Answer:
Positive natural selection.
Explanation:
The positive natural selection is a type of natural selection that increases the frequency of an allele or trait when it is advantageous for the population. What happened in the example is that the mouth with the slight change in morphology (trait) was more advantageous for the population in the south in relation to the ancestral morphology (still preserved in the population in the north), and therefore its frequency increased. This, in turn, is due to the fact that the food (prey) is not the same in the two habitats (north and south). The specific prey in the south, caused the new morphology to be selected, (increasing the frequency of individuals with the new mouth), becasue probably that trait allows the trouts in the south to hunt more effectively.
You drop it barely above the ground
Greater portions of the beach begin to appear during ebbing tides, until the maximum amount of beach is visible at low tide. They usually happens twice in a day. Beaches results from wave action by which waves or currents move sand or other loose sediments of which the beach is made as these particles are held in suspension.
B. The levels of classification increased. Previously there were only 2 domains of life, Bacteria and Eukarya, but an additional domain and Kingdom were added when the distinction of Archaea was observed.
