An earthquake causes a huge canyon to form, permanently dividing a population of wild donkeys. on the windward side of the canyon, dry conditions develop and grasses grow. on the leeward side of the canyon, rainfall is frequent and a forest grows. what is least likely to happen over the course of 100,000 years?

A geographic modification distinguishes the members of a population into more than one group. Such modifications could comprise the generation of a new waterway or a new mountain range, or the creation of new canyons. The phenomenon results in allopatric speciation.  

Due to this, mutations of different genes takes place and leads to the formation of distinct populations with time. These changes result in the development of distinct features between the two populations. As a consequence, the populations turn so different from each other that the individuals of these populations lose the tendency to interbreed.  

Thus, in the given case the population of wild donkeys will become so much different from each other that they lose the tendency to remain physically same with time in both the windward side and the leeward side.  

it has to be understood that the sea water contains a huge amount of sodium and chlorine ions and if they enter the cell of the atlantic cod fish, the cell will shrivel and the fish will die. to avoid such a condition, the fish uses active transport for the purpose of removing the ions against the gradient.

explanation:

the atlantic cod is not a maritime osmoconformer. its native application of salts is less than that of the seawater it lives in. it is continually falling water from the gills to the ocean via osmosis.

countering that, the fish is going to be swallowing seawater. but since its internal collection of salts is lower than seawater, the fish will want to go free of excess salt, and since that's going upon a gradient, then active transport, requiring energy, must be used to pump out the salt. much marine fish use the organs to filter out the salt and these fish discharge very straight urine.