World’s oldest tree? Genetic analysis traces evolution of iconic Pando forest | Hacker News Reader

World’s oldest tree? Genetic analysis traces evolution of iconic Pando forest

nature.com

119 pointspseudolus57 comments

If you're ever in central Utah you should make the trip to see Pando, it grows beside Fish Lake which is teeming with life, and surrounded by beautiful hills and mountains that make for great campsite views. The lake is full of landlocked kokanee salmon that never see an ocean in their lifetime.

Have you camped there?

I have twice, it's great. Highly recommend.

Must be a special spot!

i was once on a solo road trip. I took a turn by chance and ended up near this lake and saw the Pando being talked about here. Talk about coincidence!

Some lakes like these have populations maintained by stocking.

https://theonion.com/wildlife-officials-restock-lake-by-drop...

Nature, uhh, finds a way.

TIL Pando is not just an especially large quaking aspen, but rather a triploid mutant that can reproduce only asexually.

I once spoke with fish biologist about goldfish (or was it carasius? I don't remember), they reproduce via gynogenesis, it's like pathogenesis but they need some trigger like other fish spawning, and I said surely there must be some hidden pond in some misty mountains in China where there are still male goldfish. I asked him if he believe such hidden pond could exist somewhere and he said no and mumbled something about triploids. Scientists are not romantic.

They're romantic until romanticism gets in the way of dispassionate interpretations of what the data tells them to be the most likely truth. Would you rather have them make stuff up and undermine the very purpose of their job?

I think there's a middle ground we call "the capacity for imagination", which can be both romantic and need not conflict with empirical analysis.

The thing is, this story sounds like miscommunication/misremembering all-around because male goldfish do exist, and their "reproduction" section on wikipedia does not mention asexual reproduction at all[0]. Also, the wiki page on gynogenesis suggests that it specifically is a form of reproduction that still requires a male and a female, but that the male does not contribute any DNA to the offspring[1]. So male fish are required either way, although they are typically from an "adjacent" species.

Searching the general internet just returns articles claiming goldfish can reproduce asexually, followed by another paragraph claiming they can't (proving to me that it's all AI generated bullshit). Not even going to link examples.

Then, finally, Google Scholar points to two articles with the following titles: Genetic responses in sexual diploid and asexual triploid goldfish (Carassius auratus) introduced into a high-altitude environment and Genetic homeostasis and developmental stability in natural populations of bisexual (Carassius auratus) and unisexual (C. gibelio) goldfishes[2][3].

Reading those finally clarifies that goldfish (carassius auratus) are the diploid species that reproduces sexually, and the Prussian carp (carassius gibelio) being the adjacent triploid species that reproduces via gynogenesis, including by using sperm from goldfish.

So if the question was interpreted as "could there still be male Prussian carp somewhere in the wild?" I'm guessing the answer was "no" because being a triploid that reproduces via gynogenesis seems to be a fundamental part what defines their classification as a separate species. Any hypothetical "diploid Prussian carp" would probably be labeled as different species altogether.

[0] https://en.wikipedia.org/wiki/Goldfish#Reproduction

[1] https://en.wikipedia.org/wiki/Gynogenesis

[2] https://www.techrxiv.org/doi/full/10.22541/au.166859689.9117...

[3] https://link.springer.com/article/10.3103/S0095452709050077

[4] https://en.wikipedia.org/wiki/Prussian_carp

> they reproduce via gynogenesis, it's like pathogenesis

That's an interesting choice of word construction.

parthenogenesis -> virgin birth.

gynecogenesis -> woman birth.

[gynogenesis is an impossible form, and pathogenesis would refer to "disease birth"]

I can see how "virgin birth" is distinctive compared to ordinary birth. How is "woman birth" supposed to be different? Are people not normally born from... women?

pathogenesis was spellcheck error (I meant parthenogenesis) and gynogenesis is real https://en.wikipedia.org/wiki/Gynogenesis

> How is "woman birth" supposed to be different? Are people not normally born from... women?

It's referring to the to, not the from. But in either case, yes; however, males are usually involved. In this case, it's woman exclusive.

They simply use sperm to stimulate the urge to procreate/kick off the process. Thus, the need for other species to be spawning nearby.

Well, the article says this:

> Pando is triploid, meaning that its cells contain three copies of each chromosome, rather than two. As a result, Pando cannot reproduce sexually and mix its DNA with that of other trees

but this seems to misunderstand the nature of plants. In an animal, this kind of ploidy variability wouldn't just make the organism sterile, it would kill it. Plants are more tolerant, and many species are known which have done what this article claims is impossible. For example, redwoods are hexaploid, which doesn't interfere with their reproduction.

Wikipedia:

> Polyploidy has come to be understood as quite common in plants—with estimates ranging from 47% to 100% of flowering plants and extant ferns having derived from ancient polyploidy.

( https://en.wikipedia.org/wiki/Sequoioideae )

It just isn't an obstacle. I don't know what the article author was thinking.

>It just isn't an obstacle. I don't know what the article author was thinking.

Probably googling a term, learning how it applies to mammals and assuming that's true for plants as well.

>redwoods are hexaploid, which doesn't interfere with their reproduction

Six is divisible by two though.

What's the relevance? If you assume that a viable zygote would need to be triploid, which is already unclear, you'd expect 50% of fertilizations to meet that requirement. (Since gametes should be half-monoploid and half-diploid.) A 50% nonviability rate is high, but it's far too low to prevent reproduction. For example, the spontaneous miscarriage rate in humans is over 20%.

Because in meiosis you need to pair homologous chromosomes.

Why?

Compare https://en.wikipedia.org/wiki/Polyploidy :

> Autopolyploids possess at least three homologous chromosome sets, which can lead to high rates of multivalent pairing during meiosis (particularly in recently formed autopolyploids, also known as neopolyploids) and an associated decrease in fertility due to the production of aneuploid gametes.

Granted, there's an implication that meiosis won't split a cell into one monoploid gamete and one diploid gamete, but is more likely to divide chromosomes between gametes on a chromosome-by-chromosome basis. The implication is that the triploid organism would most likely evolve into a tetraploid organism, as described in the rest of the same paragraph:

> Natural or artificial selection for fertility can quickly stabilize meiosis in autopolyploids by restoring bivalent pairing during meiosis. Rapid adaptive evolution of the meiotic machinery, resulting in reduced levels of multivalents (and therefore stable autopolyploid meiosis) has been documented in Arabidopsis arenosa and Arabidopsis lyrata

I'm not sure what your argument is. Your quote includes the phrase "decrease in fertility."

So let's say an organism has four (A, B, C, D) chromosomes and is triploid.

Split the following cell into two daughter cells: A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3.

Besides the fact that I don't know what a cell does when it has to try to "pair" three sister chromatids, what happens when the resulting gametes are made and then attempt to fertilize each other? You will end up with 2, 3, or 4 copies of each chromosome. This is a problem not only because how does that organism do meiosis, but also, the expression levels of the genes on the various chromosomes are going to be unbalanced.

This doesn't apply to hexaploidy.

>bivalent pairing during meiosis

Even numbers.

> I'm not sure what your argument is. Your quote includes the phrase "decrease in fertility."

Here, a selection from my earlier comment:

>> A 50% nonviability rate is high, but it's far too low to prevent reproduction.

A decrease in fertility isn't the same thing as a removal of fertility.

Over multiple generations it is.

The fact that Pando is a single organism is so confusing to me. I’m guessing there are more forests like Pando that are also a single organism? Is this something unique to this particular species?

Just think of it as the root system - the "trees" are all sprouting from that.

Black Locust can produce sprouts out of its root system, but from what I've read a single organism can cover up to 1ha, and the sprouts become independent eventually, so not exactly the same.

They are also wicked with thorns when young. Someone planted a few in the 70s around here (Pine Bush reserve in Upstate NY), and they won't go away. They thrive in the pine bush and steal from the native environment. Prescribed burns help on the reserve bits, but on the private properties surrounding it is a nightmare. The amount of scars I have from these invasive trees' thorns is nuts.

Sounds like rhizomes. These are not uncommon in plants. Bluegrass lawn for instance spreads this way. But yes I never imagined a similar thing with trees.

I believe the difference is that rhizomes are special structures meant for reproduction, whereas with Pando and other quaking aspens, it's just normal tree roots that pop up near the surface and start growing into trees.

Pretty much all plants have similar abilities to reproduce clonally as a byproduct of how they grow. Normally we don't count the individuals as a collective organism the same way we do Pando though.

I thought the scientific consensus was Pando does not actually reproduce anymore and is shrinking

I've never heard that. The aboveground stems of aspens live just over a century, so Pando would be dead very quickly (in relative terms) if that was true. I see some articles online that new shoots are struggling to survive because of herbivores though.

apparently I had it wrong. The net size is decreasing over time, but new shoots do still emerge and mature into healthy structures

Forest Service says it's showing signs of decline due to "... a lack of regeneration, along with insects and disease."

https://www.fs.usda.gov/detail/fishlake/home/?cid=STELPRDB53...

You seem to dismiss that Pando is uniquely special. The claim is that Pando is the oldest organism on Earth. Do you disagree? If so, what are some organisms that might be older?

See https://en.wikipedia.org/wiki/List_of_longest-living_organis...

I've not yet seen an explanation of what counts as a single "organism" for these purposes and the estimated ages are all over the place.

My guess at a definition: All parts connected, having the same DNA, and supporting each other by sharing nutrients.

This is true of corals, and they are often considered "colonial" organisms instead of an individual.

That said, I don't think anyone who studies biology is particularly concerned with hard-line definitions, as nature tends to eschew them every chance it has.

I think Pando and corals being considered "modular bodyplans/habits" is perhaps a more useful concept than individual or clone.

I'm not dismissing that Pando is old or interesting. I'm saying that clonal reproduction is not especially uncommon in the plant kingdom and that we typically don't consider the resulting plants part of the same collective organism.

The same type of vegetative reproduction is happening every time a potato or garlic clove is planted, for example. Asparagus is an even closer analogy to Pando.

The roots of Pando are all connected though and a potato plant from a piece definitely isn’t.

> Generally speaking, yes. Each of Pando's branches is connected to the others through a shared root system.

Pando isn't a bunch of individual clones though, it's a single contiguous organism.

What is the dividiing line between single organism and clones with connecting structure, like shared roots?

It seems like a fuzzy gradient to me. Maybe some biologist can share what makes the distinction clear, but I can imagine a gradient ranging from fully distinct autonomous disconnected clones all the way to clearly a single organism that only grows outward into a large sphere.

Clearly Pando is somewhere in the middle of this gradient. What is Pando's position on that gradient and why is "bunch of individual clones" somewhere else? How is another tree sharing a roots not a single individual too?

Super confused here because the distinction seems completely clear to me? Relatively few plants, when mature, will start growing clones up from their roots, but it's a known growth pattern. They're called suckers, and I've never heard them referred to as distinct individuals.

But most plants can be cloned by taking a cutting and giving it continuous water + air and letting it start growing a new root system. I've never heard anybody suggest the cutting is not a new, distinct plant.

Hmmm, could a long generation banana plant be considered ancient? Assuming the line was kept in place for centuries.

That also has made me wonder. If these are common but not generally mapped or surveyed, then it'd be likely this is not oldest etc...

Yeah, I've noticed over the years a lot of articles about oldest, tallest, <maximum other dimension> trees and they're always in the US. Strikes me that there's a likely bias there - the biggest results occur where you're doing the most looking

The name Pando adds to the mystery of the organism. If it was called Fish Lake forest or something, it would be hard to draw any attention.

Pando has an almost mythical ring to it

All quaking aspens can reproduce through their roots systems (as well as by seeds); you typically see them as clusters in the forests they reside instead of peppered around like other trees. Pando is unique because it can only reproduce asexually as well as its huge size. Most aspen colonies are not nearly as big.

>Pando is unique because it can only reproduce asexually

Is that true? I've seen it mentioned in non-scientific articles, but have never seen anything scientific saying so. I'm not sure why Pando would be different from any other member of its species.

Japanese knotweed in Europe

>The fact that Pando is a single organism is so confusing to me.

All of the tree stalks are connected to the same roots, so it's all one big organism.

The oldest non-colonal tree is in California at 4800 some years old.

1. https://en.m.wikipedia.org/wiki/Methuselah_(pine_tree)

Anyone know if you can get sprouts from Pando to start your own mini version?

hola?

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