/* */ Rosa Rubicondior: Evolution News - Rapid Evolution of Early Tetrapods. Crisis? What Crisis?

Wednesday, 25 August 2021

Evolution News - Rapid Evolution of Early Tetrapods. Crisis? What Crisis?

Late Devonia early tetrapods
Artwork: Davide Bonadonna
Sustained fast rates of evolution explain how tetrapods evolved from fish | Department of Organismic and Evolutionary Biology

Creationist frauds flatter their willing marks by telling them the scientific Theory of Evolution is a theory in crisis, so scientists are coming to see their superstition as correct after all. This makes them feel they know more than the millions of biomedical scientists who spend their working lives applying the TOE to interpret and explain the biological data, all without having to bother with learning very much. It also enables the frauds to get away with a false dichotomy fallacy rather than show evidence for their god claim.

The extent to which this falsehood has penetrated public opinion in the USA can be gauged by two polls. One of members of the American Academy of Science on the statement, "Humans and other living things have evolved over time" (95% agreed, rising to 99% of biomedical members) and a 2015 Pew Research Poll on the question, "Do scientists generally agree about evolution?" where only 66% thought they did (29% thought they disagreed!). Public perception of the degree of scientific support for evolution is thus very different in the USA to the actual support.

In this paper we can see how biologists take the TOE as fundamental to any explanation of the data and how the data only makes sense from an evolutionary perspective. Never, at any point, is a mystery settled for as unknowable or is data taken as evidence of an unproven, supernatural entity, plucked from one or other of Earth's many cultural origin myths.

The team from Harvard University's Organismic and Evolutionary Biology Department have addressed what they say is one of the biggest questions in evolution - when and how a major taxon first arises. This is what Creationists call ‘macro-evolution’ which, for unexplained reasons, they claim is impossible without god magic.

The major taxon in question is the terrestrial tetrapods - the transition of fish into limbed, air-breathing land animals, which happened between 400 and 360 million years ago between the Middle and Late Devonian, to give the stem group from which all subsequent terrestrial vertebrates, and many aquatic reptiles, mammals and birds, have evolved.

The team believe they have shown not only when this happened, to a high degree of accuracy, but also, typical of a new taxon exploding into a new ecological niche, that it happened at an accelerated rate when compared to the normal pace of evolution. Meanwhile, probably because they were already well-adapted to their environment, the related lobe-finned fish ancestor of this taxon changed little over the same time-span. They used not only the fossils of these early tetrapods but also the fossil tracks they left in mud. Maybe because fossilisation of the animals was rare in that water-margin environment, in contrast to the opportunities to leave tracks in mud, these fossil tracks pre-date the earliest fossils by several million years.

From the Harvard University news release:
Normally footprint data shows up after body fossils of their track makers. In this case, we have tetrapod footprints much older than the first body fossils by several million years, which is extremely unusual. By combining both footprint and body fossils, we could search for a more precise age for the rise of tetrapods.

Professor Stephanie E. Pierce, Co-author
Museum of Comparative Zoology & Department of Organismic and Evolutionary Biology
Harvard University, Cambridge, MA, USA
In a study published August 23 in Nature Ecology and Evolution Harvard researchers establish the origin date of the earliest tetrapods and discover they acquired several of the major new adaptive traits that enabled vertebrate life on land at accelerated evolutionary rates.

The study led by Dr. Tiago R. Simões, postdoctoral researcher, and senior author Professor Stephanie E. Pierce, both from the Department of Organismic and Evolutionary Biology, Harvard University, applied recently developed statistical methods (Bayesian evolutionary analysis) to precisely estimate the time and rates of anatomical evolution during the rise of tetrapods. The Bayesian method was adapted from methods originally developed in epidemiology to study how viruses like
We were able to provide a very precise age for the origin of tetrapods at approximately 390 million years ago, 15 million years older than the oldest tetrapod body fossil.

On the other hand, we discovered the evolutionary lineages leading to the first tetrapods broke away from that stable pattern, acquiring several of the major new adaptive traits at incredibly fast rates that were sustained for approximately 30 million years.

We see several anatomical innovations in their skull related to feeding and food procurement, enabling a transition from a fish-like suction-based mode of prey capture to tetrapod-like biting, and an increase in orbit size and location. These changes prepared tetrapods to look for food on land and to explore new food resources not available to their fish relatives.

What we've been finding in the last couple of years is that you have lots of anatomical changes during the construction of new animal body plans at short periods of geological time, generating high rates of anatomical evolution, like we're seeing with the first tetrapods. But in terms of number of species, they remained constrained and at really low numbers for a really long time, and only after tens of millions of years do they actually diversify and become higher in number of species. There’s definitely a decoupling there.

Dr. Tiago R. Simões, lead author
Museum of Comparative Zoology & Department of Organismic and Evolutionary Biology
Harvard University, Cambridge, MA, USA
COVID-19 evolve and only recently became a tool in paleontology for the study of species evolution.

The study also innovates by combining data from fossil footprints and body fossils to pinpoint the time of origin of the tetrapods…

The researchers also found that most of the close relatives to tetrapods had exceptionally slow rates of anatomical evolution, suggesting the fish relatives to tetrapods were quite well adapted to their aquatic lifestyle…

Simões and Pierce also extended molecular approaches to study how fast different parts of the early tetrapod body plan evolved—such as the skull, jaws, and limbs—and the strength of natural selection acting on each of them. They found that all parts of the tetrapod skeleton were under strong directional selection to evolve new adaptive features, but that the skull and jaws were evolving faster than the rest of the body, including the limbs.

The researchers also found that the fast rates of anatomical evolution in the tetrapod lineage were not associated with fast rates of species diversification. In fact, there were very few species around, so few they had a very low probability of being preserved in the fossil record.

This finding helps to answer an ongoing debate in evolution of whether new major animal groups originated under fast rates of anatomical change and species diversification (the classical hypothesis). Or, if there were high rates of anatomical evolution first, with increased rates of species diversification occurring only several million years later (a new hypothesis).
So, nothing makes sense in the absence of the TOE, which explains how a new taxon arises when a founder population moves into a new niche. In the case of the first terrestrial tetrapods, this new niche was the entire land surface of the
This suggest that changes in the skull had a stronger role in the initial stages of the fish-to-tetrapod transition than changes in the rest of the skeleton. The evolution of limbs to life on land was important, but mostly at a later stage in tetrapod evolution, when they became more terrestrial.

Professor Stephanie E. Pierce
Earth, with its already diversifying population of plants and probably arthropods and maybe worms.

They would then have become part of this developing ecosystem, eventually become predators or prey. Under these circumstances, those species which had evolved jaws for biting and chewing would have been able to exploit new opportunities, as would those that were better able to use eyes to detect prey or predators, or distant food plants or potential mates. Evolving limbs would eventually provide the ability to hunt and chase or run away. Not surprisingly therefore, the most obvious points of evolutionary change were in the skull - the jaws and eye-sockets or orbits.

Meanwhile the fish ancestors, with little need to change and with a relatively stable environment, would have little to drive evolution so they remained relatively unchanged.

Far from being the 'Theory in Crisis' that creationist frauds claim, the TOE is the only viable explanation for this data. There is absolutely nothing in the findings of this research team that shows any hint that the TOE is not fit for purpose and suffers from major flaws, such as an inability to explain 'macro-evolution' or the evolution of new taxons. The 'theory' in crisis, is of course creationism and its lab-coated pseudo-scientific version, Intelligent Design, which is rejected by just about all working biomedical scientists and which ofers no useful explanations and makes no testable predictions.

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