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STEM skills? OR SKILLS OF STEM??! 😂😂😂😂 I've got three or four saplings from our Oregon White Oak and... I'm not sure what to do with em. Mow? Transplant? 😮😮😮
another important thing about sporophyte is it allowed early land plants to amplify each fertilization event. in plant’s ancestors, each zygote produces just 4 spores that can go on to disperse, but when you invent the sporophyte you delay meiosis, make many more diploid cells, and now each fertilization event can give rise to millions of spores. since fertilization is more difficult on land, and the environment is more unpredictable, super important to maximize the potential of each successful fertilization event
@@supernatural_forces nahhhh, it's for those who think they're so right, they can't even imagine the possibility of being wrong. Figure it out, you know literally nothing. Edit: I don't either, so don't pretend I'm attempting to be superior (like you are)
@@supernatural_forces yes, an intelligent creator who created such a roundabout process of evolution that can be summarised as, 'use raw materials to build a roller coaster and then dismantle it for parts to build a random statue and then dismantle it to building a skyscrapper'. Very intelligent and very efficient... Go preach somewhere else
1:04 while being diploid is normal for most animals the same statement can’t be said about bees, wasps, and ants. A fertile diploid egg always develops into a female and an unfertile haploid will always hatch into a male.
All of the textbooks I read when I was young stated that ONLY mosses, ferns, mushrooms, etc. had alteration of generations; all “higher” plants just produced ova and pollen directly, like animals. I see science advanced while I wasn’t looking (at botanical textbooks)!
@@enadegheeghaghe6369 I’m not THAT old! Lord Rutherford’s experiments showed the existence of the nucleus in 1900! The last primary component of the atom, the neutron, was discovered in the 1930s by Otto Hahn and Lise Meitner, leading to you-know-what in the 1940s. I was born in 1948. I was referring to BOTANY texts and encyclopedias as late as the 1970s not mentioning alternation of generations in plants more complex than mosses and ferns. When exactly did botanists discover that pollen and ovules were not single cells like sperm and ova? This video is the first I’ve heard about this discovery!
I have been a gardener my whole life and study plants alot, but mostly ecology. This is completely new to me, and it is humbling to be reminded of how little we know even when we have spent our whole lifes studying a subject. Great video
I was good at high school biology. But one subject I feared most was plants. How they reproduce to how they generate energy they always make it complex. Understanding everything about one type of plant is like knowing everything about how factory machinery works but more diverse of course
Wait until you realize how bees work: Their females are diploid, and the males are haploid. Quite convenient if you think about it, if the sperm runs out, males will sponaneously appear (this is a gross oversimplification). And the difference between workers and queens is just based on their diet during development.
I have cactus and succulents and a WIP new garden of mine. And the very last thing I'd expect to hear would that plants can reproduce through spores. Only certain plants I'd expect. But tbh a part of me is not surprised due to the fact I can take succulent/cacti leaves and grow a new plant from that without having them flower soooo.
Insect life cycles are kind of like that, but the larva and adult are genetically identical, so it wouldn't confer the same evolutionary advantages. But from a morphological standpoint, they are very similar.
@@chrixthegreatthe way I think about holometabolous insect is that larva is essentially a free-living embryo. Like in other animal groups, insect embryos resemble their ancestral forms, like how human embryos have fish-like fill slits and monkey-like tail before those structures get reabsorbed. Insects and crustaceans evolved from animals that resembled modern annulated worms, with long simple bodies, an exoskeleton, very simple eyes and fleshy appendages that would evolve into arthropod legs. This is what holometabolous insects look like in the larval stage, and also what hemimetabolous insects look like before they hatch. The main difference between a butterfly and a cricket is that the butterfly hatches out very early on in the developmental process looking more like a worm than an adult butterfly, while the cricket goes through the whole thing and then hatches as a miniature version of adult crickets.
This is wild. It's one of those things that changes how I look at the world. I just looked at pollen as plant sperm, but it's more than that. It's funny how it's often facts about plants that do that to me.
The gametophytes mentioned in the video exist in pollen grains. They release sperm only when in contact with the female plant parts. So pollen grains are not plant sperm, they're a tiny male plant in a container.
Wow! I think this goes to show how any time we rigorously define a specific word in biology, in this case "generation", we inevitably end up with something counter-intuitive.
When considering what made a very old trait advantageous, it is good to consider that it may or may not still be advantageous. It doesn't matter whether it is advantageous or not these days because they are often stuck that way by this point.
@@zerutycan't, male mosquitoes are polinizers and an important food source for many animals, even if you only extinct the small percentage of species that feed on humans that's still 210 species wiped out
@@zerutyWould be ironic if mosquitos and viruses were the reason why humans existed in the first place anf exterminating/erradicating them caused the end of civilization and humanity. The butterfly effect is real. Be careful what you wish for. Maybe SARS will trigger a cure for a horrible future disease in the future from alien planets just like how sickle cell anemia helped ppl survive malaria.
Kinda like Rubisco. It evolved during times of higher CO2 concentration. This day and age, it's somewhat inefficient, especially at warm temps. Plants developed alternate photosynthetic pathways to compensate, but you only have so much flexibility
A thousand thanks for all the helpful replies explaining the details for those of us who don't quite get it after watching the video. This community is awesome!
Yet another time I realise that I am somewhat well educated about animal evolution, but pretty much know nothing about plant evolution. But learning is what we're here for.
Awesome, maybe you've gone over how the sporophytes and gametophytes are being defined as separate plants enough to count as different generations? The fern example looked clear enough, but the way it was described for the mosses and for the flowering plants and trees and such sounded more like it's just a sort of specialized organ that may or may not be temporary. Even if you've just got resources or terms to help point me in the right direction on that (preferably to sources that I can still understand when I haven't been in school for a decade), it'd be really helpful.
I could never get into plants beyond a single semester at uni, but I did know their genetics, at least, were insane. Nice to know that knowledge is spreading out from there!
I learned about this in grade school. For a few years i was creeped out by ferns because my teacher pointed out its spores. Looking back on it, i think it was trypophobia caused by looking at spores.
Ok I’m kinda freaking out. Not about alternation of generations I learned about that as a freshman in college. I’m freaking out because they told us that alternation of generations was specific to certain types of non-flowering plants. Like when we were describing certain lineages of plants “alteration of generations” was a characteristic used to describe them and differentiate them from other plants. I realize they often teach a convenient oversimplifications at a basic level and then explain how things really work at a more advanced level. The thing is we were all biology majors taking a course only available to biology majors. Why didn’t they say “all plants do alternation of generations but in flowering plants the haploid generation existed inside the flowers of its parent plant”. Either they thought that very simple fact was too complicated for us biology undergrads (which is insulting); or this was something that was discovered or proven after I graduated (which makes me feel old). I have no problem with the information. In fact I find it incredibly cool. I’m just upset nobody taught me this when I was studying biology in college.
1:28 "All land plants alternate between being diploid and haploid organisms..." No, that's waaay too easy. Plants can be triploid, tetraploid, pentaploid, hexaploid... I don't think there even is a posh name for the black mulberry's 44x chromosne structure.
it seems clear that, if one of the organisms is going to be small and numerous, then it should be the haploid one. Being more mutable is a double edged sword, better to be more abundant to compensate for all the failures.
I feel like I’m missing something because the video says **all** land plants alternate between Diploid and Haploid generations but what about polyploid plants like Hibiscus, Wheat, Sugarcane, that have triploid, tetraploid, octoploid, etc.?
The tetraploid/octoploid plants simply have multiple copies of their genome. Their gametes have half of what the sporophyte has. eg. gametes of octoploid plants are tetraploid. Their polypliodity is a genome-wide mutation. With triploid plants, shit gets weird.
They will still have a gametophyte stage that is half the number of chromosomes as the diploid stage. So if the sporophyte was octoploid the matching gametophyte would be tetraploid.
@@KohuGaly lol uneven genomes throwing a wrench in everything. Thanks! I figured it was something along those lines but it explicitly said diploid and haploid so I was a little confused.
I was (foolishly) super sceptical of the title of this video, but omg, this turned out to be so much more interesting than I expected! How is this not covered in high school or even A-level biology!?
Then there's triploid plants. I know about them because of the fruit trees we keep at home. Triploid plants require two pollinators in addition to the egg cell.
@@CL-go2ji Not kidding. Triploid plants, notably several varieties of apple (only some varieties of apple are triploid) require two distinct varieties other than themselves to pollinate and set fruit. Whether diploid or triploid, all the trees in question need to be in flower during the same window. As it was explained to me all apple trees internally require two distinct varieties of pollen to set fruit but can use their own for one of them. However, triploid varieties don't make pollen or have sterile pollen and not not only need two additional pollinators but can't be relied upon to pollinate other trees. Why then would any of them be used? I don't know the reason, perhaps just coincidence, but many heritage varieties and several of the best producers and keepers are triploid. To accommodate this there are varieties planted specifically to be pollinators even if their fruit is less useful.
I’ll have to look that up, just your brief description intrigues me. I read “Brightness Falls From the Air” and the short story “The Only Neat Thing to Do” for an English class in college, liked them both, but never read anything else of hers. You’ve renewed my interest!
@@NancyLebovitz yes, I remember finding “Brightness Falls From the Air” to be rather a downer, especially compared to other SF that I like, such as Larry Niven.
The fact that they have a different genome from their parent! In many green algae, similar to the ancestors of land plants, sporophytes and gametophytes are actually entirely separate, free-living individuals.
I think the fern at 3:45 is a good example. Those gametophytes are living on their own outside of the plant. They are their own organism, and their life cycle will culminate in (hopefully) creating more ferns. Other species' gametophytes might stay within their parent plant, but they're still their own Thing operating separately.
@@karlmuster263 in flowering plants, it sort of is! Male gametophytes (i.e. pollen grains) typically consist of three cells, while female gametophytes (i.e. ovules) are most commoly six-celled. They are not far from having single-celled gametes like we do.
From what I remember in school, they are considered a different organism because in the past (and in some very primitive plants today if I'm not mistaken) the haploid would bud off and become a fully independent organism. It was capable of living away and completely separate from the diploid generation, and often growing to a full size and living in different niches. Over time in some groups, the role of the haploid was reduced, getting smaller and with a shorter life span, until today they are so small that they never leave the parent flower. Functionally they act the same way as a sex organ, but because they were once a separate organism they are still considered to be so now. During the flowering faze, the haploid does do it's own act of reproduction to produce specialized cells the same way it used to in the past.
Okay but with phases that lopsided can you really consider the gamete producers separate organisms themselves at that point they're basically like organs almost no different than having ovaries or testes to produce egg and sperm
The best comparison I can make is to the gut bacteria in animals, they never leave the gut, and some are potentially even incapable of leaving the animal, but nonetheless they have different genetics
Ovaries/testes are still diploid and genetically identical to the rest of the body. They just produce haploid gametes. With plants, the gamete-producing organs are haploid already. In case of pollen, they aren't even part of its parent plant, and only produce the gametes once the pollination happens. Even in animals, you can find cases where one of the sexes to be reduced basically just to a reproductive organ that "parasites" on the opposite sex. It'd be overly reductive to call it just an organ of the opposite sex.
@@determinedhelicopter2948 Sperm and egg cells have different genetics from the animal they come from too, but we don't consider them to be a unicellular organism that is an intermediary generation between parent and offspring. I just don't see these gametophytes as separate organisms, any more than I do egg and sperm as separate organisms, must because they are multicellular and more complex. And the evolutionary argument doesn't make sense to me either. Bat wings evolved from what used to be hands in predacessor animals, but they have evolved, they are wings now, we don't classify them as hands because of what they were in the past.
@@erinm9445 Perhaps my phrasing was bad. Well, how it used to be is that the plants can 'grow' multiple 'sex organisms' in places separated from themselves, but eventually these had a more and more reduced role in plants, but still present for the plant, basically like if humans made an embryo that then made sperm or eggs and stayed in the body the whole time. So using the bat example, yes the wings are still sorta hands, just with extreme webbing adapted for flight use.
@@determinedhelicopter2948 Thanks for explaining further. To me this all underscores that it's a mistake for biology to continue to classify the gametophytes of seeded plants as an organism or as a generation. If we humans made little haploid embryos that never left our bodies, and those embroyos made the eggs and sperm, this would seem completely normal to us, and we would not consider those embryos to be intermediate generations, they would just be steps in our reproductive process. Especially if these little haploid embryos looked nothing like diploid embryos we know and love (just as pollen and stamens look nothing like plant embryos, ie seeds). The genetics would be the same as what we have now, just with some mitotic cell devisions in the haploid cell line before you get to the gamete. And again, bats don't have hands. That's straightforward. Sure, they kinda have hands if you think about it in the right light and understand their evolutionary history, but they don't actually have hands. Seed plant gametophytes seem the same to me.
An episode of Star Trek is forming in my mind about an alien race who reproduce with a gametophyte generation and the problems that arise when the federation contacts them...
@@robspiess Yes I know, I also knew someone would point that out 😅 (English isn't my main language so I tried to keep it simple, but I'm a chemical engineer so I know how those biochemical reactions go 😁)
This is why the seedbank thats in the top soil is so important. It's not just "oh just put some more dirt there" Where are you getting that dirt from? Is that place filled with weeds?
Oooh, I vaguely remember this from biology class! Unfortunately, this was a class held early Sunday morning, and I fell asleep halfway through nearly every lecture.
As a gardener, I drives me a little batty in trying to convince plants to provide seeds. Sometimes, instead of waiting for the flowers to fruit, I need to clone through cuttings and then those plants give seeds. Now, this makes a lot of sense.
That is mostly to do with cloning by any of a half dozen different means. Very few plants breed true to seed, even if you have homogeneous stock. Plants want to make variety with their seeds because, they (most of them at least) can clone themselves quite readily. Why would they need to waste seeds making more of the same?
Butterflies and caterpillars are different generations, too, though not quite the same way - iirc, both are made at one time and then the butterfly is dormant and undeveloped till the caterpillar makes her cocoon
I think it makes perfect sense for a stationary species to clone itself and then distribute those clones as a method for mate-finding. It keeps the original copy intact for as long as possible, and moves the area of influence to wherever the new plant lands. 4 is also a great number because the species can distribute one sample to each direction and "move" to the most ideal location over subsequent generations.
[reading the video title] "This sounds like some weird clickbait title but it's SciShow so let's check it out anyway" [watching the actual video] "THIS IS SO MUCH WEIRDER THAN I EVER COULD HAVE IMAGINED, I NEVER KNEW." You were not even kidding. Wow.
@@mrosskne he's not got two either. Also, my name's not in it=>not obvious. If it's about the first part of the OP, it's obvious: (Half of all) (plants are invisible), or (half of) (all plants are invisible). Parsing is ambiguous but easy.
The question "What advantage does this give to plants?" is kind of the wrong question -- or at least coming at it from the wrong angle. Plants didn't start out diploid and then evolve a haploid stage later: they evolved from the same unicellular, haploid, asexually reproducing organisms that all multicellular life did. The advent of eukaryotic sexual reproduction was a complex affair, and involved multiple developmental adaptations. In plants, the ability to form gametophytes emerged first, which we can see in modern species that have retained more basal traits, like green algae, such as volvox. These organisms give us a glimpse at the likely course of evolution that diplotonic plants followed. To oversimplify, the single-celled ancestors of plants evolved from earlier eukaryotes, which had already evolved the ability to respond to stress by developing diploidy and sexual reproduction. This new stage of life was very useful for adapting quickly to new environmental conditions, including -- as mentioned -- dry land. Over time, certain groups of eukaryotes evolved to prioritize developmental adaptations in the diploid state. Some, like mosses and algae, continue to mainly stay in the haploid stage, briefly splashing into diploidy for reproductive purposes, while others simply maintain that "excursion" for far longer. Humans have taken that strategy so far that our haploid "generation" can't even survive on its own, and only exists for just long enough to fuse with another haploid human cell!
Thank you! This is the comment I was looking for. A much more sophisticated explanation that gives a more accurate and nuanced picture! (I am not a biologist, just a critical viewer, but aspects of the video were clearly oversimplified). It does seem like questions of the advantageousness of various strategies apply once this evolutionary history is established. For example, in simpler and unicellular forms of life a preference for the haploid stage has remained--so there wasn't much advantage to leaning into diploidy--which I assume is costly? Whereas leaning into diploidy seems to have been essential for enabling more complex life forms. In this sense, both seeded vascular plants and animals followed the same strategy--by different routes and on different timelines--evolving to a place where the haploid phase is just a transient part of the sexual reproduction process and the haploid "generation", as you say, can't survive on its own; though plants' haploid generation is much more complex than for animals. (Spore plants can be seen as an intermediary step in this evolution, where they've mostly made this transition, but the haploid generation is able to have an independent, planty existence). What does and doesn't count as a generation for parent/grandparent purposes really becomes a matter of human definition at that point, and to me, "can survive and do life things all on its own" seems like a good line, but biology seems to have settled on something like, "can grow from a unicellular to a multicellular structure?" or perhaps "has an evolutionary history in which it used to be able to survive and do life things on its own." I am curious though: in the evolution of sexual reproduction in animals, did very early animals or proto-animals have the equivalent of gametophytes, or did the animal lineage start with single-celled haploids right out of the gate? Or do we not know?
There's something so wise about alternating processes through generations. And the notion that spores spread further than gametes but gametes have a more 'stable', but still changing, genetic story (I could be thinking about that wrongly). Thinking about culture and age groups and generations, leveraging cultures' different ways of doing and being, and different ways to transfer knowledge and information across various distances could be good way to maintain and develop cultures over time. Spread and consolidation happening simultaneously, both always dynamic. As a young spore, going to other cultures and sharing the information of your own culture, and adapting to their culture. Coming back to your parent plant / culture of origin and sharing those learnings. Simultaneously, other 'spores' have come into your parent plant and shared their information, altering the culture. When you arrive home, you have to adapt to the changes made and they listen to the information you have and then you become part of the parent plant as other generations go off as spores.
this kinda feels like an efficiency thing! it seems easier to just produce "half an offspring" with less genes, solely for the task to "build" your offspring! even tho it seems weird, it also kinda makes sense!
Isn't this exactly what animals do to? We produce "half an offspring"--it just happens to only have one cell--solely for the task to build our offspring, no?
@@mho... Yes, I've watched the video, and spent a lot of time reading through and pondering comments. I'm unconvinced that there's really much of a differerence between gamophytes for seeded plants and gametes (sperm and eggs), except that one is multicellular and the other is unicellular. For spore plants, it's different, since their gamophytes actually live independent little plant lives totally on their own, before reproducing. But for seeded plants, can you explain the difference to me, aside from uni/multicellular?
Despite talking about diploid/haploid, many plants have more than two gene copies (even up to pentaploid, hexaploid, heptaploid, octaploid, etc.). How does this process work with polyploid plants?
It depends. Usually the haploid generation simply has half the chromosome sets of the parent generation. Sometimes the haploid generation does get reduced all the way to single copy of the genome. Plants with odd number of gene copies are usually infertile.
This seems like a bit of a stretch. The difference of one cell (in animals) and a handful (in plants) seems like hair splitting when calling one an alternation of generations and the other not.
It seems like it, until you pick up a fruit, test it genetically and realize it's actually composed of cells that come from several genetically distinct individuals. Some parts are the actual diploid embryo, some parts are its triploid sibling, some are its haploid mother and the rest is its diploid grandmother. Which parts are which and in what proportion varies by species.
@@KohuGaly I still feel like one can easily imagine an equivalent in animals, in which, say, the menstrual lining was made of a mix of diploid maternal cells and haploid cells descended from the egg and/or sperm. That isn't how animal evolution went, but in theory it could have gone that way, and it's easy to see that that wouldn't make the sperm/egg the father/mother (and the parent really the grandparent). Reading around on the web, it really seems like the main reason biology has decided that gametophytes are a generation and an organism is because they are multicellular, and seems really arbitrary to me. I would say that makes them a haploid sexual organ, not a separate organism. It's different in the case of spore plants, where the gametophyte has a whole independent life that it lives. I also just looked it up, and from what I can tell it sounds like most fruits develop from the plant ovary and contain the same diploid dna as the rest of the plant, but some fruits develop from other structures of the flower, and it sounds like in some cases that includes the gametophyte? Which fruits are these? Just curious on this one!
spore is a single cell that directly grows into an organism. Gamete needs to fuse with another gamete (fertilization) to form a zygote that grows into an organism. Reproduction through spores is asexual, because the DNA of a child comes from a single parent.
Child: *Mom? I’m bored of playing Marco Polo. Can we play find the invisible cow this time?”* Mom: *What? Where are you? I don’t want you to get lost in the mall again looking for glucose*
Nature: Hey plants, I've invented serveral methods of reproducing. Which one do you want to use to conquer the earth? Plants: yes Nature: Well, you have to deci- Plants: YES! Nature: Ok *sigh
Why are haploid phase/diploid phase considered separate generations? Isn't it similar to animals growing sperm and egg cells in organs in their bodies? Similarly, flowers/cones can be considered as a separate organ meant for reproduction rather than separate generation, right? It's still confusing.
Yes. Although stuff can get weird with polyploid plants. Sometimes the mutation-preventing mechanisms kicks in during meiosis and the gametophyte gets properly reduced down to haploid state. The seeds are then diploid like normal.
I knew ferns did this but I didn't know it was all plant. I guess that explains why plants are more evolved then the other eukaryotic kingdoms of life.
I think the inspiration for the Xenomorphs of Aliens was largely a parasitic wasp. With the larvae eating the host from the inside out. Though the haploid thing also makes sense because, as seen in both the third Alien movie and the Alien vs Predator movies, we see that the larvae which is deposited by the face hugger takes on traits of the host. If the face hugger is a haploid organism that is functionally similar to an endosperm, in this case who's task is to deposit it's twin sibling to a host. And the larvae is also initially a haploid organism that not only incubates in the host but literally rips off significant portions of the hosts genome to fill the gaps and instantly adapt to whatever environment the host is native to. Or maybe the face hugger does the gene splicing before depositing the complete embryo of the larvae to incubate and falling off.
To what extent is the extreme case not a reversion to a single organism? In ferns the two plants are more obviously different organisms, but in angiosperms are they necessarily two generations or could the gametophyte not just be considered an internal organ of one individual? What makes is a single organism and not a compound...
What makes it a single organism is the fact that is has genetic material distinct from its parent. The genome of the gametophyte is produced via meiosis (including crossing over) - its chromosomes are not identical to the parent's chromosomes. You could argue that the female gametophyte is "just an organ", but for the male gametophyte (the polen grain) that argument doesn't really work, since it lives its live detached from the parent plant.
@KohuGaly yeah thats the main idea, though its insufficiency does show up. an extreme example: chimeras and mosaics are not uncommon, where one organism has two or more sets of genes, sometimes from mutation and others from embryo fusion. cancer also has different genes to the rest of you. more generally, cloning raises an issue: the most common ant, black crazy ants, do something wierd where the queens and males maintain their own sex by cloning: the queens are all clones of each other, and the males clones of each other, and those genes dont mix. mieosis only occurs for the workers, which themselves can also clone themselves without meisosis. Are the queens all the same individual? One could extend this to asexually reproducing bacteria and so on too. As for indepenedence: Pollen lives its life *mostly* off the stamen, but cant eat except for its stored nutrients, not really any different from sperm.
They are invisible to the naked eye, because they are either too small to see or hidden inside its parent's flowers. However, the statement that it's half of all plants is not true. The gametophytes outnumber sporophytes 1000:1 at minimum. Note that every pollen grain contains male gametophyte and every flower usually contains several female gametophytes.
@@thekaxmax although I can't find anything about doing this to an extinct species even wirh frozen samples, I mean I believe you but if you have a source I love ecology and genetics so I'd live to peruse is
@@thekaxmax unfortunately even with those specifications I can not find any papers about it, the best I can come up with is bringing back aincent Silene stenophylla from seeds sealed in permafrost can you provide any actual information about it so I can look harder? I'm trying to meet you half way but I can't find anything about it so if you or someone else knows that would be helpful. Do you at least know when this was or where you heard about it so I can narrow down the search parameters
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are yall ever gonna post comments that arent ads?
Thanks Reid for another great informative show!
STEM skills? OR SKILLS OF STEM??!
😂😂😂😂
I've got three or four saplings from our Oregon White Oak and... I'm not sure what to do with em. Mow? Transplant? 😮😮😮
So plants are like caterpillars, or vice versa.
another important thing about sporophyte is it allowed early land plants to amplify each fertilization event. in plant’s ancestors, each zygote produces just 4 spores that can go on to disperse, but when you invent the sporophyte you delay meiosis, make many more diploid cells, and now each fertilization event can give rise to millions of spores. since fertilization is more difficult on land, and the environment is more unpredictable, super important to maximize the potential of each successful fertilization event
Ok
@@supernatural_forces this just went sideways real fast
@@supernatural_forcesshhhhhhhhhhh
@@supernatural_forces nahhhh, it's for those who think they're so right, they can't even imagine the possibility of being wrong. Figure it out, you know literally nothing.
Edit: I don't either, so don't pretend I'm attempting to be superior (like you are)
@@supernatural_forces yes, an intelligent creator who created such a roundabout process of evolution that can be summarised as, 'use raw materials to build a roller coaster and then dismantle it for parts to build a random statue and then dismantle it to building a skyscrapper'. Very intelligent and very efficient...
Go preach somewhere else
1:04 while being diploid is normal for most animals the same statement can’t be said about bees, wasps, and ants. A fertile diploid egg always develops into a female and an unfertile haploid will always hatch into a male.
@641mamaluigi …triploid honey bees enter the chat
Another fine example of why biology is so incredibly fascinating. Thank you.
All of the textbooks I read when I was young stated that ONLY mosses, ferns, mushrooms, etc. had alteration of generations; all “higher” plants just produced ova and pollen directly, like animals. I see science advanced while I wasn’t looking (at botanical textbooks)!
The fact that pollen is multicellular and produces two sperm cells that fertilize two separate cells in the ovule should have been a hint.
@@KohuGaly None of which was mentioned in the older books!
When I was a kid, we were thought that atoms where the smallest unit of matter. Now we know about so many subatomic particles. It's crazy
Same.
@@enadegheeghaghe6369 I’m not THAT old! Lord Rutherford’s experiments showed the existence of the nucleus in 1900! The last primary component of the atom, the neutron, was discovered in the 1930s by Otto Hahn and Lise Meitner, leading to you-know-what in the 1940s. I was born in 1948. I was referring to BOTANY texts and encyclopedias as late as the 1970s not mentioning alternation of generations in plants more complex than mosses and ferns. When exactly did botanists discover that pollen and ovules were not single cells like sperm and ova? This video is the first I’ve heard about this discovery!
I have been a gardener my whole life and study plants alot, but mostly ecology. This is completely new to me, and it is humbling to be reminded of how little we know even when we have spent our whole lifes studying a subject. Great video
I was good at high school biology. But one subject I feared most was plants. How they reproduce to how they generate energy they always make it complex. Understanding everything about one type of plant is like knowing everything about how factory machinery works but more diverse of course
Funny that inspired me to become a mycologist and botanist but also weed and shrooms
I have an A3 poster on the photosynthesis process. It's aimed at final year university students and in detail the process is *crazy* complex.
All biology eventually boils down to incredibly long and complex chains of chemical reactions... that's why I'm not a bio major.
For real. If some sci fi writer just used straight plant facts for alien biology I would never notice. Animal biology is much more intuitive to me.
Animal reproduction is so much simpler than like every other eukaryote lol.
I learned from growing mushrooms that they have a haploid phase and a diploid phase, but I didn't realize plants were the same.
🤨👮🏻♀️🚓
@@ssgoko88 You know, there are a half dozen psychoactive mushrooms and literally dozens that are cultivated to eat :)
psychoactive mushrooms are made to eat too,arent they?! so far i havent heard of anyone smoking or injecting shrooms, tbh 😅
Wait until you realize how bees work: Their females are diploid, and the males are haploid. Quite convenient if you think about it, if the sperm runs out, males will sponaneously appear (this is a gross oversimplification). And the difference between workers and queens is just based on their diet during development.
I have cactus and succulents and a WIP new garden of mine. And the very last thing I'd expect to hear would that plants can reproduce through spores. Only certain plants I'd expect. But tbh a part of me is not surprised due to the fact I can take succulent/cacti leaves and grow a new plant from that without having them flower soooo.
imagine if chickens laid seeds that sprouted into trees that bear eggs instead of fruit and when they were ripe they hatched into more seed chickens
Insect life cycles are kind of like that, but the larva and adult are genetically identical, so it wouldn't confer the same evolutionary advantages. But from a morphological standpoint, they are very similar.
@@chrixthegreatthe way I think about holometabolous insect is that larva is essentially a free-living embryo. Like in other animal groups, insect embryos resemble their ancestral forms, like how human embryos have fish-like fill slits and monkey-like tail before those structures get reabsorbed. Insects and crustaceans evolved from animals that resembled modern annulated worms, with long simple bodies, an exoskeleton, very simple eyes and fleshy appendages that would evolve into arthropod legs. This is what holometabolous insects look like in the larval stage, and also what hemimetabolous insects look like before they hatch. The main difference between a butterfly and a cricket is that the butterfly hatches out very early on in the developmental process looking more like a worm than an adult butterfly, while the cricket goes through the whole thing and then hatches as a miniature version of adult crickets.
Those “tree chickens” would literally be “eggplants!”
eggplants
@@khango6138 That would make a lot of sense. Good observation.
When I learned about this in my botany class my mind was absolutely blown lmao I thought it was only nonvascular plants that worked this way
Taking "silent generation" to a whole new meaning. Another fine example of why biology is so incredibly fascinating. Thank you..
This is wild. It's one of those things that changes how I look at the world. I just looked at pollen as plant sperm, but it's more than that. It's funny how it's often facts about plants that do that to me.
@lasagnahog my kids and I always joke every spring about how all the plant sex is trying to murder us (with the pollen.)
The gametophytes mentioned in the video exist in pollen grains. They release sperm only when in contact with the female plant parts. So pollen grains are not plant sperm, they're a tiny male plant in a container.
Wow! I think this goes to show how any time we rigorously define a specific word in biology, in this case "generation", we inevitably end up with something counter-intuitive.
When considering what made a very old trait advantageous, it is good to consider that it may or may not still be advantageous. It doesn't matter whether it is advantageous or not these days because they are often stuck that way by this point.
Unless the trait makes a species desirable/undesirable by humans, who will either help said organism thrive or go exinct
@@silopanteI want mosquitoes to go extinct. Let's get it done
@@zerutycan't, male mosquitoes are polinizers and an important food source for many animals, even if you only extinct the small percentage of species that feed on humans that's still 210 species wiped out
@@zerutyWould be ironic if mosquitos and viruses were the reason why humans existed in the first place anf exterminating/erradicating them caused the end of civilization and humanity. The butterfly effect is real. Be careful what you wish for. Maybe SARS will trigger a cure for a horrible future disease in the future from alien planets just like how sickle cell anemia helped ppl survive malaria.
Kinda like Rubisco. It evolved during times of higher CO2 concentration. This day and age, it's somewhat inefficient, especially at warm temps. Plants developed alternate photosynthetic pathways to compensate, but you only have so much flexibility
A thousand thanks for all the helpful replies explaining the details for those of us who don't quite get it after watching the video. This community is awesome!
Yet another time I realise that I am somewhat well educated about animal evolution, but pretty much know nothing about plant evolution. But learning is what we're here for.
I thought this was about plants being literally invisible but it's actually about what I'm learning in school right now. Thank you.
Awesome, maybe you've gone over how the sporophytes and gametophytes are being defined as separate plants enough to count as different generations? The fern example looked clear enough, but the way it was described for the mosses and for the flowering plants and trees and such sounded more like it's just a sort of specialized organ that may or may not be temporary. Even if you've just got resources or terms to help point me in the right direction on that (preferably to sources that I can still understand when I haven't been in school for a decade), it'd be really helpful.
I could never get into plants beyond a single semester at uni, but I did know their genetics, at least, were insane.
Nice to know that knowledge is spreading out from there!
I don't know why, but your voice is always unexpected and I love it.
I like to think that he's dropping by because Earth is part of space, too.
I learned about this in grade school. For a few years i was creeped out by ferns because my teacher pointed out its spores. Looking back on it, i think it was trypophobia caused by looking at spores.
Same, they look kinda gross.
Ok I’m kinda freaking out. Not about alternation of generations I learned about that as a freshman in college.
I’m freaking out because they told us that alternation of generations was specific to certain types of non-flowering plants. Like when we were describing certain lineages of plants “alteration of generations” was a characteristic used to describe them and differentiate them from other plants.
I realize they often teach a convenient oversimplifications at a basic level and then explain how things really work at a more advanced level. The thing is we were all biology majors taking a course only available to biology majors. Why didn’t they say “all plants do alternation of generations but in flowering plants the haploid generation existed inside the flowers of its parent plant”.
Either they thought that very simple fact was too complicated for us biology undergrads (which is insulting); or this was something that was discovered or proven after I graduated (which makes me feel old).
I have no problem with the information. In fact I find it incredibly cool. I’m just upset nobody taught me this when I was studying biology in college.
Surely they must have thought you about the double fertilization, how it works and where the cells involved in it come from.
this is one of the topics that confused me the most from my plan biology classes in college, but this video helped clarify it a lot!!
1:28 "All land plants alternate between being diploid and haploid organisms..." No, that's waaay too easy. Plants can be triploid, tetraploid, pentaploid, hexaploid... I don't think there even is a posh name for the black mulberry's 44x chromosne structure.
'Imagine that in people' proceeds to come up with cursed metaphor
Do the invisible half of plants still have collision? It is really annoying to try and go somewhere and get stuck on unseen geometry.
Ok
it seems clear that, if one of the organisms is going to be small and numerous, then it should be the haploid one. Being more mutable is a double edged sword, better to be more abundant to compensate for all the failures.
Thanks, without you I'm pretty sure that I never would have known this🌱
I feel like I’m missing something because the video says **all** land plants alternate between Diploid and Haploid generations but what about polyploid plants like Hibiscus, Wheat, Sugarcane, that have triploid, tetraploid, octoploid, etc.?
The tetraploid/octoploid plants simply have multiple copies of their genome. Their gametes have half of what the sporophyte has. eg. gametes of octoploid plants are tetraploid. Their polypliodity is a genome-wide mutation.
With triploid plants, shit gets weird.
They will still have a gametophyte stage that is half the number of chromosomes as the diploid stage. So if the sporophyte was octoploid the matching gametophyte would be tetraploid.
@@KohuGaly lol uneven genomes throwing a wrench in everything. Thanks! I figured it was something along those lines but it explicitly said diploid and haploid so I was a little confused.
@@Biophile23 sick! Thanks. I was going down that thinking path but the explicitly stated diploid and haploid threw me for a loop. Much appreciated!
I was (foolishly) super sceptical of the title of this video, but omg, this turned out to be so much more interesting than I expected! How is this not covered in high school or even A-level biology!?
I think it is. In modern textbooks anyway
Then there's triploid plants. I know about them because of the fruit trees we keep at home. Triploid plants require two pollinators in addition to the egg cell.
You are kidding.
Are you kidding?
Please be kidding ...
@@CL-go2ji Not kidding. Triploid plants, notably several varieties of apple (only some varieties of apple are triploid) require two distinct varieties other than themselves to pollinate and set fruit. Whether diploid or triploid, all the trees in question need to be in flower during the same window. As it was explained to me all apple trees internally require two distinct varieties of pollen to set fruit but can use their own for one of them. However, triploid varieties don't make pollen or have sterile pollen and not not only need two additional pollinators but can't be relied upon to pollinate other trees. Why then would any of them be used? I don't know the reason, perhaps just coincidence, but many heritage varieties and several of the best producers and keepers are triploid. To accommodate this there are varieties planted specifically to be pollinators even if their fruit is less useful.
Thanks for the info!
I will NEVER understand tree reproduction ... @@ckl9390
Science fiction story with alternation of generations for humanoids: "Your Haploid Heart" by James Tiptree.
I’ll have to look that up, just your brief description intrigues me. I read “Brightness Falls From the Air” and the short story “The Only Neat Thing to Do” for an English class in college, liked them both, but never read anything else of hers. You’ve renewed my interest!
@@jpe1 She was very good, but except for a few humorous stories, very depressing. You've been warned.
@@NancyLebovitz yes, I remember finding “Brightness Falls From the Air” to be rather a downer, especially compared to other SF that I like, such as Larry Niven.
Yes. @@NancyLebovitz
I just saw the news that Hank’s cancer is in remission. I’m so glad to hear that! ❤
I was thought this in my 1st year class of biology in univ. It was so confusing concept at first, lucky my prof really helped me to understand it well
Very interesting. Thank you for sharing.
never expected his voice to sound like that kind of soothing for some reason
I'm confused, what makes those haploid individuals different organisms and not just parts of the sex organs of the parent plant...
The fact that they have a different genome from their parent! In many green algae, similar to the ancestors of land plants, sporophytes and gametophytes are actually entirely separate, free-living individuals.
I think the fern at 3:45 is a good example. Those gametophytes are living on their own outside of the plant. They are their own organism, and their life cycle will culminate in (hopefully) creating more ferns. Other species' gametophytes might stay within their parent plant, but they're still their own Thing operating separately.
It seems like a pretty fine line.
@@karlmuster263 in flowering plants, it sort of is! Male gametophytes (i.e. pollen grains) typically consist of three cells, while female gametophytes (i.e. ovules) are most commoly six-celled. They are not far from having single-celled gametes like we do.
From what I remember in school, they are considered a different organism because in the past (and in some very primitive plants today if I'm not mistaken) the haploid would bud off and become a fully independent organism. It was capable of living away and completely separate from the diploid generation, and often growing to a full size and living in different niches. Over time in some groups, the role of the haploid was reduced, getting smaller and with a shorter life span, until today they are so small that they never leave the parent flower. Functionally they act the same way as a sex organ, but because they were once a separate organism they are still considered to be so now. During the flowering faze, the haploid does do it's own act of reproduction to produce specialized cells the same way it used to in the past.
This is the most interesting video (to me) you guys have ever made really new knowledge to me!
Okay but with phases that lopsided can you really consider the gamete producers separate organisms themselves at that point they're basically like organs almost no different than having ovaries or testes to produce egg and sperm
The best comparison I can make is to the gut bacteria in animals, they never leave the gut, and some are potentially even incapable of leaving the animal, but nonetheless they have different genetics
Ovaries/testes are still diploid and genetically identical to the rest of the body. They just produce haploid gametes. With plants, the gamete-producing organs are haploid already. In case of pollen, they aren't even part of its parent plant, and only produce the gametes once the pollination happens.
Even in animals, you can find cases where one of the sexes to be reduced basically just to a reproductive organ that "parasites" on the opposite sex. It'd be overly reductive to call it just an organ of the opposite sex.
@@determinedhelicopter2948 Sperm and egg cells have different genetics from the animal they come from too, but we don't consider them to be a unicellular organism that is an intermediary generation between parent and offspring. I just don't see these gametophytes as separate organisms, any more than I do egg and sperm as separate organisms, must because they are multicellular and more complex.
And the evolutionary argument doesn't make sense to me either. Bat wings evolved from what used to be hands in predacessor animals, but they have evolved, they are wings now, we don't classify them as hands because of what they were in the past.
@@erinm9445 Perhaps my phrasing was bad. Well, how it used to be is that the plants can 'grow' multiple 'sex organisms' in places separated from themselves, but eventually these had a more and more reduced role in plants, but still present for the plant, basically like if humans made an embryo that then made sperm or eggs and stayed in the body the whole time. So using the bat example, yes the wings are still sorta hands, just with extreme webbing adapted for flight use.
@@determinedhelicopter2948 Thanks for explaining further. To me this all underscores that it's a mistake for biology to continue to classify the gametophytes of seeded plants as an organism or as a generation.
If we humans made little haploid embryos that never left our bodies, and those embroyos made the eggs and sperm, this would seem completely normal to us, and we would not consider those embryos to be intermediate generations, they would just be steps in our reproductive process. Especially if these little haploid embryos looked nothing like diploid embryos we know and love (just as pollen and stamens look nothing like plant embryos, ie seeds). The genetics would be the same as what we have now, just with some mitotic cell devisions in the haploid cell line before you get to the gamete.
And again, bats don't have hands. That's straightforward. Sure, they kinda have hands if you think about it in the right light and understand their evolutionary history, but they don't actually have hands. Seed plant gametophytes seem the same to me.
An episode of Star Trek is forming in my mind about an alien race who reproduce with a gametophyte generation and the problems that arise when the federation contacts them...
Every day, I find something else I have no frigging idea about. Amazing.
Once you find out in elementary school that plants make food out of light, they never seem simple.
well, they use light to convert chemicals into food (and other things), but yeah, plants are neat!
I am a biology teacher, and I can tell you my students start out thinking that there can't possibly be much to say about plants. Poor children 😅
@@robspiess Yes I know, I also knew someone would point that out 😅 (English isn't my main language so I tried to keep it simple, but I'm a chemical engineer so I know how those biochemical reactions go 😁)
very enjoyable and enlightening.
I totally read the title as half of all planets are invisible.
I knew it from school, but never really understood how it worked. Not like I do now but it reminded me of this thing, which is still cool.
Wow. I love learning new things.
Better late than never. Incredible!
This is why the seedbank thats in the top soil is so important. It's not just "oh just put some more dirt there" Where are you getting that dirt from? Is that place filled with weeds?
Such a great presentation. Thank you for the review. Bonnie The Botanist
Oooh, I vaguely remember this from biology class! Unfortunately, this was a class held early Sunday morning, and I fell asleep halfway through nearly every lecture.
As a gardener, I drives me a little batty in trying to convince plants to provide seeds.
Sometimes, instead of waiting for the flowers to fruit, I need to clone through cuttings and then those plants give seeds.
Now, this makes a lot of sense.
I always wondered how gardens managed to grow so many duplicate plants without any changes from year to year
That is mostly to do with cloning by any of a half dozen different means. Very few plants breed true to seed, even if you have homogeneous stock. Plants want to make variety with their seeds because, they (most of them at least) can clone themselves quite readily. Why would they need to waste seeds making more of the same?
Excelent and revealing Botany explanation
Butterflies and caterpillars are different generations, too, though not quite the same way - iirc, both are made at one time and then the butterfly is dormant and undeveloped till the caterpillar makes her cocoon
one of the better explanations of this kinda simple but kinda hard to get your head around phenomenon of alternation of generations
That's part of why I went on to study botany: plants are so inconspicuous, but sooo much wilder than animals.
Very interesting. May I suggest that you do fungi next? Or is that too complicated for a video like this?
I think it makes perfect sense for a stationary species to clone itself and then distribute those clones as a method for mate-finding. It keeps the original copy intact for as long as possible, and moves the area of influence to wherever the new plant lands. 4 is also a great number because the species can distribute one sample to each direction and "move" to the most ideal location over subsequent generations.
[reading the video title] "This sounds like some weird clickbait title but it's SciShow so let's check it out anyway"
[watching the actual video] "THIS IS SO MUCH WEIRDER THAN I EVER COULD HAVE IMAGINED, I NEVER KNEW."
You were not even kidding. Wow.
Half of all plants are invisible, or half of all plants are invisible? I was worried i had been stomping on unseen plants all this time
'half of what plants are is invisible'. Easier to think about? :P
why did you say the same thing twice?
@@mrosskne I didn't. YT's been weird on posts for me and others, though
@@thekaxmax I'm obviously not talking to you
@@mrosskne he's not got two either. Also, my name's not in it=>not obvious.
If it's about the first part of the OP, it's obvious: (Half of all) (plants are invisible), or (half of) (all plants are invisible). Parsing is ambiguous but easy.
Glad you all made this for today, because I've been thinking about Alternation of Generations in plants a lot lately.
I remember learning about the "Alternation of Generations" in high school and it really messed with my brain as I could not keep it straight!
Same here, I bombed that part of the test ....
I didn't know this at all! Thank you very much for expanding my knowledge
The question "What advantage does this give to plants?" is kind of the wrong question -- or at least coming at it from the wrong angle. Plants didn't start out diploid and then evolve a haploid stage later: they evolved from the same unicellular, haploid, asexually reproducing organisms that all multicellular life did.
The advent of eukaryotic sexual reproduction was a complex affair, and involved multiple developmental adaptations. In plants, the ability to form gametophytes emerged first, which we can see in modern species that have retained more basal traits, like green algae, such as volvox. These organisms give us a glimpse at the likely course of evolution that diplotonic plants followed.
To oversimplify, the single-celled ancestors of plants evolved from earlier eukaryotes, which had already evolved the ability to respond to stress by developing diploidy and sexual reproduction. This new stage of life was very useful for adapting quickly to new environmental conditions, including -- as mentioned -- dry land.
Over time, certain groups of eukaryotes evolved to prioritize developmental adaptations in the diploid state. Some, like mosses and algae, continue to mainly stay in the haploid stage, briefly splashing into diploidy for reproductive purposes, while others simply maintain that "excursion" for far longer. Humans have taken that strategy so far that our haploid "generation" can't even survive on its own, and only exists for just long enough to fuse with another haploid human cell!
Thank you! This is the comment I was looking for. A much more sophisticated explanation that gives a more accurate and nuanced picture! (I am not a biologist, just a critical viewer, but aspects of the video were clearly oversimplified).
It does seem like questions of the advantageousness of various strategies apply once this evolutionary history is established. For example, in simpler and unicellular forms of life a preference for the haploid stage has remained--so there wasn't much advantage to leaning into diploidy--which I assume is costly? Whereas leaning into diploidy seems to have been essential for enabling more complex life forms.
In this sense, both seeded vascular plants and animals followed the same strategy--by different routes and on different timelines--evolving to a place where the haploid phase is just a transient part of the sexual reproduction process and the haploid "generation", as you say, can't survive on its own; though plants' haploid generation is much more complex than for animals. (Spore plants can be seen as an intermediary step in this evolution, where they've mostly made this transition, but the haploid generation is able to have an independent, planty existence). What does and doesn't count as a generation for parent/grandparent purposes really becomes a matter of human definition at that point, and to me, "can survive and do life things all on its own" seems like a good line, but biology seems to have settled on something like, "can grow from a unicellular to a multicellular structure?" or perhaps "has an evolutionary history in which it used to be able to survive and do life things on its own."
I am curious though: in the evolution of sexual reproduction in animals, did very early animals or proto-animals have the equivalent of gametophytes, or did the animal lineage start with single-celled haploids right out of the gate? Or do we not know?
I wonder if this could be manipulated to allow apples to be selectively bred? 6:53
Yessssss!! The public needs to know about the sporophyte gametophyte 2 part lifestyle of plants
There's something so wise about alternating processes through generations. And the notion that spores spread further than gametes but gametes have a more 'stable', but still changing, genetic story (I could be thinking about that wrongly).
Thinking about culture and age groups and generations, leveraging cultures' different ways of doing and being, and different ways to transfer knowledge and information across various distances could be good way to maintain and develop cultures over time. Spread and consolidation happening simultaneously, both always dynamic. As a young spore, going to other cultures and sharing the information of your own culture, and adapting to their culture. Coming back to your parent plant / culture of origin and sharing those learnings. Simultaneously, other 'spores' have come into your parent plant and shared their information, altering the culture. When you arrive home, you have to adapt to the changes made and they listen to the information you have and then you become part of the parent plant as other generations go off as spores.
this kinda feels like an efficiency thing!
it seems easier to just produce "half an offspring" with less genes, solely for the task to "build" your offspring! even tho it seems weird, it also kinda makes sense!
I feel like you captured the essence of the video in just a few sentences. Well put 👏
Isn't this exactly what animals do to? We produce "half an offspring"--it just happens to only have one cell--solely for the task to build our offspring, no?
@@erinm9445 have you even watched video?!, u might need to rewatch again & try to understand the difference!
@@mho... Yes, I've watched the video, and spent a lot of time reading through and pondering comments. I'm unconvinced that there's really much of a differerence between gamophytes for seeded plants and gametes (sperm and eggs), except that one is multicellular and the other is unicellular.
For spore plants, it's different, since their gamophytes actually live independent little plant lives totally on their own, before reproducing. But for seeded plants, can you explain the difference to me, aside from uni/multicellular?
Same number of genes, different number of copies per organism.
That title sounds like it came from the botton tier of a fringe conspiracy theory iceberg.
Thanks for adding to what I learned in school so long ago!
Thanks, I have to write an exam on that topic next week! :D
This is so strange to me lol it's like having babies with extra steps, kind of like the face hugger of the xenomorph life cycle
Is this the reason heritage corn has different colored kernels? Because each kernel is basically a different grandchild of the original plant?
It is because each one has to be fertilized individually, so the color changes based on what fertilized the kernel.
Despite talking about diploid/haploid, many plants have more than two gene copies (even up to pentaploid, hexaploid, heptaploid, octaploid, etc.). How does this process work with polyploid plants?
It depends. Usually the haploid generation simply has half the chromosome sets of the parent generation. Sometimes the haploid generation does get reduced all the way to single copy of the genome. Plants with odd number of gene copies are usually infertile.
What a beautiful voice Reid, nice video too, but what a beautiful voice...
This seems like a bit of a stretch. The difference of one cell (in animals) and a handful (in plants) seems like hair splitting when calling one an alternation of generations and the other not.
It seems like it, until you pick up a fruit, test it genetically and realize it's actually composed of cells that come from several genetically distinct individuals. Some parts are the actual diploid embryo, some parts are its triploid sibling, some are its haploid mother and the rest is its diploid grandmother. Which parts are which and in what proportion varies by species.
@@KohuGaly I still feel like one can easily imagine an equivalent in animals, in which, say, the menstrual lining was made of a mix of diploid maternal cells and haploid cells descended from the egg and/or sperm. That isn't how animal evolution went, but in theory it could have gone that way, and it's easy to see that that wouldn't make the sperm/egg the father/mother (and the parent really the grandparent). Reading around on the web, it really seems like the main reason biology has decided that gametophytes are a generation and an organism is because they are multicellular, and seems really arbitrary to me. I would say that makes them a haploid sexual organ, not a separate organism. It's different in the case of spore plants, where the gametophyte has a whole independent life that it lives.
I also just looked it up, and from what I can tell it sounds like most fruits develop from the plant ovary and contain the same diploid dna as the rest of the plant, but some fruits develop from other structures of the flower, and it sounds like in some cases that includes the gametophyte? Which fruits are these? Just curious on this one!
what's the different between a plant spore and plant gamete?
spore is a single cell that directly grows into an organism. Gamete needs to fuse with another gamete (fertilization) to form a zygote that grows into an organism. Reproduction through spores is asexual, because the DNA of a child comes from a single parent.
This video made me remember learning this in biology class like 25 years ago.
5:00
It's me. The Surprise from nature.
Child: *Mom? I’m bored of playing Marco Polo. Can we play find the invisible cow this time?”* Mom: *What? Where are you? I don’t want you to get lost in the mall again looking for glucose*
Very cool video. Thank you for sharing. Any plans of going to Nebula?
Nature: Hey plants, I've invented serveral methods of reproducing. Which one do you want to use to conquer the earth?
Plants: yes
Nature: Well, you have to deci-
Plants: YES!
Nature: Ok *sigh
Why are haploid phase/diploid phase considered separate generations? Isn't it similar to animals growing sperm and egg cells in organs in their bodies? Similarly, flowers/cones can be considered as a separate organ meant for reproduction rather than separate generation, right? It's still confusing.
Amazing one.
Saying that people don’t notice pollen for the most part feels unfair to everyone with allergies
Annnnd, Sci Show makes my teaching easier, yet again!!!
How does this play out for tetraploid plants like durum wheat (Triticum durum)? Are the sporophytes diploid?
Yes. Although stuff can get weird with polyploid plants. Sometimes the mutation-preventing mechanisms kicks in during meiosis and the gametophyte gets properly reduced down to haploid state. The seeds are then diploid like normal.
Had a feeling this would be about the alternation of generations. One of the things that actually changed how I perceive life in undergrad. Haha
great video. your voice sounds like the midpoint in a gradient from neil degrasse tyson to dennis prager.
This is just one reason why plants have a much longer genome than humans
That just sounds like one generation with extra steps
😮 Oh boy , have no idea plants have such complicated reproduction processes ... 🌷🌿
Ok but what about all the polyploid plant species?
I love this host. :) I mean they are all pretty cool honestly but this guy is awesome 🎉
damn. read the title and really hoped they finally found out about plants that only reflect infared light
I knew ferns did this but I didn't know it was all plant. I guess that explains why plants are more evolved then the other eukaryotic kingdoms of life.
Wonder if the creators of Aliens took inspiration from this. Eg. The facehuggers are gametophyte, the queen is sporophyte.
I think the inspiration for the Xenomorphs of Aliens was largely a parasitic wasp. With the larvae eating the host from the inside out. Though the haploid thing also makes sense because, as seen in both the third Alien movie and the Alien vs Predator movies, we see that the larvae which is deposited by the face hugger takes on traits of the host. If the face hugger is a haploid organism that is functionally similar to an endosperm, in this case who's task is to deposit it's twin sibling to a host. And the larvae is also initially a haploid organism that not only incubates in the host but literally rips off significant portions of the hosts genome to fill the gaps and instantly adapt to whatever environment the host is native to. Or maybe the face hugger does the gene splicing before depositing the complete embryo of the larvae to incubate and falling off.
To what extent is the extreme case not a reversion to a single organism? In ferns the two plants are more obviously different organisms, but in angiosperms are they necessarily two generations or could the gametophyte not just be considered an internal organ of one individual?
What makes is a single organism and not a compound...
What makes it a single organism is the fact that is has genetic material distinct from its parent. The genome of the gametophyte is produced via meiosis (including crossing over) - its chromosomes are not identical to the parent's chromosomes.
You could argue that the female gametophyte is "just an organ", but for the male gametophyte (the polen grain) that argument doesn't really work, since it lives its live detached from the parent plant.
@KohuGaly yeah thats the main idea, though its insufficiency does show up. an extreme example: chimeras and mosaics are not uncommon, where one organism has two or more sets of genes, sometimes from mutation and others from embryo fusion. cancer also has different genes to the rest of you.
more generally, cloning raises an issue: the most common ant, black crazy ants, do something wierd where the queens and males maintain their own sex by cloning: the queens are all clones of each other, and the males clones of each other, and those genes dont mix. mieosis only occurs for the workers, which themselves can also clone themselves without meisosis.
Are the queens all the same individual? One could extend this to asexually reproducing bacteria and so on too.
As for indepenedence: Pollen lives its life *mostly* off the stamen, but cant eat except for its stored nutrients, not really any different from sperm.
In what way are they invisible though? I didn't quite understand that part. Are the haploid stages invisible?
They are invisible to the naked eye, because they are either too small to see or hidden inside its parent's flowers. However, the statement that it's half of all plants is not true. The gametophytes outnumber sporophytes 1000:1 at minimum. Note that every pollen grain contains male gametophyte and every flower usually contains several female gametophytes.
I heard that mosquitoes are involved about this transferring to thing two thing to give it life is it true?
What about dioecious plants like juniper, hops and cannabis?
Could we recover extinct plants with preserved pollen? (like in amber or deliberately preserved ones)
we have done this. Although with frozen spores, not amberised.
@@thekaxmax yeah I'm wondering how ling it lasts, pollen is relatively stable so it could be actually pretty promising for some pretty old plants
@@thekaxmax although I can't find anything about doing this to an extinct species even wirh frozen samples, I mean I believe you but if you have a source I love ecology and genetics so I'd live to peruse is
@@ConstantChaos1Pollen from the last major ice age has been grown, unexitincting the plant involved. But DNA has a half-life.
@@thekaxmax unfortunately even with those specifications I can not find any papers about it, the best I can come up with is bringing back aincent Silene stenophylla from seeds sealed in permafrost can you provide any actual information about it so I can look harder? I'm trying to meet you half way but I can't find anything about it so if you or someone else knows that would be helpful. Do you at least know when this was or where you heard about it so I can narrow down the search parameters