Cladistics Part 2: Monophyly, Paraphyly, and Polyphyly
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- Опубліковано 23 лис 2021
- Now that we know how to construct cladograms, we have to learn some new terminology. These are the terms monophyly, paraphyly, and polyphyly, and they help us distinguish between any old taxon and true clades. Let's learn more about cladistics now!
Script by Ryan Helcoski
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0:39 I like to think of it more like... Taxons are an early attempt at describing and categorizing life, that was limited in scope. Clades on the other hand are recursive, they allow for a theoretically infinite number of nested clades, and a theoretically infinitely-fine-grained description of evolutionary history. Where there can't be a kingdom within a phylum, a clade can always be nested within another clade.
And that recursiveness better reflects how life works, the processes don't fundamentally change over time, it's always the same mechanisms, just as the same mechanism dictates how the animal kingdom arises and how the mammal (...order?) arises. They're the same sort of thing, they're all clades, all the way down.
The Law of Monophyly states that you can never grow out of your Ancestry, meaning that once an organism belongs to a clade, it always remains within that clade (& the specific criteria for that clade will always describe them).
Humans are *Eukaryotes:* Organisms with cellular *DNA* contained within a *Nucleus* protected by a *Nuclear Envelope.* This characteristic evolved way back when our ancestors were still single-celled microbes (during the Proterozoic Eon, approximately 2.1 - 1.6 Billion years ago), but despite since having evolved into much more complex, multi-cellular lifeforms, we are still members of the Eukaryote Clade & always will be.
~⊚~
Anyone interested in Biology (especially Evolutionary Biology & Cladistics), I highly recommend that you watch *AronRa's* (Paleontologist) brilliant UA-cam Series:
*_The Systematic Classification of Life._*
Over the series, he follows through most of the *50+ Clades* in the Human / Homo Sapiens lineage (plus discussing the evolution of several other clades) all the way from the beginning (or as close as we can currently get) through to modern day. It's profoundly fascinating & utterly addicting. ; )
[ ua-cam.com/play/PLXJ4dsU0oGMLnubJLPuw0dzD0AvAHAotW.html ]
comment for the algorithm!
same
Dave your english motivates me
Nice informative explanation. Thanks for this 👍
Mr. Dave, I really enjoy your content. If more of these videos reached more fanatical "anti-evo/creation/flat-earth" believers maybe society could break through the "I need to believe to exsist" population. Good job and keep the educational content coming. I know what is but I am willing to change my view when new evidence arises. I just wish humans would realize that we can't survive if we can't see what's really true. Save the other animals on this planet is what I "believe"
very helpful explanation, thanks so much
Thank you jesus.
Mono-, para- and polyphyly is a confusing area in cladistic.
Hallo Dr. Dave, can we dive deeper into the point "basal/primitiv and modern" characteristic?
Great work, Professor Dave! Looking forward to the next installment when you start in on whole Kingdoms! Kent Hovind must be going nuts right about now since this series blows a huge hole in his creationist battleship. Maybe you can demonstrate for him using a cladogram how horses descended from a rock (j/k)!
Kunt will just ignore it, blatant lies make him way to much money for him to ever change his script.. aron ra done a whole series debunking kunts lies in the textbooks series but i think you've already seen it, your name looks familiar
thank you chemistry jesus 🙏🙏
Bruhhhh I’m learning this for my finals. You explained it in seconds . Amazing
Great video. Thanks!
Thank you sir. So concise
Hey Dave, big fan here. I am not very into the biology videos but just giving a "like" and "view". I know it has to be hard to make all these videos and I enjoy most of them.
Wow, Professor Dave's show is really advanced. That is why I haven't seen a lot of it. A lot is beyond me.
Everything I learned about classification in the 1960s & 70s has been thrown out the window. I first realized this when I was 'corrected' several times by people much younger than me, who learned within the new system. It's weird for a former honors biology student to feel archaic. The obsolete man, so to speak.
@Sage I'm so glad nobody ever subjected me to creationism in school.
Check out aron ra the systematic classification of life.. it's well worth it.. in my opinion it's the best series on UA-cam (sorry professor Dave), I've seen it at least half a dozen times already and i intend watching it again at least a few more times.. it's about 50 10 minute videos and it's easy to understand in little bite size pieces
Thank you!
With the help of cladistics we get different branches of species characters of common ancestry something that are similar but their phylum were different, yah!
Amen to that Chemistry Jesus
Thank you Professor! ^.^
Ur so helpful
I have been in so many arguments about the term reptile not being monophyletic that it beggars the imagination.
*Edit to clarify that I know the term is not monophyletic, but several others apparently don't.
Thanks professor
I searched “chemistry Jesus” on UA-cam and it took me here
same
Thank you professor Jesus, we love you
I like to move it move it!
I assume you've contained this discussion to the animal kingdom, excluding other basal life forms such as plants, fungi, bacteria etc. for simplicity? As such it seems some may misinterpret cladistics to apply only to animals. Please correct me if I'm missing something. Otherwise, I found excellent value in the discussion.
Plants are covered in the botany series, fungi in the mycology series, and bacteria in the microbiology series. This is the zoology series.
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Is there a part 3?
Thank you chemistry Jesus
Monophyly? More like "My, these videos are regarded highly!" Thanks again for making and sharing so much exceptional academic content.
Can you explain about psudoscirncr of Ayurveda
Is there a fundamental difference between paraphyly and polyphyly, or is it just semantics? Because I believe you _could_ construct any paraphyletic group out of a complex arrangement of polyphyla, and you could describe a polyphyletic grouping as a very exclusive paraphyletic grouping
I suppose a good way to separate them, without watching the video in case this is already answered, would be "what is easier to describe", between "a monophyletic group PLUS some other monophyletic group" (polyphyly) and "a monophyletic group MINUS some monophyletic subset of (the logical extension of) that group" (paraphyly)
Mmm, whether or not a non-monophyletic group includes the most recent common ancestor of all included organisms is a good diagnostic trait distinguishing between paraphyly (includes MRCA) and polyphyly (does not include MRCA)
Hi
I do this for the meme:
Thank you Chemistry Jesus
Mudah di pahami semoga hari mu menyenangkan
Thankyou cladistic Jesus
re: calling organisms basal and not primitive- is it justifiable to say that something is indeed less evolved, if it has changed very little since the divergence? it's a strange thought because something could just as easily change to become simpler. but still, it has "evolved more"
I just saw on Instagram a post about you, a screenshot of a comment when someone called you "chemistry Jesus" . He cannot be less wrong
If sponges and humans have both been involving for the same time, why are humans so much more complex?
The worm in mollusca looks sus.
Thank you teaching jesus
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Lots of great things in this video but I have one nit pick. Historically, I think, the term basal was used to refer to fossil taxa found in older rocks. As you mention, it's since been used to refer to living taxa that are less nested within a phylogenetically hierarchy for avoiding the misleading phrase primitive. However, the phrase basal has now simply become a synonym for "primitive" with all the same baggage. The fact that most people would never refer to Mammalia as the most basal clade of Amniota is evidence of this phenomenon. Their (false) anthropocentric perception of Mammalia as the most advanced amniotes stops them from doing it. "Least nested" is a better phrase because it refers to the shape of the tree in question.
Primitive
1. Of or pertaining to the beginning or origin, or to early
times; original; primordial; primeval; first.
2. Of or pertaining to a former time; old-fashioned;
characterized by simplicity.
3. Original; primary; radical; not derived.
@@DS127 you seem to have missed the point.
@@QT5656 Primitive isn't misleading. It has a technical definition that's the antonym of derived.
@@DS127 You *have* missed the point. Primitive is indeed misleading in the context of this video which is discussing taxa in the context of trees and cladograms. As Professor Dave explains at 4:40. ALL animals alive today have been evolving for the same length of time. There are no living animals that represent ancestors. Therefore, it is misleading to refer to any living (extant) taxa as more primitive than another. Individual anatomical traits may be described as primitive relative to other traits and it is possible that some taxa have more traits inferred to be primitive that others. However, *all* living animals are a mixture of primitive and derived anatomical traits. Referring to living taxon as primitive is misleading and leads to circular reasoning when evaluating their anatomical traits: that all or most of their traits are primitive. There are many examples when such assumptions were made and further research showed that these assumptions were incorrect.
@@QT5656 You are correct. I misread you. I blame lack of sleep, skimming your comment, and carelessness. I was talking about possible meanings of the word itself. One could argue that referring to living taxa as basal/primitive is not just misleading, but self contradictory.
I don’t understand how these are important to learn? Like sure maybe it’s important to know the names but I don’t understand why we would only look at some of them on the cladogram and call them polophyly
I get a lot of flack when I call for the inclusion of paraphyletic grades, like Reptiles. Reptiles have so much in common and birds are such a departure from common reptile traits that it makes sense to see them as two distinct classes, but alas, the cladists have taken over the narrative. Of course, polyphyletic groups can never be taxa, lacking a close common ancestor.
@Sage Related means they share a common ancestor and have similar features, but also that they are distinct in some ways as well. The concept of clades tells us that they share a common ancestor with each other that the don't share with any outgroup. The concept of grades tells us that birds have lost certain reptilian traits found in snakes, lizards, turtles and crocodiles and gained special avian traits like wings, beaks and feathers. I guess the trend now is to just include birds as another order of Reptiles rather than having their own status as a class. I can live with that.
Evolution involves both ancestral traits shared by closely related clades and derived traits that are found in descendants. That makes different taxa similar in some ways but different in other ways. It seems to me that clades emphasize common ancestry while evolutionary grades focus on derived traits. Regardless of how we classify organisms, I like to look at both of these views.
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Came here from a meme ,now studying for the test tomorrow 🥲💀.
How'd your test go?
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