How do organisms survive in and adapt to novel, stressful conditions? Genetic variation that is not exposed in a normal environment (called cryptic genetic variation) may nevertheless be exposed through phenotypic plasticity in novel environments. A key gap in our understanding of cryptic genetic variation is the identification of its molecular basis and evolution. When exposed to ecologically relevant stressful environments in the lab, the nematode Caenorhabditis remanei evolves rapidly in response to selection, and populations alter their response to alternative environments. The PIs will use next-generation sequencing technology to identify the key genetic and transcriptional changes that have occurred in these evolved lines, enabling the identification of genes and developmental pathways that expose cryptic variation in new environments.
Currently little is known about how the exposure of this cryptic genetic variation by a new environment can impact evolution in natural populations. As global climate change rapidly alters habitats and creates novel environments, many species of economic and conservation concern are faced with new environmental challenges. Thus it is becoming increasingly important to understand how environmental factors interact with genes in populations to direct evolutionary change. This research improves our understanding of this process.
Intellectual Merit. How do organisms survive in, and adapt to, stressful conditions? Changes in the frequencies of different genes variations can allow organisms to adapt to such novel environments. Organisms may also acclimate to new environments by differentially utilizing genetic variation, a process called phenotypic plasticity. A consequence of phenotypic plasticity is that cryptic genetic variation, which normally doesn’t contribute to organismal trait variation, may be exposed in a novel environment and be recruited for subsequent evolutionary change. The environment can therefore both expose and sort genetic variation over time. A key gap in our understanding of cryptic genetic variation is understanding the molecular nature of the variation, as well as how this variation evolves over time. An experimental evolution study in the laboratory showed that when exposed to ecologically relevant stressful heat and oxidative environments, the nematode worm Caenorhabditis remanei evolves rapidly in response to selection, and populations alter their response to alternative environments. This research used next-generation sequencing technology to identify the key genetic and transcriptional changes that occurred in these evolved lines, enabling the identification of genes and developmental pathways that exposed cryptic variation in new environments. This work not only provides fundamental insights into how cryptic genetic variation contributes to evolution in this small worm, but also provides candidate genes and pathways for broader studies in other organisms. Broader Impacts. Global climate change is rapidly altering habitats, and many species of economic and conservation concern are now faced with novel environmental challenges. As global climate change rapidly alters habitats, it is becoming increasingly important to understand how environmental factors interact with genes in populations to direct evolutionary change. The exposure of cryptic genetic variation by the environment in natural populations may be key in their survival in response to global climate change. Through the successful completion of this project we have generated new understandings of how cryptic genetic variation is exposed in organisms that are subjected to novel, stressful environments. This information may prove useful for considering mitigating genetic interventions in rare or endangered organisms threatened by global climate change.
