"On the face of it higher rates of photosynthesis, more shoots, etc sound great but in practice there could be all kinds of selective pressures on wild crops th

"On the face of it higher rates of photosynthesis, more shoots, etc sound great but in practice there could be all kinds of selective pressures on wild crops that would make these adaptations undesirable." Thank you for a very valuable comment. It's nice to see understanding of plant ecophysiology in Hacker News. So, I went to the original article [1] and this is about how they measure fitness: "Measurement of photosynthetic rates [...] We used glasshouse-grown GE and non-GE F3 plants" "Seed germination experiment [...] Seeds were germinated on wet filter paper in Petri dishes." "Field experiments [...] Common garden experiments were conducted [...] 36 plants were planted in a 6x6 grid with 20 cm between plants [...] weeds were removed by hand-weeding [...] urea (nitrogen) per 100 m2 was applied [...] Insecticides that are commonly used in rice fields were applied" So, fitness is measured in (i) glasshouse (ii) on wet filter paper in laboratory and (iii) in garden conditions, with fertilizers and insecticides applied. Now, the original article doesn't claim anything beyond that, and a case can be made that the natural environment of a weed is in in the rice field (with fertilizers and insecticides), but the Nature article says "effects of such modification have the potential to extend beyond farms and into the wild" and like you said, measuring fitness in glasshouse/lab/garden conditions tells pretty much nothing about fitness in the wild beyond farms. [1] http://onlinelibrary.wiley.com/doi/10.1111/nph.12428/abstract http://onlinelibrary.wiley.com/doi/10.1111/nph.12428/abstrac...