Gene expression analysis of native and invasive Centaurea diffusa, in benign control and drought treatments.
Code and data associated with:
Turner KG, Nurkowski KA, Rieseberg LH. Gene expression and drought response in an invasive thistle. Biological Invasions. (in press).
This data is also deposited at Dryad:
Turner K, Nurkowski K, Rieseberg L Data from: Gene expression and drought response in an invasive thistle. Biological Invasions http://dx.doi.org/10.5061/dryad.r2k76
Directories "code_ms", "data_ms", and "figures_ms" contain mostly R code, but also perl and bash, some data, and figures associated with the final manuscript and supplementary material. "draft_code_figures" and "data_raw_intermediate" contain earlier versions of data and code, quite messy. These files were all separated at the end, so you may need to add file location information to read data and scripts into R correctly. "code_ms" scripts may contain references to draft code or raw data.
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.