Increased expression diversity buffers the loss of adaptive potential caused by reduction of genetic diversity in new unfavourable environments

Mechanisms underlying adaptation to rapid environmental change are issues in evolutionary biology. It is widely accepted that reduction in genetic diversity when suddenly exposed to an unfavourable environment limits the adaptive potential of populations. With growing empirical evidence that expression diversity is likely to increase in the new environment, the role that expression diversity plays in adaptation needs to be theorized. Here, we first established a negative exponential relationship between expression diversity and genetic diversity using a phenomenological differential equation. We then derived a complex trade-off relationship between the changes of expression and genetic diversity, which followed a combination of exponential functions. Furthermore, we found the increase in expression diversity could buffer the loss of adaptive potential as genetic diversity decreased to a certain extent. These theoretical deductions were validated by transcriptomic data of Miscanthus lutarioriparius grown i...