Phenotypic plasticity, genetic variation, and the origins of novel, complex traits

生物学家早就认识到，生物体的特征(表型)可能会随着环境的变化而变化，但在匆忙识别影响特征的基因时，这种表型可塑性传统上被忽视了。近年来，许多科学家开始问表型可塑性是否可能在培育新的、复杂的特征的起源方面发挥重要作用。然而，这种观点认为表型可塑性本身是遗传变异的基础，但很少有研究确定自然种群，特别是脊椎动物的表型可塑性的遗传基础。这些数据对于澄清可塑性的原因和后果至关重要，包括它在新的、复杂的特征的起源和随后的阐述中可能扮演的角色。这项研究的目标是确定沙漠青蛙蝌蚪中一种壮观的可塑性形式背后的遗传变异。PI还将确定这种遗传变异来自哪里，以及它影响了哪些组成部分的性状。总体而言，这项研究有望为表型可塑性的原因和后果提供新的线索，表型可塑性是联合生物学不同领域的新兴前沿。通过这样做，这项研究将有助于解释生物体的基因组如何与其环境相互作用，以塑造复杂特征的表达和进化。一个长期存在的问题是理解新颖性是如何产生的。根据塑性引导进化(PLE)假说，当环境的变化通过表型可塑性触发表型转变时，新的特征就会出现。然而，人们对这一过程背后的基因知之甚少。这项研究将确定与一种新的、复杂的表型相关的基因座和遗传变异，这种表型似乎是通过PLE出现的。作为对吃肉的反应，墨西哥铁锹蝌蚪发育成一种新的食肉动物形态，之前的研究表明这种形态是通过PLE进化而来的。在这项研究中，PI将从受控杂交中培育蝌蚪，以确定这种新的表型背后的基因座。有了这些数据，PI将确定--正如他们的初步数据所预测的那样--许多这样的基因座是否与新陈代谢和环境评估有关。然后，PI将在半自然环境中饲养蝌蚪，它们将在生态上改变，以区分与食肉动物表型本身相关的基因座与与适应性环境评估和可塑性相关的基因座。有了这些数据，PI将确定适应性可塑性和由该可塑性产生的表型是受相同的基因座调控，还是--正如理论预测的--不同的基因座。最后，PI将对来自众多自然种群的个体进行排序，以阐明站立遗传变异和导入变异在新的食肉动物表型进化中的作用。总之，这些目标将为可塑性的遗传架构提供新的线索，从而帮助阐明推动PLE的遗传机制。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Biologists have long recognized that an organism’s features (its ‘phenotype’) can change depending on its environment, but such ‘phenotypic plasticity’ has traditionally been overlooked in the rush to identify the genes that influence traits. In recent years, many scientists have begun asking if phenotypic plasticity might play an important role in fostering the origins of novel, complex traits. However, this idea assumes that phenotypic plasticity is itself underlain by genetic variation, but few studies have identified the genetic bases of phenotypic plasticity in natural populations, especially in vertebrates. Such data are crucial for clarifying the causes and consequences of plasticity, including its possible role in the origins––and subsequent elaboration––of novel, complex traits. The goals of this research are to identify genetic variation underlying a spectacular form of plasticity among the tadpoles of desert frogs. The PIs will also determine where this genetic variation comes from and what component traits it influences. Overall, this research promises to shed new light on the causes and consequences of phenotypic plasticity, an emerging frontier that unites diverse areas of biology. In doing so, this research will help explain how an organism’s genome interacts with its environment to shape the expression and evolution of complex features. A longstanding problem is understanding how novelty arises. According to the plasticity-led evolution (PLE) hypothesis, novel traits arise when a change in the environment triggers a shift in phenotype via phenotypic plasticity. Yet, little is known about the genes underlying this process. This research will identify loci and genetic variation associated with a novel, complex phenotype that appears to have arisen via PLE. In response to eating meat, Mexican spadefoot toad tadpoles develop into a novel carnivore morph, which previous work suggests has evolved via PLE. For this research, the PIs will rear tadpoles from controlled crosses to identify loci underlying this novel phenotype. With these data, the PIs will determine if––as predicted by their preliminary data––many such loci are involved in metabolism and environmental assessment. The PIs will then rear tadpoles in semi-natural environments that they will alter ecologically to differentiate loci associated with the carnivore phenotype per se from loci associated with adaptive environmental assessment and plasticity. With these data, the PIs will determine if adaptive plasticity and phenotypes resulting from that plasticity are regulated by the same or––as predicted by theory––different loci. Finally, the PIs will sequence individuals from numerous natural populations to clarify the roles of standing genetic variation versus introgressed variation in the evolution of the novel carnivore phenotype. Together, these aims will shed new light onto the genetic architecture of plasticity and thereby help illuminate the genetic mechanisms that propel PLE.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.