nNot all changes
improve fitness, they may:
nImprove the fitness of an organism (very unlikely)
nBe neutral, having no effect on fitness
nBe detrimental, decreasing an organisms fitness (most
likely)
nThe bigger the
change the more likely it is to be significantly
detrimental
nDarwin argued that evolution is the accumulation of many small changes that improve fitness, big changes are unlikely to
result in improved fitness.
n“Many large groups
of facts are intelligible only on the principle that species have been evolved by very small steps.”
nThe Origin of Species Chapter VII under “Reasons for disbelieving in great and abrupt modifications”