Adaptive Differentiation of Quantitative Traits in the Globally Distributed Weed, Wild Radish (Raphanus raphanistrum)

Abstract

Weedy species with wide geographical distributions may face strong selection to adapt to new environments, which can lead to adaptive genetic differentiation among populations. However, genetic drift, particularly due to founder effects, will also commonly result in differentiation in colonizing species. To test whether selection has contributed to trait divergence, we compared differentiation at eight microsatellite loci (measured as F ST ) to differentiation of quantitative floral and phenological traits (measured as Q ST ) of wild radish (Raphanus raphanistrum) across populations from three continents. We sampled eight populations: seven naturalized populations and one from its native range. By comparing estimates of Q ST and F ST , we found that petal size was the only floral trait that may have diverged more than expected due to drift alone, but inflorescence height, flowering time, and rosette formation have greatly diverged between the native and nonnative populations. Our results suggest the loss of a rosette and the evolution of early flowering time may have been the key adaptations enabling wild radish to become a major agricultural weed. Floral adaptation to different pollinators does not seem to have been as necessary for the success of wild radish in new environments.

What's the meaning of local? Using molecular markers to define seed transfer zones for ecological restoration in Norway

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Consequences of Whole-Genome Triplication as Revealed by Comparative Genomic Analyses of the Wild RadishRaphanus raphanistrumand Three Other Brassicaceae Species

“…raphanistrum is native to the Mediterranean region and is a close relative of the cultivated radish (Raphanus sativus). The wild radish has evolved a weedy form that is a global agricultural pest (Warwick and Francis, 2005), and it is also a model for the study of ecology and evolution (Sahli et al, 2008;Conner et al, 2009). Thus, availability of genomic and transcriptomic resources for Raphanus will contribute to a better understanding of the molecular basis and evolutionary characteristics of weediness and aid in improvement of cultivated radish.…”

Signatures of volcanism and aridity in the evolution of an insular pine (Pinus canariensis Chr. Sm. Ex DC in Buch)

“…For each bootstrap replicate, the mean F ST value was calculated from the neutral loci sampled, and from that the predicted w 2 distribution of F ST was determined from the Lewontin-Krakauer approach (Lewontin and Krakauer, 1973). Q ST was considered to be statistically different from F ST when 95% confidence intervals of Q ST did not overlap 95% confidence intervals of F ST (Sahli et al, 2008). The mean survival and growth values per population in the last year of measurement were calculated in the four common gardens to detect spatial and climate patterns of genetic differentiation using regression analyses.…”