NSF Award
2306276
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. <br/><br/>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.<br/><br/>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.
