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.
Evolution can occur by processes other than natural selection, especially genetic drift. And. natural selection can occur without any evolutionary change, as when natural selection. maintains the status quo by eliminating deviants from the optimal phenotype. Many definitions of natural selection have been proposed (Endler 1986).