Macro and Micro Evolution

Really?! What do they all do? How does it work? Any links?(rant) And it's sexes not genders. Words have genders; organisms have sexes. And lucky organisms have sex. (/rant)

LOL, Mr JackI'll be interested in the answer to this question. Maybe like some of the physics of flight or swimming with low resistance there is something we can learn that will be useful.

quote:

---

And lucky organisms have sex

---

Cmon..you know it has nothing to do with luck..it all depends on what kind of car you drive.

When you walk the pathway of the true topic, without leaving any tracks of goofy side comments, then you will achieve true enlightenment.Focus, Weedhopper. Adminnemooseus------------------
Comments on moderation procedures? - Go to
Change in Moderation?
or
too fast closure of threads

quote:

---

quote:

---

The idea is that gender starts at the genetic level, in single-cell or colonial organisms. For instance slime molds have some 50 different genders or so.

---

​

Really?! What do they all do? How does it work? Any links?

---

It's hard to find specifics, but I've seen numerous sites state that there are 13 sexes in some kinds of slime molds. In this page about the life cycle of slime molds, they mention that slime molds, in amoeba form, can "mate" (fuse with) other amoebae with with "complementary mating alleles" (the amoeba form is haploid).According to this page, any one sex can mate with any of the others. Furthermore, some species of mushrooms have as many as 32,000 sexes, with the same basic rule. I'm still having trouble getting specifics, though.Ah! My old favorite, Tom Volk's Fungi, finally answers the question. Here's about a fungus with 28,000 sexes (Shizophyllum communite). There is a single locus in many types which can have multiple alleles; if this locus has the same gene in both fungi, they don't "mate". It's to encourage diversification of the species. Some have taken it further, and have multiple locii. This particular fungus has two locii, with over 300 alleles for one and over 90 for the other. The sexes are not physically different in appearence at all, however. Here's Tom's page about slime molds. He's also got a number of pictures, and even a movie.Also, as a side note, slime molds can solve mazes. ------------------
"Illuminant light,
illuminate me."

Very interesting. Thanks Rei.

Greetings to all present. I am brand spaking new to this board, and hope to lurk around and soak things up. I am in my third year of studying a degree in genetics and ecology, and I am a moderator of the evolution versus creation forum at Internet Infidels Discussion Board. For that forum, a few months ago, I composed this short piece looking at a few of the many different definitions of macroevolution. I repost it here with minor modifications for context.

quote:

---

Macroevolution is easily one of the most heavily used but least understood terms in the public understanding of evolutionary biology. In the global creation/evolution debate as a whole, it is probably almost as commonly used a word as "it", "but", and "stupid".

​

... But does anyone know what it means?

​

I used to think I did at one stage. Here, for example, I spoke of macroevolution:

​

quote:

---

It's about the effect of large scale patterns on the course of evolution. It's about speciation, but it doesn't mean speciation specifically. It's also about the influence of ecological principles, geology, and still more advanced concepts than I think we even understand. It's NOT neccesarily about "one sort of thing changing into a different sort of thing".

---

​

This is PZ’s (a fellow moderator at IIDB, and a professor of developmental biology) take on the matter:

​

quote:

---

It's just a term that describes a process that is currently the subject of active research, which contains phenomena that we don't entirely understand yet.

​

I'll cite Gould here, in The Structure of Evolutionary Theory:

​

I should be clear that I intend only the purely descriptive definition when I write "macroevolution" -- that is, a designation of evolutionary phenomenology from the origin of species on up, in contrast with evolutionary change within populations of a single species. In so doing, I follow Goldschmidt's own definitional preferences (1940) in the book that established his apostasy within the Modern Synthesis. Misunderstanding has arisen because, to some, the word "macroevolution" has implied a theoretical claim for distinct causes, particularly for nonstandard genetic mechanisms, that conflict with, or do not occur at, the microevolutionary level. But Goldschmidt--and I follow him here--urged a nonconfrontational definition that could stand as a neutral descriptor for a set of results that would then permit evolutionists to pose tough questions without prejudice: does macroevolutionary phenomenology demand unique macroevolutionary mechanics? Thus, in his book, "macroevolution" is descriptive higher-level phenomenology, not pugnacious anti-Darwinian interpretation.

​

I think it is a useful term, and one that is going to become increasingly significant. Think of the difference between transmission genetics and population genetics: it's an extremely useful distinction, even though we don't imagine that special forces operate in populations that defy the rules of heredity for individuals.

---

​

RufusAtticus, another of our moderators whos area is population genetics, prefers this succinct definition:

​

quote:

---

Evolution: The change of properties of populations of organisms over time.
Microevolution: Evolution apparent within species.
Macroevolution: Evolution apparent between species.

---

​

When I asked him to expand on that final line, he supplied this elucidation:

​

quote:

---

That macroevolutionary differences are differences between species, nothing more, nothing less. The reason why I phrase it the way I do is to try to point out that microevolutionary differences and macroevolutionary differences are the result of the same process: evolution. The distinction between macroevolution and microevolution is an artifact of the history of our human investigation into biology. It does not reflect any real distinction present in the biological world. Paleontologists do often use "macroevolution" to refer to process of long-scale trends in the fossil record. But for the most part, biologists like me don't use it that way.

---

​

If the different perspectives I have seen offered up by three of this forums own moderators isn’t confusing enough, here are some more:

​

Talkorigins has this FAQ about what macroevolution is. It starts well, with this opening paragraph:

quote:

---

In evolutionary biology today, macroevolution is used to refer to any evolutionary change at or above the level of species. It means the splitting of a species into two (speciation, or cladogenesis, from the Greek meaning "the origin of a branch") or the change of a species over time into another (anagenesis, not nowadays generally used). Any changes that occur at higher levels, such as the evolution of new families, phyla or genera, is also therefore macroevolution, but the term is not restricted to the origin of those higher taxa.

---

​

Punctuated equilibrium, Phyletic gradualism, Species selection and species sorting are all listed as examples of macroevolution. However, after a look at the history of the terms, the FAQ concludes with this:

quote:

---

There is no difference between micro- and macroevolution except that genes between species usually diverge, while genes within species usually combine. The same processes that cause within-species evolution are responsible for above-species evolution

---

​

This appears to me at least to constitute a contradiction. I don’t see how punctuated equilibrium, a theory tied intimately to such broad fields as ecology and geography, can be said to be the result of the same processes as intra-species population genetics. If it is, what is the point of classifying it as distinctively ‘macro’?

​

Again at talkorigins, The famous 29+ evidences for macroevolution FAQ contains another definition of the word in its introduction.

​

quote:

---

Macroevolution, as used here, is the theory of descent by gradual modification from a common ancestor.

---

​

Here, it simply means common descent. Nothing more, nothing less. Perhaps it is a definition geared up to directly combat the creationist interpretation of the word, which is still more mutable itself. I have seen creationists define macroevolution as speciation, as common descent, as a crossing of the created kind barrier, as large-scale morphological change. There seem to be the ideas that the 29+ evidences FAQ is designed to deal with, but can macroevolution really be classified simply as ‘common descent’? If so, where does microevolution, something that no-one would claim is not involved in common descent, enter the picture?

​

Some more, subtly different definitions from popular general biology texts:

quote:

---

A major question in evolutionary theory is whether microevolution (the gradual changes that take place within species) can account for macroevolution (the diversity among families, orders, classes, and phyla). The process of speciation - the formation of new species-is considered of central importance in answering this question."
Curtis and Barnes, Biology, pg 1029. (emphasis mine)

---

​

Here, macroevolution is framed not as a process or a theory, but as a fact: something to be accounted for by either microevolution or some other process.

​

This definition is the one that I most often return to.

quote:

---

Macroevolution:
Evolutionary change on a grand scale, encompassing the origin of new taxonomic groups, evolutionary trends, adaptive radiation, and mass extinction.
Campbell, Biology, 6th Edition

---

​

In other words, macroevolution is practically everything in evolutionary biology that isn’t bounded in by a species barrier. Genetic drift: (the bottleneck effect, the founder effect) and natural selection: (gene flow, mutation) are possibly the only things excluded by this definition.
The main problem I have with the term ‘macroevolution’ is not with what it is, but with when it is used. As I have shown in this post, people of all walks of life are using this term for only one of its many meanings. When people mean anagenesis, they say ‘macroevolution’. When they mean cladogenesis, they say ‘macroevolution’. Common descent, paleontological patterns, origins of diversity, genesis of novel properties, are all specific aspects of the great evolutionary canopy, but all are frequently substituted for the single word ‘macroevolution’. It is my opinion that the worth of this term has been, and is being diminished by frantic overuse.

---

I strongly disagree with interpretations I have read in this thread that refer to speciation as a microevolutionary phenomenon. That does not gel with anything I have read on the topic.Thank you for listening, and it's nice to be here.[This message has been edited by Didymus, 11-21-2003]

Welcome Didymus.You will probably find some friends here,as I believe some of our members also post at IIDB.------------------
AdminAsgara
Queen of the Universe

Hi Didymus,I'm a regular lurker over at IIDB. Great site.

quote:

---

I strongly disagree with interpretations I have read in this thread that refer to speciation as a microevolutionary phenomenon. That does not gel with anything I have read on the topic.

---

I think the reason for attempting to justify a distinct division between micro and macroevolution is that creationists often claim they believe in micro but not macro evolution and have succussfully drawn non-creationists into debating the terms. The distinctions as you have noted by most definitions, is in time scale but not in underlying process (at the molecular level).

quote:

---

I strongly disagree with interpretations I have read in this thread that refer to speciation as a microevolutionary phenomenon. That does not gel with anything I have read on the topic.

---

However, the underlying population genetic principles are identical for both which then begs the question, why even bother defining it as micro and macro. I think it is better to think in terms of RuffusAtticus' definition coupled with the definition from Campbell . The problem is compounded as there is no absolute clear species definition. So trying to assign a clear distinction between micro and macro evolution based on a fuzzy concept like species will naturally lead to a muddled concept as well.cheers,
M

Hi DD,Welcome to evcforum! Glad to see you over here. As you pointed out in your opening post, there are quite a few different ways of looking at the terms macro- and microevolution. I think the reality is that neither term - since they've been so badly overused, especially in the e vs c context - is very useful. Both are significantly open to interpretation.I think there is justification, if we're planning on using the terms at all, to treat the distinction as based on time, rather than type. Macroevolution - origin of "higher" taxa (cf, Futuyma, "Evolutionary Biology" 3d ed, pg 85) and their characteristics and distribution over time - would seem to only be observable or even discernable at evolutionary time scales. Macroevolution in this context can represent speciation through either anagenesis OR cladogenesis (after all, cladogenesis is basically just speciation - the node has to start with some organism). It is still basically just speciation, except spread out over very long timescales. As such, it is best understood as a paleontological concept.OTOH, so-called microevolution, which Futuyma for one defines as evolution witin populations and species (ibid, pg 447), seems to beg the question when considered in the evc context. Most creationists claim that microevolution = variation within a "kind" (whatever the hell that is). However, this variation they accept usually includes a huge amount of both inter- and intraspecies differentiation. IOW, it includes speciation - both classical anagenesis, and if the "kind" is different enough, what scientists understand as cladogenesis (sometimes up to the level of family). In either case, the term represents a biological concept.To avoid the popular misconceptions so commonly exploited by creationists to confuse the masses, I would argue that if we're going to use the term at all, the distinction should be based on time: macroevolution = evolutionary or geological timescales; microevolution = ecological timescales (to borrow a term from island biogeography). We can, of course, argue about just where that line should be drawn . Bottom line: trying to restrict speciation to macroevolution simply confuses the issue, because whenever the subject comes up in arguments with creationists they constantly and repetitively argue that "they're still trilobites". Getting them to agree that speciation can occur (under their acceptable "microevolution") is the first step in getting them to admit there isn't an difference between population dynamics and the pattern observed over long timescales in the fossil record.Quetzal = Morpho. Cladogenesis in action from IIDB to EVC...

welcome D,You have provided something here to comment on as Q and M did above. After your citing of Gould I was expecting to read "transmission and physiological genetics" as this pair is often instead thought to be nostaglic in some evolutionary discussions. I will comment later much as I have in the past when I asked Mammy (with respect to bacteria) if this is the strong or weak form. But as I need to "clean" up my own posts (on form-making) so it may be a time before I get back here. Taxonomy and Classification are not really the same thing and I am only guessing seeing some of the comments of Quetzal and Mammy that you may have over used the descriptive content which is an error I KNOW M has not done. Still it may be true that biology is coming out about a materialized concept of different levels of causation. My understanding is that there would need to be a LOT of population genetics done to show the different possibilites of such a hierachization and I have not seen this in the literature but I have not explictly looked for it either. My College Scholar Contract at Cornell was to investigate the nature of DOWNWARD causation (from higher levels of organization to lower)(hence my indeterminate response on the level of the bacteria being a level below that I had much of any experience with) so I would be most interested if you maintain a consistent point of view no matter what it is.

*sigh*http://www.geocities.com/jesussavedusall/index.html?10691...

What do you think that site has to do with the thread topic?In any case, it is usual to use a site link as support for a point. You haven't made any point at all.Please try to read over the guidelines and look at some posts.

Over on the Biblical Accuracy forum, Quiz posted this paragraph. I am hoping that he will join the discussion over here to see just what is wrong with his statement.------------------
Asgara
"An unexamined life is not worth living" Socrates via Plato

I was hopeing that someone would point out, how off the topic scr and I were. Yes I agree with that statment and I also add that Macro-evolution requires some faith, that is, blind hope that which it predicts will occur.Quiz