Mutations Evolution can only go where mutations lead it. There must be some traits that never appear through mutation, e.g. wheels with axles. Yet, mutations do not appear to limit evolution strongly, in the sense that the immense diversity in rates of morphological evolution does not correlate with rates of evolution at the DNA level. A recent experiment by de Visser et al. Although differential survival and reproduction cause changes to a population, these changes are not instantaneous.
Selection is less effective in small populations than in large populations.
Consequently, one of the risks faced by small populations is that they will be unable to evolve fast enough to a changing environment. In such cases, the inefficiency of natural selection limits the rate of evolution. Linkage - A gene can be advantageous and spread in a population when considered on its own, but genes are never on their own. By chance, this mutation happened in an individual with many blue genes and few red genes. Even though the mutation is favorable, it will likely be lost unless sex occurs and mixes up the different genes.