Ecological novelty by hybridization: experimental evidence for increased thermal tolerance by transgressive segregation in Tigriopus californicus

Early generations of hybrids can express both genetic incompatibilities and phenotypic novelty. Insights into whether these conflicting interactions between intrinsic and extrinsic selection persist after a few generations of recombination require experimental studies. To address this question, we use interpopulation crosses and recombinant inbred lines (RILs) of the copepod Tigriopus californicus, and focus on two traits that are relevant for the diversification of this species: survivorship during development and tolerance to thermal stress. Experimental crosses between two population pairs show that most RILs between two heat-tolerant populations show enhanced tolerance to temperatures that are lethal to the respective parentals, whereas RILs between a heat-tolerant and a heat-sensitive population are intermediate. Although interpopulation crosses are affected by intrinsic selection at early generational hybrids, most of the sampled F9 RILs have recovered fitness to the level of thei...

早期世代的杂种可同时表现出遗传不相容性与表型新奇性。若要探究内在选择与外在选择之间的这类冲突互作是否会在数代重组后仍持续存在，亟需开展实验研究予以解答。为解决这一科学问题，本研究采用桡足类物种加州虎猛水蚤（Tigriopus californicus）的种群间杂交组合与重组自交系（RILs），并聚焦于与该物种分化相关的两个性状：发育存活率与热胁迫耐受性。针对两个种群对的实验杂交结果显示：两个耐热种群所产生的多数重组自交系，对原本可致死其亲本的高温表现出更强的耐受性；而耐热种群与热敏种群杂交得到的重组自交系，其耐热性则介于两者之间。尽管早期世代杂种的种群间杂交会受到内在选择的影响，但本次采样的多数F9代重组自交系，其适合度已恢复至