AP BIOLOGY

Detailed explanation-1: -Phyletic gradualism. Phyletic gradualism holds that morphological evolution is gradual and occurs independently of speciation. Most of the studies supporting this mode of evolution involve organisms that can be minutely sampled through continuous rock sequences.

Detailed explanation-2: -General Overviews. Gradualism in biology and geology refers most broadly to a theory that changes of organic life and of the Earth itself occur through gradual increments, and often that transitions between different states are more or less continual and slow rather than periodic and rapid.

Detailed explanation-3: -Charles Darwin’s 1859 theory of evolution by natural selection put forward the idea that evolutionary change or divergence accumulates steadily and slowly, in small steps, as one species succeeds the previous one in the struggle for existence.

Detailed explanation-4: -Such continuous changes can produce major differences among species only by accumulating over many thousands to millions of years. A simple statement of Darwin’s theory of gradualism is that accumulation of quantitative changes leads to qualitative change.

Detailed explanation-5: -Gradualism is a school of thought which claims that, throughout Earth history, geological and biological processes have operated at rates observed at present. In geology, gradualism is commonly deemed to have started with James Hutton (1726–97).