# “Junk DNA” No More: Repetitive Elements as Vital Sources of Flatworm Variation

**URL:** <https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352>\
**Category:** Conversation\
**Tags:** Science\
**Created:** [October 7, 2021, 1:15pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352 "2021-10-07T13:15:30Z")\
**Posts on this page:** 20\
**Page:** 2

<div class="post-metadata">

**Author:** ![scd](https://avatars.discourse-cdn.com/v4/letter/s/6f9a4e/32.png) [@scd](https://discourse.peacefulscience.org/u/scd)\
**Post date:** [October 11, 2021, 3:48pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/21 "2021-10-11T15:48:51Z")

</div>

> [@Rumraket](#):
>
> None of that addresses the Onion test.

yes it is. maybe in the case of the onion this is indeed “junk”. which is irrelevant to the junk claim in general. this is why we should take a look at the rule and no at the exceptions.

> [@John\_Harshman](#):
>
> That’s the dog’s ass plot, and the choice of genomes is oddly biased.

we are talking about 73 different species here. do you have a better reference which checked for more species and found no such correlation?

---

<div class="post-metadata">

**Author:** ![John\_Harshman](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/john_harshman/32/1121_2.png) [@John\_Harshman](https://discourse.peacefulscience.org/u/John_Harshman)\
**Post date:** [October 11, 2021, 4:27pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/22 "2021-10-11T16:27:32Z")

</div>

> [@scd](#):
>
> do you have a better reference which chekced for more species and found no such correlation?

Have you ever heard of the c-value paradox? Have you ever seen a genome size database? [Here’s one for animals.](https://www.genomesize.com)

Look at this figure. Do you see the same pattern as in the figure you showed?  
 ![Summary figure of C-Values from Gregory 2004a](https://us1.discourse-cdn.com/flex016/uploads/peacefulscience/original/2X/7/7205fcfd75bb373cbbe9906fa0fbcffd8e7e6622.jpeg)

---

<div class="post-metadata">

**Author:** ![scd](https://avatars.discourse-cdn.com/v4/letter/s/6f9a4e/32.png) [@scd](https://discourse.peacefulscience.org/u/scd)\
**Post date:** [October 11, 2021, 4:45pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/23 "2021-10-11T16:45:42Z")

</div>

> [@John\_Harshman](#):
>
> Look at this figure. Do you see the same pattern as in the figure you showed?

the problem with that fig is that it doesnt show the organism complexity (In terms of the number of different cell types). thus its irrelevant to the argument.

---

<div class="post-metadata">

**Author:** ![Rumraket](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/rumraket/32/9328_2.png) [@Rumraket](https://discourse.peacefulscience.org/u/Rumraket)\
**Post date:** [October 11, 2021, 4:59pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/24 "2021-10-11T16:59:46Z")

</div>

> [@scd](#):
>
> maybe in the case of the onion this is indeed “junk”.

As I said, handwaving. There’s multiple species of onion. One species has five times more DNA than another. Which one is the one without junk?

> [@scd](#):
>
> which is irrelevant to the junk claim in general. this is why we should take a look at the rule and no at the exceptions.

We should look at both, and you’ve done no work to show that any species is an exception. John Mattick’s article is noteworthy for the many species with genomes larger than humans it seems to leave out. Simply the fact that humans are among the top3 species with the largest genomes in his article makes it immediately obvious that it’s trash. By now many dozens of species with much larger genomes are known. You also have to wonder just how rigorously the “numer of distinct cell types” have been established, and what exactly is supposed to count as “distinct”.

> [@scd](#):
>
> we are talking about 73 different species here.

Since they’re clearly cherrypicked, and there’s something like ~10 million extant species on Earth, how am I supposed to find that number of _any_ signifiance?

---

<div class="post-metadata">

**Author:** ![Art](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/art/32/3805_2.png) [@Art](https://discourse.peacefulscience.org/u/Art)\
**Post date:** [October 11, 2021, 5:30pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/25 "2021-10-11T17:30:12Z")

</div>

> [@scd](#):
>
> the problem with that fig is that it doesnt show the organism complexity (In terms of the number of different cell types). thus its irrelevant to the argument.

@scd, with this statement and the figure posted by @John_Harshman, you seem to be proposing that protozoans have many more cell types than mammals. That’s an interesting claim - do you have any evidence or citations to support this?

Just wondering.

---

<div class="post-metadata">

**Author:** ![John\_Harshman](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/john_harshman/32/1121_2.png) [@John\_Harshman](https://discourse.peacefulscience.org/u/John_Harshman)\
**Post date:** [October 11, 2021, 6:58pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/26 "2021-10-11T18:58:51Z")

</div>

I find that the Cape golden-mole (the mammal with the largest genome) has a genome twice the size of yours. Do you draw any conclusions from that?

---

<div class="post-metadata">

**Author:** ![John\_Harshman](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/john_harshman/32/1121_2.png) [@John\_Harshman](https://discourse.peacefulscience.org/u/John_Harshman)\
**Post date:** [October 11, 2021, 6:58pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/27 "2021-10-11T18:58:57Z")

</div>

> [@scd](#):
>
> the problem with that fig is that it doesnt show the organism complexity (In terms of the number of different cell types)

However, from bottom to top it’s more or less arranged in Mattick’s order of organismal complexity. So why does no pattern emerge from the larger genomic sample? You seem to prefer data cherry-picked in order to fit a preconceived notion to the great mass of data actually available. Why?

---

<div class="post-metadata">

**Author:** ![CrisprCAS9](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/crisprcas9/32/9145_2.png) [@CrisprCAS9](https://discourse.peacefulscience.org/u/CrisprCAS9)\
**Post date:** [October 11, 2021, 6:59pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/28 "2021-10-11T18:59:30Z")

</div>

> [@scd](#):
>
> the problem with that fig is that it doesnt show the organism complexity (In terms of the number of different cell types).

Do all 655 species of salamander have more cell types than all mammals 6500 species of mammal?

Do frogs have a range of cell type inventory ranging from the same as agnathans to just short of salamanders?

Do most fish really have the same number of cell types as most rotifers?

Do birds really have fewer cell types than pine trees?

And most importantly, how many cell types do the single celled algae and protists have?!

---

<div class="post-metadata">

**Author:** ![Joe\_Felsenstein](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/joe_felsenstein/32/8176_2.png) [@Joe\_Felsenstein](https://discourse.peacefulscience.org/u/Joe_Felsenstein)\
**Post date:** [October 11, 2021, 8:25pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/29 "2021-10-11T20:25:55Z")

</div>

We may discount the arguments of all of us here, because we are humans, while salamanders and lungfish are much better equipped to comment.

---

<div class="post-metadata">

**Author:** ![dsterncardinale](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/dsterncardinale/32/9144_2.png) [@dsterncardinale](https://discourse.peacefulscience.org/u/dsterncardinale)\
**Post date:** [October 11, 2021, 8:41pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/30 "2021-10-11T20:41:46Z")

</div>

> [@scd](#):
>
> the problem with that fig is that it doesnt show the organism complexity (In terms of the number of different cell types). thus its irrelevant to the argument.

Uh…do we need to do that to make the point when “protozoa” are the largest? Unicellular. Number of cell types: 1. Largest genomes.

---

<div class="post-metadata">

**Author:** ![scd](https://avatars.discourse-cdn.com/v4/letter/s/6f9a4e/32.png) [@scd](https://discourse.peacefulscience.org/u/scd)\
**Post date:** [October 12, 2021, 1:34pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/31 "2021-10-12T13:34:18Z")

</div>

> [@Rumraket](#):
>
> As I said, handwaving. There’s multiple species of onion. One species has five times more DNA than another. Which one is the one without junk?

myabe all of them have junk. hard to tell without aditional data.

> [@Rumraket](#):
>
> Simply the fact that humans are among the top3 species with the largest genomes in his article makes it immediately obvious that it’s trash

why? if we see a correlation below the human genome size, we still have a good correlation between genome size and complexity. if we dont see it above that size, maybe in these cases the majoriyy of the genome is indeed junk in those specific cases. the argument still hold water even in that case.

> [@Rumraket](#):
>
> Since they’re clearly cherrypicked, and there’s something like ~10 million extant species on Earth, how am I supposed to find that number of _any_ signifiance?

all we need is a random bunch of species to get a good estimation. and i think that this is what they did. otherwise we should reject any scientific paper(if they indeed pick up specific cases and ignore the rule).

> [@Art](#):
>
> you seem to be proposing that protozoans have many more cell types than mammals. That’s an interesting claim - do you have any evidence or citations to support this?

i actually said that we should look at the rule. protozoans case is probably the exception.

> [@John\_Harshman](#):
>
> I find that the Cape golden-mole (the mammal with the largest genome) has a genome twice the size of yours. Do you draw any conclusions from that?

see above.

> [@John\_Harshman](#):
>
> However, from bottom to top it’s more or less arranged in Mattick’s order of organismal complexity.

i think its irrelevant without checking the number of cell types.

> [@CrisprCAS9](#):
>
> And most importantly, how many cell types do the single celled algae and protists have?!

> [@dsterncardinale](#):
>
> Uh…do we need to do that to make the point when “protozoa” are the largest? Unicellular. Number of cell types: 1. Largest genomes

see above.

---

<div class="post-metadata">

**Author:** ![Mercer](https://avatars.discourse-cdn.com/v4/letter/m/e274bd/32.png) [@Mercer](https://discourse.peacefulscience.org/u/Mercer)\
**Post date:** [October 12, 2021, 3:36pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/32 "2021-10-12T15:36:51Z")

</div>

> [@scd](#):
>
> i actually said that we should look at the rule. protozoans case is probably the exception.

There are so many exceptions that there is no rule.

---

<div class="post-metadata">

**Author:** ![John\_Harshman](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/john_harshman/32/1121_2.png) [@John\_Harshman](https://discourse.peacefulscience.org/u/John_Harshman)\
**Post date:** [October 12, 2021, 3:39pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/33 "2021-10-12T15:39:41Z")

</div>

Special pleading, all. No, the genomes in that study were not chosen at random. They were chosen to fit a hypothesis. (A more charitable interpretation is that Mattick picked from sequenced genomes, which tended at that time to be of two sorts: unusually small ones, like fugu and _Arabidopsis_, and close relatives of humans. No wonder we’re at the top.) If you look at the size distributions of all genomes, as in the graph I showed you, the pattern disappears. If you consider protists an exception, aren’t there more exceptions than otherwise? Nor did Mattick actually graph cell types. They’re just painted onto the graph with any real correspondence to most of the data points. You see what you want to see and ignore what you don’t.

---

<div class="post-metadata">

**Author:** ![RonSewell](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/ronsewell/32/6194_2.png) [@RonSewell](https://discourse.peacefulscience.org/u/RonSewell)\
**Post date:** [October 12, 2021, 3:42pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/34 "2021-10-12T15:42:08Z")

</div>

In any event, you cannot maintain that certain DNA isn’t junk because it has a role in evolution and speciation, and then take that as an argument against evolution and speciation.

---

<div class="post-metadata">

**Author:** ![Dan\_Eastwood](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/dan_eastwood/32/2368_2.png) [@Dan\_Eastwood](https://discourse.peacefulscience.org/u/Dan_Eastwood)\
**Post date:** [October 12, 2021, 3:43pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/35 "2021-10-12T15:43:54Z")

</div>

There’s probably going to be a thread split soon at this point. Please adjust your replies accordingly.

---

<div class="post-metadata">

**Author:** ![John\_Harshman](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/john_harshman/32/1121_2.png) [@John\_Harshman](https://discourse.peacefulscience.org/u/John_Harshman)\
**Post date:** [October 12, 2021, 4:21pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/36 "2021-10-12T16:21:45Z")

</div>

I have no clear idea what that meant. How ill it split? How should one adjust?

---

<div class="post-metadata">

**Author:** ![Dan\_Eastwood](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/dan_eastwood/32/2368_2.png) [@Dan\_Eastwood](https://discourse.peacefulscience.org/u/Dan_Eastwood)\
**Post date:** [October 12, 2021, 4:29pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/37 "2021-10-12T16:29:16Z")

</div>

By splitting comments into two replies; one to which no one could object, and another that might need to be split out. I’m referring to following comments, not past ones. Writing this now because I can see into the future (or at least the approve queue).

---

<div class="post-metadata">

**Author:** ![Roy](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/roy/32/3799_2.png) [@Roy](https://discourse.peacefulscience.org/u/Roy)\
**Post date:** [October 12, 2021, 4:41pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/38 "2021-10-12T16:41:48Z")

</div>

> [@scd](#):
>
> > [@Rumraket](#):
> >
> > Since they’re clearly cherrypicked, and there’s something like ~10 million extant species on Earth, how am I supposed to find that number of _any_ signifiance?
> 
> all we need is a random bunch of species to get a good estimation. and i think that this is what they did. otherwise we should reject any scientific paper(if they indeed pick up specific cases and ignore the rule).

If you think they chose a random bunch of species, then you are a gullible rube.

The rest of us are already rejecting that paper for picking up specific cases.

---

<div class="post-metadata">

**Author:** ![Roy](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/roy/32/3799_2.png) [@Roy](https://discourse.peacefulscience.org/u/Roy)\
**Post date:** [October 12, 2021, 4:41pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/39 "2021-10-12T16:41:53Z")

</div>

> [@scd](#):
>
> > [@Rumraket](#):
> >
> > Simply the fact that humans are among the top3 species with the largest genomes in his article makes it immediately obvious that it’s trash
> 
> why? if we see a correlation below the human genome size, …

There is no correlation below the human genome size.

> [@](#):
>
> … we still have a good correlation between genome size and complexity. if we dont see it above that size, maybe in these cases the majoriyy of the genome is indeed junk in those specific cases. the argument still hold water even in that case.

If we don’t see a correlation above a certain size, then **there is no correlation.**

---

<div class="post-metadata">

**Author:** ![Roy](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.peacefulscience.org/roy/32/3799_2.png) [@Roy](https://discourse.peacefulscience.org/u/Roy)\
**Post date:** [October 12, 2021, 4:41pm UTC](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352/40 "2021-10-12T16:41:57Z")

</div>

doin’ it now…

[Previous page](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352.md?page=1)

[Next page](https://discourse.peacefulscience.org/t/junk-dna-no-more-repetitive-elements-as-vital-sources-of-flatworm-variation/14352.md?page=3)