Answer:
Rocks from retreating glaciers
Primary succession occurs when a natural disaster like an EQ, volcanic eruption, or flood, occurs to an area where there is no plant or animal life. The first organisms to appear are lichens, which over a long period of tome, will begin to form soil.
Answer:
In order to propose a hypothesis, there is a need to first see the function of gills in fishes. The gills of fishes comprise blood vessels that exhibit inherited tendencies of getting oxygen out of the water, which was consumed by fishes from their mouths. These gills also comprise thin walls, and when water moves over these walls of blood vessels, the oxygen from water moves into the blood, and then this oxygen-enriched blood goes to various organs.
Thus, one of the hypotheses in the given case, can be the number of blood vessels, which are found in the gills of the mentioned freshwater fish to be higher in comparison to the blood vessels found in the normal fishes, and apart from this, the surface area of the thin walls, which are found in the gills is also more in the new species of freshwater fish.
Answer: plucking
Plucking is a type of glacier erosion.Plucking occurs when the ice around the broken rocks, gets displaced with the force exerted by the retreating glacier. The glacier ice plucks the freezed rocks away along with it during glacier erosion.