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 (defined as change in the genetic composition of a population) might occur due to the processes of migration, mutation, genetic drift and non-random mating as well. Lets take the case of a flowering plant. Suppose, an insect pollinates this particular species of plant and its only attracted to red colour.