The technical details are too hard for me to weigh in on, but isn’t consensus leaning towards “rapid speciation” rather than the older theory of slow, incremental speciation. (I only mention it because it suggests that speciation is a different mechanism from micro evolution adaptation.)
You are talking about
punctuated equilibrium ("rapid speciation") versus
phyletic gradualism ("slow, incremental speciation"). And the answer, surprising to some, is these are not mutually exclusive ideas. In other words, it's not an either/or choice. Both punctuated equilibrium and phyletic gradualism are describing the same thing—just at different scales, as observed by Kenneth R. Miller in his book
Finding Darwin's God. The only thing that makes punctuated equilibrium appear novel, he said, is the choice of a timescale with which to present the data. Once you expand the brief ‘punctuation’ interval, stretching it to its actual temporal length, the pattern resolves into the same incremental change Darwin described—long periods of stasis followed by speciation or extinction. "The contrast is an artifact of how the lines are drawn, not of how evolution works."
As Miller shows, Darwin himself explicitly described long periods of stasis punctuated by intervals of modification. The single diagram in
Origin was never meant to depict slow, continuous, steady rates. Darwin wrote that "each form remains for long periods unaltered, and then again undergoes modification"—a textbook description of stasis and punctuation. The supposed gradualism/punctuation controversy is a rhetorical one; there is no substantive difference. Gould expanded on a pattern that Darwin had briefly described. The whole thing collapses once the missing timescale is restored.
Remember that [Darwin] drew exactly one diagram in the Origin, designed to allow his readers to see how he believed new species were formed over time. Darwin presented this diagram so that his readers would have some idea of how he imagined descent with modification might take place over time. Naturally, he focused on what things might look like when changes were taking place—not on what might happen when they were not. Should we take the branching lineages that Darwin drew as showing his commitment to regular, steady change over time? After presenting the drawing he wrote:
But I must here remark that I do not suppose that the process ever goes on so regularly as is represented in the diagram, though in itself made somewhat irregular, nor that it goes on continuously; it is far more probable that each form remains for long periods unaltered, and then again undergoes modification.
... [I]t turns out that Darwin got it positively and overwhelmingly right the first time.
Kenneth R. Miller,
Finding Darwin's God: A Scientist's Search for Common Ground Between God and Evolution (CliffStreet Books, 2000), pp. 112-115. Emphasis mine. The quote from Darwin is taken from
The Origin of Species, 6th ed. (1872; Oxford University Press, 1956), pp. 119-120.