In humans gene flow usually comes about through the actual migration of human populations, either voluntary or forced. Although gene flow does not change allele frequencies for a species as a whole, it can alter allele frequencies in local populations.
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The sled with a rough metal bottom would take more force to move over ice, because the rough surface would increase friction and the force needed.
Answer:
the layer of the earth's atmosphere that contains a high concentration of ions and free electrons and is able to reflect radio waves. It lies above the mesosphere and extends from about 50 to 600 miles above the earth's surface.
Explanation:
The primary function of all lymph nodes is the production of lymphocytes, which help defend the body against microorganisms and against harmful foreign particles and debris from lymph before it is returned to the blood stream. The major clusters of lymph nodes are in six areas.
