Yes. Do you read the paleontological literature much?
I happen to be working on a manuscript which deals with the exploitation of YECs of the ambiguity of the definition of macroevolution. Here is a quick survey of popular definitions that I put together for that paper. I plan to add a few more from important evolutionary biologists who study macroevolutionary processes.
Box 1: Popular definitions of macroevolution among the evolutionary biology community
Evolution: Making Sense of Life 2nd edition textbook by Zimmer and Emland (2016): “Evolution occurring above the species level, including origination, diversification, and extinction of species over long periods of evolutionary time.”
Evolutionary Biology 4th edition, by Futuyma and Kirkpatrick: “A vague term, usually meaning the evolution of phenotypic changes, usually great enough to place the changed lineage and its descendants in a distinct genus or higher taxon.”
Wikipedia: “Macroevolution is evolution on a scale at or above the level of species, in contrast with microevolution, which refers to smaller evolutionary changes of allele frequencies within a species or population. Macroevolution and microevolution describe fundamentally identical processes on different time scales.”
Understanding Evolution website https://evolution.berkeley.edu/evolibrary/home.php: “Microevolution happens on a small scale (within a single population), while macroevolution happens on a scale that transcends the boundaries of a single species. Despite their differences, evolution at both of these levels relies on the same, established mechanisms of evolutionary change.”
Evolution, 2nd Edition by Bergstrom and Dugatkin (Norton Publishers, 2016): These authors of a evolutionary biology textbook for undergraduate biology majors avoids the use of the term macroevolution altogether. The term does not appear in the glossary or index and I have found no uses of the terms micro and macro evolution in the text.
Doug Erwin: Unfortunately I have yet to find any simple definition that Erwin has used but his papers are important on this topic. He appears to believe there are processes that occur at levels above species that contribute to the pattern of evolution on a grand scale. i.e. macoevolution isn’t just the accumulation of lots of microevoution as one of his better known papers talks about.
My personal leaning: Macroevolution describes patterns of changes in biological diversity above the species level which can be viewed as an emergent property resulting from microevolutionary processes acting over long periods of time.
This is the most common view among paleontologists, species selection being the most obvious example of something that can’t be reduced to allele frequency change in a population. Contrary to many textbooks, there are macroevolutionary processes that aren’t just accumulated microevolution. It’s an open question just how important those processes are, but they clearly do exist.
How does ANY evolution happen without ultimately affecting ratios of alleles? … whether they be old or new?
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This definition has wandered quite far from the usual idea that YECs dont believe speciation is possible.
Hence… micro- evolution is usually a reference to adaptation WITHIN a species… while Macro- evolution is … impossible.
Im not sure whether it matters much if macro- is only an accumulation of micro-.
Plants can speciate in a single generation… by doublung their chromosomes.
Depends on whether you think changes in what species are in the biota, caused by patterns of extinction and speciation, counts as evolution. Neither changes the ratios of alleles in any population, though it changes what alleles are present in the biota.
Whether you are defining biota as a relatively isolated population or not… it isnt evolution if ratios dont change.
Even as a population declines from 5000 down to 5, there is almost certainly asymmetrical changes in allele percentages.
Even if it is a tiny pocket of individuals going extinct, the pocket is evolving uniquely from the main population.
Funny you should raise that, because I just happen to have posted a Hump piece reviewing an article questioning that genetics is necessarily central to evolution - though that emphasis has been accentuated by me, the author’s primary interest being developmental biology and body-repair mechanisms.
At the very least it gives legs to the ways in which macroevolution might involve entirely different mechanisms from microeveolution, as I think @John_Harshman was indicating, and specifically not the emergent genetic phenomena favoured by @Joel_Duff.
There are more things in heaven and earth than are dreamt of in [any favoured] philosophy.
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“Biota” is defined as all the species in some area, or sometimes the entire world. Microevolution is allele frequency change within a population. What you’re thinking of as allele frequency change in a biota (which we could argue about, but never mind) is macroevolution.
I wasn’t. The differences between species are genetic, and genetics is indeed necessarily central to evolution. There are mechanisms unique to macroevolution, but most macroevolution is still just accumulated microevolution.
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I have not heard of these mechanisms unique to macro-evolution. What would be an example?
I imagine that whole-genome duplication would have a hard time being described as “micro”!
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They’re the mechanisms which causes speciation. Geographic isolation, niche isolation, behavior driven isolation. One population spilts into two, each continues to acquire independent micro-changes until they are macro-evolved apart.
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Actually, there are many examples (particularly in plants) of species where some populations are polyploid, while others are not. So if we’re defining microevolution as “evolution occurring below the species level”, whole genome duplications sometimes can be considered microevolution. Of course, whole genome duplication also sometimes results in “instantaneous” speciation too.
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Well, @Timothy_Horton, THESE factors i’ve heard of! And i would call them factors or elements, but i dont usually see them considered uniquely a part of Macro-Evolution.
I think we can all see that these factors can also be valid causes of Micro-Evolution … if there is less exposure to one or the other.
Was it here at PeacefulScience.Org, or BioLogos.org (?), where we had a YEC blowing his stack over a very clever sentence written by E. Mayer: it said that the “processes of speciation” could be associated with Micro-Evolution.
The ernest Creationist misunderstood what was meant by this, and insisted that the Evolutionists here had been wrong in their definitions the whole time!.. that we had the 2 categories reversed.
I pointed out that until the “operations leading to speciation” were complete, they could always be paused or even reversed… and thus these operations, prior to completion, are rightly considered a part Micro-Evolution!
The most obvious example is species selection. For example, the Chicxulub impact exerted strong selection against large land animals, not by selecting against larger size within any species but by preferentially causing the extinction of large species. No allele frequency change, no microevolution. But the character of the biota was fundamentally altered.
That’s actually a fuzzy case. But I would say that it makes sense to call it macroevolutionary because it can result in instant new species.
I’m not sure @jongarvey realizes it, but he’s actually talking about allopolyploidy.
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He realises it, having learned about polyploidy 50 years ago. But blog posts have their own standards of terminological rigor.
Thanks for causing me to learn the difference between allopolyploidy and autopolyploidy. I was already familiar with polyploidy but hadn’t paused to consider these two types.
(I vaguely recall a project reported some years ago where a tuber-based wild grass was a promising biofuel for electricity generation. The scientists were working to produce a seed-reproducing version because it was far too expensive to divide the corms to make more of the grass plants. So, if I recall correctly, they were manipulating what you are calling an allopolyploid hybrid to make it commercially viable.)
Creationism leads to some interesting and obvious contradictions.
I rhink macro-evolution is best understood in connection with speciation… not just BIG changes in genome (which may not actually create a species).
You wrote the following: “They’re the mechanisms which causes
speciation. Geographic isolation, niche isolation, behavior driven
isolation. One population splits into two, each continues to acquire
independent micro-changes until they are macro-evolved apart.”
Your discussion appears quite sound … which is one of the reasons I
was having difficulty comprehending the existence of factors
unique to macro-evolution. As you and I understand the matter,
these forces apply to both kinds of evolution (micro- vs. macro-),
which is not guaranteed to create macro-evolution, but is known to do
so if all the relevant circumstances last long enough.
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