Change is Good!
Why does a duck have a rounded bill and a heron have a long pointed bill? Why does a skunk have black and white fur and scent glands? All organisms are uniquely adapted for their environments. Scientists know that over long periods of time organisms have changed or adapted to better survive in their environments. They call this slow process of change evolution.
Individuals within an animal species are not exactly the same. Just like you are not exactly like your parents or your friends or any other human on earth. Each organism in a species has a slightly different genetic makeup. Organisms within a species that have characteristics that help them survive in their environment tend to breed and pass on those positive characteristics. Individuals that have characteristics that make survival more difficult may not survive to pass on their characteristics. Basically, characteristics that help an organism survive and thrive get passed on to future generations characteristics that don't slowly disappear.
Dive Into the Gene Pool
All of the genes in a population of organisms is called a gene pool. The gene pool contains all of the traits or genes in any one population that can be passed on from generation to generation. Sometimes the gene pool of a population lacks diversity or becomes contaminated with genes from a closely related species. When that happens, the species can become endangered.
In some areas, the population of a species is so small that there are few choices when mating.
The Florida panther population is limited to a very small area. The gene pool of the species lacks variety because generation after generation is descended from the same animals. When a gene pool gets too small, negative characteristics can easily be passed from one generation to the next, endangering the survival of the entire species.