Conventional wisdom holds that the development of separate species happens quickly, most often when populations become separated by a geographical barrier." this is called speciation. "even if these groups meet again and manage to mate before diverging too far from one another, their offspring will be unfit and die out." this is described as hybrid ) sympatric; viabilityb) allopatric; fertilityc) sympatric; breakdownd) allopatric; breakdown

Look at the figure above. which atmospheric layer has around 80 percent of the mass of the earth's atmosphere? (hint: it's where the clouds seen on earth are formed.) a. exosphere b. troposphere c. stratosphere d. thermosphere

Elephants in the savanna regions of africa dig holes in dried up river beds to reach water lying just below the surface. these holes provide drinking water for other animals as well. so, without the elephants, many animals might otherwise die from lack of water during the dry season. the location in which the elephants live is an example of a/n and the role they play in creating water holes is an example of a a) ecosystem; habitat b) community; niche c) habitat; niche d) niche; habitat

What does the hardy-weinberg principle relate to? a. chances of survival of an organism b. frequency of alleles in a population c. natural selection in a species d. causes of evolution among organisms