Cervical lymphadenitis is usually caused by a viral upper respiratory infection. The key symptom of lymphadenitis is the presence of a painful mass in the cervical area, often accompanied by fever, runny nose, sore throat, and cough.
Question and answer. Which of the following defines evolution? a change in environmental conditions a change in an animal's physical traits a change in a population's gene pool a change in an individual's genetic. makeup. Evolution is a change in a population's gene pool.
The basic mechanisms of evolution include natural selection, genetic drift and mutation. Natural selection is a process in which the population of organisms that have adapted to their environment increases more than the population of less well-adapted forms. This concept was first explained in Charles Darwin's theory of evolution.