Data from: Evolution of drought resistance strategies following the introduction of white clover (Trifolium repens L.)

Background and Aims: Success during colonization likely depends on growing
quickly and tolerating novel and stressful environmental conditions.
However, rapid growth, stress avoidance, and stress tolerance are
generally considered divergent physiological strategies.  
Methods: We evaluate how white clover (Trifolium repens) has evolved to a
divergent water regime following introduction to North America. We conduct
RNAseq within a dry-down experiment utilizing accessions from low and high
latitude populations from native and introduced ranges, and assess
variation in dehydration avoidance (ability to avoid wilting) and
dehydration tolerance (ability to survive wilting).   Key
Results: Introduced populations are better at avoiding dehydration, but
poorer at tolerating dehydration than native populations. There is a
strong negative correlation between avoidance and tolerance traits and
expression of most drought-associated genes exhibits similar tradeoffs.
Candidate genes with expression strongly associated with dehydration
avoidance are linked to stress signaling, closing stomata, and producing
osmoprotectants. However, genes with expression linked to dehydration
tolerance are associated with avoiding excessive ROS production and toxic
bioproducts of stress responses. Several candidate genes show differential
expression patterns between native and introduced ranges, and could
underlie differences in drought resistance syndromes between ranges.
  Conclusions: These results suggest there has been strong
selection following introduction for dehydration avoidance at the cost of
surviving dehydration. More broadly, tradeoffs between dehydration
avoidance and tolerance responses likely exist both at the genetic and
phenotypic scales that will influence evolutionary responses and
potentially limit the global spectrum of plant form and function.