Coping with Climate Change: A Genomic Perspective on Thermal Adaptation

Climate change is occurring at a fast rate globally, and one major concern is that extreme climate events can have strong impacts on natural populations. How organisms respond to stressful thermal conditions depend, in part, on how phenotypically plastic they are, to what extent they can disperse to more favorable habitats and, ultimately, on their capacity to genetically respond and eventually adapt to such changes. For genetic adaptation to occur, populations need to have variation in genes that play an important role in thermal adaptation. Several candidate genes have been identified across species, such as hsp genes, but the complexity of the processes affected by temperature involves, undoubtedly, a polygenic basis including both regulatory and structural genes. Thus, in order to predict how much populations can adapt to new thermal conditions, it is essential to understand the genomic basis of thermal adaptation and the underlying evolutionary potential and differences across populations.

Currently, there is a boom of studies involving genome-wide sequencing (DNA or RNA) in both model and non-model organisms. This allows to gather unprecedented information on genetic variation and/or on gene expression within and among populations under contrasting scenarios. Such progress is contributing to our understanding of the genomics of thermal adaptation and population differentiation in thermal responses, including emergent fields such as epigenetics and microbiome-host evolution. Nevertheless, there is still much to explore in the characterization of the genetic architecture underlying the adaptation to climate change. Many teams are addressing issues related to the genetic mechanisms of several stresses posed by the environment, including extreme temperatures. The wide panoply of methods used in evolutionary biology, from comparative approaches across species to real-time (experimental) evolution studies and inter and intra-population analysis associated with genome-wide sequencing, provide the tools needed to tackle essential questions for an integrative understanding of how populations may cope with climate change.

The objective of this Research Topic is to bring together studies contributing to a genomic perspective to understand thermal stress responses. Such studies will allow addressing several questions, among which we anticipate the following:

- Do populations present enough genetic variability to cope with climate change via evolutionary changes?
- Is (genomic) evolutionary potential to adapt to climate changes more limited in some species or populations than others?
- What are the genomic differences between populations that adapt to contrasting temporal thermal patterns?
- How much do populations differ in the genetic pathways that underly thermal adaptation?
- Are there common genes underlying thermal adaptation? What is their variation across species?
- What is the genetic basis of plastic thermal responses?
- What is the relative role of regulation of gene expression versus evolutionary genetic changes in how populations respond to climate change?
- What is the impact of temperature on microbiome-host evolution?

With this collection, we wish to contribute to a better understanding of the genomic basis of thermal adaptation and how much the genetic and genomic diversity of populations and species may present common or different challenges posed by climate change worldwide.