Have you ever sat in the mall one day, and noticed that nobody has the same features? You can sit and watch hundreds of people and never see two identical people-except twins! You can see people with the same nose, or eye color, or hair type, but they always have differences, whether they are height, skin color, attached or unattached earlobes... The possible differences are nearly endless!
In the Human Genome, there are over 25,000 known genes-a gene is a sequence of DNA that codes for a specific trait-that can be mixed and matched in all sorts of variations to make a new, unique individual. Different species have different numbers of genes, yet despite the near-endless possibilities for genetic variation, there is a decline in genetic diversity appearing in some species. Why? And also, is there a negative impact this could have on the species, the environment, or the world?
Hundreds of species are listed as either endangered or threatened. This is a key factor in the decline in genetic diversity. For example, some species of sea turtles are estimated to have only one hundred mating pairs left. That means that there are only two hundred turtles that have genes passed on to them from a species that originally had millions of members! The term used for this is "genetic bottleneck". The millions of turtles-or any other endangered animal-had hundred of millions, even billions of different arrangements of genes, and there were thousands of different genes present in their species. When there are only a few left, there are only a few possible genetic variations left, as well, and out of all the genes that were in the population, only a few are present, leading to a smaller genetic diversity.
This can lead to a stronger likelihood of new young expressing recessive genetic diseases, which would have originally been suppressed by dominant genes. Also, if the species were to ever recover, their genes would be forever limited, making it harder to have healthy young, and therefore harder to keep the species alive.
Think about it: If the survival of a species is impossible due to low genetic diversity, or anything else, for that matter, it will eventually die out, no matter what we try to do to prevent it. If one species dies, then it creates a hole in its ecosystem, and other species can lose its hunter, or its prey, or its companion. If one species dies out, then other populations can explode, and others could die out with it.
Nature maintains a balance, and it is very delicate. We need to do all we can to keep the population and genetic diversity high in species that may be threatened, and we need to do it before it is too late. If we wait too long, the problem will spiral out of control, and it will be beyond us to help, and there is no telling what the loss of any single species will do to the environment, or us. Humans need to finally realize that we aren't the center of the world, and we rely on everything else just as much as any other species on Earth.