All about flowers - with Pamela Soltis (University of Florida)

today it's all about flowers we talk about the origin and evolution of flowers and some of the strategies and trade-offs that they use in order to adapt to their environment including some of their defense mechanisms that they use as well as some of their strategies for attracting pollinators like why they are certain colors then we have a nice discussion on environmentalism and some of the issues related to that including climate change and invasive species and how that affects some of the local ecologies of [Music] flowers if you would talk a little bit about your expertise so hi I'm Pam suus I'm a curator and professor at the Florida museum of natural history at the University of Florida and my research expertise is in plant evolutionary biology so I started out being particularly interested in the process of speciation so how to new species arise what are the processes involved what are the genetic consequences of different types of species formation and that led me into really thinking a lot about Fields such as hybridization and polyploidy which is the basically genome duplication process and um those sorts of questions have stayed with me over the course of the last you know 40 years or so but um there are a number of other things that have also taken um you know sort of a a major place in my research program and one of these has to do with how plant groups are related to each other and this goes back to a very formative moment in uh when I was in graduate school we read a paper I even still remember this paper this is probably the fall of 1983 we read this paper in this one um discussion class the seminar class and it was about the genetic Divergence between these two species of some sort of insect I'm thinking it they were like walking sticks or something but I can't remember for sure but one of the criticisms that one of my classmates made was well this is an interesting paper but um how can we talk about speciation between these two things if we don't actually know how they're related and I remembered saying well the authors say that these are closely related and this other classmate kept saying but there's not a philogenetic tree so or an evolutionary tree showing relationships nobody has done that for this group of species so if we don't really know that things are closest relatives how can we actually study speciation and that just like totally changed my perspective on everything so I added a philogenetic analysis or family tree sort of analysis to my dissertation and I did that for the group of plants that I was studying in studying at the time and subsequently that's like snowballed and we've been spending a big chunk of our research time and expert over the last several decades trying to figure out how different plant groups are related to each other so and then that really can just provide a framework for understanding anything that you want to know about plants like how did this character arrive well or arise well you go back and you look at your tree and you say Okay given this family tree it must have originated here it Diversified there and all of that sort of things so it's like using you know a Human family Tree to understand where your traits came from so most of my work has been sort of focused on the concepts of speciation and family trees and how we can um put some of those things together to understand um how new species originate how they diversify where they go how they coexist all of those sorts of things but there's this sort of family tree framework behind all of it I imagine your field has changed quite a bit uh with the new tools the genetic tools that we have yeah yeah definitely yeah the genetic tools that have originated I mean sequencing was a dream back when I was a graduate student and now it's like routine and the other thing that has changed dramatically is computational abilities so the sorts of computational power that we have now you know couldn't even imagine we used to run um these certain Family Tree reconstructions on our you know old Apple macintoshes and you know you would would set it up and you'd put a sign on it that says please do not turn this off and it might run for months in order to get through but the software was only written for for those um old Macs um and now of course we can run it on you know super computers and all of that sort of stuff so things yeah things have changed dramatically the reason sort of the hook that I thought of for why why I wanted to talk to you to begin with was uh I guess something sort of obvious that everyone knows that flowers are meant to attract pollinators and that sort of their function but it kind of struck me that that's actually quite an odd thing in nature most things they they're trying to hide from predators they don't want to be seen But flowers advertise themselves with all colors and shapes but they also smell and they do all these things and they really want to attract attention so I I thought that was kind of just an interesting way to jump things off yeah no I think that's fascinating I mean flowers are really amazing and um and as you say you know most organism um don't advertise themselves if they do advertise themselves it's to make themselves look like something else right so that they they make themselves look like something that's deadly so that they can um Escape predation that way so flowers are really unusual they're also really unusual even among all plant groups because other groups of plants that don't produce flowers like our you know conifers and um you know other gymnos sperms and our Ferns and things also don't have particularly flashy reproduction and they don't generally involve the um activities of other organisms I mean it is true that some pads are Beal pollinated and benefit from certain um insects but most other plant groups do not have this sort of relationship with pollinators and so you know it's pretty spectacular when you think about the fact that you know we've had land plants for oh let's say 450 million years and it's not until the last maybe 150 million years or so that there were flowers and the number of flowering plant species is so much greater than all the rest of the um plant species combined so certainly over this you know shorter time span of the last 120 13050 maybe million years the the flower has definitely conferred advantage that have allowed for this crazy amount of diversification that has allowed all these species to originate and to um spread yeah so let's go from there then so flowers so you just said that they're they're very powerful tool that plants have and it's for sexual reproduction so I guess that would be my first question is what's the benefit of plants that reproduce sexually and then why why are flowers such a powerful tool in in doing that um sexual reproduction is really important for uh long-term adaptation and evolutionary longevity we might say there's been a lot of theoretical work for decades about the so-called advantages of sex and um but there are also disadvantages so it's expensive to go to all of this trouble to have separate sexes in terms of organs and processes and everything and this is true whether it's a plant or an animal and over the short term asexual reproduction could be beneficial so if an individual genotype is perfectly suited to its um environment it's great if there's just a sexual reproduction it's cheaper it's faster and it provides um you know that sort of good linkage between environment and organism but in an environment that's changing and whether that's changing temporally or changing spatially um it's much better in the longer run to have the mixing that takes place when you have sexual reproduction and so sexual reproduction generates new combinations of genetic variation and so there could be new combinations that would be um better suited to different aspects of the environment so over the long term sexual reproduction is um generally considered to be favorable so that's what happen happens in you know most of the animals we're familiar with it happens in um most um land plants as well but it is very costly in terms of flowering plants especially those that produce these you know very showy flowers that produce a lot of either nectar or pollen as rewards so a lot of resources have to go into that um in order to attract the pollinators to want to visit and then to affect pollination in the process so the the benefits must outweigh those costs or there would be selection against that I do want to focus on flowers here for a while we'll get to the cost benefits in just a bit I want to talk just super basic I know most people are familiar with flowers and I'm sure they learned about in Biology class in school but just you know get everyone up to speed with like just the the features and the function of a flower oh yeah so so flowers are so spectacular because they're all built from the same um basic building blocks um and yet different species have modified these different parts in such different ways so the basic flower consists of seil on the outside those are usually green and they protect protect the rest of the flower when the flower is still in bud so that's sort of that's our first component that's the outer part the next component is the pedals and the petals are typically the showy part the colored part and they um you know are the next in line and those are largely what provide the attractive feature for the flower in terms of attracting pollinators but they also provide um some additional protection for the actual organs that produce the gametes which are in the center of the flower when the flower is still in bud so once the flower opens the seils are on the outside the petals are next and then the third component um would be the stamans and the stamans consist generally of two parts there's a stem um of a Stam which is a little stock called a filament and then at the tip is the anther and it's the anther where the pollen is produced and that pollen can take all sorts of different forms there can be different amounts and everything but ultimately what that pollen will produce after a little bit more development the pollen will produce the sperm cells which are important for ultimately um having fertilization so that's our we got the seel the petals the STS and then in the center of the flower is the carpal and the carpal is a single unit um sometimes there are multiple carpal that are fused together and then that is often referred to as the pistol so some people you know learn the fourth sort of central component as being a pistol and and that's totally fine it's just that the pistol is often formed from you know multiple carpal so I like to think of the actual component parts of that carpal but the carpal has it as its B Bas it has the ovary and it's in the ovary where the ovules are produced we'll come back to ovules in just a second and then there's sort of a stock above the ovary and that's just um an elongated portion of the carple or pistol and then at the tip is the stigma and the stigma is the sticky sticky surface where the pollen will be deposited and whether that pollen is deposited by wind or by a pollinator you know that may vary among species but it's that sticky Sur surface of the stigma uh where the pollen is trapped so what happens after pollination is that pollen will land on the stigma and then it germinates and it grows down through the style which is that elongated part of the carpal all the way down to the ovary at the base and within the ovary are these structures called ovules and it is the ovule that will ultimately produce the egg so we've got this pollen grain germinating down through the style it enters the ovary and there's depending on the species some cell divisions that take place and that pollen grain will produce um two usually two sperm cells and those sperm cells then have specific roles once they get inside the ovary and this is so amazing it's just like you know where did this come from right so within the ovule which is in the ovary there is an egg cell and then there are a few other cells and depending on the species there might be a total of seven cells or there might be a total of five cells varies a little bit the typical number is seven cells so one of those cells is the egg and one sperm cell unites with that and that makes the zygote which will develop into the embryo and the next plant but that second sperm cell is not wasted in fact it forms has a very very important function it will Unite with the two nuclei in the center of the OVU so this OVU remember let's say in this example has seven cells the middle cell actually has two nuclei so second sperm unites with those two and that forms a really important tissue called um endosperm and it produces the nutrition for that developing embryo so you end up with after fertilization takes place you have a zygote which will become the embryo in the next generation of the plant and then you have this endosperm tissue so when we think about a flower we tend to think of this as being this showy um you know amazing sometimes really um highly specialized structure its role is to attract the pollinators and everything but it's so highly functional so all of this is um has been selected in such a way that it's not just attracting the pollinators but it get once it gets that pollen then this whole process of what we call double fertilization because there are two Fusion events that take place all of that takes place right there in the center of the flower just these um amazing um fine-tuning of these different processes that will yield ultimately a fruit the ovary will ripen into a fruit and the OVU will develop into a seed all right there in the center of that carpal in the center of the flower inside the stams and the petals and the steples and then the does that happen multiple times for each flower or that happens once so usually within a within a single flower there will be probably a single this is a little variable but probably a single um episode of like what I just described but some flowers may have um multiple carpal or a multi-p parted pistol so that the same process might happen multiple times in these different carp in the center of the flower um and then other and sometimes there might be um you know there there could be lots of ovules within a within a single carpal so you could have a lot of these events actually taking place so you could get a lot of seeds produced within a single fruit you can sometimes get multiple fruits produced from sort of within a single flower and then of course as you have multiple flowers it's happening all across um a single plant then I read uh there's sexual dimorphism in some flowers as well so they actually have different features is that right yeah so um so the way that plant species actually put these different um component parts together into flowers is highly variable so sometimes you know all four of those structures the seil petals um stamms and carpals are present in a single flower that's the typical situation but sometimes maybe the petals are missing and you know maybe for a wind pollinated plant they've lost their petals um but sometimes you also could have unisexual flowers and sometimes those two different flowers look alike except for just not having one of the sexual reproductive structures or the other but sometimes there can they can also um have appeared differently and sometimes that's related to pollination as well so there might be a flower that um like there are some orchid species that mimic insects mainly bees and wasps I guess um and they will do they will produce scents that will mimic the pheromones of the pollinator and so you know a bee or a wasp will fly into this flower and uh a male will and try to mate with the flower um and in the process it does very effective pollination there's not always the sexual dimorphism of the flowers associated with that but it's definitely related to the reproductive systems you said something before you amazed that the just the complex structure and how functional the flowers are and I was wondering do we have that evolutionary story of like how flowers sort of came to be yeah that's an awesome question um so when considering the fossil record of um the flowering plants Darwin referred to their origin and early diversification as an abominable mystery and we still are not very clear on how this uh structure of the flower um originated and um became like so quickly entrenched in the whole lineage that became the flowering plants I think the fossil evidence best tells us that the first flowers they had these same basic parts but they were very small they were maybe potentially insect pollinated but maybe wind pollinated there are some fossils that suggest sort of maybe a transition from being um a gymnosperm with naked ovules to something that was you know sort of a flower where there is the reproductive structure but with like a little called a cupule around it but we still really don't understand that um what we do know is that by 125 million years ago there were the most common group most common big group of flowering plants today our group known as the U diecuts so e e diecuts the true diecuts in other words they were everywhere around the world world we have fossil pollen that corresponds to the udy cuts almost everywhere in the world at 125 million years ago so at some for some reason they were able to spre the plants were able to spread really rapidly and we have this the history of that in the fossil record through through pollen but at that point even those fossils have very indistinct sorts of flowers so they must have started out somehow like that um and but then by let's say 110 million years ago we have a lot of groups of plants that we would recognize today as like oh that's a magnolia um that's something in the you know in the uh avocado family so there were a lot of things that were actually sort of obvious um very quickly after those other things originated so we don't really know how they got started there's some interesting work about some of the genes that control some of these organs and um through comparisons of those genes with non-flowering plants we can see that those genes were active in the non-flowering plants but they didn't produce those structures so we know some of the genetics behind the structures of the flowers but we don't know what the signals are that that basically you know led to the evolutionary switch okay yeah we'll go back to the the trade-offs and sort of the how how you build a flower and what are all the pressures that the the plant you know kind of has to consider I guess um when it's when it's building a flower in terms of their environment their predators you know whatever else yeah so we um we recognize what a lot of the adaptations of flower parts might might be in terms of their attractiveness their protection their promotion of wind pollination versus insect pollination there are a lot of things like that that seem like obvious adaptations but a lot of those things are um very expensive to produce so it takes a lot of energy to produce a lot of nectar to attract a certain type of pollinator it takes a lot of energy to produce the pollen to for a pollen collecting um pollinator and even for wind pollinated species like a lot of grasses they produce tons and tons of pollen because that pollen is just going out into the environment with no specified place for it to land and so it's like totally chance that it's going to land on an female parts of another flower so there are huge Investments That flowering plants make in order to assure that there is uh reproduction through these um methods but it must be beneficial or none of this would be taking place so what might be the benefits well one benefit is certainly the the benefit of sexual reproduction which can contribute to enhanced opportunities for adaptation to different environments so for a widespread species it might be beneficial to be able to generate different combinations that would be adaptive in different environments also in environments that change a lot either spatially or temporally having these different combinations could be beneficial and you know for the most part we don't we don't necessarily know what the conditions are that led originally to the origins of particular floral structures but uh we can hypothesize after the fact you know oh maybe this was an advantage for that a lot of times we can't actually do the test um and so the testing comes through different types of um mathematical um modeling and through simulation so you can say okay what happens if you invest this amount of res ources in a flower um but you know you only get this much benefit what's going to happen on the long term or something like that so you can investigate some of these sorts of things from from a theoretical standpoint um because we can't go unfortunately we don't really have the right time machines to go back and see what things were like at the point of origin guess just the the colors is an interesting feature to key in on why why are there so many different colors yeah the colors that plants prod produce are amazing um and then you know I think it's always kind of fun but also important to think about what the colors are as we see them versus the colors that U potential pollinators see them as a lot of animals you know don't see colors or they only see certain colors or they see colors in a certain range um they don't necessarily see what we're seeing so for a lot of plants that are um you know we might look at them and we see blue it's the underlying pigments that matter to the pollinators are not the blue pigments that we see but instead they might be um the yellow pigments that underly the the blues that are there you know some people working on certain types of pollination biology will actually photograph flowers under ultraviolet light or under different types of light in order to uh get a better um handle on the uh what different potential pollinators might be seeing and a lot of times even the you know we might look at a flower and we might see on the petal that it's just yellow but a pollinator might actually see these little St Stripes um that are there because there are stripes in the other compounds things that we don't see but that are obvious to the pollinators and they're like little Landing strips that sort of guide the the um pollinators in toward the center of the flower so there's there's a lot you know I keep saying this I guess there's a lot we don't know about uh flower pigments I mean we do know that there are a couple of broad classes of pigments that flowering plants produce so the main category that plants use for things like Reds and blue pigments those are called anthocyanin and they're um very widespread category of compound they're related to some of the secondary defense compounds that a lot of plants make and um and there small deviations in those flowers you know or in those uh chemicals will yield blue versus pink versus you know red or purple sorts of flowers um there's another broad category called Balin and those are all restricted to one particular group of plants but they're also highly diverse but they produce the same colors as the antoin Reds Blues pinks and purples and things like the um cacti have um produced that um particular class of compounds and then there are compounds that are in the yell that are various shades of yellow um that are often produced as you know what we could kind of think of them as background color um because they're produced even when there are these pinks and blues and reds um that are produced but we we don't see them unless there's a mutation in the red colors it doesn't get um produced so so there's you know there's a lot of chemistry that goes into um also into building flowers in terms of their color certain pollinators that are then of course attracted to um different colors so we think of um hummingbirds as being attracted to generally red not always but generally red tubular flowers um a lot of bees will visit blue or or white or sometimes even yellow flowers um but and then Hawk moths uh will visit typically white flowers and white flowers that are open at night and the hawk moths will visit for um nectar you know there are a lot of these um syndromes that don't hold up 100% but that are General categories of uh pollination so certain flower colors and shapes might attract a certain pollinator and that's always a good hypothesis then for what the pollinators might be because in most cases we don't actually know what the real pollinators are okay that feeds well into my next question I was wondering why flowers would select for specific pollinators to my thoughts it would just be the more the marrier you know the more things you can get in here the famous case is the the Darwin flower right the flower that's we hypothesized there must be this animal because it needs to be pollinated by something with a very specific tool to get into the flower and it just seemed weird to me that a flower would adopt the these features to exclude everything but like one one pollinator so yeah yeah no really so I mean I guess some of this is sort of just reflects that natural selection doesn't always follow what we think might be the best strategy right so um I would say there are generally multiple ways to solve a problem so the problem is Assurance of of pollination and and reproduction there can be selection on a number of different ways of going about that so one strategy that some plants have is to be generalists and they actually don't care who their pollinators are as long as it's something they'll produce a flower that's you know very open that has you know moderate amount of pollen or Nector and stuff and you might then get a bunch of different things like a bunch of different types of maybe bees um maybe some flies and things and so through having this generalist strategy you tend to maximize your pollination likelihood but then there are other species as you mentioned that have this oneon-one relationship with a pollinator and that might work super well under super under certain conditions because that pollinator is only going to visit that plant and that means that okay you know that there's there will be visits but if something happens to that pollinator then there could be um some serious um repercussions for the plant plant and vice versa and actually it's interesting because this is something that we're seeing right now with climate change is that plants and their pollinators are not always responding in the same way to changing temperatures so some plants are flowering earlier and flowering longer than they did previously we have lots and lots of data to support that and some pollinators are emerging at different times um because of changes in in temperature in particular and so what's happening is that plants and their pollinators are not always in sync with each other anymore and so there are a lot of pollinators that don't have the plants that they're adapted to feeding on as food sources and there are a lot of plants that don't have the pollinators that they're adapted for um for actually um doing the pollination and so there's um a lot of concern particular I would say probably more among insects biologists about this pollinator mismatch that seems to be arising um maybe more concerned from that side than from the plant side because often a lot of plants will have a backup system which is self self fertilization that the pollination between plants doesn't work they've always they a lot of them have a backup I want talk a little bit about the defense mechanisms that flowers have too they have some physical defenses but also some chemical defenses yeah so tons of drugs right are made out of flowers and a lot of those are chemical defenses or used somehow um so yeah we can talk about both those yeah yeah so flowering plants are amazing factories of of chemistry and um a lot of that chemistry can be harnessed for human use and has been but there's so much more that we don't know that could also be put to human benefit it's one of the arguments that people often made for what make for why it's so important to conserve species worldwide I mean it's not and it's not just true of plants um fungi provide a lot of the same sorts of potential benefits but and we know even less about fungi than we do about flowering plants but certainly the potential for drugs is something that that a lot of people will argue for why we need to be much better stewards of the plants on our planet but those plants were um are not making those compounds for us as um you know potential Cancer Treatments or whatever the the possible use might be they're using them in defense and they're using them to deter herbivores and interestingly sometimes pollinators are also herbivores and so there's all there are often very interesting relationships there as well that um a plant might be signaling to a species to come pollinate it but the leaves might actually not be well they might be toxic to that pollinator so there can be some really interesting things going on there but in general that types of compounds that plants make and there's a huge range like lots of different categories of of chemistry that the plants use um in defense and then there are some compounds that it's not really clear what the plants are doing with them they're often referred to as um secondary chemistry they're not particularly toxic to insects or other animals um but they don't seem to have special roles in primary plant metabolism either so it's kind of thought that together maybe they just form this toxic um cocktail that holded together with some of the other more potent compounds but then of course there are the this types of physical um defense mechanisms as well so some plants invest in Thorns or spines or hairs or other sorts of structures that make it really difficult for an animal to chew on on them then there's always sort of this um arms race between herbivores and plants so are they mostly geared towards insects or like the these bigger animals that know yeah yeah so so a lot of the chemistry I think is um probably uh focused on um insect herbivores or or maybe very other you know maybe small mammals or something but a lot of that those bigger um um armaments have evolved to as deterrents for large vertebrates so I know of some work that some colleagues have done in Africa on you know some of the big thorns and some of the other you know large structures as deterrence for you know against elephants or giraffes um you know chewing on on these specific trees in parts of Africa so so some of them are yeah definitely aimed at very small scale herbivores and others that much larger ones and fungus too right a lot of the chem chemicals yeah definitely yeah so there are you know certain types of compounds that plants will produce that will confer resistance to um fungi or bacteria and I wonder too um most of the drugs are like insecticides or so somehow they're meant to deter but do they use drugs at all as a method of attracting animals yeah yeah so I mean there are some really unusual things that different plant groups will do so there are certain plants that actually um provide homes for types of fungi and then the fungi will then provide some defense against other potential either pathogens or pests and so sometimes you can see these very complicated sets of you can almost think of them as being social interactions even though they're involving organisms that are do not really have social sociality it can get like really sort of complicated and those are highly unusual situations but super interesting when when they're discovered and there are probably many more of those sorts of things that we're just not really aware of but do they actually produce um you know I mean but what are what would be the what are the signals I mean we don't necessarily even know that but yeah I mean other than the fragrances of course that the flowers will produce um then those you know of course are attracting um other organisms so yeah flowers will produce a lot of different um sorts of compounds yeah I was just wondering that because so many of the recreational as well as medicinal drugs that we use come from flowers I was just wondering if you know animal pollinators if they try to attract them you know give them a dopamine hit of cocaine or something that they that they would like can come back to not just the the food and you know the normal yeah that's really interesting I don't know if anybody has investigated that but you know the the fact that um you know there plants that naturally produce th those compounds um you know what are the effects are there effects on the um herbivores um or the the pollinators yeah that's really interesting question okay let's move on to the seeds then and how the the transformation from the pollinated flower you talked a little bit about the pollination or the fertilization process but then there's a whole other process of creating the seeds building up the structure of the seeds and getting those in you know out into the world to create new plants right so there's a lot of features there that that are important um and are interesting I guess yeah so um so we always tell our classes that if you want to understand the seed you have to understand the ovule and so when we were talking about the structure of the flower before I referred to the ovule as being this very special structure that is also found in other seed plants not just flowering plants but it's responsible for what will become the seeds so we have this amazing transformation of the egg being fertilized by one sperm cell to form the zygote and these two other nuclei being fertilized by a second sperm cell to form the endosperm and once those two fertilization events take place and we call this double fertilization once those two events take place then the outer sort of covering of the ovule begins to tr be transformed into a harder structure and that will become the seed coat and so you have these layers of protection around the ovule even though the ovule is down inside the ovary you have these layers of protection around the ovule that um eventually then will harden and become the seed coat now at the same time as that's happening the the zygote is developing into a little embryo and it's getting to the point where it will be able to eventually um be Shed from that parent plant and go out and be able to germinate at the same time the that endosperm tissue is rapidly dividing and making the food for the embryo that's developing and so you have this uh little embryo growing within the within the ovule which is the developing seed and you have that that endosperm nourishing that and so then um eventually you like toward the ripening phase you've got the mature eventually the mature seed which is housed within the ovary wall and within that ovary that ovary is also undergoing transformation so the ovary will become the fruit and depending on what type of fruit that may develop a a hard outer um casing as well it may become a fleshy fruit they're all these different sorts of fruits we can think about our things that we consider fruits but we can also think about things like tomatoes which are fruits you know botanically even though we might not refer to them as a fruit so we have all of these different sorts of fruits that are basically the the vessels that the um seeds are located in and then those fruits can either be dispersed by the environment they may be dispersed by animals um and they'll go out in into the environment the fruits will either pass through an animals gut or they may just open and disperse the seeds they might um uh just decompose and the leaving the seeds and then the seeds will um under the right conditions then will germinate and form the next generation of the of the plant itself so all pretty amazing processes yeah I'd like to get into some of those there so most seeds have a hard shell there is to protect it and but you still somehow need to get a signal in there to tell it to germinate right so it's usually water I suppose but also like somehow there's some photosensitive stuff in there as well um yeah so that's kind of interesting just to begin with because you you want to protect it and seeds are they almost seem kind of inert for a long time until until they get activated yeah right yes and of course depending on the environment the type of at where the seed occurs uh where the plant occurs there will be different signals that will sort of tell the seed when it's okay to to germinate um but sometimes you know it's a combination of things so seeds from certain environments you know more Northern habitats you know often need to undergo uh what's referred to as vernalization just meaning they need to go through a cold treatment that you know even if they're produced in the summer they can't germinate until the following spring um I suppose that's an adaptation for germinating too soon and getting stuck as little seedlings you know in the in a cold winter so a lot of plants will you know need to have a combination of of water temperature and um and you know maybe just some builtin what's sometimes referred to as an after ripening period that may take a combination of time and temperature and you know and water before you can actually um have germination take place others yeah they might need the warmth of sun actually hitting them other seeds like basically as soon as they're shed if they've got water they can germinate so there are a lot of different types of signals that different species would receive that would lead to germination and yet we have some species where there are huge seed banks you know there might be seeds that are um in the soil for years maybe even decades um without germinating and that if brought out of the soil and given the right treatment they might still germinate um even though other seeds produced by that you know like at the same time maybe have already germinated and so but then there are other species that don't produce a seed bank other habitats that don't produce seed banks so there's a lot a bucket of soil could tell you about what used to be there um because there could be a lot of a lot of seeds in there so it has the shell and then it also has just a lot of energy stored in that seed right because it needs to kick off the process of growing the plant with some transformable form of energy and that's why so much of our food I suppose is seeds but I don't think most plants they they don't want their seeds to be eaten they don't they don't want that energy to go into other other animals right they want to use that for themselves so uh yeah I guess could you talk about how they use it and then like also their defenses for being eaten because I I know there's a lot of chemicals packed into seeds right yeah yeah so so it is interesting that for certain species the seed will have at maturity it will still have um some have endosperm sort of as a way of you know continuing to maybe provide for the seedling as it starts to grow but in other species the energy actually starts to get stored in particular organs of the embryo so you can think about some uh species of beans for example where they have these very fleshy um calans or seed leaves and some and those are packed with energy sometimes stored in the form of oils that um can be used to support the early germination phases there's a lot of diversity also in terms of how that um energy is stored and then provisioned to the developing embryo okay so do does the plant actually benefit from having its um seeds eaten or not well of course um it would be disadvantageous for the embryo to be destroyed in the process but there are even some there are some seed some species where actually part of the signaling that's needed for the seed to be able to germinate is like passing through the gut of another of an animal and that provides the maybe breaks in in the seed coat that will ultimately allow the the embryo to break through so sometimes there's a combination of chemical and physical weakening that an animal's gut will provide so that when the seed comes out the other end it actually is then receptive to those temperature and moisture conditions so that it can germinate and that it will not germinate if it doesn't have that treatment so it's just another example of sometimes these really tight associations between um plants and and animals in this case or or other organisms some plants do produce within their seeds a number of of compounds that could be toxic to potential herbivores as well like seed eating animals and you know things that even that we would want to eat and so it's important to have some of those those chemicals uh leeched out prior to our use of them but they could end up deterring the um you know other sorts of herbivores from eating them yeah let's move on to food a little bit for us our sort of agricultural industry is largely based around flowering plants of course you talked about grains I guess they're they have sort of a different process going on but most of the things you see in the grocery store at least in the produce section they they have flowers um I don't know if there's actually question there just just to note the importance of the the flowing plants to us and the the issues around pollination and climate change and all that kind of stuff that we're seeing yeah so I mean one thing that I think um is really underappreciated is how much of our food does you know comes from flowering plants and even you know even beyond the plants themselves that we eat the feed that is provided to chickens and livestock and also composed mostly of uh materials from flowering plants and so the flowering plants are providing the food directly and indirectly that we eat um the other thing that's really amazing about flowering plants is that you know our our main food globally you know comes from just a few crops so rice and and corn and wheat provide the Staples for a lot of our Agriculture and of course those are the the three main crops if we go back back to the origins of modern civilizations it was the domestication of the wild relatives of those three crops that led to developments of um of our societies you know in Asia India uh the Middle East and um Central and South America and so there's also in addition to the really important aspects of these three crops there's the whole Foundation of modern civilization that traces back to the these domestication events but really I think it's I can't remember the exact number but I think it's maybe around only like 30 different plants that are you know that provide most of our crops I mean and then there's maybe like another 35 or so that are interesting foods but not used that much and that's like so maybe let's say 70 species out of almost 400,000 species of flowering plants provide us with almost all of our food and and that means that there must be a lot of other things out there that have not been tested um you know we've got great potential sources of like undiscovered in terms of you know our culture in terms of food that where probably local peoples um in different parts of the world have made use of different foods you know non-traditional agriculture seems like there's a huge potential there for um helping with food security I mean obviously a lot of the food is things that we've cultivated to be that way but I suppose there's definitely more opportunities especially because we can do it a lot faster with genetic modification and stuff there's all kinds of things and I want to talk a little bit about some environmentalism and some issues surrounding that as well um you talked earlier about the the importance of genetic dver diversity in flowers for potential drugs and things like that um food as we just said so yeah I guess that's the first place to start just to talk about the genetic diversity of plants and yeah so there are an estimated 350 to 400,000 species of flowering plants we don't exactly know the right the total number um but just in terms of of species that have been um named and described scientifically it's somewhere in that 350,000 plus probably range that's a huge number of species um for comparison there are about 11,000 species of birds um 6,500 species of mammals maybe 30,000 species of fishes so that they're they're like 65,000 species of vertebrates total and here are you know 350,000 or more species of flowering plants and these flowering plants are forming the Baseline the framework for the habitats that are animal life and basically inhabits right so whether it's rainforest or desert or temperate forest or grassland it's you know the foundation and the major composition is um flowering plants and so perturbations to those to that species diversity can be um very upsetting to those communities so you know we refer to the biodiversity crisis which is the ongoing rapid loss of species species I mean the estimated number of flowering plant species that may be lost by the end of the century is staggering and I won't mention the number because I'll probably get it wrong but it's always bigger than what I could could imagine I mean it's maybe no I won't say but but a huge you know a huge fraction and so if we try to imagine our ecosystems without those estimated numbers of plant species then there will be you know some pretty dramatic repercussions and of course there's that sort of disruption to the ecosystems and to all of the other organisms that depend on those habitats but there is also the potential loss of medicinal value through plants that produce secondary compounds or defense compounds that would be could be important for human health um there are also many crop wild relatives so for every crop plant that has been domesticated there's some set of species that form the the closest relatives of those crops from which the crops were actually domesticated and sometimes there might be five to 10 of these crop wild relatives well in some cases we don't know what properties those wild relatives have that could be beneficial for um crop Improvement um either in yield or resistance to disease or whatever for moving into the future and um dealing with um problems of food security but we also have the potential to lose those crop wild relatives before we even you know could could study them um meaning that we would lose that ability to incorporate any of their beneficial traits into our um agricultural products so the fact that there is so much amazing diversity out there about which we know so little and of which so much is rapidly going extinct is you know just a a very sobering thought on so many levels we see the potential for losses of our ecosystems um and losses for potential benefits for humankind as well we know the the primary drivers of of those losses um just the ones that come to mind for me is climate change of course is the big one that everyone's concerned about but also just like habitat destruction I assume is also a big one and then I was also curious about uh invasive species because I know that's a big issue yeah to you're totally right there was um a study that was issued in um 2019 by the you well it's an intergovernmental panel on biodiversity and um ecosystem services that was convened by the UN um and they published a report that year on the main drivers of essentially of loss of biodiversity and the services that healthy ecosystems provide and they identified five five different things um and they were changes in land use um habitat destruction uh climate change which interestingly was not the number one factor at that point in time um invasive species and um over harvesting and um these didn't rep didn't apply necessarily only to plants but to species in general and so those were um those I think that I think that was the the list that was presented and then in uh 2021 one there was an updated report that was you know sort of um emphasized that same thing but yes the the roles of invasive species and driving other species to Extinction um I mean we see this I see this literally across the street from where I'm sitting right now uh we have a conservation area on our campus and there are some Bay trees that are you know related to avocado Etc and there was a a fungus that or a beetle that carries a fungus that was introduced from Asia into the Southeastern us not that long ago and it spread and it um it kills these trees and so we have you know dead young trees a few living ones but also some dead ones just right across the street from us and um you can see and that was the result of you know an invasive Beetle coming into the US from Asia and carrying its um little fungus that lives in its gut and the fungus is then re wreaking havoc on all of our native um trees in the avocado family and potentially we'll have similar effects on the avocado industry if it gets into them so the invasive species actually cost I think it's somewhere around more than $120 billion dollar per year in Damages to either native ecosystems or um economically important plants um and other organisms as well yeah every year so I heard that it's really the rate because these sort of occurrences has always happen throughout history you know animals F animals or plants or whatever find a new environment and they just happen to be well adapted for it and then you know the the environment kind of equilibrates around that some new species gets integrated then um but I I heard now it's just the just the rate that that's happening it's just throwing so many things off and it's it's causing problems where is it is it is that right where it's just things can't equilibrate fast enough to all the changes yeah definitely true yeah so um you know our our Global interconnectedness is just means that you know non-native species are being introduced onto every continent on a daily basis and despite efforts at quarantine um you know not everything can be detected and of course not everybody you know knows like wow you don't know what non-native species is going to end up having you know that sort of invas iess um associated with it there's a lot of interesting work that's going on where people are trying to predict which species will actually be invasive in under which circumstances so for example a lot of species from Eastern Asia have been introduced into eastern North America and they they're very similar climates very similar habitats and some of the native plant species are actually each other's closest relatives so but under these circumstances what happens when a species from Eastern Asia gets into eastern North America can we predict which of those are going to be invasive and which are just going to sort of okay you know I'll germinate and get along fine here but not necessarily take off as an invasive it's not really clear what the what those characteristics are so some people have predicted if something is similar to well Darwin actually addressed this question too it was his um Darwin's conundrum um our invasive species most likely to be think things that are closely related and very similar to things that are already in an area because they could take off or will the things actually be more distantly related because things that are too closely related and similar might be more likely to compete it seems like anything is possible like we like invasive species are generally defying prediction at this point unfortunately you see both those interesting yeah and I know like I I know some people are somewhat apathetic you know it's sort of survival of the fittest whatever plants are best suited fine but it's I always thought it was weird that like we in America we get invasive species from Africa and Asia but in those places they get invasive species from America that are causing problems it's like so it's not just like the biggest baddest ones are winning it's just like just this mixing itself is causing issues yeah exactly it's you know something will get introduced to a new location and it doesn't have its native pests and whether those pests are microbes you know like they're bacteria in the soil or whether they're fungi or whether they're things that would eat them or whatever they don't have their native pests and so they can do better in their novel environment than any of their close relatives do and and that happens exactly as you mentioned I we've been to Europe I remember hiking in the Pyrenees and looking down and saying that's from eastern North America you know it's like you know along a trail where you tend to see like weedy species their weedy species were from eastern North America whereas our weedy species might be from Europe so yeah it's it's it's definitely it's a global issue it this is kind of a weird question do is that eventually gonna have sort of a homogenizing effect on the world do you think U yeah no that's a I think that's a really you know interesting and you know potentially sad thought that diversity that we see in any spe you know among in any group of species um as we go around the world is you know TI to both the the characteristics of that area and also the history of that area so like you know you go to Australia and it's like everything's different from anything you've ever seen before right so animals are different plants are different but um you know invasive species have come in there and are you know really wreaked havoc with a lot of their a lot of the native animals the some of their iconic animals as well as um a lot of the plants and so if what happens is through by invasive species action you end up losing some of the particularly unique elements of the biota then the biota becomes much more similar everywhere you go and yeah you lose that um all all of that beautiful diversity okay that's kind of what I thought but wasn't sure yeah a little sad and then and then with climate change um so so I've heard that the the Earth is actually gotten Greener as things have changed and gotten War forer so I was wondering if it's beneficial for all plants that already exist here um and then are they moving migrating basically they're changing because you know climate change so the climate's changing in different places and then also do we see new adaptations as the environment is changing yeah yeah so really really good questions so let's start first um by considering how plants are are responding to a warming environment so of course different different species are going to be are going to respond in different ways and we can see evidence of species responses just by looking at well various sorts of of data um over the past few decades I mean we can people often if they've lived in the same place for a while they might be noticing that certain plants in their Gardens don't do as well as they used to and that things that they didn't used to be able to grow they're now growing without problem and so there's a very obvious change in even let's say the last 20 to 30 years in terms of what grows well in and you know and I'm coming at this from the perspective of the north temperate region right so we see different sorts of responses in different parts of the world one of the ways that we can actually detect um responses of plants to climate change over the last decades to centuries is by looking at current distributions compared to where plant species were collected and made into herbarium specimens so we have these um great um institutions called herbaria around the world they're something like what close to 4,000 of them I think and they're like museums of plant specimens so collectors would go out and still do this today collect a plant specimen press it with a special type of press and then put the plant um with special glue onto a piece of paper it's a standardized piece of paper that will persist for a long period of time and then a label will go on that on that paper or on you know on that big sheet of paper and that label will tell you the species name uh where the plant was collected ideally it would give you the latitude and longitude um now you know in the days past of course that wasn't possible um but it'll tell you who collected the plant and the date that the plant was collected and all of that information is now being digitized and so we have huge databases globally with hundreds of millions of specimens and observations that tell us where organisms occurred at different points in time so um there are somewhere probably around I don't know maybe I'll say 70 or 80 million plant specimens that are in these databases and we can look at the plant specimens for for example my region in in North Central Florida we can see what occurred here a 100 years ago and we can see where whether or not these plants still occur here or not we can also develop some models of species of like ideal habitats for species based on where these plants were collected in the past and we can say where did those ideal conditions occur now they might not occur where they were collected those ideal habitats are actually shift a little bit north and if we actually say where will the ideal habitat be located in 30 years or 50 years it's much farther north than where they currently are and we can do that all on the basis of these observations and specimens that were collected in the past and so um we've been doing that for um flowering plants in the State of Florida and we're finding um unfortunately that a lot of species will not really have any suitable habitat in even 30 years from now um the conditions will be too hot and too dry based on what they have um what what their optimal conditions are there are other species though that are adapted to hot dry conditions and when we map out where their ideal habitat is going to be instead of just this one little strip in the center part of the state which is where they actually occur now the ideal habitat is essentially the entire state so um there will be definite winners and definite losers um in this sort of climate Lottery that's taking place but what we mostly see is that the plant that the ideal habitats are going to be shifting northward now what this also means this comes back to the question we were talking about before um with invasive species and homogeneization what we're also seeing in through this modeling work is that there's likely to be a big homogenization of communities as well so certain things are just going to drop out because they're not going to make it other things are going to be like like this one that I mentioned that looks like oh yeah it'll be it could it could grow anywhere um and it you know whether it can get everywhere that's another question but it could be everywhere and the same thing could be true for some other species but the sorts of very specific local adaptations and diverse habitats that we have we have a very highly diverse Flora here um it's like patchworks of all of these different um habitats all based on just very small differences in elevation like literally like this big of a difference in elevation because um it it changes the Water Dynamics and so um whereas in other parts of like North America you actually have to go up like real elevation to get that sort of difference because of our um Limestone very porous soils here um a very small change in elevation can lead to a huge um difference in the plant um characteristics so anyway the bottom line here is that plants are already have been responding to uh warming temperatures over the past several decades and as we project that into the future um it's likely that we will see um very dramatic changes just based on on the changes in temperature and precipitation I guess we use the same categorizations that we use for animals in aured and extinct species are we are there efforts I'm sure there are to cultivate these in their environments and rebuild them yeah so fortunately there are some really good conservation efforts there are National and international organizations and also local and state and Regional organizations that are focusing on um developing local uh species to ensure that they will be able to persist into the future even if they're already threatened or endangered so for example there's one botanical garden in central Florida called Bach tower garden and it has a beautiful public garden but its really important work is on conservation of rare and endangered um Florida species and they do a lot of uh local cultivation to produce um seed that can be then used in um restoration efforts and one of the things that's very interesting about restoration efforts these days and there's um there's a group of ecologists in South Florida working on this problem is how do we go about doing restoration do we do do restoration today for today's climate or do we do restoration planning taking into account what the projections are for climate in the future so some of these conservation efforts that are um involving cultivation of of species for restoration efforts are trying to incorporate models of climate change they're considering at least putting plants in into areas where this habitat will be better for them in the future than it even might be today there are also forestry efforts that are similar to that so I remember um hearing a presentation several years ago from a forestry group in British Columbia Canada where they were already at that point planting seed lanes for their forestry industry farther north than where they currently do harvesting for any um Forest work because they're anticipating that that in 30 years or 40 years when the trees are the size that they might want to harvest them they won't be doing as well in the areas where they currently are harvesting and so they're actually planting this for the future so there are a number of especially for long lived things like that there are um a number of efforts where people people are trying to take into account generation time and stuff um but there are some plants and you alluded to this earlier that have that may actually be able to respond to uh changing climate sufficiently rapidly that they may not undergo the same sorts of threats to their existence that you know longer lived species might there was a study a few years ago of some herbaceous plants that have uh appear to have very rapid rates of evolution in terms of adaptations to shifting water tolerances or temperature and that sort of thing and that sort of LED some people at least to think that oh plants will sort it out but you know some plants might sort it out um those that have rapid generation times where they can complete a life cycle in less than a year that means that their opportuni is for adaptation that happen you like there might be 30 cycles of that happening you know over the next 30 Years or a Long Live tree like the beautiful Oaks and sweet gums that I can see out my window you know they don't have that luxury they you know they're where they are right now and any seeds that they're producing will be you know hitting reproductive sometime before that so there might be a couple of generations so really no opportunities for adaptation for especially things that we would consider our the Bas bases of our forests herbaceous species might make it but but you know then that also leads to this idea that you know our communities won't look anything like what they do now yeah I had an earlier podcast on um Extinction events for for Animals more specifically it sounds similar where the the big animals may be more resilient but they're far slower to adapt to change so you know so my mom works at a Nature Center and they they cultivate native plants and give up tons of seeds they just give them away to tell people to plant native seeds in your Gardens so could you talk about the importance of native plants um both to the environment yeah things like that yeah definitely yeah so um so that's been a big push in our uh local restoration efforts so like I mean using native plants is important for a lot of reasons one is I mean just sharing the beauty of your actual local area a lot of times we don't actually notice like what's around us right we think oh we need to bring in the Exotic tropical things or of course those are beautiful and you know I'm definitely not opposed to having some you know portion of somebody's lawn you know um as long as they're not invasive some um you know more exotic species but it's really great to use the natives because they generally are going to need less water um which is important in places you know lots of places and probably increasingly so in the future but maybe more importantly the native U plants will provide food and habitat for local um animals and so on as well so we like to plant a lot of um native plants for um pollinator purposes at our house so we have milk weeds we uh plant things from in the sunflower family that are native to our area um and we just we have monarch butterflies we have all sorts of other butterflies and insects flying around all the time and and that's just an amazing thing um that you know you don't have if you've got you know this bunch of tropical Exotics or subtropical Exotics so that especially as some of these uh habitat changes are leading to mismatches in U pollinators and plants it's important to provide as many resources for pollinators as possible and so I think that's a really important reason for um going with with native plants in in our gardening I a final question what do you think are the important research topics or questions to answer in your field and sort of your your vision of the future of your field what do you what do you see oh that's that is a big question I think one of the things that we're starting to see more of in our field and I certainly hope that more of this happens in the future is better integration between ecological studies and evolutionary studies so for a very long time evolutionary like plant evolutionary biology sort of happened on one trajectory and plant ecology happened on another trajectory and you know we were all evolutionary biologists and ecologists were maybe be sort of put together um and we would have some sort of you know camaraderie there around similar sorts of principles but the research itself tended to be largely an isolation um and what we see happening more and more of the possibility of bringing together these different fields and so more and more these family trees for plants are providing framework for studying things about ecology and the ecological context is providing more of a framework for understanding things about adaptation and evolution and so this sort of combination of of questions um I think has been super um interesting and I'm really hoping that that moves forward but what underlies any of those changes whether they're ecological or evolutionary is the genotype and so bringing in the information we can get from the Technologies developed from the Human Genome Project will mean that we can start to understand not just those relationships between ecology and evolution in terms of how things are moving but we can actually you know know start getting at the genetic control of the traits and things that are making a difference so we can understand more about okay if um a new characteristic arises that produces an adaptation in this particular environment so bringing together the ecology and the evolution we now have the tools from genomics to be able to start asking questions about what are the genes that actually led to that and so that gives us a more holistic view all the way from the level of the of the nucleus essentially the genotype all the way ultimately to the perspective of the ecosystem and it allows us to sort of span those biological scales I think it's a vision that a lot of people have it's very difficult to bring those pieces together in any single project but having the sorts of teams that are developing to address research questions I think means that sort of this very broadscale understanding is in the not too distant future you'll often hear different discussions basically happening at different levels you can ask what's the importance of this from an evolutionary perspective from biological perspective from a genetic perspective and sort of putting those together to create a holistic narrative is good uh goal I suppose I think what I mean a lot of things are enabling that um and one you know just the the tools of of genomics and stuff but we also have the tools of um AI now coming into play and methods for integrating data on in ways that you know just haven't been possible and so I think that there's a there are a lot of new opportunities you know just in terms of data Maybe we already have but just for understanding things a little bit better or yeah I know I have like a plant identifier that uses AI or you just take a picture and it knows what it is because exactly yeah yeah yeah pretty smart uh okay good um do you have any other uh comments hobby horses things you like to promote I I mean I love to promote the herbarium specimens um you know which is why I brought that up in the question of the climate change it's I think pretty fantastic to think that you know specimens that people collected and it could be herbarium specimens or you know fish and jars or stuffed birds or whatever but our our Museum collections can give us information on things that you know the people who collected them could have never dreamed of things collected centuries ago or providing us with Baseline information about species distributions and they are also in some cases providing us with physical samples that can be used to extract DNA and of course that's like centuries before DNA was discovered as being the hereditary material or before it was they were just collected before anybody knew about genetics you know it's like or Evolution it's like pretty amazing so I think that um I always like to say a good word for the value of Natural History collections um even though a lot of people will think oh those are just these old things that are over in the corner of a building um particularly as they're becoming digitized and available in a lot of um digital formats they're providing us with um amazing data resources for addressing a lot of uh really important societal questions as well as biological questions okay that's all my questions thank you very much for your time well thanks a lot thanks again for the invitation and yeah good luck with everything