The Hardy-Weinberg principle is not generally found in nature because it requires certain conditions in an environment. These conditions are the absence of the things that can cause evolution. In other words, if no mechanisms of evolution are acting on a population, evolution will not occur--the gene pool frequencies will remain unchanged.
Gum disease is a very common condition where the gums become swollen, sore or infected. The gums tend to bleed after you brush or floss your teeth, and the blood in your mouth causes the metallic taste. If left untreated, the tissues and bone that support the teeth can also become affected (known as periodontitis).
All the above medications have side effects that include producing metallic taste in mouth. Oral problems like periodontitis and gingivitis can also cause this taste. It can be the symptom or warning sign for underlying disease like cancer, ulcer, food allergy and lichen planus. Many kinds of poisoning like lead poison, mercury poison, iodine poison, cadmium poison, selenium toxicity, increased copper level can produce metallic taste in your mouth.