The most prominent disadvantage of artificially selected species is that they are very susceptible to disease. Since certain traits are bred for, variation within the species is greatly diminished, causing them to become very sensitive to changes in the environment, including both biotic and abiotic factors.
Artificial selection can also have unforeseen consequences, as in the case of Africanized honey bees, also known as killer bees. While the bees were bred to produce more honey, traits which caused an increase in aggressiveness were also inadvertently passed on. This has resulted in the deaths of several people as the bees became increasingly more defensive.
Selective breeding, another term for artificial selection, may also have a detrimental effect on the species itself, as seen in the inbreeding of dogs in order to maintain the so-called purity of certain breeds. Some breeds of dogs have many seemingly inherent complications, such as hip dysplasia and a shorter lifespan.
In other cases, such as the banana, artificial selection has produced hybrids that are very susceptible to sterility. This means that the species is unable to reproduce in the wild, opening it to a higher risk of extinction as a single disease could effectively wipe out the entire species.