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Author Topic:   Dogs will be Dogs will be ???
crashfrog
Member (Idle past 1543 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


(2)
Message 286 of 331 (654038)
02-26-2012 10:32 AM
Reply to: Message 281 by Chuck77
02-26-2012 6:13 AM


Taxonomy
I think it would be good to start by the certain catagories already set in place and go from there maybe.
When thinking about classification of animals - the study of which is called taxonomy - it's helpful to understand what actual problem taxonomists are trying to solve.
Here's an animal:
What is it? Well, that depends on who, and where, you ask. Dutch Afrikaans would call it the "earth wolf", or, in Dutch, the "aardwolf." Does that mean it's a wolf? Well, another name for it is "maanhaar jackal." So is it a jackal? And, of course, other people may call it something else. It's frequently mistaken for a hyena, so locals may refer to it as the "stripey hyena."
It's not uncommon for different people living in different places to have different names for the same plant or animal, and by the 1700's, when the "natural sciences" were really taking off, this was becoming a huge obstacle to effective communication about plants and animals, especially due to an enormous number of name collisions, where different populations were using the same name for different plants and animals. It was a mess!
So scientists wanted a set of systematic names for things, such that each species (which they really did think of back then as a "kind", a discrete and separate form of living thing) had its own systematic name, unique to it and descriptive. Since Latin was the language of scholarly endeavor at the time, the names were typically in Latin (or Greek made to sound Latin-y) and that served everybody well, since Latin was a dead language and therefore had no "common" names of its own.
In 1735 Carl Linne, a Swedish scientist, decided that another improvement could be made - the names could be made descriptive, such that an organism's scientific name would also include information about how it might be grouped with other organisms, since even by then scientists were seeing a pattern of hierarchical similarity between organisms, a pattern reflected in common use - we have living things, and then a kind of living thing called a "plant", and then a kind of plant called a "tree", and then a kind of tree called an "apple tree", and then a kind of apple tree called "Golden delicious." It's hierarchical, each level getting more and more specific.
Linne was so enamored of the system of classification he created that he Latinized his own name and started calling himself "Carolus Linnaeus." We refer to his system of classification that we now use as "Linnaean classification" - kingdom, phylum, class, order, family, genus, and species - and the use of the genus and species classification to refer to specific organisms as "binomial nomenclature" - two names, like Homo sapiens. In fact, it was Carolus Linnaeus who first provided a scientific name for human beings, and in so doing, made the origin of man a question for scientific research.
Well, ok. So now we have the system by which we name organisms. But when you name an organism, which organisms are you naming? Even just looking at Homo sapiens, that designation refers to a large number of beings who are all very different from each other - men are different than women, white people are different than black people, and so on. Does Homo sapiens refer to all of those different shapes and sizes of people? In other words - what is a species?
This is a question that is not nearly as simple as it sounds, since organisms don't come labeled - there's no part of the human body that you can look at and it says "One ANSI-standard female human being, serial no. 2345-234B." We have to group organisms according to similarity, but not too strictly, or else every single individual is its own species and we've defeated the very notion of classification.
What is a species, then? Scientists have largely settled on a definition that if two organisms are part of the same "reproductive population" - they can either breed with each other, or both breed with a third organism if given the opportunity - then we say they're part of the same species. Unfortunately that doesn't work very well for asexual organisms since they don't breed with anyone. Microbiologists have their own rules about what counts as a species but it's mostly an arbitrary amount of genetic difference.
So today we group organisms into a species, which are all the organisms that can breed with each other, and then group species into a genus, which are all the species that are most similar to each other. We group genera (plural of genus) into families, which are all the genera most similar to each other. We group families into orders, orders into classes, classes into phyla (plural of phylum), and finally phyla into kingdoms, where organisms are the least similar. Kingdom Animalia vs. Kingdom Plantae vs Kingdom Protista (fungi, yeasts.) And actually there are more kingdoms than that but that's the simple version we teach in high school.
It's important to recognize that this is all just bookkeeping. There are no classifications in nature. Animals and plants don't neatly assort themselves into categories, that's a simplifying system that we impose on the natural world. There's no such thing, physically, as a species or a "kind" because there really is no such thing as a "reproductive community." There's just two organisms involved in reproduction without regard as to who else they could hypothetically be reproducing with. The whole notion of classifying organisms is a theoretical notion. We call a dog a "dog" because it looks like other dogs to us, not because it has some kind of inherent dog-nature that separates it from wolves or cats or bears. It wasn't until the rise of molecular systematics three decades ago that we had any real way to determine similarity between organisms except by looking at them and making decisions about what kinds of similarity were more important than other kinds.

This message is a reply to:
 Message 281 by Chuck77, posted 02-26-2012 6:13 AM Chuck77 has replied

Replies to this message:
 Message 291 by Chuck77, posted 02-27-2012 1:02 AM crashfrog has replied

  
crashfrog
Member (Idle past 1543 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


(3)
Message 287 of 331 (654039)
02-26-2012 10:43 AM
Reply to: Message 271 by Chuck77
02-26-2012 2:57 AM


Re: Same kind different species?
Well, that's a good question. I'm not sure. Maybe the same kind but a different species? On the face of it I would say they were the same kind.
Sure, because you're looking at the adults.
But if you were looking at the juveniles, you would see that flying squirrels are placental mammals (like cats and dogs and humans) and gestate entirely in a uterus, while sugar gliders are marsupial mammals (like playtpuses and kangaroos) and gestate partially inside a uterus and partially inside the mother's abdominal pouch.
That's a pretty big difference, because that seems to be an enormous gulf between different sorts of mammals, both morphologically (that is, in terms of form) and genetically. Even creationists assert that marsupials and placentals are in different kinds. Evolutionists agree that flying squirrels and sugar gliders are as distantly related as any placental mammal is to any marsupial - that these two flying mammals are as dissimilar, in terms of evolutionary ancestry and genetic history, as human beings and kangaroos are.
That's why scientists don't talk about things as "kinds" - that word is just insufficiently specific to fully describe the relationship of these two organisms, or any two organisms. We talk about taxons, which are hierarchical, and allows us to point to the exact "level" of the difference: they're both alive, they're both animals, they're both vertebrates, they both have four legs, they both have fur, warm blood, and milk, making them mammals. But now is where they're different: one is a marsupial (actually a sort of possum), the other is placental.
You can see how that hierarchical system already implies a certain evolutionary history - we're the same, we're the same, we're somewhat the same, we're somewhat less the same, we're very much less the same, we're not very alike at all, we're completely different. Classification by increasingly broad categories of physical similarity is a kind of evolutionary history, because that's how new species evolve from old ones - by becoming increasingly dissimilar from them.

This message is a reply to:
 Message 271 by Chuck77, posted 02-26-2012 2:57 AM Chuck77 has replied

Replies to this message:
 Message 292 by Chuck77, posted 02-27-2012 1:15 AM crashfrog has replied

  
RAZD
Member (Idle past 1481 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 288 of 331 (654042)
02-26-2012 12:32 PM
Reply to: Message 273 by Chuck77
02-26-2012 3:53 AM


kinds and clades
Hi Chuck77,
Ooops. Yes, I made a mistake. Foxes are canine? I thought they were feline(felidae).
I wondered if that was the case. I think you would agree that this shows you the difficulty in defining macroevolution according to what you can see or not see or by having a certain number of morphological changes.
Message 271:
RADZ writes:
Would you expect one to become exactly like the other, or through convergent evolution to have similar behavior and appearance, as we see with the sugar glider (australian marsupial) and the flying squirrel (north american placental)?
Hi RAZD. I brought this post over here to respond to. You can work it into one comment with my other post if you like so we don't have multiple comments going at the same time.
Well, that's a good question. I'm not sure. Maybe the same kind but a different species? On the face of it I would say they were the same kind. Although i'm not sure. I don't think location of animals is what determines kinds. I think a bird in Australia could be same kind of bird in America, etc.
And we see this with seagulls and terns for instance, however here we have the difference between marsupial and placental mammals. The location becomes a factor when we consider reproductive isolation, and in this case Australian marsupial mammals have been isolated from placental mammals for a long time.
As has been pointed out by Huntard, the genetic\taxonomic differences between these organisms is greater than the difference between cat and fox, yet because of convergent evolution they appear very similar. There are differences that you don't see in the genetics and in the bones that are more than the differences between cat and fox.
This again shows you the difficulty in defining macroevolution according to what you can see or not see, or by having a certain number of morphological changes.
Although in your example they could be different kinds sure.
I guess I could ask what helps you determine what a kind is? How do you classify certain animals, species? I'm not so sure I have a great definition to be honest. I don't think it's easy to say just based on similar behavior and appearance. A lion could have simliar apperances as a dog but one would be feline and the other canine.
So maybe we should work on a good definition of kind before we go further.
Biology does not use "kind" as a classification, even though the taxonomic classification system was developed by Linneaus long before Darwin. Instead a number of levels are defined that show (or attempt to show) the levels of a nested hierarchy of descent from ancestors. This system is becoming increasingly unwieldy and many biologists are turning to cladistics.
quote:
Cladistics
Cladistics (Ancient Greek: κλάδος, klados, "branch") is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants (and nothing else). ...
Cladistics can be distinguished from other taxonomic systems, such as morphology-based phenetics, by its focus on shared derived characters (synapomorphies). Systems developed earlier usually employed overall morphological similarity to group species into genera, families and other higher level groups (taxa); cladistic classifications (usually in the form of trees called cladograms) are intended to reflect the relative recency of common ancestry or the sharing of homologous features. Cladistics is also distinguished by an emphasis on parsimony and hypothesis testing (particularly falsificationism), leading to a claim that cladistics is more objective than systems which rely on subjective judgements of relationship based on similarity.[2]
Now I would think that you, and other creationists, would agree that their view of a "kind" would constitute a "clade" as used by cladistics,
Evolution is True Because Life Needs It Message 105 (RAZD to Portillo)
Do you agree or disagree that a kind would form a clade of animals related to a common ancestor (ie the original created kind)?
|
                         ^ a
                        / \
                       /   \
                      /     ^ b
                   c ^     / \
                    / \   /   \
Here "a" is a common ancestor to the four end groups, "b" is a common ancestor to the two right side groups, and "c" is a common ancestor to the two left side groups.
We see this pattern in DNA and in the fossil record, so we know that this pattern of development of daughter groups from parent groups is a fact in nature.
Do you agree or disagree that this is the pattern for the evolution within a kind?
Here "a" would be the basal type for a "kind" would it not?
We don't need to know what level of taxonomy "a" "b" "c" and the four end groups are, they have all descended from the basal "a" kind\group. Here "b" and "c" could be wolves and foxes, and one of the right hand end groups could be dogs.
Their descendants will always be members of the dog clade, always be members of the wolf clade, always be members of the "a" clade.
Message 278: How about starting here:
Canidae - Wikipedia:
Can we call the family Canidae a "kind"?
We could, but that could be interpreted as claiming that "kind" is defined by "family" taxon, and I would rather not be side-tracked by that issue.
We can instead call it the Canidae clade, and avoid that issue.
In any event, what evolution predicts is that offspring of any individuals within a clade will continue to be members of that clade, no matter how distinctive or differently they or their descendants evolve in later generations.
The questions then become (a) what can evolve from a specific breeding population, and (b) how different do they need to become for you, creationists, to accept that macroevolution has in fact occurred, that the diversity of life has increased.
If we go back to dogs and the OP for this thread:
quote:
Message 1: Back to the original quote:
"The fossil record shows variations of all sorts of things but will time turn a dog kind into something that we would say is clearly not a dog? " ...
So what would you like this to become?
Would a horse be enough? Would you dispute that a horse is clearly not a dog?
Note that this is an artistic interpretation of an actual fossil.
Enjoy.
Edited by RAZD, : added info, changed subtitle
Edited by RAZD, : code

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)

This message is a reply to:
 Message 273 by Chuck77, posted 02-26-2012 3:53 AM Chuck77 has replied

Replies to this message:
 Message 293 by Chuck77, posted 02-27-2012 1:49 AM RAZD has replied
 Message 315 by Chuck77, posted 03-15-2012 6:14 AM RAZD has seen this message but not replied

  
RAZD
Member (Idle past 1481 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


(1)
Message 289 of 331 (654056)
02-26-2012 4:02 PM
Reply to: Message 270 by Chuck77
02-26-2012 1:35 AM


moving forward: how much variation constitutes enough change
Hi again Chuck77,
RAZD writes:
(Message 1): We'll start with those - and see what turns up.
Cool.
This refers to the questions at the end of Message 1:
quote:
So the questions that creationists must answer are:
(1) If your definition of macroevolution is different from evolutionary biology what is it?
(2) Why do you think it is a valid definition?
(3) How much change is necessary?
(4) Why isn't the difference between cat and fox a valid criteria?
You replied in Message 270.
For (1) you answered:
"Macro" to me would be land mammal to sea mammal or vice versa. Much much more change.
Of course, you must realize that "much much much more change" is difficult to quantify. We also see that the amount of difference between cat and fox is less than the amount of variation we see in dogs. It would be difficult to apply this as a definition of macroevolution, don't you think?
For (2) you answered:
I can't say. Like I said I don't use the terms really. ... So I think it's a stretch to assume they change out of that kind. ...
Note that this implies an added element to your definition of macroevolution -- that it involves a change out of the parent kind. This is a fairly common creationist view, however it has nothing to do with evolution nor the fossil record of life on earth.
When we look at clades all descendants are still members of the "a" clade, that they can evolve to be different, but they cannot evolve out of that clade. To expand the clade example:
|
                         ^ a
                        / \
                       /   \
                      /     \
                     /       ^ b
                  c ^       / \
                   / \     /   \
                  d   e   f     g
"a" "b" "c" "d" "e" "f" and "h" are all members of the "a" clade, none of them have evolved out of the "a" clade, however "d" "e" "f" and "g" are different species.
If "a" is carnivora, "b" is canine, "c" is feline, "d" is house cat and "f" is red fox, they are still members of the carnivora clade even though they have evolved to be different.
Further the "out of kind" metric does not fit with the evidence that the differences between cat and fox are less than the variations seen within the dog species:
Message 1:
quote:
The question will be whether the difference in the traits between the cat and the red fox is MORE or LESS than the maximum differences found in varieties of dogs from the wolf. We'll call this factor "deltaFactor" with these categories:
+3 = much more difference between cat and fox than between dog and wolf
+2 = more difference between cat and fox than between dog and wolf
+1 = a little more difference between cat and fox than between dog and wolf
 0 = no difference between cat and fox than between dog and wolf
-1 = a little less difference between cat and fox than between dog and wolf
-2 = less difference between cat and fox than between dog and wolf
-3 = much less difference between cat and fox than between dog and wolf
Trait House Cat Red Fox deltaFactor
Nose small small -2
Whiskers long long -2
Tooth size small small -3
Tooth type carnassial pair canine +1
Tongue keratin hooks standard +2
food carnivorous carnivorous -3
Snout small/short small/long -3
Eyes 2 2 0
Eye pupils slitted slitted 0
Eye color several gold/yellow 0
Ears 2 2 0
Ear shape Pointed Pointed -3
Ear size small small -3
Ear control good good -3
Head size small small -3
Neck short short -3
body size small small -3
legs 4 4 0
leg/body length short short -3
paws 4 4 0
claws 5x4 5x4 0
Claws retractable not +3
Tail long long -3
Fur short to long long -2
Fur type straight straight -3
....

(subtotal) -36
(average so far) -1.44
Those are most of the visible differences. Feel free to add to the list with whatever comes to mind. In a lot of the -3 cases the needle is pegged at much much less difference between cat and fox than between the extreme varieties of dog and wolf.
When we compare the skeletons, we can match bone for bone from cat to fox to dog to wolf, but we see much more variation in size and proportions between dog and wolf than between cat and fox. There are no bones that are special to cats or foxes or dogs. This can be counted as a -3 x number of bones.
For additional comparisons see:
Cat skeleton
Red Fox skeleton
Dog skeleton
Wolf skeleton
When we compare internal organs, we can match organ for organ from cat to fox to dog, but we see much more variation in size and proportions between dog and wolf than between cat and fox. There are no organs that are special to cats or foxes or dogs. This can be counted as a -3 x number of organs.
Conclusion: from feature to feature to feature, a cat is more similar to a red fox than some dogs are like wolves.
As most creationists would claim that foxes and cats are different kinds, it would not appear to me that either major morphological change nor change "out of kind" is necessary to distinguish one from the other. Please correct me if I am wrong.
To (3) you answered:
A lot? I'm not sure. 50,000 - 100,000 morphological changes? How many ever are needed to adapt. It would seem much easier for a Fox to Cat than Horse to Whale?
So you are asking for a larger degree of change than just from one kind to essentially be similar to another, yes?
The development of something that did not exist previously in the fossil record perhaps?
Such as evolving from something like a dog into the modern horse?
To (4) you answered:
Because their the same kind (feline). I wouldn't consider it "macro" but "micro".
Now that you have corrected your error (in Message 273: "Yes, I made a mistake. Foxes are canine... ") do you want to answer this again?
In Message 273 you also said:
Would it be ok then to say I don't believe the fox can evolve "into" a cat then?
Now I, and I believe other evolutionists here would agree, don't believe that a fox can evolve into a cat, strictly speaking, but they could evolve into something resembling a cat in the way a sugar glider (australian marsupial) has evolved into something resembling the flying squirrel (north american placental).
I would also argue that the numerous similar evidences of convergent evolution can be taken as examples of one "kind" evolving "out of" it's original "kind" and into another: they have evolved into similar organisms.
Can you tell me why convergent evolution would not be evidence of one kind evolving into another?
Enjoy.
Edited by RAZD, : added last q

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)

This message is a reply to:
 Message 270 by Chuck77, posted 02-26-2012 1:35 AM Chuck77 has replied

Replies to this message:
 Message 294 by Chuck77, posted 02-27-2012 2:29 AM RAZD has replied

  
Chuck77
Inactive Member


(1)
Message 290 of 331 (654121)
02-27-2012 12:36 AM
Reply to: Message 285 by RAZD
02-26-2012 9:02 AM


Re: micro and macro
Hi RAZD.
RAZD quotes writes:
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.
Definition one reads fine except it doesn't say how long the changes take or how many.
Definition two is a little confusing. One form to another that are simliar? (I will read the whole page as you recommend).
RAZD writes:
If we observe the effect of microevolution over many generations, we can observe the accumulation and loss of a number of hereditary traits, especially when the ecological challenges and opportunities change. Microevolution is a response mechanism that filters variations for traits that are better adaptations to the existing ecology.
Arbitrary Speciation
Over many generations a population can accumulate and lose a number of traits, and thus it can appear significantly different from the ancestral population, even though there is a direct unbroken lineage of descent from parent to offspring. Sometimes these accumulated differences are sufficient for biologists to assign a new species name to the breeding population, even though this is a fairly arbitrary designation.
Ok. I think I understand. So a wolf for instance passes down herditary traits and maybe 4 generations later a species can look entirely different form the wolf? It's actually a new species. Micro evolution right?
The question here is how do new species get added to the mix, something more than the arbitrary speciation mechanism. A new species is added when a speciation event occurs:
Discrete Speciation
Speciation is the division of a parent population into two or more reproductively isolated daughter populations that then evolve independently of each other.
The reduction or loss of interbreeding (gene flow, sharing of mutations) between the daughter populations results in different, independent, evolutionary responses in the daughter populations to their different ecological opportunities.
What do you mean by daughter population? Females in the area?
So in order for this to take place a lot of factors are involved mainley location and the daughter population in that area?
Such discrete speciation events have been observed to occur, both in the lab and in the field (particularly in plants). These are not arbitrary events such as discussed above, but if you remove one of the daughter populations and looked at the accumulation and loss of hereditary traits from generation to generation from parent to daughter population you would see the same types of variation and adaptation seen that was discussed for arbitrary speciation.
Ok, this actually sounds familiar but is a little confusing. A lot of this is.
Speciation seems important. I always thought speciation was two of the same kind (until I get a better grasp of everything I hope you don't mind me using the word kind) but different species reproducing? Like say a sparrow and a robin? Both birds...different species? Is that speciation or does it go deeper than that?
Would you call speciation micro or macro? This may already be obvious but some things are gonna go over my head here.
As you can see there is a fairly obvious difference in degree of change here from what biologists consider for macroevolution.
How about something like a dog to a horse?
Hmmm. Well sure. I mean if it were to happen there is no denying it right? Wouldn't there be a trail leading both to eachother?
(For sake of argument I have to bring some things up that I don't yet agree with so don't take it as me believing it now but it will help the conversation go forward)
For instance we would see dog traits in the horse and horse traits in the dog? They look alike from a distance, both run on 4 legs...tails, no tails etc etc. Yeah I could go with it. So why aren't they in the same family you think? Are they that far apart? Even if they are that far apart what is to say to seperate them anyway?

This message is a reply to:
 Message 285 by RAZD, posted 02-26-2012 9:02 AM RAZD has replied

Replies to this message:
 Message 297 by RAZD, posted 02-27-2012 8:54 AM Chuck77 has not replied
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Chuck77
Inactive Member


Message 291 of 331 (654122)
02-27-2012 1:02 AM
Reply to: Message 286 by crashfrog
02-26-2012 10:32 AM


Re: Taxonomy
Hi Crashfrog, excellent thanks.
crashfrog writes:
What is a species, then? Scientists have largely settled on a definition that if two organisms are part of the same "reproductive population" - they can either breed with each other, or both breed with a third organism if given the opportunity - then we say they're part of the same species. Unfortunately that doesn't work very well for asexual organisms since they don't breed with anyone. Microbiologists have their own rules about what counts as a species but it's mostly an arbitrary amount of genetic difference.
How can you tell if they are of the same reproductive population? What do you mean? Not all canines can mate with all canines right? Is there something reproductivly that associates them then and that's why they are classified together?
So today we group organisms into a species, which are all the organisms that can breed with each other, and then group species into a genus, which are all the species that are most similar to each other.
Ok. So winged species in this corner, winged with tail over here, winged with tail beak over here?
It's important to recognize that this is all just bookkeeping. There are no classifications in nature. Animals and plants don't neatly assort themselves into categories, that's a simplifying system that we impose on the natural world. There's no such thing, physically, as a species or a "kind" because there really is no such thing as a "reproductive community."
Whoa. Interesting. I'm no sure I knew that. What do you mean there is no such thing as a "reproductive community"?
Don't animals usually stay within there own limitations? Don't they know who to reproduce with? I don't know what you mean and I also and confused about there are really no species.
IOW you're saying this is life, we are all here, all connected all the same yet different?
There's just two organisms involved in reproduction without regard as to who else they could hypothetically be reproducing with. The whole notion of classifying organisms is a theoretical notion. We call a dog a "dog" because it looks like other dogs to us, not because it has some kind of inherent dog-nature that separates it from wolves or cats or bears. It wasn't until the rise of molecular systematics three decades ago that we had any real way to determine similarity between organisms except by looking at them and making decisions about what kinds of similarity were more important than other kinds.
Really interesting. So I could actually say that a we are all of the same kind, different species, subspecies all the way down the line? Then, group then together the best we can based on genetics, looks, behavior and thats what makes up taxonomy? I'm just trying to determine why some are catagorized in different families. Like the sugar glider and flying squirrel...Do you think they should be in the same classification?
Plants, animals, trees, anything alive is catagorized? Then broken down and placed into other catagories with similiar features etc?

This message is a reply to:
 Message 286 by crashfrog, posted 02-26-2012 10:32 AM crashfrog has replied

Replies to this message:
 Message 301 by crashfrog, posted 02-27-2012 3:23 PM Chuck77 has not replied

  
Chuck77
Inactive Member


Message 292 of 331 (654123)
02-27-2012 1:15 AM
Reply to: Message 287 by crashfrog
02-26-2012 10:43 AM


Re: Same kind different species?
crashfrog writes:
Even creationists assert that marsupials and placentals are in different kinds.
Ahh, we do? I wonder why?
Evolutionists agree that flying squirrels and sugar gliders are as distantly related as any placental mammal is to any marsupial - that these two flying mammals are as dissimilar, in terms of evolutionary ancestry and genetic history, as human beings and kangaroos are.
Really? Wow.
But if you were looking at the juveniles, you would see that flying squirrels are placental mammals (like cats and dogs and humans) and gestate entirely in a uterus, while sugar gliders are marsupial mammals (like playtpuses and kangaroos) and gestate partially inside a uterus and partially inside the mother's abdominal pouch.
Yet they look almost exactly the same. How? One stray trait on looks got passed thru somehow? So it's more than just looks as far as taxonomy. Genetics plays a larger role then?
That's why scientists don't talk about things as "kinds" - that word is just insufficiently specific to fully describe the relationship of these two organisms, or any two organisms. We talk about taxons, which are hierarchical, and allows us to point to the exact "level" of the difference: they're both alive, they're both animals, they're both vertebrates, they both have four legs, they both have fur, warm blood, and milk, making them mammals. But now is where they're different: one is a marsupial (actually a sort of possum), the other is placental.
So those two a two utter and completly different species like us and kangaroos? Well this is going to hard to define what a kind is then, it seems.
Could they be classified different is we had different qualifications for the classifications? What actualy determines the classifications themselves? Again, it seems genetics is at the top of the list.
You can see how that hierarchical system already implies a certain evolutionary history - we're the same, we're the same, we're somewhat the same, we're somewhat less the same, we're very much less the same, we're not very alike at all, we're completely different. Classification by increasingly broad categories of physical similarity is a kind of evolutionary history, because that's how new species evolve from old ones - by becoming increasingly dissimilar from them.
Yeah interesting. I get it but at the same time I don't, but I do.

This message is a reply to:
 Message 287 by crashfrog, posted 02-26-2012 10:43 AM crashfrog has replied

Replies to this message:
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Chuck77
Inactive Member


(1)
Message 293 of 331 (654126)
02-27-2012 1:49 AM
Reply to: Message 288 by RAZD
02-26-2012 12:32 PM


Re: kinds and clades
Hi RAZD
The location becomes a factor when we consider reproductive isolation, and in this case Australian marsupial mammals have been isolated from placental mammals for a long time.
So could they actually mate at one time?
Are they are analogous? In contrast to homologous?
ABE: The above statement about analogous and homologous was from searching for "convergent evolution". This is what I found:
Traits arising through convergent evolution are termed analogous structures, in contrast to homologous structures, which have a common origin.
Convergent evolution - Wikipedia
So they don't have a common origin? The sugar glider and flying squirrel?
RAZD quotes writes:
Cladistics
Cladistics (Ancient Greek: , klados, "branch") is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants (and nothing else). ...
Cladistics can be distinguished from other taxonomic systems, such as morphology-based phenetics, by its focus on shared derived characters (synapomorphies). Systems developed earlier usually employed overall morphological similarity to group species into genera, families and other higher level groups (taxa); cladistic classifications (usually in the form of trees called cladograms) are intended to reflect the relative recency of common ancestry or the sharing of homologous features. Cladistics is also distinguished by an emphasis on parsimony and hypothesis testing (particularly falsificationism), leading to a claim that cladistics is more objective than systems which rely on subjective judgements of relationship based on similarity.[2]
Now I would think that you, and other creationists, would agree that their view of a "kind" would constitute a "clade" as used by cladistics,
Yeah, works for me.
|
^ a
/ \
/ \
/ ^ b
c ^ / \
/ \ / \
Here "a" would be the basal type for a "kind" would it not?
So far yeah. It seems it would. B and C would be other species of the "A" kind.
We don't need to know what level of taxonomy "a" "b" "c" and the four end groups are, they have all descended from the basal "a" kind\group. Here "b" and "c" could be wolves and foxes, and one of the right hand end groups could be dogs.
Their descendants will always be members of the dog clade, always be members of the wolf clade, always be members of the "a" clade.
Yes. That sounds good. Clade then would the "kind" I am taking about. What I don't get is when A,B or C of that clade...then jumps, to D,E and F. That's where I get lost. How could they?
How could they genectically? Do you understand what I mean? Like I said to Huntard, i'm trying to find where my point of contention lies.
We could, but that could be interpreted as claiming that "kind" is defined by "family" taxon, and I would rather not be side-tracked by that issue.
We can instead call it the Canidae clade, and avoid that issue.
Yep, sounds good.
The questions then become (a) what can evolve from a specific breeding population, and (b) how different do they need to become for you, creationists, to accept that macroevolution has in fact occurred, that the diversity of life has increased.
Yeah, it's a big question. I don't know.
If we go back to dogs and the OP for this thread:
quote:
Message 1: Back to the original quote:
"The fossil record shows variations of all sorts of things but will time turn a dog kind into something that we would say is clearly not a dog? " ...
So what would you like this to become?
Would a horse be enough? Would you dispute that a horse is clearly not a dog?
Note that this is an artistic interpretation of an actual fossil.
Hmm, well a Wolf isn't a dog but is canine. No one would call a bunch of wolves roaming around in the fields a bunch of dogs if they knew they were wolves. So if the Wolf is "A" and a horse was "B" or "C" then sure. What's the difference.
The queston is does that happen...such a huge change in appearence and genetically? Tho i'm not sure that works either because many species are different sizes. I don't know (again). What determines it if the horse should be grouped with the dog?
Edited by Chuck77, : No reason given.
Edited by Chuck77, : No reason given.

This message is a reply to:
 Message 288 by RAZD, posted 02-26-2012 12:32 PM RAZD has replied

Replies to this message:
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Chuck77
Inactive Member


(1)
Message 294 of 331 (654130)
02-27-2012 2:29 AM
Reply to: Message 289 by RAZD
02-26-2012 4:02 PM


Re: moving forward: how much variation constitutes enough change
Hi RAZD.
Of course, you must realize that "much much much more change" is difficult to quantify. We also see that the amount of difference between cat and fox is less than the amount of variation we see in dogs. It would be difficult to apply this as a definition of macroevolution, don't you think?
Yes, it probably would now. One thing I would say/ask you RAZD is this: If the fox and cat are closer in changes than some dogs are why are they classified differently? Shouldn't they both be in either the canine or feline clade? Why are they not classified together while dogs who are farther apart in changes are?
When we look at clades all descendants are still members of the "a" clade, that they can evolve to be different, but they cannot evolve out of that clade. To expand the clade example:
|
^ a
/ \
/ \
/ \
/ ^ b
c ^ / \
/ \ / \
d e f g
"a" "b" "c" "d" "e" "f" and "h" are all members of the "a" clade, none of them have evolved out of the "a" clade, however "d" "e" "f" and "g" are different species.
If "a" is carnivora, "b" is canine, "c" is feline, "d" is house cat and "f" is red fox, they are still members of the carnivora clade even though they have evolved to be different.
Ok. i'm confused a little. Why are you putting canine with feline in the same clade? Aren't they a little to close together?I thought we were saying clades (for understanding you better and me grasping it better) was a kind - so to speak. Are you putting feline with canine?
Shouldn't it be "A" wolf "B" dog "C" poddle...and so on down the canine clade? d,e,f,g,h...
Then totally seperate would be "A" lion "B" tiger" "C" cat?
Those are most of the visible differences. Feel free to add to the list with whatever comes to mind. In a lot of the -3 cases the needle is pegged at much much less difference between cat and fox than between the extreme varieties of dog and wolf.
When we compare the skeletons, we can match bone for bone from cat to fox to dog to wolf, but we see much more variation in size and proportions between dog and wolf than between cat and fox. There are no bones that are special to cats or foxes or dogs. This can be counted as a -3 x number of bones.
Ok I see. I wonder why they are classified differently. Do you know what the bigger difference are within the dogs? Is it much more than +3?
Conclusion: from feature to feature to feature, a cat is more similar to a red fox than some dogs are like wolves.
I understand what you're saying. You're saying if I accpet wolf to dog (which has more changes in some than fox to cat) then I should accept fox to cat (different "kinds" tho less changes) who are classified differently?
As most creationists would claim that foxes and cats are different kinds, it would not appear to me that either major morphological change nor change "out of kind" is necessary to distinguish one from the other. Please correct me if I am wrong.
See above.
Now I, and I believe other evolutionists here would agree, don't believe that a fox can evolve into a cat, strictly speaking, but they could evolve into something resembling a cat in the way a sugar glider (australian marsupial) has evolved into something resembling the flying squirrel (north american placental).
I would also argue that the numerous similar evidences of convergent evolution can be taken as examples of one "kind" evolving "out of" it's original "kind" and into another: they have evolved into similar organisms.
Can you tell me why convergent evolution would not be evidence of one kind evolving into another?
I understand RAZD. I do and thank you for explaining it to me. I think tho, were moving a little fast. I'm not so sure I agree with the way the taxonomic catagories are set up. Tho i'm not sure it really matters. As crash said it's only to help guide us.
To answer your question about convergent evolution I can't right now. I need to understand more what convergent evolution is. Maybe our (my) definition of kinds ahould be expanded a little more.
ABE: I think I missed this RAZD when you said:
but they could evolve into something resembling a cat in the way a sugar glider (australian marsupial) has evolved into something resembling the flying squirrel (north american placental).
Do you think this could or did happen? Since one is marsupial and the other placental? So they are related(?) but not classified together? Genetically their very different right?
How many changes do you think they are away from dog to wolf or fox to cat?
ABE(again): RAZD I skipped over this because I didn't understand what your meant:
So you are asking for a larger degree of change than just from one kind to essentially be similar to another, yes?
The development of something that did not exist previously in the fossil record perhaps?
Such as evolving from something like a dog into the modern horse?
What do you mean?
Edited by Chuck77, : No reason given.
Edited by Chuck77, : No reason given.

This message is a reply to:
 Message 289 by RAZD, posted 02-26-2012 4:02 PM RAZD has replied

Replies to this message:
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Chuck77
Inactive Member


Message 295 of 331 (654131)
02-27-2012 2:39 AM
Reply to: Message 284 by Percy
02-26-2012 8:26 AM


Re: Same kind different species?
Hi Percy
Percy writes:
It might be a better idea to explore what science knows about classification and speciation before making a decision about whether the concept of kind belongs in your version of creationism, otherwise you'll just be creating another version of creation that makes no sense.
Well first i'd like to see if I can come to a definition that works before I abandon it. Tho it's not going to be a tight as I thought.

This message is a reply to:
 Message 284 by Percy, posted 02-26-2012 8:26 AM Percy has seen this message but not replied

  
caffeine
Member (Idle past 1100 days)
Posts: 1800
From: Prague, Czech Republic
Joined: 10-22-2008


(1)
Message 296 of 331 (654139)
02-27-2012 5:55 AM
Reply to: Message 292 by Chuck77
02-27-2012 1:15 AM


How to classify life?
Hey Chuck,
I noticed one question that seemed to pop up repeatedly in all your last bunch of posts. You want to know how scientists decide on their classifications. If we have a bat, a pigeon and a mouse, then the bast and pigeon have wings, while the bat and mouse have breasts. How do we decide which factor is most important in splitting them into two clades?
This is actually quite a difficult question, and is one of the reasons that classifications have changed over the years with more study, in some cases quite dramatically. Let's take a look at the sugar glider and flying squirrel again. At first glance, it's hard to tell them apart. But, when you look a lot closer, you realise the similarities really are only skin deep. Under the skin, there are all sorts of differences.
Sugar gliders have a pouch, where the young complete their development, just like a kangaroo. They also have an epipubic bone, a bone that sticks forward from the pelvis which supports the pouch, again, like a kangaroo. Their kneecap is cartilage, like a kangaroo's, but not like the flying squirrel, whose is made out of bone.
Moving on from bones, you notice major differences if you start looking at sex organs. Flying squirrel females have a single vagina, which leads up to a single uterus, just like in a human. In the sugar glider, however, a glance at the naughty bits would reveal that the vagina splits into two seperate passages inside, just like in a kangaroo. To match up with this, the head of the sugar glider's penis is branched into two (like a kangaroos), while the flying squirrel has a boring, straight penis, again like humans.
There are many more details of anatomy and physiology in which sugar gliders match up with kangaroos, but not with flying squirrels (forgive the focus on genitalia, but I just yesterday read the chapter on the genital system in my comparative anatomy book, so this stuff is fresh!). The sugar glider and flying squirrel look very similar on the outside, since they live the same sort of lifestyle and need to be able to do similar things. But they clearly have a different fundamental body plan inside - this is why even creationist taxonomists were happy to put the sugar glider together with it's cousins, the wombats and kangaroos.
And, for a long time, this was pretty much how taxonomy was done. Since the details of internal similarity between the Australian marsupials seems both more numerous and more fundamental than the superficial similarities many share with placental mammals, it made sense to put them together.
But things aren't always this clear cut. It's not always simple to agree which feature is most informative taxonomically. Are all animals with a gibbety bone closely related, or are gibbety bones just the type of thing that's easy for lots of unrelated animals to evolve independently? The modern techniques of cladistics, as described by RAZD in a previous post, are an attempt to make this all a bit more scientific. They take advantage of the calculating powers of computers to classify groups of animals based around huge databases of characteristics.
When done well, you don't just pick and choose the features that you consider the most important, Instead, you include lots of features, and then calculate which nested relationships are the most likely. The more features you include, and the more animals (or plants, or microbes, or whatever) you include the more accurate your answer will be, since it's less likely to be tricked by odd convergences.
You asked before whether DNA was more important, and many of the modern analyses do rely heavily on DNA. One of the reasons for this is simply that it gives you a lot more data, and the more data you have the less likely your analysis is to be fooled by chance similarities. There's also the fact that convergence is less of a problem in the world of DNA. Since there are many arrangements of DNA that can produce functionally similar organisms, you don't need to worry about superficial similarites between distantly related organisms living different lifestlyes. It's through DNA that we've been able to confirm that some of the suspicious classifications of the past, like Insectivora (small, furry things that usually eat insects) are in fact an artificial assemblage of distantly related small, furry insect eaters. Elephant shrews and tenrecs are actually closer to elephants than to shrews, while colugos wind up nearer to primates.
Hope this helps!

This message is a reply to:
 Message 292 by Chuck77, posted 02-27-2012 1:15 AM Chuck77 has seen this message but not replied

  
RAZD
Member (Idle past 1481 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 297 of 331 (654147)
02-27-2012 8:54 AM
Reply to: Message 290 by Chuck77
02-27-2012 12:36 AM


Re: micro and macro
Hi Chuck77
Definition two is a little confusing. One form to another that are simliar? (I will read the whole page as you recommend).
I agree that it is not the best wording, but I believe what they are talking about there is the arbitrary speciation that I described, seeing as they place it before speciation and the generation of diversity.
Another resource we can look at is Berkeley's website:
quote:
An Introduction to Evolution
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.
Here "small scale evolution" is the microevolution as before, and "large scale evolution" involves speciation events and arbitrary speciation changes accumulated over many generations.
They go on to discuss nested hierarchies and have many pages of followup material -- excellent reading that you can take a bit at a time. This was developed by the biology department to be a resource for schools to teach evolution, sort of an on-line textbook.
Ok. I think I understand. So a wolf for instance passes down herditary traits and maybe 4 generations later a species can look entirely different form the wolf? It's actually a new species. Micro evolution right?
Yes microevolution, but not necessarily a new species. Wolves to dogs is a good example here: we have a lot of changes that have accumulated and so we make the arbitrary decision to classify dogs as a subspecies of wolf: Canis lupus familiaris (where the third name identifies a variety within the species.
If all we had to go on were bones in a fossil record we would likely make it a new species classification, Canis familiaris for example. As Crash said, these identifications are for our use and don't really affect the nature of two animals breeding or attacking on another (think wolf and chihuahua).
But yes, microevolution leads to speciation, both arbitrary and discrete.
What do you mean by daughter population? Females in the area?
So in order for this to take place a lot of factors are involved mainley location and the daughter population in that area?
It's just the accepted terminology for a breeding population that is an offspring from another breeding population, just as a daughter is the offspring of a parent.
When a (parent) population divides into two different areas they can take on different evolutionary traits to adapt to those areas, and when those populations become isolated from one another we call them daughter populations, even though there are males and females involved.
Speciation seems important. I always thought speciation was two of the same kind (until I get a better grasp of everything I hope you don't mind me using the word kind) but different species reproducing? Like say a sparrow and a robin? Both birds...different species? Is that speciation or does it go deeper than that?
Yes speciation would result in two species in the same clade\kind, the same genus (ie first name same, second name different). Yes sparrows and robins are different species, but a little more distantly related than recent speciation event species would be.
Lets look at how similar the daughter populations can be before speciation occurs:
quote:
The greenish warbler ring species
Greenish warblers (Phylloscopus trochiloides) inhabit forests across much of northern and central Asia. 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. By studying geographic variation in the ring of populations, we can study how speciation has occurred. This unusual situation has been termed a 'circular overlap' or 'ring species'. There are very few known examples of ring species.
Map of Asia showing the six subspecies of the greenish warbler described by Ticehurst in 1938. The crosshatched blue and red area in central Siberia shows the contact zone between viridanus and plumbeitarsus, which do not interbreed. Colors grade together where Ticehurst described gradual morphological change. The gap in northern China is most likely the result of habitat destruction.
Plumage Patterns
West Siberian greenish warblers (P. t. viridanus) and east Siberian greenish warblers (. 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.
Song
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. By measuring song spectrograms from various populations and doing a statistical analysis to illustrate the variation, we produced the following figure.
Here we have five daughter populations of varieties of the Greenish Warbler, Phylloscopus trochiloides, forming a ring around the Tibetan high plateau, with four hybrid zones in between. The hybrid zones mean that the neighboring varietal populations, and the fact that these hybrids do not spread into either neighboring varietal population area means that they are not better adapted there. Thus we have limited gene flow between neighboring daughter varieties, with very very little gene flow between the end varieties.
Where these two end varieties overlap in Siberia they do not see each other as mating material and do not mate: they are reproductively isolated daughter populations. Without the other intermediate daughter varieties we would say that speciation has occurred.
Note that there is just a little bit of difference in plumage and just a little bit of difference in mating songs, but that is enough.
Note that this is a lot less variation than seen in dogs.
Would you call speciation micro or macro? This may already be obvious but some things are gonna go over my head here.
I would say that speciation is the boundary between micro and macro. Before speciation the breeding population shares the gene pool, while after speciation the gene pool is divided into two discrete pools. Once speciation occurs each daughter population then continues to evolve (via microevolution within their breeding population) and they frequently evolve away from each other (because they are isolated or to reduce competition if they interact). As time passes, they will continue to evolve generation by generation, in the manner discussed for arbitrary speciation, and, as the chances of similar mutations occurring being very very small, they become more and more distinct as separate species.
Another element of macroevolution that you will see mentioned is the formation of nested hierarchies. With a speciation event you have a parent population and then two (or more) branches of daughter populations.
                         |
                         ^ a
                        / \
                       /   \
                      /     \
                     /       ^ b
                  c ^       / \
                   / \     /   \
                  d   e   f     g
Here "a" "b" and "c" are speciation events, and they cause the nested pattern seen here. Thus speciation is a critical element of macroevolution, even though the evolutionary process is all microevolution (confused yet?).
Hmmm. Well sure. I mean if it were to happen there is no denying it right? Wouldn't there be a trail leading both to each other?
(For sake of argument I have to bring some things up that I don't yet agree with so don't take it as me believing it now but it will help the conversation go forward)
For instance we would see dog traits in the horse and horse traits in the dog? They look alike from a distance, both run on 4 legs...tails, no tails etc etc. Yeah I could go with it. So why aren't they in the same family you think? Are they that far apart? Even if they are that far apart what is to say to seperate them anyway?
The critter shown is an ancestor to the horse, although from appearances it is very similar to a dog, and their skeletons appear very similar. What we can do is walk through the evolution of the horse from this ancestor, using the variation within dogs as a metric for how much variation is allowable between ancestors along the way.
Thus we can keep within the boundaries of microevolution at each stage to then show the accumulated large scale macroevolution at the end.
We can take it as slow as you want.
Enjoy.

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This message is a reply to:
 Message 290 by Chuck77, posted 02-27-2012 12:36 AM Chuck77 has not replied

  
Percy
Member
Posts: 22604
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.9


Message 298 of 331 (654148)
02-27-2012 8:55 AM
Reply to: Message 290 by Chuck77
02-27-2012 12:36 AM


Re: micro and macro
Chuck77 writes:
Ok. I think I understand. So a wolf for instance passes down herditary traits and maybe 4 generations later a species can look entirely different form the wolf? It's actually a new species. Micro evolution right?
Informally, microevolution is change within a species, while macroevolution is change from one species to another or more.
Each generation is microevolution, a minute amount of change. Over time the tiny changes of microevolution can accumulate into the large and significant changes of macroevolution. The 4 generations you suggest for a wolf to change into a different species is far too small. For a mammal I would think that something in the neighborhood of a thousand generations is the minimum to produce a new species. If it turned out to be 500 or 10,000 I wouldn't be surprised, but definitely nothing near a mere 4 generations can produce a new species. If that were all it took there would be thousands of new species being discovered every year. You wouldn't even be the same species as your great great grandparents, let alone the same species as Jesus.
What do you mean by daughter population? Females in the area?
A daughter population is just a descendant population - it has nothing to do with gender. The original population is the parent population, and the descendant population is the daughter population. I guess we could instead call it a son population, but we don't.
Speciation seems important. I always thought speciation was two of the same kind (until I get a better grasp of everything I hope you don't mind me using the word kind) but different species reproducing? Like say a sparrow and a robin? Both birds...different species? Is that speciation or does it go deeper than that?
It is possible for speciation to happen when two closely related species interbreed, but this is rare. It is also sudden, and most speciation is gradual. The "closely related" part is important. Two species that are closely related and are still to some extent mutually interfertile must have shared a common ancestor species in the not too distant past. Hence, wolves can breed with dogs, asian leopard cats can breed with the domestic house cat, but chipmunks cannot breed with moles.
--Percy

This message is a reply to:
 Message 290 by Chuck77, posted 02-27-2012 12:36 AM Chuck77 has not replied

  
RAZD
Member (Idle past 1481 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 299 of 331 (654150)
02-27-2012 9:26 AM
Reply to: Message 293 by Chuck77
02-27-2012 1:49 AM


Re: kinds and clades
Hi again Chuck77,
So could they actually mate at one time?
Yes and no. At one time in the distant past they shared a common ancestor, a parent population that divided into two daughter populations, one became placental mammals and one became marsupial mammals.
What you are seeing are two modern species that did not exist back then.
Are they are analogous? In contrast to homologous?
ABE: The above statement about analogous and homologous was from searching for "convergent evolution". This is what I found:
Excellent. They have analogous traits, and this is why they appear so similar at first.
Just as the fox and the cat have analogous traits as well as homologous traits ... the homologous traits are those they share because they are both mammals and descended from a common (placental) mammal ancestor, while the analogous traits involve size and body shape that make them seem similar at first, but one has evolved from a canidae ancestor and the other from a felidae ancestor that are less similar.
So they don't have a common origin? The sugar glider and flying squirrel?
They do (according to the fossil record), but it was an ancient mammal or proto-mammal, before they divided into the two daughter branches of mammals.
Yeah, works for me.
                         |
                         ^ a
                        / \
                       /   \
                      /     \
                     /       ^ b
                  c ^       / \
                   / \     /   \
                  d   e   f     g
Here "a" would be the basal type for a "kind" would it not?
So far yeah. It seems it would. B and C would be other species of the "A" kind.
Excellent. We can also say B would be a different genus from C within the "A" family, while D, E, F and G are different species. This is why cladistics works better for me than traditional taxonomy in discussing kinds.
Yes. That sounds good. Clade then would the "kind" I am taking about. What I don't get is when A,B or C of that clade...then jumps, to D,E and F. That's where I get lost. How could they?
How could they genectically? Do you understand what I mean? Like I said to Huntard, i'm trying to find where my point of contention lies.
It's not a big jump, just another step of the same type: both B and C also form a clade for their descendants, D and E from C, F and G from B. D belongs to both the A and the C clade... and this would be similar to dogs, wolves and foxes all being of the same kind\clade as canids.
Yep, sounds good.
Good.
Yeah, it's a big question. I don't know.
Hmm, well a Wolf isn't a dog but is canine. No one would call a bunch of wolves roaming around in the fields a bunch of dogs if they knew they were wolves. So if the Wolf is "A" and a horse was "B" or "C" then sure. What's the difference.
Again, the picture shown is not of an ancestor for the wolf, but it is an ancestor for the horse. What we have here is a fossil ancestor to the horse that appears to be similar to modern dogs/wolves -- we can consider this an example of convergent evolution as the traits that are similar are analogous in their similarity (and homologous in being placental mammal traits).
What we can do is review this critter in comparison to the modern dog\wolf and see if it is more or less different than the variation seen within dogs.
We can take this as slow as you want.
Enjoy.

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by our ability to understand
Rebel American Zen Deist
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This message is a reply to:
 Message 293 by Chuck77, posted 02-27-2012 1:49 AM Chuck77 has not replied

  
RAZD
Member (Idle past 1481 days)
Posts: 20714
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Joined: 03-14-2004


Message 300 of 331 (654154)
02-27-2012 10:04 AM
Reply to: Message 294 by Chuck77
02-27-2012 2:29 AM


Re: moving forward: how much variation constitutes enough change
Hi again Chuck77,
Yes, it probably would now. One thing I would say/ask you RAZD is this: If the fox and cat are closer in changes than some dogs are why are they classified differently? Shouldn't they both be in either the canine or feline clade? Why are they not classified together while dogs who are farther apart in changes are?
The fox and cat are another example of convergent evolution, where branches with more diverse ancestors have offspring that take on similar traits in response to the ecological opportunities and challenges. The traits that make them appear more similar than wolves and tigers are analogous (size, bone length, etc).
                         |
                         ^ a
                        / \
                       /   \
                      /     \
                     /       ^ b
                  c ^       / \
                   / \     /   \
                  d   e   f     g
Ok. i'm confused a little. Why are you putting canine with feline in the same clade? Aren't they a little to close together?I thought we were saying clades (for understanding you better and me grasping it better) was a kind - so to speak. Are you putting feline with canine?
Shouldn't it be "A" wolf "B" dog "C" poddle...and so on down the canine clade? d,e,f,g,h...
Then totally seperate would be "A" lion "B" tiger" "C" cat?
We can do that, but there is also a common ancestor between canidae and felidae in the fossil record.
Where you want to draw your line for kinds is up to you.
Ok I see. I wonder why they are classified differently. Do you know what the bigger difference are within the dogs? Is it much more than +3?
The differences within dogs is defined as 0 so any plus is more different and any minus is less different.
I understand what you're saying. You're saying if I accpet wolf to dog (which has more changes in some than fox to cat) then I should accept fox to cat (different "kinds" tho less changes) who are classified differently?
Accept the possibility of fox to cat-like. Again we are talking about convergent evolution and the development of analogous traits rather than a strict one into the other evolution (which is more of a creationist concept than an evolutionist one).
I understand RAZD. I do and thank you for explaining it to me. I think tho, were moving a little fast. I'm not so sure I agree with the way the taxonomic catagories are set up. Tho i'm not sure it really matters. As crash said it's only to help guide us.
To answer your question about convergent evolution I can't right now. I need to understand more what convergent evolution is. Maybe our (my) definition of kinds ahould be expanded a little more.
We can take it as slow as you want. If you go to the Berkeley page on convergent evolution you will see some additional information:
quote:
Homologies and Analogies
Since a phylogenetic tree is a hypothesis about evolutionary relationships, we want to use characters that are reliable indicators of common ancestry to build that tree. We use homologous characterscharacters in different organisms that are similar because they were inherited from a common ancestor that also had that character. An example of homologous characters is the four limbs of tetrapods. Birds, bats, mice, and crocodiles all have four limbs. Sharks and bony fish do not. The ancestor of tetrapods evolved four limbs, and its descendents have inherited that featureso the presence of four limbs is a homology.
There is more information on that page and subsequent ones.
Do you think this could or did happen? Since one is marsupial and the other placental? So they are related(?) but not classified together? Genetically their very different right?
The fossil record shows they have a common ancestor. They are classified together under mammalia. The genetics are about as different as we are from kangaroos.
How many changes do you think they are away from dog to wolf or fox to cat?
Lots. Many many generations. The common ancestor is back at the original formation of the mammal clade from reptiles, and predates the extinction of the dinosaurs.
ABE(again): RAZD I skipped over this because I didn't understand what your meant:
So you are asking for a larger degree of change than just from one kind to essentially be similar to another, yes?
The development of something that did not exist previously in the fossil record perhaps?
Such as evolving from something like a dog into the modern horse?
What do you mean?
It is common for creationists to ask for evidence of the evolution of something new that did not exist before, and it's a question of degree again, on how much change needs to be shown by the fossil record.
This is going in the opposite direction from convergent evolution.
Again we can take this as slow as you want.
Enjoy.

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)

This message is a reply to:
 Message 294 by Chuck77, posted 02-27-2012 2:29 AM Chuck77 has not replied

  
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