[HN Gopher] A popular household fern may be the first known euso...
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A popular household fern may be the first known eusocial plant
Author : pseudolus
Score : 153 points
Date : 2021-06-12 10:39 UTC (12 hours ago)
(HTM) web link (blog.pnas.org)
(TXT) w3m dump (blog.pnas.org)
| ri4932 wrote:
| I have to go inspect my ferns now. I had no idea each frond is a
| separate individual.
| chadlavi wrote:
| Doesn't this also imply a level of conscious decision making that
| a fern is probably not capable of making?
|
| Occam's razor would suggest that exposure to light, orientation
| relative to gravity, etc are more likely causes for the divergent
| characteristics of ferns at different positions, not any kind of
| purposeful social organization.
| 7952 wrote:
| A lot of behaviour is in response to stimuli (like light) The
| "purpose" of that behaviour is that it helps certain genes
| reproduce. This behaviour could be complex and unexpected or
| much simpler.
|
| Animals may be able to exhibit more complex behaviour, but it
| is still mostly just a response to stimuli. An ant doesn't know
| why it cooperates, it does not have a purpose in a human sense.
| It has genes that have survived because they encourage social
| behaviour. It behaves socially in response to stimuli and helps
| the genes to spread.
| strogonoff wrote:
| > Animals may be able to exhibit more complex behaviour, but
| it is still mostly just a response to stimuli. An ant doesn't
| know why it cooperates, it does not have a purpose in a human
| sense. It has genes that have survived because they encourage
| social behaviour. It behaves socially in response to stimuli
| and helps the genes to spread.
|
| Fun thought experiment: what if humans are the same?
|
| When was the last time you did something that didn't help
| genes to spread, or wasn't part of a longer strategy with
| that as eventual purpose?
| 7952 wrote:
| Well we are the same. But our brains and culture let us go
| beyond that.
| strogonoff wrote:
| What makes you so sure it's different for humans and all
| that isn't merely an elaborate way of post-rationalizing
| our gene-driven behavior?
| redeux wrote:
| Probably when I got a vasectomy.
| strogonoff wrote:
| Isn't it said that genes' spread doesn't necessarily
| imply individual gene carrier's survival or having more
| children? Like a thumping bunny that makes itself
| noticeable to a predator but helps relatives survive.
| cratermoon wrote:
| It's more than that. Most eusocial insects have only one
| reproductive member per unit - the queen. All of the rest
| of the members are children of the queen and work to
| ensure her ability to reproduce, thus maintaining their
| own gene line. The future queens will be sisters of the
| non-reproducing insects.
|
| Very vague recollection of mine, but I believe there was
| a study about the role of homosexuality in propagating
| the species. In very complex social animals likes humans,
| we can also ask about the reproductive "utility" of such
| things as art and music, which don't directly contribute
| to the basic needs of survival.
| 7952 wrote:
| I think that traits have to be sufficiently detrimental
| to reproductive success for evolution to remove them. For
| example a genetic predisposition for cancer in old age is
| unlikely to have an effect on reproductive success.
| Whilst a gene that reduces fertility in young people
| would.
|
| It is possible that things like art and music are the
| result of traits in our genome that are beneficial in
| other ways. Or the traits just didn't inhibit
| reproduction.
|
| Maybe a hypothetical "gay gene" could have survived in
| women simply because they historically lacked choice
| about reproduction.
| mellavora wrote:
| well, that would depend on how one defines conscious, and also
| on the assumption that eusociality depends on conscious
| decisions.
|
| Occam's razor could equally well be used to cut out the
| dependence on consciousness for the development of eusocial
| behavior.
|
| do we ascribe the eusocial organization of ants to conscious
| decisions made by individual ants?
| mcherm wrote:
| Eusocial behavior does not imply conscious decisions.
|
| Ants do not apply their conscious intelligence to choose
| whether to become a worker drone or soldier drone; it is
| controlled by chemical signals. Bee hives feed royal honey to
| form a new queen when the colony lacks a queen or is so large
| it may be able to split... but none of that is "conscious".
|
| Exposure to light, orientation relative to gravity, and such
| likely ARE the direct causes of the ferns' different growth
| patterns. But the end effect of a property that says "if you
| get light from above, grow waxy leaves that help filter water
| into the clump" is (maybe) that the clump consists of
| "cooperating" individuals and does better than individual
| fronds would.
| rnhmjoj wrote:
| Well, when worker bees communicate[1] the direction and
| distance of a foraging ground to each other, that seems
| pretty conscious to me. Saying everything boils down to
| chemical signals is true but it's probably too reductive.
|
| [1]: https://en.wikipedia.org/wiki/Waggle_dance
| otabdeveloper4 wrote:
| > Ants do not apply their conscious intelligence to choose
| whether to become a worker drone or soldier drone; it is
| controlled by chemical signals.
|
| From what I know of antkeeping, this isn't true and they
| actually do make a conscious decision. (Based on things like
| food availability, perceived threat, etc.)
| mcherm wrote:
| Most people do not consider ants to be conscious.
|
| But, on reflection, I'm not going to disagree with you. I'm
| not sure that the word "conscious" actually has a clear
| meaning other than human exceptionalism.
| fredgrott wrote:
| be careful with that bad assumption
|
| Conscious behavior emerges from a set of cell signaling
| subsystems borrowed from plants and re-purposed...
|
| Those subsystems are known as the nervous system, hormones,
| neurotransmitters
|
| We as of yet in the continuum of emergent behavior yet to
| have properly deined where conscious lies
| ordu wrote:
| _> Occam 's razor would suggest that exposure to light,
| orientation relative to gravity, etc are more likely causes for
| the divergent characteristics of ferns at different
| positions..._
|
| It is not Occam's razor but a reduction. We do not need to talk
| about macroparameters in thermodynamics because they can be
| explained by microparameters. So there are no pressure and
| temperature, only positions and kinetic energies of individual
| particles.
|
| "Eusociality" here is not an explanation of a phenomenon, it is
| not a cause of a phenomenon but a classification. Eusociality
| doesn't explain (at least in this particular case), it just a
| mark for the phenomenon to be a member of the wider class of
| phenomena. At the same time exposure to light, orientation
| relative to gravity, etc might explain observed eusociality, so
| they might be targets for Occam's razor.
| djmips wrote:
| I don't know what the boundaries of eusociality are, but some
| cellular slime molds and bacteria exhibit a social behavior where
| they differentiate function based on position in a colony but can
| also live on their own.
| carapace wrote:
| There's also the trichoplax, a kind of "tribe" of cells that is
| "made up of a few thousand cells of six types in three distinct
| layers: dorsal epithelia cells and ventral epithelia cells,
| each with a single cilium ("monociliate"), ventral gland cells,
| syncytial fiber cells, lipophils, and crystal cells (each
| containing a birefringent crystal, arrayed around the rim)."
|
| They can be pressed through a sieve so that the cells split
| apart and move as individuals. The cells will reform the
| organism. Two trichoplax organisms can be split like this and
| the cells from each will reform with each other.
|
| https://en.wikipedia.org/wiki/Trichoplax
| pvaldes wrote:
| > I don't know what the boundaries of eusociality are
|
| Even my chicken would fit in that description.
| istjohn wrote:
| If you find this interesting, you will probably also enjoy this
| TED talk from Suzanne Simard on how trees communicate. She also
| was in an interesting Fresh Air segment recently.
|
| https://www.ted.com/talks/suzanne_simard_how_trees_talk_to_e...
| oblak wrote:
| One of the most memorable things from Avatar was Weaver's (and
| mine) excitement about this very thing.
| ohlookabird wrote:
| Thanks! There is also the nice book by Peter Wohlleben touching
| on this subject (the "wood wide web"): The Hidden Life of
| Trees.
| chrisweekly wrote:
| Also "Overstory: A Novel" by Richard Powers; profound,
| transformative... words fail me.
| latchkey wrote:
| These are really neat plants. My father had a huge one on his
| second floor house deck that was doing really well because he
| would water and care for it all the time. They love a banana peel
| for nutrients.
|
| At some point, another one, just like it, appeared across the
| street (probably a good 100' away) growing on a corner side of
| another house at the same vertical height.
|
| Many years later, it is also huge and doing really well. It has
| never been watered or cared for because it is impossible to reach
| from the ground without a ladder. It also hasn't seemed to spread
| further, yet.
| gumby wrote:
| A characteristic of a eusocial colony is one of interdependence.
| The evolution of the forms described in this article could also
| be satisfied by parasitism.
|
| The morphology of the ones at the top could simply be explained
| by local environment (more access to sun and water and a need to
| regulate water intake, both increase access and shed excess). The
| ones lower would be driven by similar epigenetic expression to
| take advantage of a different environment (less sunlight, try to
| collect and retain the diminished amount of water arriving.
|
| To consider the growth a true colony we'd have to answer the
| question: how do the ones at the bottom provide benefit to the
| ones at the top and what is the incentive for the ones at the top
| to have water-shedding disk fronds _as a way of helping those
| below_ (as opposed to simply for the upper plants' "selfish"
| reasons)?
|
| The only possible answer is that the lower ones would have to
| spread their dna (which they share with the upper ones) more
| widely than the upper ones can on their own. Which is possible
| but unproven.
| oasisbob wrote:
| As an aside, the moisture gradient in a tree typically becomes
| drier as you move towards the top of the crown.
|
| Thinking solely about throughfall can be misleading- exposure
| dominates by driving drying.
| gumby wrote:
| That's very interesting, thanks!
| atomicbeanie wrote:
| Is this just anthropomorphism of an emergent pattern, of the same
| nature as cell division and specialization? That a pattern
| resembles that of an ant colony where its members make billions
| of neurological real-time decisions which reinforce the perceived
| structure, these growth patterns are set with few active
| decisions and do not quickly change even with no active
| reinforcement.
| beambot wrote:
| Your question is a bit tautological. If you're going to claim
| that the plants' eusocial behavior is emergent, then I'd argue
| that so is human consciousness. The mere act of comparing them
| is the definition of "anthropomorphism" -- it's just that we
| only have first hand experience with human consciousness.
| zeckalpha wrote:
| Humans are not generally considered eusocial.
| lucb1e wrote:
| Summarizing a bit for those like me who are interested but not
| biologist-level interested:
|
| Eusociality is like bees that don't reproduce but support a queen
| that does. With that in mind:
|
| > "[Ferns] at top seem to be water and nutrient capturers; ones
| below seem to store water." [...] the number of reproductive
| [leaves/ferns] increased with the height of the colony, and 40%
| percent of ferns didn't reproduce at all. Reproductive division
| of labor
|
| For textbook eusociality, there are two more conditions that have
| not yet been proven to be met by ferns. However, more interesting
| perhaps is
|
| > what defines an individual fern. If a colony can begin with a
| small plume of strap fronds sticking up from a few nest fronds
| and then spread asexually on the same roots, perhaps it is a
| single plant
|
| There is an argument to be made that they're not a single plant,
| because
|
| > [The ferns] differ markedly in morphology and reproduction
| depending on their role in the colony.
|
| So it hinges a bit on what you call eusocial and what you call a
| single plant.
|
| The headline made me think that ferns have a queen-like somehow
| or somewhere, and while there is some division of labor... the
| jury's still out on which definition it'll fall under, and it'll
| probably just end up being a footnote in a biology book
| somewhere.
|
| In conclusion, the interesting takeaway to me is that different
| ferns support each other, and 40% of them don't reproduce at all.
| There is a parallel to be made with how bees don't individually
| all reproduce, but whether the mechanism is actually identical to
| a meaningful extent is yet to be debated.
| pvaldes wrote:
| > 40% of them don't reproduce at all
|
| Plants can reproduce asexually and ferns do it all the time.
| lucb1e wrote:
| Ctrl+f "40%" in the article, that's what I'm referring to.
| (Heck, it's even one of the parts I cited in my comment. I'm
| not making new stuff up.)
| philshem wrote:
| > Eusociality: ... the highest level of organization of
| sociality, is defined by the following characteristics:
| cooperative brood care (including care of offspring from other
| individuals), overlapping generations within a colony of adults,
| and a division of labor into reproductive and non-reproductive
| groups.
|
| > Eusociality exists in certain insects, crustaceans and mammals.
|
| https://en.wikipedia.org/wiki/Eusociality
| pvaldes wrote:
| This is like saying that an apple and its leaf belong to
| different castes. They have very different roles and are clearly
| distinguishable in structure. And one of them has as main purpose
| to protect and nurture the brood.
|
| ALL ferns have complex life cycles with 2 different lifes, (not
| only the Platycerium). A plant called gametophyte normally short
| lived and tiny, and another plant called sporophyte that we call
| fern. Botanists know that since thousands of years ago. There is
| nothing in Platycerium different or strange.
|
| They just aren't understanding what is an individual. A leaf is
| not an individual and your hair is not a society of hair that
| grow in the same direction following the orders of a hairbee
| queen.
|
| Equaling animals and plants and finding a "soul" in everything
| (for fame and money none less) is getting more and more annoying
| each day. I wish we could focus in the real problems of the
| biology, instead to try to rebuild mythology.
| PaulDavisThe1st wrote:
| Absolutely. Because a member of the School of Biological
| Sciences at Victoria University, Wellington, would have no idea
| about any of those things, and would thus easily walk into the
| simple misunderstanding that you've thankfully rescued us from.
|
| I think you should write a letter to the editors at Ecology,
| where the actual paper was published.
| pvaldes wrote:
| I'm sure that the contributions from the Victoria University
| to the history of Pteridology are outsanding but I would not
| put them on the same level of impact as people like
| Takhtajan, Cronquist, Zimmerman, Klekowsky, Cunningham, Mutis
| or, of course Linnee, among other.
|
| https://en.wikipedia.org/wiki/Argument_from_authority
| OJFord wrote:
| (totally off-topic just a 'DM')
|
| I wasn't looking to email you, but just to say your bio
| mentions your 'email below', but doesn't then specify one.
|
| The email field in HN profile edit form is actually
| private, to display an email address you need to put it
| separately (and probably want to obfuscate it) in the
| general bio text area.
| antoncohen wrote:
| > Eusociality typically requires two other conditions. ... And
| since the ferns spread asexually on shared roots, they don't
| actually exhibit an active system of resource acquisition typical
| of brood care.
|
| > One key question is what defines an individual fern. If a
| colony can begin with a small plume of strap fronds sticking up
| from a few nest fronds and then spread asexually on the same
| roots, perhaps it is a single plant
|
| There is a lot of talk about the amazing cooperation of these
| plants. And then they say it is actually one plant. Is it
| interesting if one plant grows different leaves at different
| heights?
| rackjack wrote:
| "But Uli Ernst, a behavioral ecologist at the the Apicultural
| State Institute at the University of Hohenheim, Germany, adds
| that _since older and younger ferns (their clones) live
| together sharing water and nutrients, one could technically
| call these overlapping generations and brood care._ " (emphasis
| mine)
|
| In the same paragraph, clones, not the same plant. Strawberries
| clone themselves. They aren't the same plant.
|
| "The difference, Burns says, is that _the whole strawberry
| patch looks the same_. _The ferns, by contrast, differ markedly
| in morphology and reproduction depending on their role in the
| colony_. " (emphasis mine)
|
| Right underneath the paragraph you were quoting, they have
| different roles, not just different heights.
|
| Also,
|
| "Drawing conclusions about staghorn social organization _may
| ultimately hinge on the nuances of eusociality_ --some
| definitions frame the concept as more of a spectrum, notes
| evolutionary biologist Guy Cooper, at the University of Oxford
| in the UK, who was not involved in the fern study." (emphasis
| mine)
|
| So I guess its significance depends on how you define
| "eusocial".
| pvaldes wrote:
| > The difference is that the whole strawberry patch looks the
| same.
|
| In fact this depends a lot on the location, soil and age of
| the clones.
|
| > The ferns, by contrast, differ markedly in morphology and
| reproduction depending on their role in the colony."
|
| First of all, population is not the same as colony.
|
| Second, many plants have auxiliary structures (temporary,
| marcescent or permanent). The concept of bract, thorn,
| nectarium or stipula is not a strange one for botanists but
| those are parts of one individual, not individuals in a
| colony.
|
| Is well known that gametophytes and sporophytes are different
| individuals. Many algae and ferns have it. If we want to bend
| the concepts for non useful reasons, then any pregnant woman
| should be called an "eusocial colony" with three individuals.
| marcosdumay wrote:
| What is the difference between a very cooperative colony of
| independent single cell organisms and a multi-cellular
| organism?
|
| On practice the only difference is on the level of
| collaboration. You get a similar phenomenon here, it's
| different because those plants collaborate less than the leaves
| of a single plant, so we give them a different name. From that
| point of view, this finding is quite boring. What makes it
| interesting is that it's an independent evolution of
| collaborative behavior.
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