Abrupt shifts in the evolution of animals have long been a challenge for theorists like Darwin. A new research paper supports the idea that even the sudden changes are underpinned by a gradual process of successive incremental changes.
Evolutionary biologists from the University of Reading propose a new statistical model to explain the sudden changes and long periods of stasis that have been seen in the evolutionary history of some species.
The team led by Professor Mark Pagel developed a statistical model that reconstructed the body-size changes that occurred throughout the 170 million-year history of mammals.
The authors found that even though there are periods for some mammals during which abrupt changes in size occur, these occurrences can be understood as normal changes that draw on the natural variability that evolution adds to natural populations.
Prof Mark Pagel is the lead author of the paper.
The basis for accommodating what has previously been a thorn in the side of theorists such as Darwin is provided by our statistical model.
Darwin's theory of evolution by natural selection predicts gradual andIncremental changes to organisms over a long period of time. For at least fifty years, fossils have been used to challenge the Darwinian orthodoxy by showing sudden changes in the sizes, shapes, colors and other features of organisms.
We show in this paper that even these abrupt changes are easy to explain when natural selection pulls a trait in one direction. There are no special extra-Darwinian mechanisms required.
The rise of many different mammal groups from earlier forms occurred around 60-70 million years ago. Over a 100,000 year period, an early small animal, ancestral to today's modern cows, antelopes, and giraffes, increased in size over 70%. The baleen whales have increased in size over the course of 7 million years, which is more than the time it took for humans to evolve.
More information: General statistical model shows that macroevolutionary patterns and processes are consistent with Darwinian gradualism, Nature Communications (2022). DOI: 10.1038/s41467-022-28595-z Journal information: Nature Communications Citation: Gradual evolution is back: Darwinian theory of gradual process explained in new research (2022, March 2) retrieved 2 March 2022 from https://phys.org/news/2022-03-gradual-evolution-darwinian-theory.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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