This 2021 study investigated evolutionary histories of Brassica oleracea:
“Cultivated Brassica oleracea has intrigued researchers for centuries due to its wide diversity in forms, which include cabbage, broccoli, cauliflower, kale, kohlrabi, and Brussels sprouts. With such different vegetables produced from a single species, B. oleracea is a model organism for understanding the power of artificial selection.
Evidence from genome-scale, multilocus data along with archeology, literature, and environmental niche modeling best support a single Eastern Mediterranean domestication origin for B. oleracea, corroborating conclusions based on literary sources and linguistics Our analyses point to Aegean endemic B. cretica as the closest living relative of cultivated B. oleracea.
We identify several feral lineages, suggesting that cultivated plants of this species can revert to a wild-like state with relative ease. Progenitor species would likely be good starting material for future research related to de novo domestication via selective breeding or gene editing. Feral populations may also provide additional avenues to explore evolutionary capacity for range expansion and phenotypic plasticity.
Crop wild relatives provide pools of allelic diversity that at one time were shared through a common ancestor with cultivated relatives. Since many of these wild species are very narrow endemics and are valuable for both crop improvement and for nature conservation, their identification and preservation are urgent.”
https://academic.oup.com/mbe/article/38/10/4419/6304875 “The Evolutionary History of Wild, Domesticated, and Feral Brassica oleracea (Brassicaceae)”