Using Genomes to Track the Evolution of Life on Earth and Beyond

this program is a presentation of uctv for educational and non-commercial use only check out our YouTube original channel you see TV Prime at youtube.com slash you see TV prime subscribe today to get new programs every week funding for this program was provided by the UCLA office of instructional development these are the prairies of central Nebraska where my ancestors got off the train to homestead and started their search for a better future as a result of that I've always been interested in my ancestors and I think everyone in the world is especially Americans are interested in where we've come from but we're also interested in knowing where earlier ancestors came from and where they came from we're interested in knowing the origins of humans we'd like to know how are we related to NAND or tall's and furthermore we'd like to know how we're related to two other organism to even deeper organisms so first I wanted to tell you a couple of things about evolution and talk to you about well the curiosity where we came from and then how to improve human health what do organisms tell us about improving health well for example if we can find the early ancestors they tell us about signaling pathways but we must get the correct trees in other words we'd have to get the correct pathways to make sense of everything that's known from the biology similarly they promise to tell us how to design new bioenergy mechanisms the mechanism of photosynthesis is absolutely transformed the earth and I'll talk to you about that later but if we know the steps in which that happened then we also know how to put all of the pieces together so that we can start to understand photosynthesis and and devise new biofuels now Charles Darwin started evolution off he and Alfred Wallace with the bifurcating tree a bifurcating tree is that starts from one organism to make 2 & 2 to 4 and 4 to 8 and so forth meanwhile these organisms start to compete with each other okay so I like to call it the survival of the fittest and that's an interesting metaphor that's existed but there's another type of evolution that we need to know about and that's starting to become more important and that is convergences where two organisms come together to make one and of course we're in a sense we're at an example of a convergence I mean we had the sperm from our father and the egg from our mother and we're the descendants so we really have to have genomes coming together to make a new type of individual but this has done time and time again in evolution but it's not studied the reason is that it's very complex to do to do convergences and tree-like at the same time in fact if you think about it the tree of humans is a tree but of course it's not a tree if you know if anybody's interested in genealogy you realize they don't draw trees they draw all the parents and they do this and they get into a far more complicated arrangement so the question becomes what how do we go about this and what's triggering this interest it turns out that evolutionary biology is really in transition we were sure absolutely sure that when we got the first genomes that these would tell us about dude The Tree of Life we'd have every little bit of life understood there'd be no problem it didn't happen we in fact began to wonder and different people proposed well we have horizontal gene transfer x' and of course that was part of what our lab proposed as well that individuals when they live together they start to exchange genes so that there's a really complex arrangement of gene changes that's in fact when we looked at the genes from various genomes we find out there's no single tree that every gene tells a different story if it's turning out that we can start to derive rings and I'll talk to about this ring of life but I want to first of all tell you about the organisms that make up life in general there are two types of organisms they're prokaryotes and eukaryotes prokaryotes were are the organisms that are present its earliest in the fossil record they're very small single-cell organisms they don't have a nucleus they can photosynthesize they were on the earth as people like Bill shop from UCLA have shown for very long periods of life and they they are extremely important they have changed the way the earth is the eukaryotes are like us like Chancellor block referred to we are we're different you know we have big cells we have a nucleus and in addition to that we have organelles like the mitochondrion and the chloroplast now the chloroplast is the is the organism shown in these slaw is the organelle shown in these slides it's in red these are plant cells and these chloroplasts are busy taking the light in and they make food for the cell from the sunlight it's absolutely remarkable because without plants we would never have had animals because animals have to eat this food that's made from the sunlight and none of us would be here so thank a plant today anyway eukaryotes like us also have organelles because we have two we learned a trick well we didn't learn it we stole it from the prokaryotes the trick of how to breathe oxygen and how to thereby enable us to get more than you know maybe ten times more energy out of the foods that we eat so this happens to be the tails of two tails of a bat sperm so this is a sink one single cell now the bat sperm has one main thing to do and it is to move as fast as it can to try to find to try to find the egg and against all the competition and fertilize the egg so these little things in it and remember this is all just one cell our mitochondria so they're making the energy and if you wanted to go with the fastest you've got to make the most fuel and that's why they have evolved to just be totally filled with mitochondria to to succeed okay now the question I've been talking about trees and graphs but I haven't told you how to derive them and I wanted to a lot of this is intuitive if you think for example of cats and lions and dogs you can say well gee a cat and the lion they have a lot in common you know they have similar teeth to have a similar skull and we could say in something that would be the phenotype of the animal in some ways the cat is more similar to the lion than either the cat is to the dog or the lioness to the dog and that's the way we can use phenotypes genotypes now give you the same sorts of results sometimes but we may not have quite the same numbers of the same might not be the same lengths of the branches but they are usually they can be compatible but they contain a lot more information so they're much more reliable again if we had gene evolution then we have long genes thousands of nucleotides and the nucleotides are the the bases in the RNA and they have four different names AC G and T and we can compare say the cat sequence which is the order of these nucleotides on a gene in the cat with that in the lion and we'll find there are a few changes but there are a lot similar it's these changes and similarities that guide us and we can count the number we can actually do sort of bean counting in which we say how many how many times do I have changes versus how many times do I have the same there similarly you can do something like that with genome evolution except instead of having thousands for it for a gene you can have thousands tens of thousands of genes and you can treat them is this gene present in the cat for example is it present in the lion now we don't and we can look for differences just like we did over here are they absent in one president and the other president both president one absent and the other we can do all of these things and we can also build trees but we can also build graphs and that makes the gene absences presence is more powerful furthermore we can get further back in evolution because our goal is you know always to go push the envelope try to go back as far as we can so if genes change very fast you know they can change and position can change in 100,000 years but proteins are gained and lost very slowly maybe in the millions or tens of million years now the slower something changes the further back in the past it can take you and that's what we want to do so we have a problem though and that is about absence absences what does it mean to say that a gene is absent in in both of something we don't even know what gene it is so how can we say which gene is absent it's sort of like having a glass in front of you where you ask is this an is this an empty glass of wine or is this an empty glass of water and I looking at this group I have a feeling what it'll be after the reception ok so anyway if I mentioned being counting so I thought I would show you an example from Cambridge for Chancellor blocks at him former overseas fellow and when you go to high table and that's sort of this little table you sit at and you wear gowns and all of this stuff you sign up before and you take a guess so if Laurel and I were to go we would you know we might take two guests we'd sign up for but there's maybe have forty twenty pages in this list and people can't take the time to go through and is there one here and they do the addition and they get it all mixed up so you're also if you have if it's Lawren me and two guests we would take four beans we put the beans in the carafe and just about one o'clock in the afternoon when they start preparing the dinner they'll come they'll count the beans they don't have to worry about who's there they just want to know how many beans and how many dinners to prepare so that's the origin of bean counting these are our kids Jeremy and Caroline when they were young and this sort of got me out of the field of ribosome structure I mean it was such a I did it for several reasons one was bill shop founding week here the Wednesday evening evolution group but also I kept getting more and more interested in evolution and we used to go to these petting ponds at aquarium one day you know they have starfish and things that won't hurt them if you examine them and and one day I decided that I wanted to they said this is a sea hare and I said I don't know why to see hair is what what could that possibly possibly be so I went back to back to UCLA and I got a book started reading about it and it turns out its scientific name is Aplysia if they had said Aplysia then I would have known it because that's an organism the big nerves but I looked further and I realized we don't we don't know how it's related to other things very well in fact the more I looked I realized we didn't know anything so our lab had been very busy sequencing ribosomal RNAs and I said you know none of these plants have been ever sequence or not plants these animals have ever been sequenced and we ought to start trying this so we started doing it and that's how we developed ultimately the new animal phylogeny I'll tell you the first part of it it says that the starfish these sort of five symmetry fold organisms are close more closely related to the court chordates those animals with the spinal cord and over on the other side that the arthropods which are things like insects and and and and crabs and so forth are more closely related to the mollusks we you know which are which are which are clams and all of their like so these are the bilateral animals so bilateral animals are the ones that have a left and right side and we're approximately symmetric now I wanted to tell you a little bit about some of these animals because they are really in credit this is a tardigrade and it is just barely visible with the eye with the naked eye you can if you want to see some you can go up in the coast and take a little moss off the tree shake them out and there will be some things you could put them on a white paper and you just barely see them most of them are in a dormant phase so you take them back to the lab and you add them to a little drop of water and now on a microscope slide so you can watch them and they'll be down at the bottom and they'll start in about a minute or two they'll start walking along the bottom the bottom of the slide I mean it's just like adding you know instant coffee and in insects so you add it and you go on and they are the most amazing creatures because of this ability to to dry out desiccate they've been taken into space and they've been put out in the vacuum of space and left for several weeks taken they take all the radiation everything the take back take them back to earth put them in a drop of water in a minute or two they start walking around they're just fine he can reproduce everything so the record that I know was a museum specimen which was a hundred years old bit of moss and somebody said let's see if there are any tardigrades in here they flicked it took out the tardigrades and added water and two minutes later they started walking and two minutes later after that they died but nevertheless but nevertheless they walked so that is one Hardy animal okay now another another type of animal that I'm going to mention is our the firown' ins this is a wonderful picture taken by a former colleague from Shiprock California now the Shiprock is you know it's west of Catalina but these are beautiful throne ins in the background I don't have any close-ups of them it's taken by Jim Mora and former UCLA faculty member and but this is a bryozoa it's very similar they have these tentacles which are called Lofa fours and they filter feed they fill that feed on other very tiny eukaryotes so forth and grow that way now in the Tree of Life the old view they were close to the kind of Durham's and the chordates so we thought that they were good models to use for human evolution you know I mean the distant models because if we go down here hopefully we can find out something about signaling pathways their evolution turned out they aren't we've got the sequences and immediately they popped over here into a new group they were closer to the worms to the annelids now that's because I think by their form they're so different that you can't really compare them with anything and that that's many of the changes involved that kind of change similarly we had the nematode worms which are over here we used to think they were good models for for example things like longevity because you starve them and they live far longer and we said well this really applied to our closest relatives humans up here in the deuterostomes but we now know they are more closely related to the arthropods and the nematodes and they you ask well what do they have in common it turns out that they both mold now you know growing up in Nebraska we had lots of insects lots of grasshoppers you'd see these little grasshopper shells from when when the animals had gotten too big for their exoskeleton they broke it and then they'd go and then see-cret they'd be vulnerable to predators for a day or so and then they'd secrete a new exoskeleton and go on with the process that was a very important thing because the most specie of animal group we have is insects this adaptation was absolutely remarkable but it did show that molting is it did show that helped us clean up and understand better where our ancestors are our closest ancestors so that's what I mean when I say evolution is an important framework for understanding evolution now the Chancellor block mentioned that's what I won the Darwin Wallace medal for this this may and I wanted to tell you just a little tiny bit about that because it's such an amazing place it's where Darwin and Wallace first presented their paper in 1858 and so you go into the place and on the far side you see this portrait by John Collier of Darwin very famous but the eyes are just crazy you know they you walk in and of course he's sort of looking over here and back behind me would be on the other side of portrait of Wallace so they're kind of looking at each other but whoever goes in say it's they always feel that the eyes of Darwin are watching them so I don't know I don't know about I I do know that it's a weird feeling it's a wonderful feeling too so now let's talk about plans because I told you they were important we wouldn't be here as animals without plants this is a cover from nature the scientific journal and if you look at it carefully I love this cover this is a DNA helix but it's made of potato chips and then the base is linking them are a french fries so so that's inventive science by itself I mean you need something like that to get published in nature any any way the potato genome this only came out about four weeks ago but it's extremely interesting I think it's interesting about what we say is our in our perceptions as being sort of at the top of the feeding order in the world and it on earth because we think we're so smart and so bright and we had this big brain and you know we thought for sure when the human genome came out that we would have the biggest animal brain but we don't I mean we all animals have pretty much the same number of genes in our brain I meant a number of genes I didn't mean brain so so we end up all animals but surely animals have to be a lot smarter than plants this just cannot be well it turns out in the genome plants have about 40% 45% more genes than humans so we have roughly 23,000 and they have 34 35,000 so so I guess the take home lesson is next time somebody calls you a potato head take that as a compliment now I like quotes and I like you know a lot of people give talks famous speakers like decart and so forth are famous famous people and so here's my famous quote for the next subject it is in my career I found that thinking outside the box better if I know what's inside the box okay it only has one drawback the author isn't so well-known Starbucks Starbucks coffee quote number 153 anyway but we do in talking about prokaryotes we want to know about what's in the box and I'll tell you a little bit about that their diversity now this is at least the people in the first couple of rows can see this but these are lots of people's faces and human fat eye is very good at picking out different faces but if you look at them carefully you'll realize it's just four people in different poses different smiles all sorts of things now our problem with reconstructing prokaryotic life has to do with the horizontal gene transfer we want to minimize that process so we've made as big groups as possible of the prokaryotes because remember I said like organisms related organisms prefer to transfer genes with each other so if we get big groups then sort of like in this picture everything fits within the square with maybe a little exception and think of those as transferred the rare transfers between groups so it reduces that effect means now we can start to look at what are the big groups one group are the methanogens and the methanogens consists of organisms that eat carbon sources and but they breathe hydrogen so that so they make methane in fact when you turn on the kitchen stove if you don't have an electric one if you have a gas stove or a gas furnace you're burning methane probably produced by methanogens in the past the other another group are the double membrane prokaryotes we've known about these for 125 years they were first called the gram-negative prokaryotes by identified by their biochem you know by how they stained for light microscopy and these include things like the cyanobacteria there are a lot of photosynthetic groups in fact almost every single photosynthetic bacterium except for one little organism is found in this group so there's something about the double membrane arrangement that helps photosynthesis but they includes the cyanobacteria and I'll come back to the cyanobacteria in just a minute because they're so important another group includes the firmicutes now the best-known one would be anthrax after 9/11 because it's a bacterium that makes anthrax it has a very interesting history but but also it includes Clostridium which are fermenting organisms and within the Clostridium air is one photo synthesizer and then we have the Actinobacteria Actinobacteria form these sometimes form these complicated structures of multi cells but they aren't really quite multicellular they include also parasites like the one Mycobacterium tuberculosis causes tuberculosis or the or a bacterium that causes leprosy those are important those are those four represent pretty much the diversity of prokaryotic life now we use the presences and absences to start to look and construct a tree of just these four but it turned out to be more complicated than we had thought because the double membranes have two origins they in fact have are represent the convergence and it answers some questions right away about photosynthesis because there's this lone photosynthesis eyes are out here but this branch created part of the double membranes it was half of the convergence the other half came from the actinobacteria so we still don't know exactly all the details but we do have an idea about how things may have happened the single membrane prokaryotes have as a name says a single membrane that photosynthesize er the single membrane has the photosystems within the membrane and if it can move it has flagella that the wag and that move it around it's also surrounded by an outside container which is kept to the glycan and that protects it from from for this delicate membrane inside from from rupturing the double membrane prokaryotes look exactly the same way except they have an extra membrane here on the outside but they're if they're photosynthetic they have them here if they had this inner membrane it's almost as if a the outside it's almost as if in one double one single membrane prokaryote engulfed another and this is and then lost its single membrane so this is a this is an interesting arrangement you have to ask what does this do what does this what's unusual about this how can this be so successful because this double membrane arrangement represents more than 98% of all prokaryotic species it's really gotten successful because of this coming together this convergence or this cooperation now what can it do well it makes two compartments for one thing and we've learned from things like human sanitation that is nice to have compartments you know you don't want to put the sewage in the drinking water and it's kind of its kind of like that with this we want to have we want to keep some compounds here we're going to keep some compounds here so we can do everything in a more coordinated way I think that's the reason for the success and this convergence and cooperation that resulted from the double membranes is really quite impressive now as a result of that convergence you made the cyanobacteria these cyanobacteria that are the called they're called pond scum this happened to be in a geyser in Nevada this green scum those are cyanobacteria and between 2.7 and 2.4 billion years ago they had by that time made enough oxygen because they split water h2o into hydrogen which is used biochemically and then - oxygen which is released into the atmosphere and in this process they started putting their oxygen in the atmosphere by that long ago it has started to build up and it's a toxic waste really was nobody you know no other organisms could use it but it set the stage by remember I told you changing the energy system so that you can get a lot more ATP's which is which is the way cells get their energy from a given amount of food and maybe increases it by almost an order of magnitude and once oxygen could be used to increase the yield of ATP that meant we could have big organisms because they didn't have to eat as much and there they had less surface so they didn't need all that surface to get their food and it meant we could get eukaryotes like us and now I want to step back to the beginning of genomes and tell you about a problem we had early on and when we first got our genes we started excuse me when we first started looking at genes from G sequence genomes I told you different genes had different histories well some genes operational genes we discovered in eukaryotes have the history that that they are well they're in eukaryotes there are different type of genes they've come from the double membrane prokaryotes and furthermore these double membrane prokaryotes sorry I got a little distracted there the double membrane prokaryotes are those operational genes make protein and they're making enzymes and they make functional things that are used like peptidoglycan like different molecules used within the cell and on the other hand there's informational genes like DNA and RNA DNA and RNA they process the information molecules they make they use protease facilitate protein synthesis the making of proteins so two very different types genes they tended to be operational genes who had found in eukaryotes were found in bacteria and then another group the EO sites had informational genes well within the last few years we've started to understand this better so we did again rings the president's absences of genes we found out eukaryotes so let me explain I talked about eukaryotes I talked about prokaryotes now we're going to talk about the origin of eukaryotes from prokaryotes we realized these sites contributed genes to the eukaryotes in this ring proteobacteria in the Sinai honor bacteria contributed other genes to the eukaryotes so this is really quite a starting now to make sense it looks as if there must have also been another example of coming together of fusion to make the first eukaryote we don't know the ancestors and so forth but now that now the summary is we know all the organism cells we had the methanogens the double membrane prokaryotes Firmicutes and Actinobacteria and then we have the oldest eukaryotes is represented by an oldest Charles Darwin and then a and then we have this group the EO sites and these turn out to be extremely thermophilic organisms for the most part their sulfur they eat sulfur they breathe hydrogen they live that some of them can live in above boiling temperature my wife calls the macho sites so talking about macho sites we come to the next part and that is where life may have started and this is not so much our research but it's but but I wanted to just take all bases and talk to you about this some people have proposed that life started on earth early in in hydrothermal vents these vents are quite remarkable in the Pacific they're very deep temperatures are 300 Celsius so that's about 700 Fahrenheit I mean this is really hot you say well why doesn't this just boil away but it's so deep but the pressure is so much that the water camp doesn't boil at 700 but at adjacent to it of course is water which is very very nearly freezing so we have this incredible source of contrasts of temperature and we have total of contrasts of chemical contrasts totally different chemistry in this water in this water it's an ideal place with all the energy gradients and all the gradients for a life to have started but there's some alternative sites that have lately been discovered one is the lost city which is event off of Florida about I don't know 1500 miles in the Atlantic and it has much lower temperatures 150 270 so it's not really boiling and at the same time it's alkaline so whereas these are extremely acidic and the alkaline is a much more like people who do prebiotic chemistry much prefer the alkaline so let's now move on the last part of this and I'd like to talk to you about Mars because I'm I'm a member of the astrobiology Institute of NASA and I'm interested in what's going on in Mars well first question to ask is is there life on Mars is there water if we want to know if there's life we'd like to find the evidence for water well we sent up about six or seven maybe I don't know how many years ago now six maybe two Rovers opportunity is one in spirit is the other now they were supposed to search around on Mars and test things for which minerals are present could the minerals tell us it was water present they I think they were supposed to last 90 days they're guaranteed maybe it's 180 I'm not sure but up here this is on day 1600 so that's in Martian days which are about like Earth days so that's a long time opportunity now is probably up to about 2300 I haven't checked it but and spirit died about a year ago during the winter it just couldn't get the right orientation to keep enough sunlight to keep alive during the winter but you know for government work that's pretty good anyway then we put down another another Lander called Phoenix and that was really a remarkable one Phoenix went I think maybe four years ago three and a half years ago and landed on Mars in the Arctic plane during the during this summer when it was warming up and it probably held me 70 below who knows but we also wanted to know exactly where Phoenix was and it turned out that these high-rise images are taken from a camera in orbit around Mars now this is no ordinary camera I mean it must have a you talk about it you sort of think of a little thing like it's got a lens about like this I mean it can resolve from high in orbit you know hundreds of miles away to grapefruit so it's it's pretty it's pretty remarkable and they said well we don't know exactly where it's going to land and they they said hey you know what we have high rise maybe we could take a big area a big photograph like 50 miles by 50 miles and then shoot it just as Phoenix is coming down and they did that and then they started searching the photograph and they found out that there were three white blips this is this is the one that is Phoenix there's the parachute there are the lines down to it and there is the lander Phoenix quite amazing so now we have something on Mars we had something on Mars which lasts which we know it's location to within a foot on the surface of Mars because we could follow it down really quite remarkable anyway more remarkable was what happened though when we got there started digging into the ground looking for things it found this white stuff up here are minerals which have been deposited so don't worry so much about that but if you can look carefully there's sort of three things down here which are like three little ice cube okay this is on day 20 by day 24 they had evaporated they were gone said that and so so water was proven very near the surface so we're talking about maybe within 3 inches of the surface coming down this is 2/3 of an inch and water doesn't melt on Mars there's too little atmosphere so under those conditions water evaporates just you know as ice supposed to melt and tarry evaporates but we now know that there's water on Mars there are also clouds on Mars and the clouds change with the times they basically as as the South Pole is warming up it releases water which gets frozen travels across the Mars and gets frozen on the North Pole when the North Pole melts it moves again goes to the South Pole so we know a lot about Mars now the next question is is there life well we have one more Rover that's now being readied and it's called curiosity this has taken about three months about three months ago when it was still at Jet Propulsion lab it's not it's now at Cape Canaveral being ready to take off curiosity is going to look at a strange bit of topography it's a mountain which is about five kilometers high so that's roughly if I can do the calculations I don't know maybe two miles high but it's surrounded by our Basin deep in the soil where water may have been and from again this high rise photos of this start to show various layers all the way around and so that's where curiosity is going to land it's got a mass spec in it all sorts of instruments that are going to look for the molecules of life it's going to dig into those rocks and try to find it but not just that at the very earliest phases of Martian of Martian evolution so Laura and I have been invited to see it we're going to be in Florida the day after the day after Thanksgiving for a launch we don't know if it'll start and we've stayed booked two extra days but we're looking for in case we missed it you never know for sure but we're gonna see what happens and so I want to summarize a little bit about cooperation and survival of the fittest I think I've I hope I've shown you that there's a new wave in evolutionists this not entirely about the harsh realities of life about the survival of the fittest it's also about cooperation but I don't want to give you the feeling that cooperation isn't enforced sometimes I mean our mitochondria within us that are making us live and exist in breathe this terrible toxic oxygen are you know they're probably we're taking screaming screaming and yelling there but their net result is they've been able to extend their existence for for very long time periods so we're changing our understanding of the evolution of life on Earth and I wanted to mention three people who have been really important in my career okay there three people are no longer with us they are Colin Patterson Colin Patterson was head of the paleontology department at at the Natural History Museum in London and an absolutely he was a person who introduced cladistics into the UK and pretty much in part ways into the US which was a very analytical way of thinking about evolution and I think also we can answer the question about Colin I think his empty glass was wine another person is Alan Wilson who's probably the most imaginative scientist I have ever known in my life call Alan was a person who first when he realized you could sequence DNA he obtained placentas from people all over the world because percent is the mitochondria are inherited through the female side so he showed that we are all related to a woman who lived in Africa about 300,000 years about 200,000 years ago this is this is just amazing to me and he took a lot of he took a lot of abuse for that but like all of these things that turned out that he was right and Alan is no longer with us but he's absolute absolute force in science and I you know speaking of this abuse you know science is that way this is the way things get fought out the new animal phylogeny really took a very long time initially people were yelling and screaming and everybody had different reasons why it was wrong but it took until that was started probably in 1995 the crucial paper was published and it took 10 years for four people to come around and it was only in 2009 when the when the Royal Society had a meeting to honor the 300th anniversary of Linnaeus that that was incredible and audience to auditorium of 500 people every speaker got up and talked about the new animal phylogeny and so but initially it was a really big fight and that's the way that's the way science is by that time I had sort of said to myself well you know we'll answer the questions but what you say how emotional you are doesn't really make a difference because they'll be little the science will decide it and that's what does it in the end and then the last person I want to mention is Walter Fitch who died about five months ago and Walter came to UCLA through week again this Wednesday evening group I mentioned before and we used to have just terrible debates he was wonderful debates actually but very strong and he would he I would tell him what we were doing he said no you're doing that all wrong and then I'd say no no he's got to be this this he said no no and then he'd tell me why and I think about it next week I'd see Walter and that's it you know Walter you were right but we have a new result I wanted to tell you about now we really understand this and he say no no no you're wrong and it just you know it went on like that maybe five or six times and I every time I learned so much from him I think probably the last one I got him but I'm I'm not sure that anyway last I wanted to thank Laura for putting up with me thank you and I'll be glad to take any questions and also I want to thank the audience you guys were just great thank you that was a fascinating talk and thank you for forgiving it so in trying to construct a genetic tree that is consistent with you know what we know from from other sources the more traditional sources you know do you think I wouldn't have wouldn't necessarily expect them to converge with each other and this is my reasoning you know you can take 26 letters in an alphabet and from that depending on how you combine them you could write a manual for a washing machine war war on peace right so with 20,000 or so genes you don't really need to necessarily see differences between them it's just the way they're combined that makes them difference the same teams make a caterpillar as a butterfly so you know where are the are the mutations just kind of a marker for you know mutations that have randomly occurred but they don't really explain the differences in the tree of life so that's my question okay that's that that that's a very good question I think what you're referring to is the fact that some mutations are random and in fact a lot of them are random not all of them are the lucky things that converts it ends I'm to something that does something else or makes it change as a gene absolutely so we're using the gene we're using these sometimes it does though and those are very memorable circumstances but we're using the genes as a clock so we say on average a gene will change you know a nucleotide will change every so many years and we just are counting them and we're using the timing to tell us what the trees look like and then we're using what we know about the biology to guess what's happening great okay see we have a question here on the aisle just wait one second from microphone please have we ever found any horizontal gene transfer in single-celled eukaryotes or is all the convergent evolution just going on oh no oh well there there I'm certain I won't say for sure but I but I'm reasonably certain that yes yes we have found them in fact in single-celled organism we've found some really incredible things we've found we found something called nuclear morphs which are entire in the dinoflagellates which you know make the ocean colored and so forth we find that some dinoflagellates which used to be photosynthetic lost their chloroplasts and in return they have captured they have swallowed an entire photosynthetic eukaryotic cell and they've kept the chloroplasts and they had to keep a little bit of the nucleus which is called the nuclear morph but you know these little animals you know little eukaryotes can swallow other eukaryotes too so the whole process is going on a lot all right thank you we have a question here toward the center of this row we right I don't want to answer questions from this guy okay I will will call security if he gets out of line professor Lake that was a wonderful lecture and let me give you a softball question but it is something that everyone in this audience would be interested in hearing you talk about we're spending a lot of money we're going to Mars you're an astrobiologist you're interested in the possible existence of life elsewhere tell us please oh great sir are we gonna find anything and and if so let's assume we do why will it matter and you call that a soft question could I take your hard questions instead no I think the first thing why does it matter it's always this question of curiosity we don't know what's going to happen Watson and Crick didn't know what was going to happen when they thought we'll take x-rays of this silly molecule DNA I mean science is not predictable and when you try to predict it you get it turns into sort of business as opposed to the exploration and I think truly important discoveries get made that way discovery of the new world you know we couldn't why do you why would you want to go to a new world there's no gold there I mean there's no you know but it happened thank you thanks Bill we have a question back here toward the aisle question here so I have a question about your idea of this convergence so we usually you have to arrow is coming together but if you think about origin of eukaryotes it seems like we have the mitochondria so that was one arrow but then you said that our regular genes come from either you bacteria or you sites so doesn't know not that regular the the operational genes come from you bacteria come from you bacteria or cyanobacteria so it could be the organelles bringing that in we don't know but there could be other endosymbiosis involved as you think there may have been more than one convergence between tools I think there may have been I think the history is going to be very complex and very exciting great thank you if we can get a question here on the next aisle this thank you may I ask if your remarkable insights into the past allow you to project on future trends in evolution I'm sorry you know you absolutely never know what's going to happen I mean in this in this business you say oh I got it wrong so many times that but but I think that's the excitement of it is is you never know when you what will happen and yes when we get things wrong we acknowledge it and that's and you go on and you say well does this lead us to do something else better so I just I just love the excitement of it actually just one follow-up to that and Jim if I could ask what is the evidence that evolution continues to occur well that's very good we have we have a lot of experiments that have been done there's a experiment that's been done at Michigan State where they've taken a bacterium and they've grown the bacterium into they've been very long-term studies so they grew this initial ecoli bacterium into I don't know maybe 8 or 16 different groups and then they followed the evolution of these groups and evolution within them and so forth and you can just see the DNA change with time and some of these bacteria change some of their proteins some of the proteins change so this has been all observed in the left in the laboratory so wonderful thank you okay we have a question down here toward the front on the aisle thank you that was a very interesting lecture I recently read an article that 90% of all human DNA is based on microorganisms and yet if we all evolved from microorganisms why wouldn't it have been a hundred percent or is there a time in the transition that there was human DNA well I I didn't I haven't read the article so I don't I don't know what the article could say I mean I could think of think of lots of things but if it's 90% you know sometimes you can't tell the difference between 90% and 100% it's like these are these are all statistical questions and you really have that's one lesson that I really didn't understand until I got into evolution but my training has been as a physicist because I wanted before my brain froze I knew I wanted to be a biologist before I started purifying RNAs and things I I took all these you know graduate courses in quantum field theory and general relativity all those things and then I decide then then I realized oh my god I should have also been taking courses in statistics because everything gets proven by numbers and statistics is such a subtle beautiful science and I don't know enough of it but I just see that as part of a lack in our scientific education but it's really powerful really powerful one toward the center there yes please yes thank you very much for the lecture referencing the double membrane I don't see where you are okay referencing the double membrane on the mitochondrion and also the chloroplast potentially having been or almost for sure having been organisms that were incorporated can you speak toward the nucleus and it's double membrane or is that different enough that there was no chance that that was at one point an organism that was incorporated well that's you know this is almost a planted question I think but it's not I I personally think that the nucleus is an end of symbiont and that's when we started public we have actually published several papers on maybe three or four and some high-visibility publications like nature and science so that's an idea that's out there that idea seemed to be going nowhere till about five years ago and within the last last three years there have been a number of papers written about that very idea supporting it by because the details of it dependent upon being able to go back very early in time and just to make a short answer science had a wonderful article about it about this work of other people who have started to prove this and it's sort of working feeling to me a little bit like when the new animal phylogeny came out I think the world is now starting to be prepared for that so that's wonderful that you came up with that idea too and I wish more people would thank you all you videocassette copies of this program are available for purchase from the UCLA instructional media library call toll-free 1-800 additional information about the people places and ideas discussed in this program is available at our website WWF cast UCLA edu

Channel: University of California Television (UCTV)

Views: 18,366

Rating: 4.8373985 out of 5

Keywords: evolution, molecular evolution, James Lake, genomes, genetics, Prokaryote, Eukaryote

Id: zxLLIedO2RI

Length: 58min 45sec (3525 seconds)

Published: Thu Mar 08 2012

Reddit Comments

[u/saibling]

very interesting, thanks for posting!