Two critically endangered Amur Leopard cubs were born a few weeks ago at the St Louis Zoo. Considering that there are fewer than 120 of these cats left in the wild, their births are an important milestone in animal conservation. The evolution of conservation and breeding of animals has led to the protection and increase of the given species, but has also been a source for a gene phenomenon where the species isn’t able to fare in the wild. The breeding of animals in conservation zones, such as zoos, has allowed for the mixing of genes in various animals, creating subspecies. Creatures such as the Liger, for example, are man-made, as a lion and tiger cannot breed naturally in the wild due to habitat and environmental attractions. In the wild, inbreeding is usually undesired, but occurs if a population of animals cannot find another population to mingle with. If this does not occur, the gene pool cannot diversify, and hence, weaker genes will eventually become more apparent, and cease to disappear over generations. Population isolation may also occur as a result, and the endangerment of a species may further become easier.