HUNKERING down is the safe option if leaving home is risky, but it’s a strategy that could leave you out on an evolutionary limb. Surrounded mostly by concrete rather than fertile soil, urban weeds have evolved – in just a dozen generations – to keep their seeds close to home, which could amplify the genetic isolation produced by habitat fragmentation.
Population geneticist Pierre-Olivier Cheptou and his colleagues at the Centre for Functional and Evolutionary Ecology in Montpellier, France, studied a population of Crepis sancta, a small, chicory-like weed that grows in the tiny patches of soil around city trees. Crepis can…
