Let's study ID: a way to study adaptation times (Introduction)

by David Turell @, Sunday, January 02, 2022, 15:27 (18 days ago) @ David Turell

The gaps in the fossil record are discussed as an intro to a new math method:


"Do we have evidence that traits appear abruptly in the fossil record, and that these sorts of calculations apply? The introduction to the paper provides a rich review of examples of this from biological history, showing that their model is highly applicable to biological reality:

"For instance, the fossil record is often interpreted as having long periods of stasis, interrupted by more abrupt changes and “explosive” origins. These changes include, for instance, the evolution of life, photo-synthesis, multicellularity and the “Avalon Explosion”, animal body plans and the “Cambrian Explosion”, complex eyes, vertebrate jaws and teeth, terrestrialization (e.g., in vascular plants, arthropods, and tetrapods), insect metamorphosis, animal flight and feathers, reproductive systems, including angiosperm flowers, amniote eggs, and the mammalian placenta, echolocation in whales and bats, and even cognitive skills of modern man. Based on radiometric dating of the available windows of time in the fossil record, these genetic changes are believed to have happened very quickly on a macroevolutionary timescale. In order to evaluate the chances for a neo-Darwinian process to bring about such major phenotypic changes, it is important to give rough but reasonable estimates of the time it would take for a population to evolve so that the required multiple genetic changes occur. (internal citations omitted)

"There is thus ample precedent for investigating such a question in biohistory. Many complex features of living organisms appear abruptly in the fossil record, where it seems that multiple coordinated changes were necessary before any advantageous functional trait arose. The mathematical model developed in this paper is aptly suited to understanding how long it would take for such a trait to arise.

"As I noted, this paper is methodological, meaning it’s only developing a mathematical model and not yet applying it to real world biological systems. One hopes in the future the team will apply their model to real biological systems. We will then see what the implications are for the viability of standard evolutionary mechanisms to account for the origin of such traits."

Comment: So the gaps are not just the Cambrian as noted in biohistory. As the paper shows multiple coordinated mutations are required for such gaps. Sudden appearance of a new body part is difficult to explain by chance events.

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