University Place  Scott Gilbert We are All Lichens: Symbiosis and the Restructuring of Individuality  December 12, 2012 UP817  cc >> Welcome everyone to Wednesday Nite at the Lab. I'm Tom Zinnen. I work here at the UW Madison Biotechnology Center. I also work for UW Extension and Cooperative Extension. And on behalf of those folks and our other organizers, Wisconsin Public Television, Wisconsin Alumni Association, and The Science Alliance here at UW-Madison, thanks for coming to Wednesday Nite at the Lab. We do this every Wednesday night, 50 times a year. Tonight's a special honor for me to get to introduce to you our visiting speaker from Swarthmore College, Professor Scott Gilbert. He is the Howard A. Schneiderman Professor of Biology at Swarthmore, where he teaches developmental genetics, embryology and the history and critiques of biology. He received his BA in both biology and religion from Wesleyan University in 1971, and he earned his PhD in biology from the pediatric genetics laboratory of Dr. Barbara Migeon at the Johns Hopkins University in 1976. His MA in the history of science is also from the Johns Hopkins University. 

He pursued postdoc research here at the University of Wisconsin in the laboratories of Dr. Masayasu Nomura and Dr. Robert Auerbach. Doctor Gilbert is a fellow of the American Association for the Advancement of Science, and also of the St. Petersburg Society of Naturalists in Russia. He currently has three books in print, "Developmental Biology," which is a textbook in its eighth edition, "Bioethics in the New Embryology," a volume that's co-authored with two students, and that discusses new findings in developmental biology, with respect to philosophy and religion, and "Ecological Developmental Biology," a textbook co-authored with David Epel, which integrates developmental plasticity, epigenetics and the symbiosis into discussions of medicine and evolution. Scott has received several awards, including the Medal of Francois I from the College de France, the Dwight J. Ingle Memorial Writing Award, the Choice Outstanding Academic Book Award, honorary doctorates from the University of Helsinki, and the University of Tartu, and a John Simon Guggenheim Foundation Grant. In 2002, the Society for Developmental Biology awarded him its first Viktor Hamburger Prize for Excellence in Education. In 2004, he was awarded the Kowalevsky Prize in Evolutionary Developmental Biology. He has recently become a Finland Distinguished Professor at the University of Helsinki, and has received a grant from the National Science Foundation to work on the most interesting of topics, how the turtle forms its shell, and he continues to do research and write in both developmental biology and in the history and philosophy of biology. I usually say, "in his spare time," but I don't know what that would be, outside the class and laboratory, his interests include hiking, photography, and he plays piano in KNISH, one of Swarthmore's premier Klezmer bands. I think he's got one of the great topics ever on what's it mean to be you and me; what's it mean to be an individual; are we all lichens. I'm "lichen" it, I'm hoping that you will, too. 

[laughter] Please join me in welcoming Scott Gilbert to Wednesday Nite at the Lab. [applause]  >> It is a huge honor to be here today, where I had been a postdoc, although this building, of course, did not exist. It's also with some fear and trepidation that I give this lecture in a place which has so much remarkable research on this very topic. So really, it's just an incredible privilege. I'm going to be talking today about what it means to be an individual, especially what it means to be an individual in the biological sense. I'll be arguing that we are not individuals, and that we never were individuals, that we were like lichens, you know that mixture of algae and fungus, that never really is itself until they come together. Notice I put down here that this is a lecture by "Team Scott Gilbert." Yeah, we'll talk about that later on. But yeah, I'm really a composite speaking here today. What we mean by individuality depends on what area of biology you're coming from. There's been basically six major definitions of biological individuality. 

The first has to do with your anatomy, you know, your physical body. The unified body is an individual, and it comes from a collection of cells. The parts form a unified whole. Okay, anatomical individuality. There's physiological individuality, which is that there's a purpose of this that unifies all the systems for a common end, that those, we're all parts that are functioning together. We're eating together. We're digesting together. We're breathing together. We're circulating blood together. What's even more interesting is that even though the parts change, the whole remains the same. 

As a matter of fact, this is one of the major definitions of life, the metabolic definition of life, that says you are alive when the form persists even though the parts change. You are constantly changing yourselves. You are constantly changing your molecules. That's why you eat. You bring in, you put out. You eat, you defecate. You keep on changing your parts as you survive. The physiologist in the 19th century used a wave as a metaphor. Think of a wave on the beach. There's a wave; there's the wave; there's the wave. 

Same wave, there's the wave. There's the wave, but the molecules of water are changing. Whirlpools. There's the whirlpool. There's the same whirlpool, but its molecules are changed. It could not keep its form without changing its parts, this physiological individuality. There's developmental individuality. The organism is the organism from ovum to ovum. We are the progeny of the fertilized egg. All of our cells arose from the mitoses of the fertilized egg. 

That's what constitutes our individuality. That's very similar, actually, to genetic individuality. It's that genome, which has been propagated and multiplied over and over again that makes you your genetic individual. That's often manifested as immune individuality. Immunology has been described as the science of self/non-self discrimination. If I were to put my spin onto you, you would reject it, because your genes are different. Your histocompatibility proteins are different. So immune individuality, you can recognize what is not you. Then, there's evolutionary individuality, that which gets selected, that which can be a unit of selection. Okay, so these are the six major types of individuality that biologists discuss. 

Now, symbiosis is when the organisms have to be in really close proximity to each other to survive, and they're part of each other's life cycle. You have mutualism, where two organisms of different species interact biologically in a relationship that each of them benefits from. So, as in the lichen, you know, I'll give you food if you'll give me protection from predators, or if you give me protection from desiccation, and back and forth. You know, I have this that you need; you have something that I need. So that's mutualism. The other major type of symbiosis is parasitism, where one of the two organisms benefits at the expense of the other. So here we have a tape worm, and here we have cuckoos, a cuckoo egg. Here, one organism has benefited from the other, but it needs the other to complete its life cycle. Now symbiosis is the evolutionary strategy that really supports life on this planet. It is not a planet of individuals. 

Our nitrogen for making our proteinsm nitrogen in the atmosphere is fixed by rhizobacteria, which are in the legumes of plants. Again lots of research at the University of Wisconsin on that. Mycorrhizal fungus interact with the plant roots and seeds. The beauty of the orchid is made possible by the fungus. The orchid seed is so small, and it lacks carbon sources such that it cannot germinate. The orchid seed cannot germinate by itself. It needs to have a fungus enter into it in order to germinate. So, the beauty of the orchid is determined by the fungus. There's also endophytic fungi protecting against desiccation. These are the fungi that actually penetrate the plant cells and give plants protection against desiccation and other things. 

So, symbiosis is a major strategy on this planet. You'll notice that what I've been talking about have been plants. Plants and fungi. The zoology people have kind of resisted symbiosis, and it has those six categories of individuality. So let's go through them. Here's part of the hive near where I grew up. I want to talk about anatomical individuality. He mentioned KNISH, the band I was in. This is one of the few Japanese prints that mentions KNISH. [laughter] It was done by --, who taught at Pratt Institute. 

Anyway, take one of those. Okay, so humans are really not anatomical individuals, because over 90% of the cells in our body are prokaryote. They're bacterial. They are prokaryotic cells. They have specific locations in our bodies. We have 160 major species per person living on us, and about 1100 species per human species. They been called the 11th organ system, and each of our areas that are exposed to the outside environment, the gut, the reproductive tract, our pores, the skin, airways. Each have their own different groups of bacteria. So, this is something that we're living with. Now, again, Wisconsin, I don't have to tell you, that an organism isn't an organism without it's bacteria. 

I don't know if you have these anymore. Yeah? [laughter] But, this has given rise to the concept of the holobiont, which is the large animal, the vertebrate for instance here, with its persistent microbial communities. So we know that the cow needs its ruminant bacteria in order to digest the grass that it eats. The concept of holobiont was invented by the Rosenbergs to discuss coral bleaching. When we think of a coral, this is what we think of. This is a dead coral. The coral here has been bleached. The white coral has been bleached. This coral has zooxanthellae in it. It has protists, which actually undergo photosynthesis. 

It's critically important for the health of the coral. What we call a coral is not just the, you know, anemone-like creature, it's also the bacteria. What we call a cow isn't just the vertebrate, it's also the symbionts. Now, the kind of poster organism for this has been has been mastotermes darwiniensis, this termite. And the reproductive unit of the termite is the hive, the nest defended by the workers. The worker here can't reproduce itself. It needs the hive to reproduce. And it is the worker that digests trees, digests homes. It eats wood. But it actually can't eat wood. 

It has a symbiont in its gut that eats the wood, Mixotricha paradoxa. Mixotricha paradoxa is what eats the wood, but actually it doesn't eat the wood. [laughter] It has bacteria inside it that eat the wood. So, where is this organism? This is a composite organism. This is an obvious composite. We are also composites, maybe less so than the termite. But the termite whose function, you know, is kind of let's get some calories from the wood, can't do it without the symbiont. The symbiont really doesn't exist as an independent organism, and neither does the worker. It can't survive without it's hive structure. So anatomically, animals are not really individuals. 

What about physiologically? Well, physiological individuality is where the organism is an individual whose component parts cooperate for the benefit of the whole. So Thomas Hobbs here, or-- All these humans here, this composite organism making the Kingdom, Henri Milne-Edwards, Rudolph-- some of the biologists who were looking at this view. Okay, component parts cooperating for the benefit of the whole. Okay? This is kind of the Russian doll structure here, is planococcus, which is a bug, a mealy bug. Planococcus can make phenylalanine. Only it can't make phenylalanine. It needs tremblaya, a bacterium inside its cells to make phenylalanine with it. But even those two can't make phenylalanine. The bacteria has inside it another bacteria, which has been tentatively called moranella. It has some of the enzymes that are encoded in its genome. 

So you can start here in tremblaya, in the bacterium. It makes compounds that diffuses into moranella, moranella makes compounds using its enzymes, which will go back into the bacterium, which will eventually go into the mealy bug cytoplasm, which will make phenylalanine. Three organisms cooperating together to make an essential amino acid. Now, invertebrates. One sees this a lot in the regulation of intestinal health by symbiotic bacteria. This work by -- looked at the importance of symbiotic bacteria for the health of our colon. And basically, he and others found that the bacteria help induce the gut-associated lymphoid tissue. This is the central lymphoid tissue in our body. They expand the Helper T Cells that are associated with the lymphoid tissue. As a matter fact, without microbes, mice have been AIDS-like immunodeficiency. 

Moreover, bacteroides fragilis can protect mice from helical bacter-induced colitis. So if you take susceptible mice and you add helical bacter, to them they get colitis. If you then add to that mix bacteroides fragilis, which is wild-type, it has polysaccharide A, the colitis is lessened. Here, if the bacteroides does not have PSA, colitis is just as bad as it was and here's wild type without the colitis inducing bacteria. Okay, so this bacterium, bacteroides fragilis, can offset the disease caused by another bacterium, helical bacter. It does this in an interesting way that I won't go into, but basically it's causing the production of interleukin-10, which is an anti-inflammatory protein. Without the bacteroides, helical bacter will induce the cells to make interferon and interleukin- 12, which are pro-inflammatory, interleukin-17 which is pro-inflammatory. Interleukin-10 actually stops the inflammation, so this bacteria is able to interfere with the disease process. Bacteria have also been associated now with obesity. This is when the Italian government lent the statue of David to the United States. 

[Laughter] Okay. Different mouse strains select for different gut bacteria, and those gut bacteria can influence the obesity. This is a leptin-deficient mouse. This is an OB mouse. This is a obese mouse. This is a wild-type littermate if you look at the bacteria, you'll find that they have different bacteria populations they'll have firmicutes and bacteroides. Those are the two major families of bacteria in our gut. In a obese mice, one has more firmicutes at the expense of bacteroides. Okay, so in addition to be leptin deficient, it also has a different bacterial population. What's really interesting, is that when you take germ-free wild-type animals, the wild-type animals that have not been exposed to bacteria, they are born into sterile environments, they are born by cesarean section, they are born in a sterile environment from sterile mice. 

The mice don't have bacteria. When you take these germ-free mice, and you add bacteria from either the obese animals or the wild-type animals, with their different bacterial populations, you get an increase in body fat in those wild-type mice that have been given the obese bacteria. This has also been found when human bacteria are put into mice as well. That different bacterial strains, will utilize food differently and make more or less calories. So, the bacteria are important in us. The bacteria are critically important. They are actually inducing gene expression in our gut's tissues. They are telling the gut tissues, the -- cells of the intestine, make things like angiogen-4, things that are involved in making blood vessels. Make colipase. The bacteria are inducing the genes of our cells to express certain proteins, certain --. 

When I say our, I mean as mammals. But this does explain some things about humans. For instance, human milk contains complex sugars that can't be used by human infants. So why does the mother make these critically important, lots of these glycans, these complex sugars, why are they being made? Well, apparently some of these oligosaccharides are really good growth promoters for bacteria such as bifidobacterium longum, which are the good guys. We want these in our gut, and so we help them colonize the baby's guts by giving them the food they like. Similarly, the intestine, which had been thought of as a vestigial organ, but it has a valve structure which doesn't look vestigial. It looks like it's functional. Well, in most places in the world, especially around the equitoral regions, diarriah is one of the most important health problems that one has. Many things can cause diarrhea. Perhaps what the appendix is doing is basically working as a storage place, a reservoir, such that when one evacuates one's colon, one can get the bacterium back. 

One can get the bacterium back from the appendix. One can restore the bacteria that one had. Now this restoration of bacteria has really been fascinating in recent years, in the past, really, three years. Because sometimes people are given huge amounts of antibiotics to get rid of bacteria. Often this is done in hospitals. One of the dangers is that there's a lot of nasty bacteria floating around in hospitals, including clostridium. People have gotten clostridium dificile-assocaited diarrhea. It's often associated with antibiotic-induced diarrhea or colitis, and it's thought to result from the antibiotic's disruption of one's normal commensal bacteria, one's normal mutualistic bacteria. The way this is being cured now is fecal transplantation. You take the feces of a spouse, usually, a good friend. 

After evacuating your feces, you put in your spouse's feces. It cures them. There are numerous papers talking about fecal transplantation. Another important thing about physiology and seeing bacteria as part of our physiology, the bacteria are very important for guarding the gates. They're at every pore, they're at every orifice. They're at every part of the body which is exposed to the outside environment. What happens if one genetically modifies these? There's now coming on to the market genetically modified probiotics. For instance, this is lactobacillus. This was a paper in PNAS a year or so ago. Lactobacillus we know is fairly good at keeping colon health, and it's used in many of the yogurts and everything. 

If you give mice dextran sulfate-induced colitis, you get a production on interferon. That's this line over here, IL-12 and IL-10. Okay, here's IL-10, that's the anti-inflammatory, interleukin-12 and interferon are pro-inflammatory. Okay, you get inflammation. You get colitis when you have the dextran sulfate injection. The lactobacillus, the regular strain of lactobacillus, it's okay at reducing some of the interferon. But what if you get rid of the LTA, the substance which induces interleukin-12 production. What happens is, now the interleukin-12 goes down, but so does interferon, and you get a huge spike in the production of interleukin-10. This genetically modified bacteria is even better than the normal strain at getting rid of experimentally induced colitis. You can see how the bacteria are involved in us and how we could actually go about using that to make our own protection. 

The next slide is almost science fiction. The next slide is something four years ago I would not have shown. But the data has come out, and this basically says that the normal microbes modulate normal brain development and behavior. People are starting to talk about the microbiota-gut-brain axis. Now we have all these bacteria in our gut, trillions of bacteria. They're producing products. They're producing propionic acid. They're producing acidic acid. They're producing all sorts of agents that can go through the blood-brain barrier. Well, germ-free mice have increased motor activity. 

Germ-free mice had elevated levels of dopamine, Norepinephrine. They also had lowered amounts of the transcription factor NGF-1-A, which is involved in neuronal plasticity. This is basically a mouse colonized with known bacteria. This is germ-free. You can see, this just kind of graded amounts of transcription factor NGF-1-A. BDNF, brain derived neurotrophic factor, this is another thing which is involved in plasticity and learning. It's much more frequent, you see it much more abundantly, in those mice with bacteria than those mice without bacteria. The authors conclude that during evolution the colonization of gut microbiota has become integrated into the programming brain development, affecting motor control and anxiety-like behavior. Another recent paper in PNAS, showed that lactobacillus can actually regulate stress response. So here you have the corticosteral level in mice, this was unstressed, and were given broth. 

They were stressed and given broth. Okay. They're stressed, yeah, lots of corticosterone. Here they're control, they're not stressed, Okay, good. They're not stressed. Not given anything else either. Fine, the bacteria doesn't stress them. Here's the interesting one. This is where they stress the mice, but they give it this lactobacillius and they lessen the stress response. They lessen corticosterone. 

What's interesting is that this effect doesn't happen if you cut the vegus nerve. There's some interactions which we knew nothing about, where the bacteria have become really integrated into our physiology. So we are not anatomically individuals, we are not physiologically individuals. What about developmentally? Okay, so this slide is just used so you can see the optical illusion here. Here's the fetus. Here's the eyes, the hands, the legs. The embryo is co-constructed with the environment. But symbionts do effect normal development. They do it both parasitically and symbiotically. This is a nice example of developmental symbioses under the parasitism mode. 

This is maculinea arion, the large blue butterfly of Scandinavia and England. It lays it's eggs on gentian. Once they hatch the caterpillars fall off, and they get picked up by a myrmica ant. They exude a cocktail of compounds that makes it smell like an ant larva. So what's this ant larva doing out here, I'm going to bring it back to the nest. And it does. What do the ant workers do? They feed the larva. The larva then grows and grows and eventually feeds on some of the worker ants. Then it hatches and leaves as a butterfly. So for this part of the life-cycle, the ants are critical. 

What happened actually in Britain was they changed the pasture laws. They didn't allow cattle to crop there, and as a result the grass changed and a new species of ants came. They took the larva and ate it. They had to actually re-populate from Scandinavia. This is the parasitic mode, but we get our symbionts naturally. We get our symbionts in one of two ways. Animals get their symbionts in one of two ways. Insects get them from the germ line, often. Here is the germarium of -- and if I were to ask my students, what does this show. Here's these red dots over here. 

I hope that they would say, oh, there's some substance being transmitted from the nerve cells, 15 nerve cells into the one oocyte. Than substance could be --. It could be ribosomes. Lot of things being transported into the egg from the nerve cells. What they're transporting in this case is Wolbachia bacteria. The Wolbachia bacteria get into the oocyte and from there into most of the cells of the embryo and larva. Arthropods such as insects get their symbionts from the mother. They get them directly from the germ line. We get our symbionts, vertebrates mostly get their symbionts from transmition. We get infected with our symbionts. 

We develop rather aseptically in a sterile environment. We have an amnion which keeps the bacteria away. But as soon as the amnion breaks, as soon as the water sack breaks, we're exposed to the mother's bacteria. As a matter of fact, that bacteria has changed during the last trimester of pregnancy. The bacteria then are able to colonize. The whole notion of colonization of the fetus being born is just an amazing story, of how that colonization occurs. This is just starting to become known. Now in insects, developmentally, this could be really important. Here we have a situation where if this insect, Asobera, doesn't have it's Wolbachia bacteria, the females can't reproduce. Here we have, all this white stuff over here, this is propridium iodide staining of DNA. 

Here's the nucleus. These are all bacteria here. Lots more than up here. You can get rid of all this bacteria by putting them in Refampicin or some other antibiotic. It kills the bacteria. Okay. What happens to the organism? Well, if it's female, it's ovaries degenerate. Here we have the reproductive system of the one's with the symbionts. This is tunnel-staining over here, which stains cells undergoing death. Very little. 

But here is the same stain in to ovaries of an organism without the bacteria. The cells die. Symbiotic, asymbiotic. Okay? The cells die without the microbes. Invertebrates, as I mentioned before, our intestines need the microbes. This is the intestinal vasculature in green, without microbes, in a germ-free mouse. If you add microbes back to that mouse. You take the microbes that have been in a regular mouse and put them now into the germ-free mouse. Within ten days you start getting good microvasculature. You get the vasculature on the villi necessary for digestion. 

Here we have dome and the follicle of the immune system, the activated lymphocites of the gut-associated lymphoid tissue in the intestine. Without gut microbes you don't have either. So lymphoid tissue, blood vessels, it's all being helped along by the symbionts. As I mentioned before, what the symbionts are doing, they're inducing gene expression in the mammalian cells. Here's relative MRNA abundance. Here's germ-free mice. Colipase, angiogen, should be angiogen-4, SPRR2A which is a matrix protein, and germ-free mice is set to 1.0. That's your 100% level. You can see that conventionally raised mice, with their normal bacteria, have six times as much colipase MRNA. They have ten times as much angiogen-4 MRNA, and they have about 50 fold more SPRR2A MRNA. 

These bacteria are inducing gene expression in our bodies, and it's expected gene expression. We've outsourced the gene expression, the developmental signals, to the microbes. They're always going to be there. Fine. We feed them, we might as well have them do something. They'll help make our guts. Zebra fish-- The stem cells of the gut are regulated to divide-- The division rates of the stem cells of the gut are regulated by the bacteria. Germ-free zebra fish intestines, they lack the traditional alkaline phosphatase, they lack enteroendocrine cells, they lack the goblet cells. They are not good intestines. You can see over here, they're even smaller than usual because they don't have the cell division of the intestinal stem cells. 

This is important for a number of reasons. This whole notion of developmental symbiosis. One's, for instance, you can kill the host by killing the symbiont. This is interesting in medicine. This is mansonella, a filarasis worm. It's not the elephantitiasis type of worm, but it's related to it. It gives you lethargy. This worm can be killed, but it can't be killed by the standard drugs which kill worm infections because this guy has evolved a resistance to it. What will kill this worm is doxycycline, an antibacterial. Because without its bacteria symbiont it can't molt and it dies. 

Unfortunately, we're seeing some die-off in the spotted salamander in the Midwest. Spotted salamander, Ambystoma, makes an egg mass, this huge volume of eggs that it makes. You can see here, it's green. The reason it's green is because the egg mass is befouled by algae. There's a type of algae, and the only thing the algae can eat is the egg jelly of Ambystoma egg masses. It's rather specialized. However, Atrazine and other chemicals that are used as herbicides, are going into rivers from the farms and the river are putting them into the lakes where they do what they're supposed to do. They kill plants. They're killing off the algae. This algae actually gets into the larva. 

It's really great. Here's the larva here, you can see the eye, here are the gills. Here's that algae-filled egg. What happens during development earlier on, and this has just been stained so you can see the algae better. Some of the algae has gotten inside the egg jelly and it's actually going into the blastopore over here, and from there into the whole embryo. Eventually, in the females it ends up in the reproductive tract where, when the eggs are laid, out come the algae with the eggs. Here at Wisconsin Margaret McFall-Ngai, Ed Ruby and others, are studying the interaction between euprymna, the squid, the Hawaiian bobtail squid, and vibrio, vibrio fischeri, which is a microbe, a bacterium which is in the ocean. What the squid and the bacteria do is they interact with each other. And when they interact with each other it forms the squid's light organ. The squid is born with a surface that can collect bacteria and through a really remarkable set of interactions eventually only vibrio fischeri is collected and this vibrio fischeri is then collected and aggregated in a way which will make it light up. 

What this does, it allows the squid to hunt at night. The moon, instead of casting a shadow on it, the squid's light organ will prevent the shadow from forming. So other preditors don't know that the squid is around. Here's an organ, the light organ, which is formed by a collaboration between the host and the symbiont. What we see developmentally is, throughout the animal kingdoms, one sees that development is itself symbiotic. We are not individuals by developmental criteria. So what about genetic criteria? Okay, genetic criteria. Well, here I want to talk about something that we see every day. That is this notion that is being repeated to us inexorably that DNA is your soul. This is from a book that Dot Nelkin and Susan Lindee wrote called, The DNA Mystique. 

They looked at how DNA was represented in literature. Not PNAS and Science and Nature, but Vogue, Cosmopolitan, Red Book, New York Times, Newsweek, Time Magazine. How is the larger culture being told about DNA? Their conclusion was, DNA is the secular analog of soul. It's that which determines what you are, that which determines your behaviors and that from which you can be resurrected after death, ala Jurassic Park. We're being taught this. Again, it's part of the anti-abortion, anti-stem cell debates. Know that you are who you are at fertilization. That's what this thing, you know-- and even more amazingly, intelligence and personality, the way you look and feel, are already in place in your genetic code. At the moment of conception, you were essentially and uniquely you. Your self was determined at fertilization. 

Okay. We see this all the time. I have 11 of these ads. This is the most egregious, a mid-sized Hummer. "Same DNA, smaller chromosomes." Okay. It's the same soul, the same essence. We're being told that DNA is our essence. My wife who's of Finnish background gets the Finnish American newsletter, and it says that the sauna is in the DNA of every Fin. [laughter] There's a lot of Fins that have had their DNA-- The sauna is not there. It's in the soul of everything. 

DNA has been used as the basis of individuality, but it's not a very good one. Certainly we have loads of different organisms, each with their own genome. There's horizontal transfer of genetic material. Certain transposons may have facilitated really major anatomical evolution. For instance, the expression of the prolactin gene in the female reproductive system seems to come in through a transposon. The symbiont's basically a second genetic system. This is what I want to go into now. The second genetic system. Can this be actually used for evolution? I want to talk about aphids primarily. In certain strains of aphids color variation is determined by the symbiont, Rickettsiella. 

Without the Rickettsiella a red aphid will remain a red aphid. But with Rickettsiella a red aphid can become a green adult. This is very important if you're living on leaf. This is very important if you're living on the ground. It's selectable variation, and Rickettsiella actually induces a synthesis of quinones in the aphids. What about temperature dependence? Well, there's another symbiont of the aphid, Buchnera. Buchnera is also found in many of the aphid's cells, and it produces a chaperone protein, a heat shock protein. And there are different alleles of the bacterial gene. Depending on which strain you get, you can either have, as in this dark pink, you can get the heat resistance. At a higher temperature, you have heat tolerance, thermo-tolerance. 

But at lower temperatures you have less fecundity. It's a trade off, but it depends of which allele you get from the bacteria. These are parthenogenic species, so their female to female to female to female. There's no males here. Where are they getting their variation from? Some of the variation is coming from bacteria. Here's another interesting one, Hamiltonella. Hamiltonella is a bacteria. It protects the aphid against parasitoid wasp infections. Parasitoid wasps, something else studied at the University of Wisconsin, can inject their eggs into the aphid and cause the egg to develop inside the aphid. It will eventually eat the aphid from the inside, then bore a hole through it's skin and reproduce and leave. 

It's a horrible way to die for this aphid. It's kind of being dissed at the same time. There's a bacteria that will actually protect the aphid against this wasp egg. It isn't really the bacteria that's doing it. It's the lysogenic phage inside the bacteria. So if the bacteria doesn't have the phage, it doesn't work. It's a symbiont within a symbiont that's doing the protecting. In the pea aphid, you have three types of bacteria, each of them giving selectable variation. In humans this might too. This is really fascinating stuff in that in Japan, there's a bacteriodes strain, Bacteriodes plebeious, which differs from the bacteriodes strain in America. 

What it's done, it's horizontally inherited two genes which are involved in metabolizing complex sugars found on seaweeds. The bacteria that it probably got these genes from is a strain very similar to bacteriodes that lives on seaweed. You have, basically, sushi digesting bacteria in the Japanese populations of bacteria. It's just kind of neat. Bacteria might even be responsible for mating preference in drosophila. This is again from the Rosenberg's lab. Usually drosophila like to mate with those other drosophila that eat the same food as they did, either starch or molasses. What happens is, it looks like lactobacillus is found on starch more than it is on molasses. It's this lactobacillus that seems to be involved in making the contact pheromones involved in mate selection. At least it's helping make them. 

If you get rid of the bacteria, you get rid of the mating preference. Even in evolution you get selection of the symbiont-host complex, the holobiont. Here's a really interesting thing. There are solar powered sea slugs. Sea slugs that have cloroplasts in them. Here we have this mollusk which ate one meal. It ate seaweed. It takes the cloroplasts from the seaweed and is able to use them for making starch, making sugars. So we have some really fascinating examples of symbiosis during development. What Oliver said in the paper over here about the aphid, "In our system the evolutionary interests of phages, bacterial symbionts in aphids, are all alines against that parasitoid wasp that threatens them all. 

The phage is implicated in conferring protection to the aphid and thus contributes to the spread and maintance of H defense of the bacteria in natural -- aphid populations." No-- [laughter] Okay. It's really not group selection. It's something different than group selection. It's more like ecological succession. You're selecting partnerships. This is a new thing in evolution. Can evolution select for partnerships? We're seeing some fascinating thing coming out in the literature. Here's, again, a mammalian immune system. Usually we're used to thinking of the immune system as this army that protects this pure body from the invasions of the bacteria. But look at these. 

"These results underscore the adaptive immune system's critical role in establishing a sustainable host/microbial relationship. This may involve the creation of an optimal symbiotic environment on the interior of the Peyer's patches. Therefore, commensal bacteria exploit the toll-like receptor pathway to actively suppress immunity. We propose that the immune system can discriminate between pathogens and the microbiota though recognition of symbiotic bacterial molecules in a process that engenders commensal colonization." So the immune system is not only defending us, but it's also allowing good bacteria to get in. It's not so much an army as it is passport control, or a bouncer. You know, we know you. You're good. You can come in. We know you, you're bad. You stay out. 

Last, we never were individuals. This is the work of Nicole King at Berkeley. It's basically saying that if you look at choanoflagellates, which are the closest organisms to the animals, the closest protists to the animals, they are unicellular protists. Except when they're exposed to certain bacteria which are found in their environment. When they're exposed to this bacteria they change their development. They do not divide completely and separate. They form instead an extracellular matrix. They form cytoplasmic connections between the cells. They make rosettes. They become multicellular. 

Metazoans may have originated in some sort of symbiosis between choanoflagellates protists and their bacteria. It's a fascinating model that's just now being worked on. So, biological individuality for animals, not. Anatomical individuality, nine out of every ten of our cell are micobiotic. Physiological individuality, animals have joined metabolic pathways. They have collective purpose. They have collective defense. Developmentally, gut microbes help build our guts, help build our immune systems, things like the light organ, ovarian cell death in Asobera. No, not even developmentally. Immune individuality? Not only do the microbes help build the immune system, they also expand the lymphocyte repertoire. 

The microbes are allowed to become part of ourselves. The immune system acting more like a bouncer than an army. Genetic individuality? The genome evolved for those of our symbionts. We have over a hundred different genomes in our body. Many have phenotypic outcomes, as I showed you with the aphids. They're used during development. Evolutionary individuality, the symbionts can provide selectable variation. There might even be selection for partnerships. Basically, we are teams. Okay? We are teams. 

Everything you want to know about organisms can be learned by looking at the Packers. [laughter] A collection of individuals for a common goal, group identification. Even the fans. You have a friend who is a Chicago fan, you hope that you're going to go and say, we really whipped you! WE, you know. Division on labor, based on morphology and physiology. Plasticity, one member can play several roles if needed. There's only one member that's very specialized. He's the one with the clean jersey who kicks the ball. Group identity is kept by changing the parts. No one member is irreplaceable, as we've learned here. 

Communication within the group is critical. Although there may be a script, improvisation is critical, both of parts and the whole. There's both individual and group selection. Usually excellence of the part is good for the whole. Each person wants to get in the record book, but it's the team that wins or loses. That's where selection is. Today, if you saw the interview with Rogers, he's trying to deflect the praise of himself onto the team. So happy 12/12/12. Thank you very much. [applause]