Not that the authors or their PR team put it that way, but from “Rapid Evolution Within Single Crop-Growing Season Increases Insect Pest Numbers” (ScienceDaily Aug. 15, 2011), we learn the limits. Aphids (pant-sucking pests) Mate once in the fall, and thereafter the females mainly just clone themselves (which explains how they become so numerous so swiftly). Researchers decided to compare the growth rates between a polulation where all members were from a single clone against one where therer were two lineages. They found that hey found that evolving populations grew in number up to 42 percent faster. Their conclusion?
“This shows that even without human interference natural selection acting on aphid populations causes rapid evolution,” said Martin M. Turcotte, who led the research as a graduate student in ecology, evolution and organismal biology at UC Riverside. “Even stronger effects might be expected when pesticides are in use. For decades, evolution was deemed too slow and, hence, it was not considered when studying population growth — an oversight that needs to be corrected.”
Will non-Darwinists be forgiven for asking what this aphid population growth study has to do with evolution, given that it lead to no physical change at all? Change only in numbers hardly counts.
See also: Researchers discover supergene that controls butterfly mimicry patterns