Such comparisons are dominated by the scenery, the relatively unchanging backcloth of the action. It is not possible to make much sense of the plot or the action as it is seen at such a point in time. Most of our knowledge of the structure and diversity of plant communities comes from describing areas of vegetation at points in time and by imposing for the purpose of human value, a scale on a system to which this may be irrelevant. Monocultures and other simple crop rotations, homogeneous crop cultivars, and farming trends intensifying and simplifying managed habitats exacerbate this condition. Natural selection allows the best adapted weed species and individuals in those environments to increase in frequency relative to less well-adapted plants over time.
Weeds are well-adapted because they produce excess, highly fit, offspring than can survive.
Weeds are well-adapted because they are highly diverse in terms of genotype, phenotype and fitness. This weed biodiversity and fecundity allows them to successfully exploit the niche-vacuum left vacant in managed habitats.