Continental drift was a theory that explained how continents shift position on Earth's surface. Set forth in 1912 by Alfred Wegener, a geophysicist and meteorologist, continental drift also explained why look-alike animal and plant fossils, and similar rock formations, are found on different continents.
Alleles are the individual genes that give rise to certain characteristics in an organism.
When an allele is "fixed" to a population, this means that the characteristic will be constant & most likely will not change until the environment changes as well.
Like with arctic hare, the alleles that influence the color of their coats (white in the winter & brown in the spring/summer) will stay because any fur pattern other than the aforementioned characteristics with result in becoming someone else's food with the lack of camouflage.
Hope that helps!
No doubt, the United States is a powerful country in the world today. It has made its mark in the history by building a strong economy that every other nation envies, and idolizes as well. But, all that glitters is not gold. And every country has its pluses and minuses. There are some serious social issues in the United States as well that need to be dealt with to maintain the position of power and prestige, and set a true example of ideal society in the world.
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Not a specific genetic sequence, some doctors and scientists believe it could be hereditary and others do not believe it is genetic but instead develops due to psychological and environmental factors. Look up the rat park study.
