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Author Topic:   Stasis and Evolution
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(1)
Message 1 of 61 (528250)
10-05-2009 11:17 AM


Near the end of Calypsis4's "Living fossils" thread, Arphy expressed an interest in debating the importance of stasis in evolutionary biology (Source: Arphy's Summation).
It is his contention that the ToE should not allow the long bouts of stasis that we see in the fossil record. Elsewhere, other creationists (including Kaichos Man) have brought up issues related to the rate of change and the quantity of change.
I think the topic deserves some special attention, so I propose a thread to discuss stasis in evolution.
My perspective is that Arphy’s contention is a misunderstanding of evolution that stems mainly from the format of discourse in the biological sciences. Biologists talk about mutation and natural selection, and often characterize them as mechanisms, which creationists find troubling because of the apparent circularity or vague, story-like feel to the definition.
In a post in the free-for-all Lossy Adaptation via..., I gave a description of the actual mechanisms behind mutation and natural selection (AChristianDarkly used a three-part, A-B-C model to link a source, a mechanism and an outcome, and that’s the motif I used in that post).
The problem is that neither mutation nor natural selection really refers to anything mechanistic. Biology has hundreds, probably thousands of actual mechanisms at play, and these can be collected into two groups based on the effects they have on organisms:
  • Mutation: random processes that add diversity (these mechanisms are usually chemical processes that act at the molecular level)
  • Natural Selection: non-random processes that diminish diversity (these mechanisms are ecological processes that act at the organismal level).
With this in mind, one should remember that, when a biologist says, Natural selection favors the fit, he is not referring to an actual force or entity that is causing some things to die, while allowing others to live. Rather, he is referring to a collection of mechanisms (or a subset of mechanisms from that collection) that are unrelated, but relatively similar in outcome.
Examples of mechanisms include predation, pathogens, resource fluctuations, sparring for dominance, mate preferences, etc. They are all different, and each has varying shades of influence on fitness depending on the effectiveness of the predator, the severity and character of the resource flux, the lethality of the pathogen, the rules of the sparring contest, or the personality of the choosy mate.
Since all of these mechanisms are part of evolution, and since they don’t all have the same influence in all scenarios, we should expect to see a variety of responses (in terms of quantity, direction, rate and form of the response) in different animals. And, organisms will have to deal with multiple mechanisms over time, so sequence will also come into play. So, there are literally millions of ways these different mechanisms can interact to shape evolution of life on Earth, and that’s why there are literally millions of different types of organisms, each responding to a different set of pressures that act on different time scales, with different intensities, and different fluctuations.
Here is a tabular representation, with a number of pressures, or mechanisms, listed across the top, and the characteristics of the response along the side:
Responses of one species to a plethora of natural selection mechanisms
Predator 1Predator 2Pathogen 1Pathogen 2Prey 1Prey 2Water availabilityCompetitorFemale Selectivity
Amount of change0.143.156.63.012.782.00.440.0990.1
Direction of change1.04.12.30.80.199.134.4215.362.1
Rate of change6.0813.145.234.4512.316.187.726.517.13
Form of changeABCDEFGHI
(Don’t get hung up on the numbers: they’re just fillers). This is just for one organism. It is conceivable, (and probable, under the evolutionary model), with so many different possible ways to respond to so many different mechanisms, which act on so many different temporal and spatial scales, that there would be great variety in the outcome of selection on different lineages of organisms.
So, in summary, my position is that Arphy’s view (that stasis should not happen if things evolve) comes from an oversimplified understanding of evolution, and of the processes and functions of life.
Forum recommendation: Biological Evolution"
Edited by Bluejay, : column missing from table
Edited by Bluejay, : Better formatting and a couple additions around the table
Edited by Bluejay, : I swear I fixed this twice already! Thanks, Perdition.
Edited by Bluejay, : Table caption and mechanism categories

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

Replies to this message:
 Message 3 by Perdition, posted 10-05-2009 5:12 PM Blue Jay has replied
 Message 4 by RAZD, posted 10-05-2009 7:00 PM Blue Jay has not replied
 Message 16 by Arphy, posted 10-14-2009 6:51 AM Blue Jay has replied
 Message 28 by Kaichos Man, posted 10-26-2009 10:22 PM Blue Jay has replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(1)
Message 5 of 61 (528384)
10-06-2009 12:21 AM
Reply to: Message 3 by Perdition
10-05-2009 5:12 PM


Explaining the Selection Table
Hi, Perdition.
Meh. The table was just there to show how many different factors there can be contributing to evolution. And, I kind of wanted something to break up all the text.
I guess I could have explained it better, though. The values in the cells are supposed to represent some fictitional measurement of various parameters of the response (along the side) to a selection mechanism/pressure (across the top). These could be measurements of an accumulated total change since some arbitrary point in the past, or they could be all the pressures that the population is being exposed to and is having to deal with concurrently.
Each cell thus represents one evolutionary pathway or event. So, each one is one way in which the evolution of two different species might diverge.
Admittedly, it probably isn't the best way to present it, but it did give me the chance to practice HTML tables. If it causes too much trouble with the creationists, I'll just take it down and focus on text for my arguments.
Thanks, Perdition.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 3 by Perdition, posted 10-05-2009 5:12 PM Perdition has replied

Replies to this message:
 Message 6 by Perdition, posted 10-06-2009 11:12 AM Blue Jay has not replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(1)
Message 8 of 61 (528683)
10-06-2009 4:34 PM
Reply to: Message 7 by RAZD
10-06-2009 12:04 PM


Hint for Creationists
Hi, RAZD.
Glad I could provide you a place to plug all your past threads at EvC!
Now, if only some creationists would come and read it, maybe our efforts won't have been in vain...

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 7 by RAZD, posted 10-06-2009 12:04 PM RAZD has seen this message but not replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(1)
Message 9 of 61 (530020)
10-11-2009 10:25 PM


Bump for Arphy
Hi, Arphy.
If you would like to discuss stasis in evolution, I've provided this thread as an opportunity to do so.
I look forward to reading your arguments.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

Replies to this message:
 Message 10 by Arphy, posted 10-12-2009 4:46 AM Blue Jay has seen this message but not replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(1)
Message 17 of 61 (530636)
10-14-2009 11:30 AM
Reply to: Message 16 by Arphy
10-14-2009 6:51 AM


Phase 1: Defining "Stasis"
Hi, Arphy
Good to hear from you.
Let’s ignore, for the moment, what my personal opinion about stasis is, and focus on the evidence in the fossil record and the logical implications of the Theory of Evolution about stasis.
The first thing we need to do is establish what is meant by stasis. It wasn’t particularly clear in the other thread, but we could (and, in that thread, actually did) define stasis in two different ways:
  1. Persistence of a species across the fossil record (phylogenetic stasis).
  2. Persistence of a morphological form or feature across the fossil record (morphological stasis).
We do not see the first type of stasis: we see a species persisting across maybe 10 million years' worth of geological strata, only to be replaced by a new species.
However, we do see the second type: many organisms show very little gross morphological change over time.
The confusion over stasis comes in when someone like Calypsis4 sees morphological stasis, and treats it as if it were phylogenetic stasis. For instance, a Jurassic scorpionfly is similar to a modern scorpionfly in gross morphology. However, closer examination of, for instance, the wing venation shows that the Jurassic species is distinct from all living species (and from all species that have existed between then and now).
This is clear evidence of change over time, isn’t it?
So, the debate must only be about how much change occurs over time, right?
This is where my primer in the OP comes in. It becomes important to establish how much change should occur under the Theory of Evolution.
The first step in that process is for us to determine what causes evolutionary change. Once we have established an agreed-upon suite of causes, then we can determine a reasonable expectation for the amount of change (and the variance in that amount) that should happen due to those causes.
I have presented an argument that evolutionary change is due to a whole plethora of different mechanisms that are expressed differently in different situations, and that we thus shouldn’t expect all things to show the same degree and type of change over the same period of time.
Do you accept this argument?
-----
Once you have provided a commentary on this, we can proceed to discuss the range of different rates that could theoretically be seen, and determine whether long-lasting morphological stasis is plausible.
Because Punctuated Equilibrium deals with variance in the rate of change, and we haven't even agreed upon an acceptable range for that rate yet... let's leave punctuated equilibrium out for now. But, I'm sure we'll get to it before too long, anyway.
Edited by Bluejay, : added "only to be replaced by a new species"

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 16 by Arphy, posted 10-14-2009 6:51 AM Arphy has replied

Replies to this message:
 Message 18 by Arphy, posted 10-16-2009 10:24 PM Blue Jay has replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(1)
Message 23 of 61 (531324)
10-17-2009 2:11 AM
Reply to: Message 18 by Arphy
10-16-2009 10:24 PM


Re: Phase 1: Defining "Stasis"
Hi, Arphy.
Thanks for the response.
Arphy writes:
So you want me to produce a fossil and a living organism that have the same species name?
No: I merely want to know if what you think of as "stasis" is the same as what I think of as "stasis."
I can think of two pro-creationist arguments that you might be making with this "stasis" angle:
  1. Lack of large changes over time shows that microevolution can happen, but not macroevolution.
  2. The only changes we see in the fossil record are the emergence of new species, which suggests de novo creation, not gradual change over time.
Since I don't know which of these angles you want to take yet, I thought it prudent to determine what it is you think "stasis" means, and thereby determine what kinf o argument I might need to deal with.
We don't have to take the entire debate in one post.
-----
Arphy writes:
Unfortunatly species are often named differently just because they are found in different places in the fossil record...
I'm quite certain that this is incorrect (and the article you cited doesn't say anything about it, either). It may happen, for sure, but I very strongly doubt that it happens often.
-----
Arphy writes:
First again note that the debate about change is not necessarily how much but rather what type of change.
So, can you provide me with some objective criteria whereby you judge which types of change are possible and which types are not? I suspect that "types of change," in the end, will still end up being "amounts of change," anyway.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 18 by Arphy, posted 10-16-2009 10:24 PM Arphy has replied

Replies to this message:
 Message 25 by Arphy, posted 10-17-2009 7:54 AM Blue Jay has replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(1)
Message 24 of 61 (531325)
10-17-2009 2:21 AM
Reply to: Message 22 by Arphy
10-17-2009 1:35 AM


Re: Phase 1: Defining "Stasis"
Hi, Arphy.
Arphy writes:
Rapid speciation is a directly observable phenomenon. Slow speciation isn't.
If it can happen rapidly, why can't it happen slowly?
-----
Arphy writes:
No we are not going to throw the baby out with the bathwater, so to speak, when it comes to evolutionist research, but we do take it with a grain of salt, so to speak.
You should take all arguments with a grain of salt.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 22 by Arphy, posted 10-17-2009 1:35 AM Arphy has not replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(1)
Message 26 of 61 (531427)
10-17-2009 6:06 PM
Reply to: Message 25 by Arphy
10-17-2009 7:54 AM


Re: Phase 1: Defining "Stasis"
Hi, Arphy.
Arphy writes:
I am arguing that a lack of significant change in the morphology of organisms over vast periods of time is not compatible with the general evolutionary framework.
And I have been trying to get you to be more specific. What counts as "significant change"? And, what counts as "vast periods of time"?
Here is a list of types of change in evolutionary biology:
Changes in the structure of important molecules
Changes in immune chemistry
Changes in hormone activation
Changes in developmental timing and sequencing
Changes in tissue specialization
Changes in the efficiency of organs
Changes in the function of organs
Changes in the size of body parts
Changes in the arrangement of body parts
Changes in the shape of body parts
Fusion of two body parts into one
Division of one body part into two
Changes in the number of body parts
Changes from asexual to sexual reproduction
Changes from ovipary (egg laying) to vivipary (live birth)
Which of these types of change, in your mind, count as significant change?
And, why do you think these things have to happen under the general evolutionary framework?
-----
Arphy writes:
If speciation is the accumulation of very small changes then surely this would mean that genomes are always "moving" in some sort of direction and that these changes would be too small to be picked up by natural selection.
There is no reason to believe that natural selection cannot act on small changes.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 25 by Arphy, posted 10-17-2009 7:54 AM Arphy has replied

Replies to this message:
 Message 27 by Arphy, posted 10-26-2009 3:51 AM Blue Jay has replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(2)
Message 40 of 61 (532920)
10-27-2009 9:23 AM
Reply to: Message 27 by Arphy
10-26-2009 3:51 AM


Phase 2: The Problem with "Stasis"
Hi, Arphy.
Welcome.
So, you suggest that stasis is lack of morphological change over millions or billions of years.
Good. Let's run with it.
My next question is why a lack of morphological change over millions of years is a problem. It seems like you're already ready to get into that, so let's get to it.
Arphy writes:
Because if one of the major forces that drives evolution is competition, then lack of change or lack of competitiveness is not helpful in survival of the fittest.
You don't have to win a competition to survive. Probably most of the world's biota survives by avoiding competition, rather than by winning it.
But, again, let's look at the crocodile. What morphological changes are required for the crocodile to retain its niche as a coastal ambush predator?
Does ambushing grazing mammals at a water hole require a different set of adaptations from ambushing comparable dinosaurs at a water hole?
Does waiting at the end of the rapids for modern fish require a different set of adaptations from waiting at the end of rapids for ancient fish?
Perhaps more to the point:
What traits could grazing mammals have evolved that would have helped them avoid being ambushed by crocodiles at water holes?
What could today's fish have evolved that would have helped them avoid crocodiles waiting at the end of rapids?
The point is that some strategies will always be successful enough to persist without major changes. If you want to argue that changes must occur, please explain to me why such changes are needed. And be specific: use my crocodile example.
-----
Arphy writes:
Bluejay writes:
There is no reason to believe that natural selection cannot act on small changes.
e.g. What about "neutral" mutations?
There is also no reason to believe that all small changes are neutral.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 27 by Arphy, posted 10-26-2009 3:51 AM Arphy has not replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(2)
Message 42 of 61 (532922)
10-27-2009 9:30 AM
Reply to: Message 39 by Kaichos Man
10-27-2009 9:09 AM


Hi, Kaichos Man.
Kaichos Man writes:
The problem for evolution lies in the fact that if I evolved from a microbe, then every one of my thousands of transitional ancestors must have played -and won- that game of chicken with extinction. And this is true -to a greater or lesser degree- for every creature alive today.
Three points:
1. I don't see a problem with this.
2. Practically all of my "thousands of transitional ancestors" are the same as your "thousands of transitional ancestors." In fact, most of them are also the same as the "thousands of transitional ancestors" for pronghorn antelopes and mudpuppies, too. So, the situation isn't as dire as you are painting it.
3. What does this have to do with stasis?
-----
Kaichos Man writes:
...mathematicians have established a working definition of impossibility. It's 1 to 1050. Which is interesting, because Hoyle and Wickramasinge calculated the chance creation of a single living cell as 1 to 1065.
Again, three points:
1. Your probabilities fetish is not serving you well.
2. How can you calculate the probability of the occurrence of something if you don't know what's required to make it happen (which we don't know)?
3. What does this have to do with stasis?

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 39 by Kaichos Man, posted 10-27-2009 9:09 AM Kaichos Man has not replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(2)
Message 44 of 61 (532924)
10-27-2009 9:47 AM
Reply to: Message 28 by Kaichos Man
10-26-2009 10:22 PM


Hi, Kaichos Man.
Kaichos Man writes:
I take your point that if the the organism is being successful, then natural selection should hold it in stasis...
...if stasis indicates success, then phenotypic modification must indicate failure.
You've made two illogical leaps there:
1. That some successful strategies remain in stasis does not mean stasis is an indicator of success.
2. That stasis indicates success does not mean that non-stasis means failure
Remember the gold standard in evolution: survival. It is survival, not stasis, that indicates success.
Stasis merely indicates that the strategy is successful in a broad range of circumstances, so that, even as things change around you, your don't have to change much to adapt to them. But, this doesn't mean that those animals who are changing are not successful: remember, their lineages have survived just as long as the static lineage has, so they must be doing something right, yeah?
-----
Kaichos Man writes:
The second problem is that vast amounts of time spent in stasis greatly reduce the time available to evolve.
Stasis indicates that change has not been necessary for survival in the past, so what makes you believe it will be required in the future? I'm not saying that it won't be required (because there are probably situations in which it will be required), but I am saying that this is not a problem for evolution.
-----
Kaichos Man writes:
I believe Gould and Eldredge suggested that most organisms spend 99% of their life span in stasis. That would mean man would have to evolve from the common ancestor in just 17 mutations!
I would argue that, evolutionarily speaking, all organisms spend 100% of their lifespan in stasis.
Individual organisms do not evolve.
-----
Kaichos Man writes:
Stasis is obvious from the fossil record. It is observed and documented.
Agreed. I would add that gradualism is also obvious from the fossil record; and that it is also observed and documented.
-----
Kaichos Man writes:
Its [Stasis's] ramifications for the ToE are that evolution has very little time to bring about phenotypic change, and can only do so while playing "chicken" with extinction.
Your gift for anthropomorphization is limitless.
Naturally, I argue that not all evolutionary pressures have to be dramatic, extinction-level cataclysms. Evolution "innovation" can also come about by gradual, subtle changes in fitness due to random mutations.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 28 by Kaichos Man, posted 10-26-2009 10:22 PM Kaichos Man has not replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 46 of 61 (532927)
10-27-2009 10:04 AM
Reply to: Message 31 by Arphy
10-27-2009 4:48 AM


Phase 2: The problem with Stasis
Hi, Arphy.
Arphy writes:
I guess it would be good to understand what Bluejay's take on stasis and punctuated equalibrium is, otherwise we will just be stabbing in the dark as to what his position might be.
Once again, we're not talking about Bluejay's take on stasis or punctuated equilibrium. Your beef is with evolutionary biology, not with Bluejay: you obviously didn't need to know my opinion before you took a stance on this issue, so why do you need to know now?
Furthermore, given how you ignored the substance of my arguments in another thread in order to pursue a clumsy psychoanalysis of me and my religious beliefs, I feel no motivation whatsoever to reveal anything about myself to you. It would only distract you from the topic I actually want to discuss.
We're only talking about why you think stasis is a problem for evolutionary biology. That means that, for the sake of this debate, we are assuming that there is stasis in the fossil record, and we are trying to show whether this can be used as evidence against evolution.

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 31 by Arphy, posted 10-27-2009 4:48 AM Arphy has not replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(1)
Message 54 of 61 (533204)
10-29-2009 11:06 AM
Reply to: Message 50 by Kaichos Man
10-29-2009 1:48 AM


Re: Someone must win
Hi, Kaichos Man
Kaichos Man writes:
The probability of any given result is irrelevant unless it is specified.
And, since evolution does not specify its results, your probability argument is irrelevant, right?
Well, it certainly is irrelevant to this topic: stop discussing it here!

-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.

This message is a reply to:
 Message 50 by Kaichos Man, posted 10-29-2009 1:48 AM Kaichos Man has replied

Replies to this message:
 Message 55 by Kaichos Man, posted 10-31-2009 8:42 AM Blue Jay has not replied

  
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