Data from: Gene expression and drought response in an invasive thistle

Though rapid phenotypic evolution has been observed in many invasive plant
species, less is known about the associated genetic mechanisms. Some
hypotheses invoke the evolution of trade-offs in resource allocation to
explain phenotypic differences between the native and invaded ranges of a
species. Alternately, invasive species may benefit from a generalist
strategy and perform well in many environments. Identification of the
molecular changes associated with successful invasions can offer clues
regarding the mechanistic basis of such hypotheses, even in non-model
organisms. To complement studies of phenotypic variation, we investigate
gene expression during drought response that might underlie variation in
drought tolerance between native and introduced populations of diffuse
knapweed (Centaurea diffusa), and possibly contribute to invasion success.
Using species-specific microarrays and tissue sampled under drought and
control conditions at three time points, we identified genes whose
expression either varied constitutively or responded to drought stress
differently between ranges. Further, we functionally investigate these
genes. Based on these data, invasive populations have constitutively
higher levels of expression relating to energy production and lower levels
of signal transduction expression relative to native populations. Under
drought conditions, invasive populations may maintain energy production
and react less strongly to drought than native populations, which may
allow them to maintain fitness across moderate environmental variation.
This supports the expectation of invasive populations consisting of
generalist genotypes capable of fitness homeostasis, which may have
facilitated the successful invasion of many environments in North America.