A tracheotomy is performed if enough air is not getting to the lungs, if the person cannot breathe without help, or is having problems with mucus and other secretions getting into the windpipe because of difficulty swallowing. There are many reasons why air cannot get to the lungs.
Trending Now. Answers. Best Answer: Yes, the smallest unit of evolution is the population. The reason is, the techical definition of evolution is change in allele frequency. You have to have a population in order to run the statistics to measure if there has been a change. Remember, a population does not necessarily mean all animals of one species.
This usually results because the species live in similar environments and fill similar ecological roles. The structures in this case are known as analogous structures. The process that brings these traits forward is called convergent evolution. Convergent evolution is natural selection that favors the same type of structure in different ancestors. The similarity between convergent evolution-affected species is called homoplasy, which literally means 'from the same mold or form.' Examples of Convergent Evolution