Is a new evolutionary synthesis necessary?
The current (synthetic) theory of evolution has been criticized on the grounds that it implies that macroevolutionary processes (speciation and morphological diversification) are gradual. The extent to which macroevolution is gradual or punctuational remains to be ascertained. Macroevolutionary processes are underlain by microevolutionary phenomena and are compatible with the synthetic theory of evolution. But microevolutionary principles are compatible with both gradualism and punctualism; therefore, logically they entail neither. Thus, macroevolution and microevolution are decoupled in the important sense that macroevolutionary patterns cannot be deduced from microevolutionary principles.
Stebbins
G L
GL
Ayala
F J
FJ