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Author Topic:   MACROevolution vs MICROevolution - what is it?
RAZD
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Message 1 of 908 (385009)
02-13-2007 9:07 PM


This is the essence of the debate isn't it?

In several recent posts there have been the usual references to "macro"evolution and "micro"evolution:

EpicThought in Message 9

While I personally believe that evolution should be taught in schools (along with ID) I don't believe in any theory I have seen on macro evolution.


nemesis_juggernaut in Message 17
I believe there is a limit on the speed of beneficial evolution that hits a wall, which thus, would render evolution on a macro scale impossible.

Oliver in Message 196
The way I see it is that the whole of nature disproves macro-evolution but not micro-evolution. We simply cannot directly observe macro-evolution and if someone could provide an example I would greatly appreciate it.

where I have responded each time with a rather simple request:

Please define "macro"evolution - so we can be sure we are (a) talking about evolution and (b) we are talking about the same thing.

Also define "micro"evolution just to be sure we are talking about something different.

It should be easy eh?.

I think this and the current responses should be discussed in a new thread because it is fairly central to the whole debate and to keep other threads from going off-topic.

Response from EpicThought in Message 14

Please define "macro"evolution

evolution at the species level or above

Also define "micro"evolution"

evolution belowe the species level

Response from nemesis_juggernaut -- none to date.

Response from Oliver in Message 198

Micro, as in variation and adaptation.
Macro, as in complete change fronm one creature into another.
Thanks..

My response to Oliver is in Message 200, where I asked for further clarification of what were the limits on each "type" of evolution. The critical elements of the reply are:

Micro, as in variation and adaptation.

Do you mean all mechanisms of evolution that have been observed in the process of change in phenotype and genotype of a species population up to and including what is called "speciation" - using a standard biological species definition of non-breeding populations as a definition of species?
Macro, as in complete change fronm one creature into another.

How much change and in what time-frame?

In one sense this occurs at the moment of speciation: one species has become another. They no longer interbreed because they are different.

Or do you need the accumulated change from, say, two speciation events, to show that change is continuous and necessarily divergent rather than convergent? That second generation daughter (grand-daughter) species are more different from the original parent species than the intermediate ones?

... there's more to it, and so far there has been no response.

I will be moving my reply to EpicThought here to keep it out of the {Why should ID be taught in science classes...} topic discussion:

To EpicThought Message 14:

So when speciation has occurred it is due to "micro"evolution, and when that new species continues to evolve it is due to "macro"evolution?

That isn't saying much, nor is it any kind of problem for evolution and it matches the evidence we have already of continued evidence of evolution after speciation.

In essence once a second speciation has occurred then de facto "macro" evolution has been observed to occur.

We can look at the fossil evidence of foraminifa for instance:
http://www.don-lindsay-archive.org/...on/foram_article3.html

quote:
Drs. Tony Arnold (Ph.D., Harvard) and Bill Parker (Ph.D., Chicago) are the developers of what reportedly is the largest, most complete set of data ever compiled on the evolutionary history of an organism. The two scientists have painstakingly pieced together a virtually unbroken fossil record that shows in stunning detail how a single-celled marine organism has evolved during the past 66 million years. Apparently, it's the only fossil record known to science that has no obvious gaps -- no "missing links."

"We've literally seen hundreds of speciation events," Arnold added. "This allows us to check for patterns, to determine what exactly is going on. We can quickly tell whether something is a recurring phenomenon -- a pattern -- or whether it's just an anomaly.


Thus we have observed "macro"evolution.

This also means that no other mechanism is needed for "macro"evolution to occur than is needed for "micro"evolution -- the continued evolution within each differentiated species -- and thus there is no barrier to "macro"evolution to continue to happen and increase the differentiation between the species as time passes.

This also matches what we see in the fossil record.


(note to admins & others: The above reply will be deleted from the ID thread when this topic is promoted).

This is the essence of the debate: when does change become sufficient to be "macro"evolution and how does it occur.

What is the difference between "genus" "family" "order" and all those other taxonomic classifications? When does one become the next level? What is the change that is involved?

Enjoy.

Edited by RAZD, : updated sig


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RAZD
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Posts: 20069
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Message 14 of 908 (385345)
02-15-2007 8:27 AM
Reply to: Message 4 by mick
02-13-2007 11:45 PM


No YEC's YET?
First, there seems to be a taxonomic usage of the term "macroevolution". Opponents of evolution are often using the term as a proxy for folk taxonomy. Dogs, cats, spiders, ants, birds, snakes, human beings, monkeys, flowers, etc. are all taken to be macroevolutionary units because they all correspond to an uninformed folk taxonomy that we learned as children.

I think this covers the problem best. What we see are the results of long term evolution, where it is convenient to break things into similar groups of animals, but that the patterns for what we see being caused by common ancestors is not so apparent.

You often hear them say things like "nobody has ever seen a dog evolve into a cat" or whatnot, in which case macroevolution is presumably equivalent to the diversification of new Linnean families;

It's like they expect a new branch of a tree to appear suddenly and full grown, with leaves and twigs.

An alternative usage is in terms of biological structures. Microevolution is taken to be molecular evolution and the evolution of proteins, while macroevolution is taken to be the evolution of body parts (especially tissues and organs) or body plans. So we often get "how does evolution create hair/wings/hearts/brains/eyes/larvae/sexes" etc. ... In general it boils down to the idea that microevolution is the modification of a single modular trait, while macroevolution is the coordinated evolution of multiple traits or the origin of new "modules" which change the systematic functioning of the organism.

That is rather reducing micro to a minimum effect and pushing macro to a maximum effect, when in fact there is a spectrum in between.

The real question it seems to me is when do two recently diverged species descendants become sufficiently distinctive that "macro"evolution has occurred: what is the minimal requirement?

I had proposed this to be a question for YEC's to answer, and have not seen one yet.

Thanks to the others for their responses as well. I don't think there is much "controversy" on the evolution side.


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RAZD
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Message 15 of 908 (385420)
02-15-2007 4:11 PM


The place of SPECIATION in MACROevolution
This is the generally accepted dividing line (currently) between "macro"evolution and "micro"evolution, in both biology and creationism.

In biology the process of "micro"evolution is mutation, genetic drift, etc, causing variation within the gene pool, and then selection by survival and breeding to pass genes on to the next generation, or natural selection of "more fit" individuals over "less fit" individuals for the particular {environmental\inner-population} dynamics that prevail.

In creationism this is often referred to as "variation and adaptation" but is the exact same mechanism, just using a different {words\names} to say the same thing (possibly to hand wave away any implication that we are really discussing "evolution").

In biology the process of "macro"evolution is the accumulation of differences between populations that have become dis-linked after speciation has occurred: the more time that passes the greater the likelihood that differences will be noticeable as being significant.

In creationism there is often a "cognitive dissonance" issue regarding what evolution actually says happens and a common belief that something else happens on a comparatively brief time-scale and that causes some kind of sudden significant change.

The point of this topic is to dissect this common - and erroneous - belief and show how it is false.

There are several definitions of "species" that make this "dividing line" a little muddy.

Most of the muddiness involves asexual species, species that reproduce only by cell division. In essence each individual is a sub-population that does not interact genetically with the other sub-populations (except by horizontal gene transfer, which is not necessarily species inter-specific either). Thus in asexual species the definition is fairly arbitrary: they are classed into species by the degree of similarity within groups. This is similar to the classification of species into higher taxons in traditional taxonomy.

The real issue for "macro"evolution with creationists involves sexual species, so the species definition for asexual species is not that big an issue. For sexual species it is fairly well accepted that the failure to breed between two populations is sufficient evidence of speciation -- whether the two population can breed and produce viable hybrids is not considered relevant when the two populations by behavior don't breed.

We can use ring species, such as the Asian Greenish Warblers (Phylloscopus trochiloides) to demonstrate that it doesn't take much difference to create a behavior barrier to mating:

quote:
In central Siberia, two distinct forms of greenish warbler coexist without interbreeding, and therefore these forms can be considered distinct species. The two forms are connected by a long chain of populations encircling the Tibetan Plateau to the south, and traits change gradually through this ring of populations. There is no place where there is an obvious species boundary along the southern side of the ring. Hence the two distinct 'species' in Siberia are apparently connected by gene flow.

West Siberian greenish warblers (P. t. viridanus) and east Siberian greenish warblers (P. t. plumbeitarsus) differ subtly in their plumage patterns, most notably in their wing bars, which are used in communication. While viridanus has a single wing bar, plumbeitarsus has two. Around the southern side of the ring, plumage patterns change gradually.

Male greenish warblers are very active singers, using song both to attract females and to defend their territories. Each male has a repertoire of song units, and songs are made by stringing together units in various ways. There is much geographical variation in both the song units and the rules by which units are assembled into songs.

There is a clear gradient in song characteristics around the ring, with the northern forms viridanus and plumbeitarsus differing dramatically in their songs.



A modest change in plumage and mating song and there is no breeding behavior between the two populations. Remove the intermediate varieties and speciation has occurred. To visualize speciation occurring in time rather than space all one needs to do is consider the intermediate varieties to be ancestral rather than geographically removed.

One wing bar to two is not a significant change, but it is a change in a feature visible on the two different varieties. Change in mating behavior - song patterns - is a little different: it would not be something that would be recorded in any preserved specimens, but it is a distinctive part of mating behavior for all sexual species.

We can also look at the fossil record to see if there is a similar pattern with such ancestral rather than geographic separations. One such example is Pelycodus:

quote:

Click to enlarge

The numbers down the left hand side indicate the depth (in feet) at which each group of fossils was found. As is usual in geology, the diagram gives the data for the deepest (oldest) fossils at the bottom, and the upper (youngest) fossils at the top. The diagram covers about five million years.

The numbers across the bottom are a measure of body size. Each horizontal line shows the range of sizes that were found at that depth. The dark part of each line shows the average value, and the standard deviation around the average.

The dashed lines show the overall trend. The species at the bottom is Pelycodus ralstoni, but at the top we find two species, Notharctus nunienus and Notharctus venticolus.


What we see is a gradual trend towards increase in size with time (what has been called "Cope's Rule" as hypothesized by Edward Drinker Cope, who also first identified Pelycodus jarrovii in 1874, the "type" species of the adapid genus Pelycodus), until a branching point is reached at which time one population rapidly (by comparison - still over a period of many thousands of years) decreases in size.

The distinction of species from Pelycodus ralstoni to Pelycodus trigonodus to Pelycodus jarrovii can be considered fairly arbitrary: we don't know whether they could interbreed or not, and the classifications are based on small changes in skeletal structures and size.

Likewise the distinctions between Pelycodus jarrovii and Notharctus nunienus or between Pelycodus jarrovii and Notharctus venticolus could be considered arbitrary (especially in the absence of the other), but the distinction between Notharctus nunienus and Notharctus venticolus is not arbitrary: there is a clear division between the two populations with no overlap in sizes. Whether they could interbreed or not is not an issue - they were reproductively isolated by the time the top of this diagram is reached. Thus we see the same pattern in ancestral species resulting in non-breeding subpopulations as we saw with the ring species warblers.

Pelycodus is tantalizing here, because the above article goes on to say:

quote:
The two species later became even more distinct, and the descendants of nunienus are now labeled as genus Smilodectes instead of genus Notharctus.

Where 'genus' is the next level up from 'species' in the standard taxonomy and thus we have a pending "macro"evolution division of species into two different genus taxons. The point made is that it doesn't happen when the speciation event happens, but is a later accumulation of differences between the two daughter populations that are classified into two different genus groups.

Generally a 'higher' taxon group includes several co-existing species, all descended from an ancestral species (such as either Notharctus nunienus or Notharctus venticolus here) after a speciation event. Thus "macro"evolution starts with speciation but is only classified as "macro" (it never really "ends") after several more speciation events have occurred and where the difference is noticeable enough to justify an additional classification.

One could say that the mechanism for "macro"evolution is speciation, but there is nothing special about higher classifications other than that they are convenient for discussing the relative relations of various species. In this sense "macro"evolution is nothing more than an arbitrary convenience for biologists to classify species and is not really different from "micro"evolution.

This can be simplified as a series of non-arbitrary speciation events: we can have a species {A} that divides into two non-breeding daughter populations, species {B} and species {C}. Both {B} and {C} will continue to be {A} descendants ("dogs will always be dogs"), but equally {B} will not be {C} (dogs are not foxes, but both are canines). At this point {B} and {C} would still be in 'genus' {A}.

Further non-arbitrary speciation events would divide {B} into {D} and {E} and {C} into {F} and {G}, where now they would all be the same 'family' {A}, but {D} and {E} would be in 'genus' {B} while {F} and {G} would be in 'genus' {C}.

There would be more difference between {{D} or {E}} and {{F} or {G}} than between {D} and {E} or between {F} and {G} due to greater divergence of each species since the common ancestral species.

The only difference between evolution before speciation and after speciation, is the loss of gene flow once speciation has occurred, and the different population dynamics between formerly cooperating populations that are now in competition for the same resources. This change in population dynamics will drive an increased rate of divergence between the two populations, as selection will be for divergence away from each other rather than towards common ground -- or one will out-compete the other (ie - leads to extinction).

This change in dynamics may be one reason for the appearance of "punctuated equilibrium" (punk eek) in some fossil records. In fact one interpretation for Pelycodus evolution involves punk eek (it also includes some additional species and uses an alternate name for Notharctus nunienus - Pelycodus frugiverous - and moves Pelycodus jarrovii higher on the diagram):
http://www.mun.ca/biology/scarr/Pelycodus_punctuated.htm

Note that this shows there is some disagreement on the exact evolution path that occurred in this lineage, but that both agree that non-arbitrary speciation occurred at the point where Notharctus nunienus (Pelycodus frugiverous) or Notharctus venticolus have diverged into non-breeding populations.

This does not affect the issue of "macro"evolution being an accumulation of changes due to "micro"evolution over a period that involves numerous speciation events.

Enjoy.


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RAZD
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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" ... :rolleyes:

quote:
http://en.wikipedia.org/wiki/Hyena
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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RAZD
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From: the other end of the sidewalk
Joined: 03-14-2004
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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

    "Micro"evolution

  • 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
http://www.fossilnews.com/1996/cladistics.html
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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RAZD
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Posts: 20069
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Joined: 03-14-2004
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Message 32 of 908 (393606)
04-05-2007 10:21 PM
Reply to: Message 23 by Fosdick
04-05-2007 11:55 AM


Re: Defining the terms of evolution
Message 25
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.

How do you get Wilson having it at species level?

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.)

There is no relationship here to what time period is involved and how much micro evolution has progressed to reach the level of macroevolution. He could easily be talking about accumulated evolution over a time period that encompasses several speciation events.

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.

Which is why the two university definitions above are virtually identical. And why neither Ernst Mayr's nor E. O. Wilson's definitions contradict them.

Enjoy.


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Message 35 of 908 (393748)
04-06-2007 5:45 PM
Reply to: Message 33 by Fosdick
04-06-2007 11:25 AM


Re: Defining the terms of evolution
I made that conclusion based on my understanding that Wilson implies "speciation" in the word "evolution." If he doesn't imply that then I am wrong. So I took his definitions to mean: 1) microevolution implies subspeciation, while 2) macroevolution (i.e., evolution) implies speciation.

I don't see Wilson as defining macroevolution, at least not there. Rather his comment is to refine the degree of change in microevolution, the span of it's application. Nor does he mention speciation, so where he puts that in his lexicography is indeterminate from this information.

And he defines "evolution" as:

quote:
Any gradual change. Organic evolution, often referred to as evolution for short, is any genetic change in organisms from generation to generation, or more strictly, a change in gene frequecies within populations from generation to generation.

I've just been through a long evaluation of the various definitions of evolution as mentioned in Message 18 and where I posted the two university definitions for micro and macro (that also agree substantially with Mayr). This definition of evolution fits with those others.

From where I stand on this, I think "microevolution" can happen without speciation, but "macroevolution" (or just "evolution") entails speciation. What do you think?

The evolution that occurs after speciation still occurs within species, it is still "micro"evolution, building towards the next speciation schist. All speciation amounts to is the division of populations into new populations within which evolution occurs. This results in opportunity for greater diversity, as the different populations pursue different paths, but doesn't necessarily result in such.

I did a google on {E. O. Wilson macroevolution} and got a couple of hits, but not one of the ones I looked at had a definition. The closest concerned a book of his:

http://search.barnesandnoble.com/booksearch/isbnInquiry.asp?isbn=0393319407&itm=3
Diversity of Life
by Edward O. Wilson

quote:
He examines organic history in terms of reproductive isolation, nucleotide variation (microevolution) and adaptive radiation (macroevolution). Wilson focuses on the abundance of life forms within tropical rain forests, especially pointing out that both vanishing species and their threatened natural habitats (hot spots) must be saved if we are to maintain the earth's rich and needed genetic reservoir.

That still leaves us with the line between them or reference to speciation undefined.

But the other side of the coin is: what is macroevolution? Other than accumulating a record of descent from common ancestors and the mapping out of the resulting diversity of life, there isn't much to it, is there?

Enjoy.


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Message 37 of 908 (393770)
04-06-2007 9:39 PM
Reply to: Message 36 by Fosdick
04-06-2007 8:35 PM


Re: Defining the terms of evolution
both terms waffle like Philadelphia lawyers around the concept of “speciation.”

Do they?

Micro includes evolution up to speciation, macro is division of species by relationships to common ancestors and is made above speciation levels.

Do I include speciation in micro or in macro? Does it matter? Is zero a positive or a negative number? Does it matter?

Enjoy.


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Message 38 of 908 (394722)
04-12-2007 9:12 PM
Reply to: Message 18 by RAZD
04-03-2007 10:22 PM


Bump for jjsemsch
From Message 33

You'll have to forgive me for going off topic, but another example of the evidence not changing the theory is transitional forms. Charles Darwin believed that simpler life forms evolved into more complex life forms gradually over millions of years. He also believed that the fossil record would show this. To date there are only a handful of disputed transitional forms and every day more of those are shown to either be extinct species or hoaxes. Mainstream science looking at this evidence would never say perhaps evolution is false. Instead the mechanism for evolutionary theory becomes punctuated equilibrium not because of evidence, but because of a lack of evidence.

You'll notice first off that the actual theory of evolution is different than what you referenced. If you use a different definition for words than what is used by scientists you are talking about something else.

Most of this paragraph is just another typical creationist PRATT. There is no difference in evolution with punk-eek and evolution before punk-eek: it is still the change in inheritable characteristics within populations over time.

Nor is the fossil record the only evidence for descent from common ancestors (which is the part of evolution that you are referring too). Failure to find fossils for specific organisms does not mean that the organisms did not exist, just that they either did not fossilize or that such fossils have not yet been found.

I asked you for what theory had been invalidated. This argument of yours -- even if valid (it isn't) -- does not invalidate the theory of evolution. To invalidate the theory you need to show that it is not possible for common ancestors to be true. You haven't done that.

At best all you have done is deny evidence that does exist.

Enjoy.

Edited by RAZD, : ’


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Message 48 of 908 (395539)
04-16-2007 9:50 PM
Reply to: Message 39 by jjsemsch
04-16-2007 2:49 PM


Replies for jjsemsch
Message 39
What is the mechanism for evolution? It's natural selection and mutation right?

There are a number of mechanisms, but these are the major ones. See Message 18.

Message 41
Have scientists ever observed a mutation that introduced new genes?

Yes, it's been observed. Some examples have been listed already.

I thought mutations were genetic copying mistakes that usually hinder progress.

What progress? All that is involved in evolution is the change in inheritable traits within populations over time. This can make a species become larger, or it can make a species become smaller: which one is "progress"?

When it is the mutation that allows selection of the larger or smaller individuals within the populations (by survival and breeding), then how does such mutation hinder the process?

Does natural selection actually help macro-evolution? Natural selection is picking one favorable gene and eliminating a less favorable gene right?

All evolution occurs at the micro-evolution scale in terms of selection of genetic variations caused by mutations within a population.

Macro-evolution is just the increased accumulation of diverse variations over time as micro-evolution continues to occur within populations, so that the further two species are from a common ancestor the greater the opportunity there is for them to have more noticeable (to humans) differences.

Thus both mutation and natural selection operate to "help" macro-evolution via continued micro-evolution.

Are there other mechanisms for macro-evolution or am I missing something?

What is macro-evolution? What is needed other than continued micro-evolution within daughter populations since their divergence (speciation) from common ancestor populations over longer periods of time? More time = more opportunity for greater diversity.

To evolve from fish to philosopher there has to be a huge increase in genetic information.

Nope. They both have brains. Check out:
http://www.earthtrust.org/delrings.html

That is dolphin and not fish, but it is only a matter of scale in terms of brain size - a difference in quantity rather than kind.

What a fish would philosophize over would likely be different from what humans would, but that doesn't mean they would be incapable of it.

Message 43
So if you have 2 copies of the same book, do you have twice as much information?

You have the opportunity for one copy to remain useful as the original book and for the other to be used for something else. Or you can lend one to a friend, and if the books are how-to books on house construction, then your friend can assist you in building houses.

Your friend may also decide to work on a different part of the house, and perhaps put in a window in the roof instead of the wall: now you have a new feature, a skylight. If it is a normal window it will likely leak in this new position, but we can repair this with other information from the book on how to seal things. If we start with such a window in a steep part of the roof and gradually introduce it into flatter sections of roof as we learn to seal them, we eventually end up with something that is not a window but a functional skylight in a flat roof.

In this case the "information" didn't change, but the use of the information ends up being for something new and different.

We can also compare the houses from generation to generation and see that there is little difference between the {window\skylight} features in the different closely related houses, but that when we look at the first house and the last house we see a "significant" (to humans) change that amounts to a big (to humans) change. We have a macro change by micro evolution.

Enjoy.

Edited by RAZD, : compare combs. mines green, yours is orange ...


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Message 51 of 908 (395551)
04-16-2007 10:47 PM
Reply to: Message 49 by ICANT
04-16-2007 10:10 PM


stretching the analogy again ...
It doesn't have to (for macro-change to be observed), but if we take this analogy and see how far we can stretch it's credibility ...

First, what develops from it will always be descended from the original house, so what you are really asking is "how long till it no longer looks like a house to us" yes?

Second, we haven't gone further in the analogy than what can be called arbitrary speciation events - the houses being built are increasingly different from the original, but all the houses currently being built are pretty similar and they are all being used as houses.

Third, to complete the analogy we need a selection process in addition to the mutation process: the buyers for the houses would affect whether houses with no skylights or houses with lots of skylights would be preferred, affecting demand for the next generation of houses. As long as all buyers are selecting the overall house building pattern there won't be any extreme developments unless everyone wants it.

Now, lets assume there is an argument between the two friends: one wants to put in lots of skylights and the other wants to build more traditional homes. They part company, each building houses more in their personal direction.

These attract different subsets of buyers (different selection pressure on the different house types), that further drive the changes in the houses being built. Soon there are two different kinds of houses, one victorian with peaked roofs, normal windows and lots of filigree, and one modern, cubist, with lots of skylights and few embellishments.

People in the houses start to use areas in different ways, the victorians going for height and looking down and out over the countryside enjoy panoramas and build gardens outside for enjoyment, while the cubistians enjoy direct sunlight and grow plants inside under the skylights and have studios for painting and sculpture.

Over time the victorians build taller and taller, some incorporating several living areas into one building as they build one on top of the other, and become apartments. Meanwhile the cubistians become more focused on art and less on living quarters, eventually separating living areas from art areas in different buildings, with one become art galleries. You now have victorian houses, apartment buildings, cubistian houses and art galleries.

But they are still buildings ... that still house things ... :D

Enjoy.


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Message 71 of 908 (433809)
11-12-2007 10:45 PM


micro\macro and the simple explanation for Aquilegia753
From Message 58

Micro evolution-very small changes of plants and animals to adapt to new environments (ants are attacking a plant, so the plant grows special food for the ants, which in turn defend the plant against other predators. Soon, neither can live without the other. Plants developing pestacide on their leafs to ward off bugs, which develope and immunity to the pesticide. No species change at all). Webster's-Evolutionary change below the level of the species, resulting from relatively small genetic variations.

I'm sorry but this doesn't mean much to me, it seems a little jumbled. I looked up microE on dictionary.com and got the following:

quote:
1. evolutionary change involving the gradual accumulation of mutations leading to new varieties within a species.
2. minor evolutionary change observed over a short period of time.

n. Evolution resulting from a succession of relatively small genetic variations that often cause the formation of new subspecies.


This depends on the definition of evolution which you did not provide. What it seems to say is that this is evolution below the level of speciation.

Macro evolution-the physical change from one species to another (man to human). The distinctive visible 'evolution' with large effects. Webster's-major evolutionary transition from one type of organism to another occurring at the level of the species and higher taxa

This also doesn't mean much to me and seems equally muddled (man to human?). I looked up macroE on dictionary.com and got the following:

quote:
major evolutionary transition from one type of organism to another occurring at the level of the species and higher taxa.

Large-scale evolution occurring over geologic time that results in the formation of new taxonomic groups.


Note the reference to time. This is not a physical change, one species turning into another in one generation or less, but continued evolution over many generations of a species until step by step it is different enough to be called a different species or some higher arbitrary taxon. Thus this seems to say that it is evolution beyond the level of speciation, the branching of life from common ancestors. This also still depends on the definition of evolution itself.

A useful definition of evolution is that it is the change in hereditary traits in populations from generation to generation. You can apply this definition to genetic data or that from observation of natural history (living to fossil).

Can I suggest another couple of references - universities that teaches evolution?

http://evolution.berkeley.edu/evosite/evo101/index.shtml
http://evolution.berkeley.edu/evosite/evo101/IIntro.shtml

quote:
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.

http://www.globalchange.umich.edu/globalchange1/current/lectures/speciation/speciation.html

quote:
We begin with two working definitions of biological evolution, which capture these two facets of genetics and differences among life forms.

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.


Notice that neither really tells you how macroevolution occurs (or what it is other than that it results in the taxonomic hierarchy).

Now let us suppose that all evolution occurs within a species, and that it is by definition microevolution. This kind of evolution can continue within a breeding population for a long time and encompass a remarkable (to us) degree of change, while each generation will still be similar to the ones before and after it: at every stage it will still appear to be one species - a single breeding population.

After many generations have passed the species may no longer look like the original species we started our thought experiment with, and we can say that it is a new species due to the noticeable (to us) amount of change that has accrued. This is called "Arbitrary Speciation" in evolutionary biology, and it occurs by the process of microevolution.

Speciation events that are of particular interest though, are those where branching occurs -- where one species becomes two (or more) similar species that no longer interbreed. These are called "Non-arbitrary Speciation" or "Speciation Events" in evolutionary biology, because it is not based on some subjective degree of change, but on the physical split of one breeding population into separate populations that don't interbreed. Once they no longer interbreed they will accrue difference from each other as they accumulate further change by microevolution and, with time, arbitrary speciation.

This continues until the next speciation event where the process is repeated, but now we have another branch on the tree of life, and in this way the tree of life is developed by the process of evolution, arbitrary speciation, speciation events and the branching from common ancestors. This provides the taxonomic structure where we arbitrarily make taxon divisions based on the degree (to us) of difference between existing species and their ancestors -- the higher the taxon level the greater time that has passed since the common ancestors.

You will notice that there is no reference to macroevolution. Nor is there any "half this half that" forms, just gradual evolution within breeding populations of similar organisms.

Enjoy.


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Message 72 of 908 (439381)
12-08-2007 3:29 PM


bump for beretta - macroevolution, and your chance to define\defend your view
Beretta, Message 66

The phenomenon is described relying on micromutational change. Macromutational change is believed to have occurred not because it has been observed but because it has been extrapolated from the micromutational evidence. Micromutation is provable, macromutation is inferred.Apart from that, macromutation is not at all well supported by the evidence.

The question is - what do you think macroevolution means? See if you can start with a simple basic statement.

Do you mean speciation?
Do you mean making the fundamental branches of life seen in the taxonomy of life and the genetic tree of life?

Or do you means something else, something you have not yet defined?

If you don't refer to macroevolution as used in the science of evolutionary biology, then what do you mean?

Enjoy.


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Message 74 of 908 (441515)
12-17-2007 10:13 PM
Reply to: Message 73 by mobioevo
12-16-2007 11:39 PM


Re: What is it? Nothing... Useful.
So definitions like this, ...
... has no use in modern evolutionary studies. There is no reason to have separate definitions for the same process. The only difference between the two is the length of time.

I used to think that way, and I agree that clarity in meaning is important. The problem is that {HERE} we deal with creationists, and we need to find a way to present information to creationists that is valid and that they can understand, and in that context clarity means using common terminology for common meanings.

I also have found that a large number of evolutionary biologists from Gould to Dawkins, and a number of universities teaching evolutionary biology use these terms, and a good example is the 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.

A full explanation of evolution requires that we link these two levels. Can small, gradual change produce distinct species? How does it occur, and how do we decide when species are species? Hopefully you will see the connections by the end of these three lectures.


(that last paragraph was one of the purposes behind this thread and my Evolution and the BIG LIE thread)

I changed my mind about this "micro\macro let's call the whole thing off" issue for a number of reasons. One was the common usage issue, it is a fact (particularly to creationists). Another was that it does not make much difference to the argument as long as you ARE clear about what you mean by the terminology (another one of the purposes of THIS thread).

But the kicker for me was that the differentiation between {what happens below the level of species} and {what happens above the level of species} IS different in one very simple but profound way - the population dynamics works in the opposite direction.

Within a population of breeding organisms the dynamics within the population will be to breed and mix genetic\hereditary traits. In a steady-state ecology this will give selective advantage to the more average phenotypes within the population, the ones that "stayed" in the middle - eek\stability. In a changing ecology this will give selective advantage to those phenotypes with similar trends to fitness for the new ecology, the ones that "moved" to a new center - punk\change in a unified direction. In both cases the "population dynamics" will tend to make the whole population tend towards an average phenotype, whether that average is an old one or a new one.

When we look at a (non-arbitrary) speciation event, where a population has divided into two (or more) subpopulations that are no longer interbreeding, no longer mixing genetic\hereditary traits towards a common trend, we have a sudden change from a single population with a common purpose, to two very similar but slightly different populations in competition for food, habitat, protection from predators, etc.

As I see it, this means that the biggest impact on natural selection in both those new populations will be for divergence from each other to lessen the competition, lower negative selection back towards the level that existed before speciation. I see this as a period of marked, high selection pressure that can result (and has resulted) in extinction for one or more populations. This added selection pressure to diverge did not exist before speciation and is caused directly by speciation. This higher level of selection pressure will also result in a higher rate of fixed changes in hereditary traits for divergence between populations and will cause one or both to diverge from their common ancestor population - a branch at an angle to the trend of the old population.

You can see both of these population dynamic trends - the tendency to stay to the middle and the tendency to diverge - in this example, a speciation of pelycodus:

quote:

Click to enlarge

The numbers down the left hand side indicate the depth (in feet) at which each group of fossils was found. As is usual in geology, the diagram gives the data for the deepest (oldest) fossils at the bottom, and the upper (youngest) fossils at the top. The diagram covers about five million years.

The numbers across the bottom are a measure of body size. Each horizontal line shows the range of sizes that were found at that depth. The dark part of each line shows the average value, and the standard deviation around the average.


One daughter population diverged "rapidly" from the other and at an angle to the ancestral trend. If we wanted to draw a distinction between the branches one could say that Notharctus venticolus showed continued evolution along the ancestral trend, while Notharctus nunienus showed macroevolutionary divergence from that ancestral trend. Both branches change by normal evolution - change in hereditary traits in populations from generation to generation - by "microevolution" within each species, however this does not explain the rate of change of Notharctus nunienus away from the ancestral trend that it should have been equally well adapted to.

When there is change in genetic information over time, use the term evolution. When a new species is created, use the term speciation.

The issue is that macroevolution - the divergence of related species - occurs after speciation has already occurred. This is the area of evolution that creationists are concerned about, because this is directly related to the issue of common ancestry, and whether they know it or not (usually not) their problem is not evolution per se, but common ancestry - when and how many. They are also comfortable with the concepts of a division in levels of evolution for this reason, and to make progress you need to talk with, not at, people.

That's my take on it.

Enjoy.

Edited by RAZD, : finished

Edited by RAZD, : clarity

Edited by RAZD, : clarity again

Edited by RAZD, : fixed random mutation duplication error. must be bedtime.


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This message is a reply to:
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RAZD
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Message 81 of 908 (441817)
12-18-2007 8:55 PM
Reply to: Message 77 by mobioevo
12-18-2007 5:12 PM


Re: What is it?
What I am trying to say is that separating evolution into microevolution and macroevolution is not only unnecessary, but also that it is confusing to creationists and other people not trained in evolutionary studies because the terms use the same evolutionary forces. I know that the terms microevolution and macroevolution are throw around to try to help educate people, but that does more harm than good. It makes it seem like there are two evolutionary forces acting on the organisms at different levels. The only difference between the terms is the time scale, and when a new species arises it is because of evolution and some isolation effect.

Creationists are absolutely convinced there are two mechanisms, and arguing with them about it will mean that your opinion will simply be disregarded. This will be counterproductive.

I don't know what you mean by average phenotypes, but I think you mean overdominance (heterozygous advantage/superiority). Under certain environmental conditions a heterozygote will have higher fitness than homozygotes and will cause balancing selection. But to assume the entire genome has overdominance within this environment is too much of a simplification. Each allele (assuming alleles have no affect on each other) and will have an independent reaction to the environment. Other ways alleles react within an environment is dominance, complete dominance, incomplete dominance, and underdominance.

No, I actually mean average. You need to look at the whole package of an organism, the complete phenotype, and step back from individual gene variations. Any feature will have a distribution of variation around an average, and a more average phenotype will have more features near the average of the distribution for that feature and fewer at the extremes of variation. In stable population ecological conditions the average will be best adapted to that condition, and selection returns to the center in a negative feedback loop where variation from the average is less adapted. A shift in the ecology will select for a shift in the population with the degree of shift in response being related to the degree of shift in the ecology. It's an opportunistic response system.

Be careful in your language. I have never met a population or species with a common purpose (even in human populations). Competition between subpopulations will be dependent on the speciation event. If it was sympatric or parapatric speciation under which prezygotic and postzygotic isolation are causing reproductive isolation, then yes they will compete for resources. If the speciation event was due to allopatric or peripatric speciation then they will not compete for resources because the populations have been spatial isolated.

I agree, language is a problem. Let's say it is a change from a population that was mostly cooperative into two populations where whatever benefit of cooperation that existed between them has vanished. With the pelycodus example there was competition as the fossils occurred in the same area. I agree this doesn't always apply.

I think you have a valid hypothesis
But for your argument to hold you need to show that competition between individuals in the single population before the speciation event was lower than competition between individuals in the two populations after sympatric or parapatric speciation.

Thanks. Not every confrontation needs to show a competition differece, there just needs to be an overall difference. Make one individual male and one individual female and you can visualize different behavior. You also would not have a comparable situation between two diverged population individuals to that between parent and child.

If I understand your argument correctly since these two species that divided from a single species are now competing for the same resources there will be strong selection pressure to maximize the efficiency of resource use. I do not see how this is any different from positive selection on an advantageous allele that allows for more efficient resource use.

That's one way to put it, however there has to be opportunity for the two new populations to find sufficiently diverse resources to lower competition.

{edit3} Pelycodus was first identified as Prototomus jarrovii, and then renamed pelycodus by Cope (Cope's rule), so Pelycodus jarrovii is the "type species" of the genus Pelycodus. {/edit3} From another gradualistic view of pelycodus evolution:

quote:

Click to enlarge

Gradualisitc interpretation of Pelycodus evolution
Successive fossils in the Pelycodus fossil record show the gradual evolution of increased size, which can be recognized as a series of species. The coexistence of two simultaneous size trends indicates a speciation event. (Text material © 2005 by Steven M. Carr)

This shows two earlier unsuccessful "attempts" at speciation, ones the resulted in extinction (when the ecology couldn't quite support two populations) ... and then on the third attempt there was sufficient opportunity? (He also shows a punk-eek version).

{edit3} From this diagram we can see that, Copelemur consortutus, Pelycodus frugivorus and Pelycodus jarrovii all lived at the same time in the same basic habitat, before Copelemur consortutus went extinct and Pelycodus jarrovii evolved into Notharctus venticolus continuing the ancestral trend, while Pelycodus frugivorus evolved into Notharctus nunienus, taking over the habitat from Copelemur consortutus in the process.

Without the impetus of speciation, what causes Copelemur praetutus then Copelemur feretutusCopelemur consortutus, and finally Pelycodus frugivorusNotharctus nunienus to diverge "rapidly" from the fairly steady trend of evolution from Pelycodus ralstoni to Notharctus venticolus? Extra selection? Due to added competition? {/edit3}

In my opinion your argument does not clearly seperate microevolution from macroevolution. The way beneficial mutations arise within a species and the positive selection that acts on the beneficial allele to rise in frequency is the same way beneficial alleles increase in frequency when two species are competing for the same resources. The divergence of two related species can evolutionarily occur the same way as two individuals within the same species. In fact that is how speciation events occur the divergence of individuals within a species.

{edit2} Yes, you can even think of species and speciation as being analogous to single-cell organism life and reproduction. It's similar but at a different scale. One small (microscopic) and one big (___________). {edit2}

{added2} We could also talk about mini effects\events\processes, and maxi effects\events\processes, but we already have the terms microevolution and macroevolution. We don't think of life being "notlife" when it is microscopic (microbiology).

We can use the analogy of species to single cell life to help define these different scales of interest, with

  • microevolution being the changes in hereditary traits in populations from one generation to the next (one cycle) up to speciation, and
  • macroevolution being the changes in hereditary traits in populations from one speciation to the next, speciation and above.
- where speciation is the dividing line and the mechanisms of speciation are the mechanisms of most concern in macroevolution.

Enjoy.

Edited by RAZD, : clarity at end

Edited by RAZD, : added Copelemur consortutus discussion


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This message is a reply to:
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