparative transcriptomics, I documented patterns of positive selection between the northern-dwelling planktotrophic sacoglossan sea slug Alderia modesta, which is remarkably tolerant of low temperatures and low salinities, and its southern congener Alderia willowi, which exhibits a striking flexibility for larval type in response to seasonally shifting changes in temperature and salinity. Out of over 4000 1-to-1 orthologous genes, I found a signal of positive selection between A. willowi and A. modesta for genes involved in cell membrane and cell transport, particularly ion homeostasis (aquaporin), cell-cell signal transduction, and phosphorylation (reduced nicotinamide adenine dinucleotide [NADH] dehydrogenase). Positive selection for ion homeostasis in A. modesta has implications for its ability to tolerate the lower salinity of its northern range, and in A. willowi substitutions in NADH may assist in the high temperature tolerance of its southern California habitats. Identifying these candidate genes enables future studies of their functionalization as we seek to understand the relationship between phenotype and genotype in species whose phenotypes are influenced by environmental conditions.

中文翻译：

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海蛞蝓转录组中的阳性选择信号

了解物种如何应对气候变化至关重要。占据高度异质环境的物种，例如潮间带河口栖息地，为检查表型和基因组对不同环境条件的适应性提供了理想的测试案例，这可能会影响它们对快速变化的气候条件的反应。加利福尼亚海岸预计将经历温度和盐度的变化，目前这些变化随季节和纬度而变化。使用比较转录组学，我记录了北部栖息的浮游生物 sacoglossan 海蛞蝓Alderia norma之间的正选择模式，这种海蛞蝓对低温和低盐度具有显着的耐受性，与其南部的同类植物 Alderia willowi，它对幼虫类型表现出惊人的灵活性，以响应温度和盐度的季节性变化。在 4000 多个 1 比 1 直向同源基因中，我发现A. willowi和A.温和型之间存在正选择信号，这些信号涉及细胞膜和细胞运输的基因，尤其是离子稳态（水通道蛋白）、细胞-细胞信号转导、和磷酸化（还原型烟酰胺腺嘌呤二核苷酸 [NADH] 脱氢酶）。A. 中离子稳态的正选择对其耐受北部范围和A. willowi较低盐度的能力有影响NADH 的替代可能有助于其南加州栖息地的高温耐受性。当我们试图了解表型受环境条件影响的物种中的表型和基因型之间的关系时，识别这些候选基因可以使其功能化的未来研究成为可能。