Hybridization between native and non‐native species is an ongoing global conservation threat. Hybrids that exhibit traits and tolerances that surpass parental values are of particular concern, given their potential to outperform native species. Effective management of hybrid populations requires an understanding of both physiological performance and the underlying mechanisms that drive transgressive hybrid traits. Here, we explore several aspects of the hybridization between the endangered California tiger salamander (Ambystoma californiense; CTS) and the introduced barred tiger salamander (Ambystoma mavortium; BTS). We assayed critical thermal maximum (CTMax) to compare the ability of CTS, BTS and F1 hybrids to tolerate acute thermal stress, and found that hybrids exhibit a wide range of CTMax values, with 33% (4/12) able to tolerate temperatures greater than either parent. We then quantified the genomic response, measured at the RNA transcript level, of each salamander, to explore the mechanisms underlying thermal tolerance strategies. We found that CTS and BTS have strikingly different values and tissue‐specific patterns of overall gene expression, with hybrids expressing intermediate values. F1 hybrids display abundant and variable degrees of allele‐specific expression (ASE), likely arising from extensive compensatory evolution in gene regulatory mechanisms between CTS and BTS. We found evidence that the proportion of genes with allelic imbalance in individual hybrids correlates with their CTMax, suggesting a link between ASE and expanded thermal tolerance that may contribute to the success of hybrid salamanders in California. Future climate change may further complicate management of CTS if hybrid salamanders are better equipped to deal with rising temperatures.

中文翻译：

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等位基因特异的表达和基因调控有助于解释濒临灭绝的加利福尼亚老虎A（Ambystoma californiense）的非本地杂种的过境热耐受性

本地物种与非本地物种之间的杂交是一个持续的全球保护威胁。表现出超过亲代性状的特征和耐受性的杂种，由于它们具有超越本地物种的潜力，因此尤其值得关注。对杂种种群的有效管理需要既了解生理性能，又了解驱动越境杂种特性的潜在机制。在这里，我们探讨了濒临灭绝的加利福尼亚老虎sal（Ambystoma californiense； CTS）与引进的禁止老虎sal（Ambystoma mavortium）之间杂交的几个方面。; 防弹少年团）。我们分析了临界热最大值（CTMax），以比较CTS，BTS和F1杂种耐受急性热胁迫的能力，并发现杂种表现出宽泛的CTMax值，其中33％（4/12）的杂种能够耐受更大的温度比任何一位父母 然后，我们量化了每个sal的基因组反应（在RNA转录水平上测量），以探索潜在的热耐受策略的机制。我们发现CTS和BTS具有明显不同的值和整体基因表达的组织特异性模式，而杂种表达中间值。F1杂种表现出丰富多样的等位基因特异性表达（ASE），可能是CTS和BTS之间基因调控机制的广泛补偿性进化所致。我们发现有证据表明个别杂种中具有等位基因失衡的基因比例与其CTMax相关，这表明ASE与耐热性增强之间的联系可能有助于加利福尼亚杂种sal的成功。如果混合sal更好地应对气温升高，则未来的气候变化可能会使CTS的管理更加复杂。