41. For example, birds put strong selection pressure on seeds for colour of fruits because of their enhanced vision. 42. As a side effect of these selection pressures , human evolution crossed a threshold at which language became possible. 43. To that degree, cancer stem cells constitute a rapidly evolving population subject to selection pressure = = evolution. 44. Two of the other leading causes of death are expected to have exerted limited or no selection pressure . 45. :: I believe a better question would be : Is there any form of selection pressure in humans? 46. Optimising herbicide input to the economic threshold level should avoid the unnecessary use of herbicides and reduce selection pressure . 47. The arrival of cane toads has also exerted selection pressures on the feeding behaviour and toxin tolerance of snakes. 48. Darwin supposed further that embryos were subject to less intense selection pressure than adults, and had therefore changed less. 49. Little is known about how variations in fungicide treatment affect the selection pressure to evolve resistance to that fungicide. 50. ;Genome diversity : Genome doubling provided the organism with redundant alleles that can evolve freely with little selection pressure .
