Rigid Raider said:
Okay, okay, I know GM means taking genes from one species and inserting them in another, whereas selective breeding is a much slower process where you just give Mother Nature a guiding hand.
But in the end aren't both processes achieving exactly the same effect? If so, what should we have to fear from GM as long as we took precuations to ensure the resulting hybrid didn't rampage out of control?
I agree.
I think we need to get the 'super weed' risk into perspective. Almost by definition domesticated plants are less suited to the natural environment than their wild relatives. e.g. the fruits and seeds are bigger than they need be, which imposes a significant energy penalty. Domestic grains are more tightly bound to the stalk to make them easier to harvest in one go, reducing their ability to seed themselves. Stalks are often shorter, making them more vulnerable to mildew etc. You often see wheat, barly etc growing 'wild' on the fringes of fields where it has been grown the previous year, but never in places like woodlands or natural grasslands where they will be out-competed by hardier wild species.
GM modifications are intended to make the crops even more suited to our needs, which is likely to make them even less suited to the wild. For example, the genes for herbicide resistance offer no evolutionary benefits in environments where the plants aren't sprayed, which is most places where wild plants grow, so why would they spread? They are likely to involve some cost to the plant, even if only in additional energy consumption, so the artificial modification is likely to die out naturally within a few generations of 'escaping' into the wild. Let's not forget that changing one or two genes is extremely crude compared to natural evolution and therefore very unlikely to come up with something able to compete in the wild with naturally evolved competitors. (Invasive species like Japanese Knotweed aren't GM of course, instead they are an essentially natural species placed into an environment where they have few pests and competitors, so aren't a valid example of a problem specific to GM).