Sgrò Carla M, Blows Mark W
Centre for Environmental Stress and Adaptation Research, La Trobe University, Melbourne 3083, Victoria, Australia.
Genetics. 2004 Jul;167(3):1281-91. doi: 10.1534/genetics.103.026120.
We examined the genetic basis of clinal adaptation by determining the evolutionary response of life-history traits to laboratory natural selection along a gradient of thermal stress in Drosophila serrata. A gradient of heat stress was created by exposing larvae to a heat stress of 36 degrees for 4 hr for 0, 1, 2, 3, 4, or 5 days of larval development, with the remainder of development taking place at 25 degrees. Replicated lines were exposed to each level of this stress every second generation for 30 generations. At the end of selection, we conducted a complete reciprocal transfer experiment where all populations were raised in all environments, to estimate the realized additive genetic covariance matrix among clinal environments in three life-history traits. Visualization of the genetic covariance functions of the life-history traits revealed that the genetic correlation between environments generally declined as environments became more different and even became negative between the most different environments in some cases. One exception to this general pattern was a life-history trait representing the classic trade-off between development time and body size, which responded to selection in a similar genetic fashion across all environments. Adaptation to clinal environments may involve a number of distinct genetic effects along the length of the cline, the complexity of which may not be fully revealed by focusing primarily on populations at the ends of the cline.
我们通过确定黑腹果蝇生活史性状对实验室自然选择的进化响应，沿着热应激梯度研究了渐变群适应性的遗传基础。通过在幼虫发育的0、1、2、3、4或5天，将幼虫暴露于36摄氏度的热应激4小时，其余发育阶段在25摄氏度下进行，从而创建了一个热应激梯度。每隔一代，将重复的品系暴露于这种应激的每个水平，持续30代。在选择结束时，我们进行了一项完全互交转移实验，在所有环境中饲养所有种群，以估计三种生活史性状在渐变群环境之间实现的加性遗传协方差矩阵。生活史性状遗传协方差函数的可视化显示，随着环境差异增大，环境之间的遗传相关性通常会下降，在某些情况下，在差异最大的环境之间甚至会变为负相关。这种一般模式的一个例外是一个代表发育时间和体型之间经典权衡的生活史性状，它在所有环境中以相似的遗传方式对选择做出反应。对渐变群环境的适应可能涉及沿着渐变群长度的许多不同遗传效应，主要关注渐变群两端的种群可能无法完全揭示其复杂性。
