Department of Biology, McGill University, Montréal, QC, Canada.
Wildlife Conservation Society, Bronx, NY, USA.
J Evol Biol. 2010 Oct;23(10):2091-2103. doi: 10.1111/j.1420-9101.2010.02069.x. Epub 2010 Aug 17.
Genetic adaptation and phenotypic plasticity are two ways in which organisms can adapt to local environmental conditions. We examined genetic and plastic variation in gill and brain size among swamp (low oxygen; hypoxic) and river (normal oxygen; normoxic) populations of an African cichlid fish, Pseudocrenilabrus multicolor victoriae. Larger gills and smaller brains should be advantageous when oxygen is low, and we hypothesized that the relative contribution of local genetic adaptation vs. phenotypic plasticity should be related to potential for dispersal between environments (because of gene flow's constraint on local genetic adaptation). We conducted a laboratory-rearing experiment, with broods from multiple populations raised under high-oxygen and low-oxygen conditions. We found that most of the variation in gill size was because of plasticity. However, both plastic and genetic effects on brain mass were detected, as were genetic effects on brain mass plasticity. F(1) offspring from populations with the highest potential for dispersal between environments had characteristically smaller and more plastic brains. This phenotypic pattern might be adaptive in the face of gene flow, if smaller brains and increased plasticity confer higher average fitness across environment types.
遗传适应和表型可塑性是生物适应局部环境条件的两种方式。我们研究了非洲慈鲷鱼 Pseudocrenilabrus multicolor victoriae 的沼泽（低氧；缺氧）和河流（正常氧；常氧）种群在鳃和脑大小方面的遗传和可塑性变化。当氧气不足时，较大的鳃和较小的大脑应该是有利的，我们假设局部遗传适应与表型可塑性的相对贡献应该与环境之间的扩散潜力有关（因为基因流限制了局部遗传适应）。我们进行了一项实验室饲养实验，将来自多个种群的鱼苗在高氧和低氧条件下饲养。我们发现，鳃大小的大部分变异是由于可塑性造成的。然而，我们检测到了脑质量的可塑性和遗传效应，以及脑质量可塑性的遗传效应。来自环境扩散潜力最高的种群的 F1 后代具有特征性的较小和更具可塑性的大脑。如果较小的大脑和增加的可塑性在不同环境类型中赋予更高的平均适应性，那么这种表型模式可能是适应性的。
