Inter- and intrapopulation variation in thermal reaction norms for growth rate: Evolution of latitudinal compensation in ectotherms with a genetic constraint
Inter- and intrapopulation variation in thermal reaction norms for growth rate: Evolution of latitudinal compensation in ectotherms with a genetic constraint
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DOI：
10.1111/j.1558-5646.2007.00130.x
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发表时间：
2007-07-01
期刊：
影响因子：
3.3
通讯作者：
Irie, Takahiro
中科院分区：
文献类型：
--
作者：
Yamahira, Kazunori;Kawajiri, Maiko;Irie, Takahiro
在外温动物中，高纬度环境中的低温理论上会降低个体的年增长率。如果生长缓慢和由此产生的较小的身体尺寸降低了适应性，那么高纬度地区的个体可能会进化出补偿性反应。这种纬度补偿的两种替代模型是可能的：模型I：高纬度个体的生长速率的热反应规范可能会水平移动到较低的温度范围，或模型II：反应规范可能会垂直移动，以便高纬度个体可以在所有温度下生长得更快。模型I预期在野外的年增长率仅是环境温度的函数，而模型II预期在高纬度的个体只能在一年的较短时间内生长。这两种模式的各种混合策略也是可能的，纬度种群之间的反应规范的水平与垂直变化的幅度将表明“温度”与“季节性”在纬度补偿的演变的重要性。然而，纬度补偿的形式可能会受到可能的遗传限制，由于反应规范的遗传结构。在这项研究中，我们研究了种群间和种群内的变化，在热反应规范的青鳉鱼的增长率。共同环境的实验表明，平均反应规范主要是不同的纬度人群之间的海拔高度一致的方式与模型II（适应“季节性”），这表明在高纬度地区的自然选择更喜欢个人的增长速度，即使在较短的生长季节的个人，有较长的生长季节，在较低的温度下生长。然而，种群内的反应规范的变化也是垂直的：一些全同胞家庭的增长速度比其他所有的温度检查。这种趋势在种群内的遗传变异的热反应规范可能限制了纬度补偿的演变，无论潜在的选择压力。
In ectotherms, lower temperatures in high-latitude environments would theoretically reduce the annual growth rates of individuals. If slower growth and resultant smaller body size reduce fitness, individuals in higher latitudes may evolve compensatory responses. Two alternative models of such latitudinal compensation are possible: Model I: thermal reaction norms for growth rates of high-latitude individuals may be horizontally shifted to a lower range of temperatures, or Model II: reaction norms may be vertically shifted so that high-latitude individuals can grow faster across all temperatures. Model I is expected when annual growth rates in the wild are only a function of environmental temperatures, whereas Model II is expected when individuals in higher latitudes can only grow during a shorter period of a year. A variety of mixed strategies of these two models are also possible, and the magnitude of horizontal versus vertical variation in reaction norms among latitudinal populations will be indicative of the importance of "temperature" versus "seasonality" in the evolution of latitudinal compensation. However, the form of latitudinal compensation may be affected by possible genetic constraints due to the genetic architecture of reaction norms. In this study, we examine the inter- and intrapopulation variations in thermal reaction norms for growth rate of the medaka fish Oryzias latipes. Common-environment experiments revealed that average reaction norms differed primarily in elevation among latitudinal populations in a manner consistent with Model II (adaptation to "seasonality"), suggesting that natural selection in high latitudes prefers individuals that grow faster even within a shorter growing season to individuals that have longer growing seasons by growing at lower temperatures. However, intrapopulation variation in reaction norms was also vertical: some full-sibling families grew faster than others across all temperatures examined. This tendency in intrapopulation genetic variation for thermal reaction norms may have restricted the evolution of latitudinal compensation, irrespective of the underlying selection pressure.