Economic Botany: Evolution of Cultivated Plants
Campbell, Lesley G. , Snow, Allison .
Dedomestication of radish (Raphanus sativus) – do feral populations require hybridization to persist?
Unharvested crop seeds sometimes establish naturalized, feral populations, but domestication traits often inhibit this process. We explored the potential for cultivated radish, Raphanus sativus, to become a feral weed in the vicinity of its weedy relative, R. raphanistrum. Domesticated radishes flower much later than R. raphanistrum, which produces a thinner taproot and colonizes disturbed habitats. Using a common “Red Silk” cultivar, we established five artificial populations of volunteer crop plants in Michigan, USA, and allowed them to evolve for three growing seasons. Three populations went extinct and the remaining two were inadvertently contaminated with pollen from R. raphanistrum. The two introgressed populations grew rapidly and persisted. A common garden experiment showed that the introgressed populations evolved earlier flowering and greater fecundity than the non-introgressed plants. We used an artificial selection experiment to quantify heritable variability for earlier flowering in the crop. After two generations of strong artificial selection, two of three selected lineages flowered ~5 days earlier than control lineages. In an outdoor common-garden environment, the selected lineages produced significantly more seeds per plant than controls. Finally, to identify types of radishes that may be most likely to generate feral weed populations, we asked whether radish cultivars vary in age at flowering. Several types of radish (daikon, podding, forage) flowered significantly earlier (8-18 days) than European red-rooted varieties, suggesting that certain varieties may more readily become feral. We hypothesize that earlier flowering facilitates the transition of radishes to feral weeds in temperate climates. This trait and other weedy characteristics may be most easily acquired via hybridization with R. raphanistrum. Our general approach can be applied to other cultivated species to gain a better understanding of mechanisms for the spontaneous evolution of feral weeds.
Log in to add this item to your schedule
1 - Ohio State University, Department of Evolution, Ecology and Organismal Biology, 300 Aronoff Laboratory, 318 W. 12th Ave., Columbus, Ohio, 43210-1293, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Lake Ontario/Hilton
Date: Monday, July 9th, 2007
Time: 8:15 AM