Why doesn't natural selection weed out one of the hues?
Crop rotation helps maintain high productivity by reducing pesticide use and fertilizer input and can reduce pest and pathogen incidences, weed infestation, and selection pressure for weed resistance to herbicides [58].
It is easy to see how natural selection weeds out unfavourable mutations and preserves favourable features.
Locks of Love sends the best of the hair it receives to a wig manufacturer, Taylormade Hair Replacement in Millbrae, Calif., which weeds through the selection still further, rejecting up to half.
The first stage of Kraft's 10-year astronaut training programme is physical selection – weeding out people who are not considered fit enough to make the journey.
This curious pattern suggests several possible scenarios, including that male Denisovans interbred with female modern humans, or that these unions were genetically incompatible, with natural selection weeding out some of the X chromosomes, Reich says.
By contrast natural selection weeds out mitochondria that reduce female survival as such mitochondria are less likely to be passed on to the next generation.
Our study here adds to only a small number of studies that have reported polygenic control of evolved herbicide resistance in weeds under herbicide selection (Letouze and Gasquez 2001; Preston 2003; Petit et al. 2010a, b; Busi et al. 2011b).
Natural selection will weed out most mutants.
The other reason that genetic variation can persist is that rust never sleeps: new mutations creep into the genome faster than natural selection can weed them out.
