Speciation + Evolution = More Diversity

The scene: sitting at computers all over the world ...

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This little scenario depicts, I believe, the state of many debates between creationists - people that predominantly use faith to understand the world - and "evolutionists" - people that predominantly use science to understand the world.See Evolutionary Theory Explains Diversity, Dogs will be Dogs will be ??? and What i can't understand about evolution.... threads for examples.Where does "large" change come from? - the change that makes giraffes so different from kangaroos? Simple:

• Speciation - the division of parent populations into reproductively isolated daughter populations - is also an observed and documented fact, a process that occurs frequently in the natural world around us, and
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• Evolution - the change in hereditary traits in populations from generation to generation - is an observed and documented fact, a process that occurs constantly in the natural world around us.

Speciation + Evolution = More Diversity
After speciation has occurred, the daughter populations no longer share genes through reproduction, and they are free to evolve completely different traits. The likelyhood is high that one of them will become quite different, either to inhabit a new ecology that the other is not as well suited to (could have caused the original split), or to make use of the existing ecology in a different way, and this will lessen competition between the two species rather than drive one to extinction.Continued evolution of daughter populations along different ecological paths results in increased diversity - difference - between them over time. That is how the small amount of difference we seen below can become the amount of difference we see between other bird species.Greenish warblers

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Continued evolution causes more change - in each population, from generation to generation to generation.That should be enough for starters. There is more to discuss about where change occurs, but this is long enough for now.This thread is about evolution after speciation. Enjoy.Edited by RAZD, : color, subtitleEdited by RAZD, : added block at end

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Hey Coyote, Good question. I think one of the problems is that people tend to think of species as static, that the species after many generations is still similar to the original species just after speciation, thus making them think that the common ancestor for humans and chimps, for instance, is half human and half chimp, part bare, part hairy, something in the act of transforming into one or the other.Thus I want to first discuss two kinds of speciation:(1) arbitrary speciation -- usually in fossil species, where after many generations of fossils there is noticeable difference between the latest fossil and the first one (the "type" fossil for the species), and to distinguish the differences the latest fossil is given a new species designation. This is an arbitrary designation, and there is room for doubt about the actual amount of change being enough for speciation (if reproduction could be ascertained) to be measured.(2) distinct speciation -- either in the fossil record or in existing organism, where speciation has occurred, and you now have two species instead of one: there is no doubt that speciation has occurred.For instance with Pelycodus:

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Pelycodus was a tree-dwelling primate that looked much like a modern lemur. The skull shown is probably 7.5 centimeters long.

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

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

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The dashed lines show the overall trend. The species at the bottom is Pelycodus ralstoni, but at the top we find two species, Notharctus nunienus and Notharctus venticolus. The two species later became even more distinct, and the descendants of nunienus are now labeled as genus Smilodectes instead of genus Notharctus.

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As you look from bottom to top, you will see that each group has some overlap with what came before. There are no major breaks or sudden jumps. And the form of the creatures was changing steadily.

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Color for empHAsis: this is the kind of continuing change we are talking about.Here you have both kinds of speciation shown - a series of arbitrary speciation designations from the bottom up to the divide, and then a distinct speciation event as the population divides into two distinct populations, and these daughter populations continue to diverge after the speciation event.Now one can argue that Pelycodus ralstoni (at the bottom) and Pelycodus jarrovii (just below the divide, the "parent" population), are different species, as their difference is similar in degree to the difference between Notharctus nunienus and Notharctus venticolus just after the divide, and we can argue whether there is sufficient difference for Pelycodus trigonodus to fit in between.Thus the distinction I would like to draw between arbitrary speciation and distinct speciation.It is fairly evident that arbitrary speciation is just evolution - the change in hereditary traits in populations from generation to generation, and it does not include the mechanism of speciation that involves the reproductive isolation of the daughter population from the parent - except by time.Certainly we can see that the hereditary traits of Pelycodus ralstoni and Notharctus venticolus are not similar, because of the difference in size, if nothing else.We should also expect that the hereditary traits of Pelycodus ralstoni and Notharctus nunienus are not similar, in spite of the similarity in size, because of the other traits that have changed in the interim.Enjoy.Edited by RAZD, : colorEdited by RAZD, : fixed glitch in quoteEdited by RAZD, : switched to copied picture

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Hey Coyote, Taz, lets get back to speciation for now to set the benchmarks of this discussion.As we see from the Pelycodus example, arbitrary speciation is just the acknowledgment of continuing evolution within the Pelycodus form, and that after some arbitrary level of change has occurred it is convenient to talk about a new species.I bring this point up because many fossil species are divided this way, and it helps to have a clear understanding of what this means.As each population advances from generation to generation it gains some new hereditary traits and loses some old ones: there is a succession of traits in the populations.When the older traits are lost from the population they are "extinct" so we can see that in arbitrary speciation the traits that define the "type fossil" for that species gradually are replaced by new traits in the population, until the old traits no longer exist within the population. Every time this occurs then, a step has been taken that differentiates this species from the one that existed at the speciation event that defined this branch of evolution.At that distinct speciation event the difference was minor - this is what evolution predicts - on the order of the Greenish Warblers in Message 1: Each arbitrary speciation stage add more change to the branch where it occurs, as seen in Pelycodus in Message 4: In Message 1 I said:

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After speciation has occurred, the daughter populations no longer share genes through reproduction, and they are free to evolve completely different traits. The likelyhood is high that one of them will become quite different, either to inhabit a new ecology that the other is not as well suited to (could have caused the original split), or to make use of the existing ecology in a different way, and this will lessen competition between the two species rather than drive one to extinction.

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And we can see this in Pelycodus, where one branch continues with increase in size at the same rate of evolution change as before, but the other branch diverges at a faster rate in the other direction. If it can get sufficient distance ecologically from the other then both can survive. If they can't then either they will be reunited or one will go extinct.This apparently has also happened in the Pelycodus lineage according to this presentation:

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Successive fossils in the Pelycodus fossil record show the gradual evolution of increased size, which can be recognized as a series of species. The coexistence of two simultaneous size trends indicates a speciation event.

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Where the gray branches show distinct speciation events where one branch went extinct.Enjoy.Edited by RAZD, : switched to copied pictures

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Welcome to the fray, westernjoe,Let me start with some posting tips: That is one (incomplete) version of one of the common definitions of evolution: it means the same thing -- you do not get change in hereditary traits without a change in the frequency of alleles. You do not get changing allele frequency with out change in hereditary traits.You are missing population, and that the relevant time period is from generation to generation. Your definition also cannot be applied to fossils or to observations in the wild where DNA samples are not taken.I'll also be happy to discuss this further with you, in relation to the definitions offered by two universities teaching evolution, and reference back to Darwin, but that is the subject for another thread. Perhaps you would like to discuss this at the Definition of Evolution thread? I'll copy your definition there and then comment on it okay? See Message 193Not really: the change is introduced by mutation, and this is random, but whether it is incorporated into the population is a matter of selection. Selection does not cause mutations, the two processes are independent. Now that you have proven that your straw man is false, perhaps we can talk about evolution. Having been observed and documented to occur, even by creationists, your statement is obviously false. Please participate in What i can't understand about evolution...., and once you have disabused yourself of your false opinions perhaps we can take up this topic about how continued evolution after speciation increases the difference between the daughter populations.re your Message 9: Feel free to participate in the Dogs will be Dogs will be ??? thread ... as long as you stay on topic and address the issues.Better yet, go to this new thread The Spirit Dog hypothesis? to discuss your concept. Curiously your opinion does not make the evidence disappear, nor does it affect the natural behavior - the evolution and speciation - that is going on around us. Denial of reality is not an alternative explanation, it is just denial.Now if you have any comments on this thread that apply to increased difference from generation to generation as daughter population inevitably acquire random mutations, and then select the most effective of the random mutations available at any one time by their adaptation to different ecologies, I suggest you take your opinions to another thread.Enjoy.Edited by RAZD, : added link to new threadEdited by RAZD, : added linkEdited by RAZD, : color 1st time

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If he cannot keep it to a discussion of the increasing difference between sibling species after speciation then it the discussion does not belong here.I've started a new thread for his spirit dog hypothesis - is it native american religion based? The Spirit Dog hypothesis?Feel free to comment thereEdited by RAZD, : clartyEdited by RAZD, : new thread linkEdited by RAZD, : subt

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Hi westernjoe, my reply is here: Message 193Also I would be interested to see you follow up on the spirit dog issue at The Spirit Dog hypothesis?, thanks.Enjoy.Edited by RAZD, : added linkEdited by RAZD, : addedEdited by RAZD, : color the second timeEdited by RAZD, : hideEdited by RAZD, : youme

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hi westernjoe, my reply is here: Message 193Enjoy.Edited by RAZD, : grow a clue eh?Edited by RAZD, : highlighted the THIRD timeEdited by RAZD, : ...Edited by RAZD, : No reason given.Edited by RAZD, : hideEdited by RAZD, : youme

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westernjoe my reply is here: Message 193Edited by RAZD, : hideEdited by RAZD, : youme

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well westernjoe, another diversion off-topic? my reply is here: Message 21Enjoy.Edited by RAZD, : hide

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well westernjoe, I expect to see you suspended soon. What is hilarious about all this petty posturing of yours, is that it is a completely ridiculous position when you look at the FACT that your posts have been quoted and replied to, and all your need to do is go to the appropriate threads, that the only thing keeping you from the discussion is your inability to realize this.Once again, my reply is here: Message 193Enjoy.Edited by RAZD, : hide

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westernjoe your reply is here (put your cursor over these words and right click to activate this link)Enjoy.Edited by RAZD, : ..

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westernjoe, your reply is here (put your cursor over these words and right click to activate this link)Enjoy.

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hey Rahvin, A troll doesn't cite evolution textbooks, I think he just doesn't understand (1) how many different threads there are on this site, (2) that these topics have already been discussed before, (3) that a thread dedicated to the Definition of Evolution is a better thread to discuss Definition of Evolution than any one he currently happens to be on, (4) that a thread dedicated to the Definition of Species is a better thread to discuss Definition of Species than any one he currently happens to be on, (5) that threads are limited to ~300 posts, so content that is not part of the thread debate wastes space, and (6) that I am more than ready and willing to debate him on these points on their proper threads, and have in fact already started there.Plus, I would like to see more about his spirit dog concept.Enjoy.

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hey Huntard, Most definitely ... on the appropriate threads:

Definition of Evolution

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Definition of Species

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And then, once the definitions have been resolved, perhaps we can continue with the question of continued evolution after speciation.

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We can discuss different rates of evolution, and the effect of ecology on those rates.

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From evidence such as the foraminifera we do see different rates of evolution at different times and for different reasons:

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article 8

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We can see that speciation is not a "one-shot wonder" but a repeated process that allows species to take fuller advantage of the available ecosystems. This shows in the response to the K-T extinction event:

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One of the last great extinctions occurred roughly 66 million years ago and, according to one popular theory, it resulted from Earth's receiving a direct hit from a large asteroid. Whatever the cause, the event proved to be the dinosaurs' coup de grace, and so wiped out a good portion of the marine life--including almost all species of planktonic forams.

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This period of massive death, which ended the Cretaceous Period, ushered in the modern chapter of biological development. Earth entered the new era, the Cenozoic, with a wide range of ecosystems virtually deviod of life (and thus competition between species), yet quite fertile and primed for repopulation.

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The ancient record of foram evolution reveals that the story of recovery after extinction is indeed busy and colorful. "What we've found suggests that the rate of speciation increases dramatically in a biological vacuum," says Parker. "After the Cretaceous extinction, the few surviving foram species rapidly evolved into new species, and for the first time we're able to see just how this happens, and how fast."

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As the available niches fill up with these new creatures, the speciation rates slow down, and the pressure from competition between species appears to bear down in earnest. The extinction rate then rises accordingly. This scenario, says Arnold, suggests that the speciation process is sensitive to how fully packed the biosphere is with other species, not the number of individuals. Ecologists, in referring to a given environment's ability to sustain life as its carrying capacity, generally mean the natural limit, in shear numbers, of individual organisms that any environment can support, as opposed to the number of different kinds of organisms or species. "This is an intriguing concept--a species carrying capacity, so to speak," says Arnold. "This implies that the speciation process is sensitive to how many spesies are already out there."

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Actually, I think this is the same response, each species reaches their carrying capacity for the particular ecology, branching into neighboring ecologies and speciating as necessary to fill that ecology. It's an opportunistic response: the more opportunity there is the more evolution will likely take advantage of it as individual organisms try to survive and reproduce.

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We can also see different rates of evolution in the aftermath of speciation for Pelycodus, as they evolve to reduce competition between the two daughter populations:

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

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When two similar species compete, it is not uncommon that one fairly quickly becomes different - in this case, smaller. This presumably reduces the competition between the species.

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The rate of evolution from Pelycodus jarrovii to Notharctus nunienus is faster than the overall rate of evolution from Pelycodus ralstoni to Notharctus venticolus (although one could argue that it varies around this overall trend with fast and slow periods).

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The difference in size would also result in the smaller Notharctus nunienus being able to take better advantage of feeding higher in the trees, while the larger Notharctus venticolus was able to take better advantage of feeding on the ground, thus resulting in different ecologies even if they inhabited the same geological area.

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Certainly this simple graph shows that they indeed diverged further after speciation. What would be interesting would be to follow each branch further.

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Enjoy.

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Edited by RAZD, : switched to copied pictures

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Hi Coyote, sorry about the snafu on the great debate thread. I would answer this with the evidence that invalidates the possibility of any such barrier, as I did on the great debate thread when seekingfirstthekingdom raised the issue of "genetic boundaries"From Message 33

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... the fossil record points to kinds staying within genetic boundaries instituted by our creator in genesis.

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The problem I have with this claim is convergent evolution. Consider these fellas:

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Berkeley - evolution 101:

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However, these animals also have some key differences:

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Sugar gliders live in Australia, and flying squirrels live in North America.

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Sugar gliders have a pouch (like a kangaroo does), which provides shelter and safety for their tiny babies - at birth, a baby sugar glider is smaller than a peanut! Flying squirrels, on the other hand, have much larger babies and no pouch.

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By studying their genes and other traits, biologists have figured out that sugar gliders and flying squirrels are probably not very closely related. Sugar gliders are marsupial mammals and flying squirrels are placental mammals.

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From this (and many other examples) I would conclude that there is no barrier that prevents a marsupial from evolving to be virtually identical in behavior, size, appearance, etc, to a placental mammal.

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When you look at the fossil record the ancestors of these animals are less similar than these two, so they have been evolving separately to be similar towards a common end.

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The alternative is that all mammals back to the first mammal are one "kind" - thus including not only duckbilled platypus, kangaroos, koala bears and echidna, but elephants, whales, giraffes, and mole rats ... to say nothing of humans.

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Another example of convergent evolution that extends even further into the dark ages of life on earth is the killer whale and the white shark:

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KILLER WHALE
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia

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The Orca or Killer Whale (Orcinus orca), less commonly, Blackfish or Seawolf, is the largest species of the dolphin family. It is found in all the world's oceans, from the frigid Arctic and Antarctic regions to warm, tropical seas.

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Orca are versatile and opportunistic predators. Some populations feed mostly on fish, and other populations hunt marine mammals, including sea lions, seals, walruses and even large whales. They are considered the apex predator of the marine world.

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Great white shark - Wikipedia

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WHITE SHARK
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes

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The great white shark, also known as white pointer, white shark, or white death, is an exceptionally large lamniform shark found in coastal surface waters in all major oceans. Reaching lengths of more than 6 m (20 ft) and weighing up to 2,250 kg (5,000 lb), the great white shark is arguably the world's largest known predatory fish. It is the only surviving species of its genus, Carcharodon.

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(except that a shark is not a "true" fish ...)It appears there is no "genetic barrier" that prevents mammal evolution from becoming similar to sharks, which are from an ancient order: Cartilaginous fish diverged from the branch that mammals are on over 450 million years ago, and pre-date "true fish" ... that's a lot for one "kind" eh? This puts true fish, amphibians, birds and mammals together with Cartilaginous Fish into one "Kind" ...Enjoy.Edited by RAZD, : one kind wordEdited by RAZD, : ...Edited by RAZD, : ” to -

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