Transcript for:
Plant Diversity Lecture

all right so this chapter is gonna be the first issue chapters were talking about plant diversity we're gonna get into a little bit of the history of plants and terms of how they've evolved and the different parts that they have that have allowed them to be able to live on land and we'll start getting into some of the phyla that are associated with plants so for the first three billion years there was not anything living on the ground on earth cyanobacteria they believed started to exist around 1.2 billion years ago and then around 500 million years ago it was when we started to see some form of plants and fungi and animals on land and obviously once they got ahold of land started colonizing it they have diversified so the land plants that we have now have some form of terrestrial ancestor some land plants are now aquatic but even if they were aquatic plants they had a terrestrial ancestor at some point they don't include the algae and they are a source of oxygen and a great source of food for land animals the charophytes that we talked about in chapter 28 the green algae are the closest relatives evolutionary wise to land plants and a lot of the characteristics that we see in the land plants we will also see in the protists class especially with the algae land plants is share four traits with the Chara fights the rings of cellulose synthesizing complexes peroxisome enzymes flagellated sperm and a fragment Plast so the if we look at their nuclear genes and the chloroplast genes which are fights are the closest living relatives of land plants but they are not the land plants are not descended from them they just share that common ancestor so there's the Chara all right and then there is a land plant that lives in ponds okay hora fights have a layer of durable polymer it's called spore apollomon that keeps their zygotes from drying out we see this also in plants for walls so there are benefits to moving on to land by the terrified ancestors lots of sunlight lots of carbon dioxide soil that had not been used it had lots of nutrients in it not a whole lot of herbivores or pathogens things that could destroy the plants but there were issues in terms of water and not having the support of water to be able to stand - some of the traits that they've accumulated were again to be able to survive on land and allow them to continue to colonize it there's some debate about the plant kingdom boundaries whether the algae should be a part of it and so I'm totally fine with y'all referring to plants as it came them but you will also hear them called embryo fights because they are known as plants that contain embryos okay so this is just kind of giving you showing you the relationship with the red algae and the chloroplasts and the Kotaro fights and the embryo fights aka our plants the plants again we're going to be focusing on and seeing what traits they have evolved over time for plants while they have colonized land okay derived traits traits that are present only in the plants but not in the charophytes oscillation generations that we've talked about previously in terms of their cycle multicellular and dependent embryos the wild spores that are produced in sporangia the multicellular gamete an Jia and the apical meristems and we'll talk about each of those cone up so first thing we look at are the alternation generations how they go between the two multicellular stages now mattified is haploid and can produce haploid gametes by mitosis otherwise just copying its chromosomes while fusion of the gametes gives you the diploid spore fight and then the diploid sporophyte can produce haploid spores by meiosis so that's where we're getting the genetic variation and the diploid embryo is held in the female gametophyte and then nutrients are transferred between the two by placental transfer cells and we talked about how the land plants are called embryo flights because the embryo cannot exist on its own and it has to depend on the parent alright so we've seen this one before going back to our meiosis chapter the Wold spores the sporophyte produces spores and organs that are the sporangia the diploid cells called spore sites will be able to go through meiosis to produce haploid spores and those four walls will contain that spore apollomon which helps them to be able to survive in environments that are not necessarily the best for them okay so there's an example showing the pictures a cross-section of the spores and the spring ham and then the difference between the sporophyte and the gametophyte in moss sorry multicellular gamete an gia gametes are produced within these this is how we get the female and the male parts of flowers the female gamete engineer called Archie Gonia those are the ones that produce eggs and where fertilization takes place the male gamete and year called antheridia some anthers and they're the ones that produce a sperm okay so again this is just looking at a liverwort seeing the difference between those two apical meristems plants are able to grow in part because of these apical meristems are found in your roots and your chutes and they allow additional leaves to be able to be formed especially right now we're seeing a lot of perennials start to come up because of the nutrients that are being stored in the meristem so that they can make the proteins they need to for the plant to be able to growth some other derived traits are the cuticles what we see on the cover of our leaves is what we had to why we had to take the that we use in our photosynthesis experiment and put them in with a little bit of detergent to try to break through that cuticle layer mycorrhizae symbiotic associations that help the plants to get the nutrients they need in their roots and then there's other secondary compounds that prevent herbivores and parasites from eating up the plants again we said that there's fossil evidence that plants have been on land for at least four hundred seventy-five million years because we found some and some rocks and that they've these a small number ancestral species that were out there have given rise to or gave the origins to all the different plans that we had today okay so there's looking at it from a timed perspective one is where the land plants showed up to about 50 million years laters when we had vascular plants show up and then about a hundred and twenty million years after that is when we started to see the plants that we have in existence today the gymnosperms and the angiosperms in terms of the seed plants and then we obviously still have the seedless vascular plants the mosses the lycophytes and the ferns and the Terra fights and then we have the nonvascular plants and we'll talk more about the seed plants in our next chapter but the liverworts the mosses and the hornworts and so all of these make up the land plants and we typically group land plants based on whether they have vascular tissue or not majority of them do the ones that don't are called bryophytes this is not considered to be a monophyletic group there are some relationships still to be determined with this the seedless vascular plants as opposed to the seated vascular plants can be divided into class they're paraphyletic but typically they're in the same organizational level even if there's a different number within those different types so we've got the lycophytes and the tariff is there the seeds are your embryos and then the nutrients that it needs are surrounded by a coat the see plants are their own cloud and they can be divided into the gymnosperms and the angiosperms the gymnosperms would be the seeds that are naked at conifers and then the angiosperms are your flowers or any of your plants that have flowers so those are examples of some of the living phyla and I know with the plants you are going to be focusing more on phyla I don't remember you doing all of these but I know that I think the bryophytes were separate and then you joined avascular and the the gymnosperms in the annuus angiosperms the seedless the gymnosperms the angiosperms okay no I didn't mean to put questions on here sorry about that so the next section where you talk about spry fights we have the liverworts the hornworts and the mosses there is a difference between bryophyte and bryophyte a bryophytes referring to the plants that aren't vascular bryophyte a-- is the specific file in formosa so and like we ran to the last chapter with Plasmodium be careful what you say so this is getting into how the bryophytes are able to be reproduced I am NOT getting into this much detail with you all given the period of time we're in so if you want to read about it feel free Aires is fertilization meiosis cycle and then again this going into a little bit more of the different forms of bryophytes they're the simplest of the bunch it talks a little bit about this some of them have stomata and others don't okay pictures mosses mosses can live in all sorts of environments they are often found in wet environments moist forests wetlands they can help to retain nitrogen peat moss you might have heard that refer that refer to it before it can be a fuel source and also source carbon so if you have too much of the sphagnum the peat taken out you can release a tremendous amount of co2 into our atmosphere and cause all sorts of not-so-good effects okay I don't know why didn't take all these questions sorry guys ferns other seedless vascular plants first to get taller so we've been dealing with small plants so far the bryophytes were around on bryophyte like plants for the first 100 million years when plants a started to evolve and then we started seeing vascular plants in the Devonian and Carboniferous periods which allowed these plans to get taller the seedless vascular plants have flagellated sperm and are restricted to environments that are more moist these date back to about 4 and 25 million years ago these early tiny plants had little sporophytes that allowed them to branch independently and so they are characterized by having life cycles that focus on those sporophytes having those eylem and phloem and having well-developed roots and leaves we didn't really talk about those so much with the last the bryophytes so something did something to consider it's kind of unique the vascular plants as opposed to the broadside okay where the bryophytes the sporophytes that are seedless vascular plants are in the larger generation so that's kind of opposite that of the bryophytes the gratifies are the tiny plants that will grow either on or below the saucer the soil service so again there's just another cycle of their life cycle for the vascular plants that are seen less okay so they can have a silent phloem xylem is what takes up the water in the minerals and they are strengthened by lignin phloem is what helps to take up the nutrients and these to work in concert to help plants to be able to grow taller and allowing them to have advantage evolutionary speaking okay roots help to anchor your vascular plants they help them to absorb water and nutrients and it's thought perhaps that these came from subterranean stems ones that were growing below the soil service leaves help to increase your surface area capturing more solar energy you can have microfilms would have a single bank and you can have mega fill leaves that have a highly branched vascular system present thought possibly micro fills came from stems and that mega fills evolved as webbing between flattened branches so you're seeing how kind of everything has some sort of connection to being able to survive and continue to thrive so there are examples of micro fills and there's examples of mega fills or at least a hypothesis behind it too so sporophylls are leaves that have the spring guy on them and then we talk about surahs trouble a seedless vascular plants are homeless forests so they make one type of spore that can be either female or male as a commodified the seeded plants and there are some seedless vascular plants are heterosporous which can bruise this megaspores and microspores the megaspores lead to the female gametophyte s' while the microspores lead to the male command fights okay so the two phyla that fall under the seedless vascular plant section are the Lika fighter and the terrified o we talked about those a little bit earlier so the like a fighter again are your mosses and the terrified are your ferns like Oh fight trees lived for many many many many many years and my swamps and the small herbaceous plants that exists now are the ones that's made it through that Club mosses spike mosses don't have the vascular tissues so they are not considered to be mosses and the true extent well the terrified it with the ferns there's a lots and lots of different types of ferns they're very diverse in the tropics as well as temperate forests and the wisk ferns are look a lot like the ancestral vascular plants but they are definitely related to your modern ferns so the ancestors of these lycophytes why these seedless vascular plants are being talked about so much is that they help delete to the first forest once they got growing in the demoniac Devonian and Carboniferous periods they growth in the photosynthesis that was generated as a result helped to take co2 out and help to cool the planet down and when these plants started to decay and they gave us sources of coal okay and that would be the end of chapter 29