Abstract：
Differences in morphology, ecology, and behavior through ontogeny can result in opposing selective pressures at different life stages. Most animals, however, transition through two or more distinct phenotypic phases, which is hypothesized to allow each life stage to adapt more freely to its ecological niche. How this applies to sensory systems, and in particular how sensory systems adapt across life stages at the molecular level, is not well understood. Here, we used whole-eye transcriptomes to investigate differences in gene expression between tadpole and juvenile southern leopard frogs (Lithobates sphenocephalus), which rely on vision in aquatic and terrestrial light environments, respectively. Because visual physiology changes with light levels, we also tested the effect of light and dark exposure.
We found 42% of genes were differentially expressed in the eyes of tadpoles versus juveniles and 5% for light/dark exposure. Analyses targeting a curated subset of visual genes revealed significant differential expression of genes that control aspects of visual function and development, including spectral sensitivity and lens composition. Finally, microspectrophotometry of photoreceptors confirmed shifts in spectral sensitivity predicted by the expression results, consistent with adaptation to distinct light environments.
Overall, we identified extensive expression-level differences in the eyes of tadpoles and juveniles related to observed morphological and physiological changes through metamorphosis and corresponding adaptive shifts to improve vision in the distinct aquatic and terrestrial light environments these frogs inhabit during their life cycle. More broadly, these results suggest that decoupling of gene expression can mediate the opposing selection pressures experienced by organisms with complex life cycles that inhabit different environmental conditions throughout ontogeny.
We found 42% of genes were differentially expressed in the eyes of tadpoles versus juveniles and 5% for light/dark exposure. Analyses targeting a curated subset of visual genes revealed significant differential expression of genes that control aspects of visual function and development, including spectral sensitivity and lens composition. Finally, microspectrophotometry of photoreceptors confirmed shifts in spectral sensitivity predicted by the expression results, consistent with adaptation to distinct light environments.
Overall, we identified extensive expression-level differences in the eyes of tadpoles and juveniles related to observed morphological and physiological changes through metamorphosis and corresponding adaptive shifts to improve vision in the distinct aquatic and terrestrial light environments these frogs inhabit during their life cycle. More broadly, these results suggest that decoupling of gene expression can mediate the opposing selection pressures experienced by organisms with complex life cycles that inhabit different environmental conditions throughout ontogeny.
摘要：
形态差异,生态学,和行为通过个体发育可以导致相反的选择压力在不同的生命阶段。大多数动物,然而,通过两个或多个不同的表型阶段过渡，它被假设为允许每个生命阶段更自由地适应其生态位。这如何适用于感觉系统，特别是感官系统如何在分子水平上适应不同的生命阶段，不是很了解。这里,我们使用全眼转录组来研究t和幼年南方豹蛙（Lithobotessphenhephalus）之间的基因表达差异，它依赖于在水生和陆地光环境中的视觉，分别。因为视觉生理学会随着光照水平而变化，我们还测试了明暗曝光的效果。
我们发现42％的基因在t与幼年的眼睛中差异表达，而5％的基因在光/暗暴露中差异表达。针对视觉基因的精选子集的分析揭示了控制视觉功能和发育方面的基因的显着差异表达，包括光谱灵敏度和透镜组成。最后,光感受器的显微分光光度法证实了表达结果预测的光谱灵敏度的变化，与适应不同的光环境相一致。
总的来说，我们发现了t和幼鱼眼睛中广泛的表达水平差异，这些差异与通过变态观察到的形态和生理变化以及相应的适应性变化有关，以改善这些青蛙在其生命周期中栖息的不同水生和陆地光环境中的视力。更广泛地说,这些结果表明，基因表达的解耦可以介导具有复杂生命周期的生物体所经历的相反的选择压力，这些生物体在整个个体发育过程中生活在不同的环境条件下。
我们发现42％的基因在t与幼年的眼睛中差异表达，而5％的基因在光/暗暴露中差异表达。针对视觉基因的精选子集的分析揭示了控制视觉功能和发育方面的基因的显着差异表达，包括光谱灵敏度和透镜组成。最后,光感受器的显微分光光度法证实了表达结果预测的光谱灵敏度的变化，与适应不同的光环境相一致。
总的来说，我们发现了t和幼鱼眼睛中广泛的表达水平差异，这些差异与通过变态观察到的形态和生理变化以及相应的适应性变化有关，以改善这些青蛙在其生命周期中栖息的不同水生和陆地光环境中的视力。更广泛地说,这些结果表明，基因表达的解耦可以介导具有复杂生命周期的生物体所经历的相反的选择压力，这些生物体在整个个体发育过程中生活在不同的环境条件下。
