Department of Life Science, Tunghai University, Taichung, Taiwan.
Oecologia. 2012 May;169(1):15-22. doi: 10.1007/s00442-011-2170-2. Epub 2011 Oct 29.
Harsh environments experienced early in development have immediate effects and potentially long-lasting consequences throughout ontogeny. We examined how salinity fluctuations affected survival, growth and development of Fejervarya limnocharis tadpoles. Specifically, we tested whether initial salinity effects on growth and rates of development were reversible and whether they affected the tadpoles' ability to adaptively accelerate development in response to deteriorating conditions later in development. Tadpoles were initially assigned to either low or high salinity, and then some were switched between salinity levels upon reaching either Gosner stage 30 (early switch) or 38 (late switch). All tadpoles initially experiencing low salinity survived whereas those initially experiencing high salinity had poor survival, even if switched to low salinity. Growth and developmental rates of tadpoles initially assigned to high salinity did not increase after osmotic stress release. Initial low salinity conditions allowed tadpoles to attain a fast pace of development even if exposed to high salinity afterwards. Tadpoles experiencing high salinity only late in development metamorphosed faster and at a smaller size, indicating an adaptive acceleration of development to avoid osmotic stress. Nonetheless, early exposure to high salinity precluded adaptive acceleration of development, always causing delayed metamorphosis relative to those in initially low salinity. Our results thus show that stressful environments experienced early in development can critically impact life history traits, having long-lasting or irreversible effects, and restricting their ability to produce adaptive plastic responses.
早期发育过程中经历的恶劣环境会对个体发育过程产生直接影响，并可能产生持久的后果。我们研究了盐度波动如何影响泽蛙蝌蚪的存活、生长和发育。具体来说，我们测试了生长和发育速度的初始盐度效应是否可逆，以及它们是否会影响蝌蚪在发育后期适应恶化条件时加速发育的能力。蝌蚪最初被分配到低盐度或高盐度环境中，然后在达到 Gosner 阶段 30（早期转换）或 38（晚期转换）时，一些蝌蚪在盐度水平之间进行转换。最初经历低盐度的所有蝌蚪都存活下来，而最初经历高盐度的蝌蚪则存活率较低，即使转换到低盐度环境中也是如此。在渗透胁迫解除后，最初被分配到高盐度环境中的蝌蚪的生长和发育速度并没有增加。最初处于低盐度环境的蝌蚪即使后来暴露在高盐度环境中，也能达到快速发育的步伐。在发育后期仅经历高盐度的蝌蚪会更快地变态，体型也更小，这表明它们为了避免渗透胁迫而加速了发育的适应性。然而，早期暴露于高盐度会限制它们产生适应性可塑性反应的能力，总是导致相对于最初处于低盐度环境的蝌蚪而言，变态延迟。因此，我们的研究结果表明，早期发育过程中经历的压力环境会严重影响生活史特征，产生持久或不可逆的影响。
