Warnell School of Forestry and Natural Resources, University of Georgia, 180 E. Green St., Athens, GA, 30602, USA.
School of Agriculture, Fisheries, and Human Sciences, University of Arkansas at Pine Bluff, 1200 N. University Dr., Pine Bluff, AR, 71601, USA.
Sci Rep. 2020 Jul 30;10(1):12866. doi: 10.1038/s41598-020-69911-1.
The ability to adapt to changing environments is fundamental for species persistence. Both plasticity and genetic selection are potential drivers that allow for traits to be advantageous, thus leading to increases in survival or fitness. Identifying phenotypic plasticity in life history traits of long-lived organisms can be difficult owing to high survival, long generation times, and few studies at sufficient spatial and temporal scales to elicit a plastic response within a population. To begin to understand phenotypic plasticity of a long-lived freshwater fish in response to environmental conditions, we used a long-term data set consisting of over 1,200 mark-recapture events to inform our understanding of dynamic rate functions and life history attributes. Furthermore, we used a common garden experimental approach to confirm whether changes in life history traits are in response to plasticity in the reaction norm or are genetically derived. Using these approaches, we demonstrated differences in life history traits among Pallid Sturgeon (Scaphirhynchus albus) occupying river segments of varying physical and hydrological stress. The common garden experiment corroborated plastic phenotypic expression in reaction norms for age at first maturity, longevity, fecundity, and maximum size. These growth-mediated attributes resulted in differences in overall fitness traits, where Pallid Sturgeon fecundity was greater than a tenfold difference and 3-6 times the number of life-time spawning events. Anthropogenic modifications to river form and function are likely responsible for the variation in life history attributes resulting from an increased metabolic demand for maintaining station, foraging, and migration. Collectively, our approach provided surprising insight into the capabilities of a centenarian fish to dramatically respond to a changing environment.
适应不断变化的环境的能力是物种生存的基础。可塑性和遗传选择都是潜在的驱动因素，使特征具有优势，从而导致生存或适应度的提高。由于长寿生物的高存活率、长世代时间和很少有研究在足够的空间和时间尺度上引起种群内的可塑性反应，因此识别其生活史特征中的表型可塑性可能很困难。为了开始了解长寿淡水鱼类对环境条件的表型可塑性，我们使用了一个由超过 1200 次标记-重捕事件组成的长期数据集，以了解动态率函数和生活史特征。此外，我们使用了一个共同的花园实验方法来确认生活史特征的变化是否是对反应规范中的可塑性的反应，还是遗传上的。通过这些方法，我们证明了在不同物理和水力学压力的河流段中生存的白鲟（Scaphirhynchus albus）的生活史特征存在差异。共同花园实验证实了在初次成熟、寿命、繁殖力和最大尺寸的反应规范中存在可塑性表型表达。这些与生长相关的特征导致了整体适应度特征的差异，其中白鲟的繁殖力差异超过十倍，一生的产卵次数也增加了 3-6 倍。河流形态和功能的人为改变可能是导致生活史特征变化的原因，这些变化是由于维持站位、觅食和迁徙所需的新陈代谢需求增加所致。总的来说，我们的方法提供了一个令人惊讶的见解，即一种百岁鱼类对不断变化的环境有能力做出显著的反应。
