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Author Topic:   MACROevolution vs MICROevolution - what is it?
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 16 of 908 (385703)
02-16-2007 9:36 PM
Reply to: Message 5 by Doddy
02-14-2007 12:19 AM


YEC creationist needed ...
I suggest you read what CreationWiki has to say on the issue.
quote:
Many creationists caution against using either term on the grounds that they detract from the real issue, the gain or loss of information, and are misleading in talking about the size of the change instead of the direction of the change.
Anyone get whiplash there? Sounds like "Arguments we think Creationists should NOT use ..." eh?
I also noticed that they have Hyenas as canines ... (and three varieties of wolf but no dogs???) in their picture of "Macroevolution of the Biblical Kind" ...
quote:
Hyena - Wikipedia
Although hyenas bear some physical resemblance to wild dogs, they make up a separate biological family which is most closely related to Herpestidae (the family of mongooses and meerkats).
If you can only object to "macro"evolution on the basis of a pre-supposed limited time scale, then what is the creationist limit to "macro"evolution - given the time that we actually have eh?
Certainly if they include Hyena with Wolf from a common ancestor they are talking about going back to the order of carnivora for the beginning of divergence into modern species.
That's pretty macro.
Enjoy.

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This message is a reply to:
 Message 5 by Doddy, posted 02-14-2007 12:19 AM Doddy has replied

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Doddy
Member (Idle past 5909 days)
Posts: 563
From: Brisbane, Australia
Joined: 01-04-2007


Message 17 of 908 (385784)
02-17-2007 4:21 AM
Reply to: Message 16 by RAZD
02-16-2007 9:36 PM


Re: YEC creationist needed ...
RAZD writes:
I also noticed that they have Hyenas as canines ... (and three varieties of wolf but no dogs???) in their picture of "Macroevolution of the Biblical Kind"
Lol...I'd point that out to them, but it would be even more fun to make fun of their error on EvoWiki.
That and CreationWiki is far more restrictive in allowing criticism by non-members.
Edited by Doddy, : No reason given.

"Der Mensch kann was er will; er kann aber nicht wollen was er will." (Man can do what he wills but he cannot will what he wills.) - Arthur Schopenhauer
Help inform the masses - contribute to the EvoWiki today!

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 18 of 908 (393205)
04-03-2007 10:22 PM


What Two Universities say ...
Lets review the definitions used by two universities from the list of definitions of evolution on Message 71:

(A) Berkeley

quote:
The Definition:
Biological evolution, simply put, is descent with modification. This definition encompasses small-scale evolution (changes in gene frequency in a population from one generation to the next) and large-scale evolution (the descent of different species from a common ancestor over many generations). Evolution helps us to understand the history of life.
The Explanation:
Biological evolution is not simply a matter of change over time. Lots of things change over time: trees lose their leaves, mountain ranges rise and erode, but they aren't examples of biological evolution because they don't involve descent through genetic inheritance.
The central idea of biological evolution is that all life on Earth shares a common ancestor, just as you and your cousins share a common grandmother.
Through the process of descent with modification, the common ancestor of life on Earth gave rise to the fantastic diversity that we see documented in the fossil record and around us today. Evolution means that we're all distant cousins: humans and oak trees, hummingbirds and whales.
Note the clear reference to change in species over time (descent with modification) and the application of that to both microevolution and macroevolution. It then goes on to discuss the relation of the vast evidence of time and fossil data to these concepts.

(B) University of Michigan

quote:
Definitions of Biological Evolution
We begin with two working definitions of biological evolution, which capture these two facets of genetics and differences among life forms. Then we will ask what is a species, and how does a species arise?
* Definition 1:
Changes in the genetic composition of a population with the passage of each generation
* Definition 2:
The gradual change of living things from one form into another over the course of time, the origin of species and lineages by descent of living forms from ancestral forms, and the generation of diversity
Note that the first definition emphasizes genetic change. It commonly is referred to as microevolution. The second definition emphasizes the appearance of new, physically distinct life forms that can be grouped with similar appearing life forms in a taxonomic hierarchy. It commonly is referred to as macroevolution.
Note that these are very similar, down to the distinction between (small-scale) microevolution and (large-scale) macroevolution.

Proposed Combined Definition:

We can combine these to formulate a statement of the scientific theory of biological evolution as represented by these schools that (actually) teach biological evolution:

Definition of Biological Evolution


Biological evolution is descent with modification, resulting in a change in hereditary traits within species over time. This definition encompasses small-scale evolution (microevolution) and large-scale evolution (macroevolution) as follows:(a)
  1. Microevolution is the changes in the genetic composition (the frequency of alleles) of a population with the passage of each generation
  2. Macroevolution is the descent of different species from their common ancestors over many generations.

(a) - Where the division between the two levels of evolution is marked by non-ambiguous speciation, the seperation of a previous parent population into non-breeding daughter populations.
The only difference of any significance between microevolution and macroevolution as listed above is the inclusion of the concept of descent from previous common ancestors, parent populations that existed before non-arbitrary speciation separated the daughter populations. Hereditary relationships and hierarchies are not new at this point - that is the basis for the change in the frequency of alleles from generation to generation, for descent with modification, for the change in species over time - but it is now being applied to populations of species rather than to individuals within species. Note how this also conforms to what I previously proposed for elements for microevolution:
Message 17
  • refers to speciation and
  • nothing beyond the causes up to and including speciation,
  • has been observed to occur and is
  • thus a fact.
    That it involves
  • change in species over time,
  • mutation as an observed fact,
  • natural selection as an observed fact, and
  • some other minor mechanisms such as genetic drift and horizontal gene transfer by viruses and the like.
    That it does NOT involve
  • sudden large scale change or
  • sudden appearance of whole new features or abilities.
Then we can discuss the evidence for "micro"evolution in genetics and in the fossil record.
The purpose will be to fully define what "micro"evolution is and what "micro"evolution is NOT.
(edited to match structure below)
We can further stipulate that speciation here refers to non-arbitrary speciation, where daughter populations no longer interbreed, although this "line" may take a while to be formalized completely.
From this, and from application of what we know about microevolution, we can hypothesize that recent daughter populations will:
  • Initially share a lot of common features, behaviors, genes, environments, predators, food sources, diseases, etcetera.
  • Change from cooperation between individuals within the whole population (breeding, protection, assistance, etc) to competition between the two populations (especially over the same resources).
  • Be selected for reducing competition with the sister species (with its low survival & reproductive value) through changes to features, behaviors, genes, environments, predators, food sources, diseases, etcetera.
  • Acquire divergence and diversity (with greater survival\reproductive value than stasis) as a result of those changes until the overall interactions between daughter populations is not distinguishable from overall interactions with other species.
  • Continue to evolve within their populations only through microevolution
So what can we infer would be a similar description for the elements of macroevolution based on these combined scientific definitions of biological evolution?
    "Macro"evolution
  • refers to continued evolution within each species after speciation, which
  • has been observed to occur as an ongoing process in all known current forms of life, and
  • to the different hereditary hierarchies between different species.
    Hierarchies that can be
  • inferred from from the fossil record, based on the similarity of features between species that would be due to heredity (rather than the convergent evolution of similar features), and
  • inferred from the genetic record, based on the similarity of structures in the genes that would also be due to heredity (rather than the convergent evolution of similar features), and
  • tested by comparing the fossil record with the genetic record.
    That it involves
  • continued change in species over time, microevolution, as a validated process within each species population
  • recent common ancestry of daughter species from parent species as an observed fact,
  • the mechanisms of hereditary relationships applied to whole populations (rather than within populations), and
  • reproductive isolation and some other minor mechanisms such as population dynamics, punctuated equilibrium vs gradualism, extinction events, and the like.
    That it does NOT involve
  • sudden large scale change or
  • sudden appearance of whole new features or abilities.

Information related to hereditary hierarchies:

Classic taxonomy
http://www.msu.edu/%7Enixonjos/armadillo/taxonomy.html
is based on observed hereditary hierarchies in the fossil record and current life. The levels of the different taxons is based on the length of time from the common ancestor population that is the parent of the taxon group, whether that group is species, genus, family, order, class, phylum, kingdom or all of life as we know it -- seeing how the evidence that we have fits the theory at each different level. It is also NOT dependent on the whole picture being valid to investigate the hereditary hierarchies at any level desired: that is all part of testing the theory against the evidence.
Cladistics
FossilNews.com – A Blog On All Things Fossil And More…
is based on analyzing the evolutionary relationships between groups to construct their family tree. ... classified according to their evolutionary relationships, and that the way to discover these relationships is to analyze what are called primitive and derived characters. This does away with taxon groups above species and replaces them with "Clades"
clade -nouna taxonomic group of organisms classified together on the basis of homologous features traced to a common ancestor.
Cladistics is just a different way of looking at the same data and developing the same hereditary hierarchies, without any confusion with the (un)importance of different taxons. Cladistic analysis also lends itself to analyzing genetic hereditary hierarchies with homologous genes.
The classifications are not based on, nor dependent on, special features, abilities, functions, forms or any other aspect derived by evolution, but on the hereditary relationships. Instead such derived aspects are used as the evidence of the hereditary relationships. You are not a mammal because you have four limbs, you have four limbs because you are a mammal, evolved from the first common ancestor mammal that happened to have four limbs and who's own ancestor had four limbs.
The evolution of that first common ancestor mammal - by the application of the theories of biological evolution as discussed above - would still have been a speciation event, the result of microevolution within the population of it's ancestor species until the speciation event, and then by microevolution within the daughter species as it diverged from it's ancestral stock and then diversified with speciation events that then developed new species of mammals from the first one.
This proposed combination definition shows how general evolution both involves everyday evolution and how it can result in "higher" taxonomic classifications, ... with a mechanism that exists and that can be tested (common descent).
No creationist "sudden new features" or chimeric morphing from one "kind" into another needed.
Enjoy.
Edited by RAZD, : refined

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we are limited in our ability to understand
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Replies to this message:
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Allopatrik
Member (Idle past 6187 days)
Posts: 59
Joined: 02-07-2007


Message 19 of 908 (393270)
04-04-2007 6:04 AM


quote:
The words “microevolution” and “macroevolution” are relative terms, and have only descriptive meaning; they imply no differences in the underlying causal agencies.
--Theodosius Dobzhansky, (1951) Genetics and the Origin of Species, Third Edition, Revised, p. 17

Natural Selection is not Evolution-- R.A. Fisher

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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 20 of 908 (393274)
04-04-2007 7:20 AM


As scientists use the terms, microevolution is evolution which happens in a short period of time, and macroevolution is evolution which happens over a long period of time.
That's all.
Edited by Dr Adequate, : No reason given.

  
Brad McFall
Member (Idle past 5033 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 21 of 908 (393373)
04-04-2007 4:38 PM
Reply to: Message 19 by Allopatrik
04-04-2007 6:04 AM


He also suggested the term "meso evolution" but where is the description of *this* in=between evolution in the literature?
The best you will find is probably my own references to it on EVC!!
That is pretty b(r)ad, for a state of evolUtionary thought!

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Replies to this message:
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Allopatrik
Member (Idle past 6187 days)
Posts: 59
Joined: 02-07-2007


Message 22 of 908 (393475)
04-05-2007 11:02 AM
Reply to: Message 21 by Brad McFall
04-04-2007 4:38 PM


Mesoevolution
quote:
He also suggested the term "meso evolution" but where is the description of *this* in=between evolution in the literature?
I know of several papers by Spiess, Wallace and Dobzhansky himself where it’s mentioned or described. But that doesn't change the basic fact that these terms (including 'megaevolution', for that matter, which Dobzhansky also coined) do not imply different processes at work.
A

Natural Selection is not Evolution-- R.A. Fisher

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Fosdick 
Suspended Member (Idle past 5500 days)
Posts: 1793
From: Upper Slobovia
Joined: 12-11-2006


Message 23 of 908 (393483)
04-05-2007 11:55 AM
Reply to: Message 4 by mick
02-13-2007 11:45 PM


Defining the terms of evolution
mick wrote:
Finally, they often just mean "microevolution can be observed in a lab experiment, while macroevolution cannot". So microevolution can be observed in real-time and in living organisms, while macroevolution must be inferred (for example from fossils, systematics, or whatever). The attack on evolution then amounts to an attack on the validity of scientific inference.
I find it interesting and revealing that two Harvard luminaries in evolutionary biology, Ernst Mayr and E. O. Wilson, do not specifically agree on how to define microevolution and macroevolution. E. Mayr defines these terms in his glossary of What Evolution Is (2001):
quote:
Microevolution Evolution at or below the species level.
Macroevolution Evolution above the species level; the evolution of higher taxa and the production of evolutionary novelties, such as new structures.
E. O. Wilson defines these terms differently, combining them under one definition:
quote:
Microevolution A small amount of evolutionary change, consisting of minor alterations in gene proportions, chromosome structure, or chromosome numbers (A large amount of change would be referred to as macroevolution or simply as evolution.)
It will be difficult for evolutionary biologists to agree on one set of standard definitions for these terms, and others, too. So much of their reasoning comes pre-loaded with contextual biases that are nearly impossible to resolve. Contextual battles persist in other threads (e.g., Message 101 over these terms and the contexts in which they are used.
I think it is good to have multiple opinions on these issues. But some posters here are so convinced in their contextual righteousness that they call other posters "stupid" for not agreeing with them. I have personal experience with this, concerning the definitions of evolutionary terms. What I should have done experimentally was to post Wilson's and Mayr's definitions of microevolution and mavcroevolution as my own, and then sit back and watch the dogs clamor at my "stupidity."
”HM

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Allopatrik
Member (Idle past 6187 days)
Posts: 59
Joined: 02-07-2007


Message 24 of 908 (393490)
04-05-2007 12:26 PM
Reply to: Message 23 by Fosdick
04-05-2007 11:55 AM


Re: Defining the terms of evolution
How are the two definitions you cite conceptually different?
A

Natural Selection is not Evolution-- R.A. Fisher

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Fosdick 
Suspended Member (Idle past 5500 days)
Posts: 1793
From: Upper Slobovia
Joined: 12-11-2006


Message 25 of 908 (393495)
04-05-2007 12:49 PM
Reply to: Message 24 by Allopatrik
04-05-2007 12:26 PM


Re: Defining the terms of evolution
Allopatrik wrote:
How are the two definitions you cite conceptually different?
Look carefully at those definitions in Message 23, Mayr has macroevolution occurring above the species level, while Wilson has it occurring at the species level. They also disagree on this: Mayr says microevolution can happen at the species level, while Wilson says the species level is where macroevolution occurs.
”HM

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Allopatrik
Member (Idle past 6187 days)
Posts: 59
Joined: 02-07-2007


Message 26 of 908 (393496)
04-05-2007 12:55 PM
Reply to: Message 25 by Fosdick
04-05-2007 12:49 PM


Re: Defining the terms of evolution
quote:
Wilson says the species level is where macroevolution occurs.
Wilson says nothing of the kind. He simply calls micro small and macro large.
A

Natural Selection is not Evolution-- R.A. Fisher

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Fosdick 
Suspended Member (Idle past 5500 days)
Posts: 1793
From: Upper Slobovia
Joined: 12-11-2006


Message 27 of 908 (393499)
04-05-2007 1:05 PM
Reply to: Message 26 by Allopatrik
04-05-2007 12:55 PM


Re: Defining the terms of evolution
Wilson says nothing of the kind. He simply calls micro small and macro large.
I took this part of Wilson's definition”"A large amount of change would be referred to as macroevolution or simply as evolution"”to imply speciation. I beieve that's fair.
”HM

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Allopatrik
Member (Idle past 6187 days)
Posts: 59
Joined: 02-07-2007


Message 28 of 908 (393502)
04-05-2007 1:33 PM
Reply to: Message 27 by Fosdick
04-05-2007 1:05 PM


Re: Defining the terms of evolution
quote:
took this part of Wilson's definition”"A large amount of change would be referred to as macroevolution or simply as evolution"”to imply speciation. I beieve that's fair.
So, you think that Wilson considers macroevolution to occur at the level of the species and above, while Mayr considers it to be at the genus and above. Does it matter where the line is drawn, conceptually? How does the process that results in speciation differ from the kind of divergence that results in different genera?

Natural Selection is not Evolution-- R.A. Fisher

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Fosdick 
Suspended Member (Idle past 5500 days)
Posts: 1793
From: Upper Slobovia
Joined: 12-11-2006


Message 29 of 908 (393519)
04-05-2007 2:45 PM
Reply to: Message 28 by Allopatrik
04-05-2007 1:33 PM


Re: Defining the terms of evolution
So, you think that Wilson considers macroevolution to occur at the level of the species and above, while Mayr considers it to be at the genus and above. Does it matter where the line is drawn, conceptually? How does the process that results in speciation differ from the kind of divergence that results in different genera?
Is there only one process? I can think of five know processes that can provoke an evolutionary event, or a divergence, or at least disturb a population's Hardy-Weinberg equilibrium. Knowing for sure at which levels they operate could be helpful.
”HM

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Allopatrik
Member (Idle past 6187 days)
Posts: 59
Joined: 02-07-2007


Message 30 of 908 (393526)
04-05-2007 3:20 PM
Reply to: Message 29 by Fosdick
04-05-2007 2:45 PM


Re: Defining the terms of evolution
quote:
Is there only one process? I can think of five know processes that can provoke an evolutionary event, or a divergence
It is divergence--of one population from another-- that underlies the existence of all taxonomic groups, from species to kingdoms. So it doesn't matter how many ways that divergence can occur. Divergence is the process common to both micro and macroevolution. Therefore, the terms are, as Dobzhansky said, merely descriptive in nature.
A
Edited by Allopatrik, : No reason given.

Natural Selection is not Evolution-- R.A. Fisher

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