I don’t see any graph but what could’ve caused evolution could’ve been food, water, or shelter. But most likely food.
A design of growth in which (occurs only in a different situation), the population frequency of an organism rises gradually originally, in a good acceleration time, later progresses swiftly nearing an exponential growth pace just like the J-shaped curve, however, it later declines (meaning rejects) in a bad acceleration time till at zero growth rate the population maintains. For example, yeast is a tiny fungus, so tiny, a microscope is required to view it, furthermore, it is used to produce bread and alcoholic drinks, displays the traditional S-shaped curve if raised in a test tube. Its maturity levels off as the population deplete the nutrients that are essential for its growth.
Why are plant leaves specialized structures that are generally flat and thin?
Answer: To maximize the amount of light transmission through the cell layers.