Question

How long does it usually takes for speciation to occur?

Answer 1

Across a broad range of species, the research found that for a major change to persist and for changes to accumulate, it took about one million years. The researchers wrote that this occurred repeatedly in a "remarkably consistent pattern."

"What's interesting is not that we have so much biological diversity and evolutionary change, but that we have so little," Uyeda said. "It's a paradox as to why evolution should be so slow."

Long periods of little change, Uyeda said, are called "stasis," a pattern that originally led to the concept of "punctuated equilibrium," controversial when it was first proposed in the early 1970s. This research supports the overall pattern of stasis and punctuational change. However, Uyeda says there may be different causal mechanisms at work than have often been proposed.

"We believe that for changes to persist, the underlying force that caused them has to also persist and be widespread," Uyeda said.

"This isn't just some chance genetic mutation that takes over," he said. "Evolutionary adaptations are caused by some force of natural selection such as environmental change, predation or anthropogenic disturbance, and these forces have to continue and become widespread for the change to persist and accumulate. That's slower and more rare than one might think."

Though slow, however, the process appears to be relentless. Most species change so much that they rarely ever last more than 1-10 million years before going extinct, or developing into a new species, the scientists noted.

The exact cause of these long-term, persistent evolutionary changes is not certain. The scientists said that climate change, in itself, does not appear to be a driving force, because many species have remained substantially unchanged over time periods when climates changed dramatically.

This study is one of the first of its type to help reconcile the rapid evolution seen by biologists in contemporary species; the slow, stable changes observed by paleontologists; and dramatic, macroevolutionary differences in body sizes.

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