cc  >> Robin Chapman: Welcome  to the Complex Systems  and Chaos Seminar.  We're delighted today to have  Eve Emshwiller in the Department  of Botany at the University of  Wisconsin-Madison.  She's going to speak to us on  crop eco-diversity and the need  to maintain it.  Eve.  >> Eve Emshwiller: Okay,  thank you.  Hear me okay? Yep.  Okay, well, I'm really pleased  to have this opportunity to  share with you a little bit  about the reasons why we should  be concerned about the diversity  of crop plants and their wild  relatives, and what are some of  the things that we need to know  to be able to do that and use my  research on the tuber crop  that's grown and eaten in the  Andes of South America as an  example of research in this  area.  So, as she said, my name is Eve  Emshwiller from the Botany  Department.  Sorry about this.  Time for an edit. 

 So this is under the broader  umbrella of my studies in  ethno-botany.  And ethno-botany is defined as  the scientific study of  interactions between plants and  human cultures.  And that's not just medicinal  plants, it's not just  archaeology, it's not just  surveys of people's naming of  different plants and  classification, it's all  interactions between humans and  plants.  So in my case, looking at crop  diversity and how to conserve it  and how it's evolved under human  influence is the part of that  that I study.  I'd like to take you back to the  early part of the 20th century  to Nikolai Vavilov.  He was one of the first people  to start studying the, well not  the first because there were  some in the 19th century, but  one of the fathers of the study  of the origins of crops, the  crop domestication and also the  concerns about conserving the  diversity of crop plants.  He was a Russian botanist and  geneticist in the earlier 20th  century when being a geneticist  in the Soviet Union could cost  you your life.  It's hard to think about that  now, but just as we have people  in the United States now who  don't believe in certain aspects  of science such as evolution, at  that time the thing that was not  politically correct to believe  in was genetics.  And he was, after doing years of  expeditions all over the world  looking at the diversity of crop  plants, his initial goal was to  reduce famine in his country and  in the world by gaining genes  from the diversity of different  crops and using them to breed  more resistant crops that could  avoid famine but realized that  what you needed to do was to go  to the parts of the world where  those crops were originally  domesticated.  He was one of the first people  to say that in order to look for  where crops where initially  domesticated, where they  originated, one should look at  the places where those crops  have the greatest diversity. 

 We now know that there are some  exceptions to that, but it still  is a pretty nice rule of thumb.  Unfortunately, because Stalin  favored Lysenko's return to  Lamarckianism instead of  genetics, eventually geneticists  were thrown in jail or killed,  and that included Vavilov who  died of starvation in a Soviet  prison.  But before he did that, he  mapped out the areas of the  world where he thought that  crops originated based on his  expeditions and his study of the  diversity of crop plants from  different parts of the world.  He kept updating this and  changing this throughout his  life as he got more information,  and so he did not have the  information that we have today.  Here's a recent map of areas of  domestication of crops.  Some of the ones are exactly the  same areas that he talked about  of what's now Mexico, of the  Andes, of the Fertile Crescent  area and China.  But some others were areas that  he talked about Abyssinia or  Ethiopia but not about the whole  Sahelian region.  So this is still an active area  of study and so there's a lot of  updated information about where  things come from.  >> Please define the word  domestication.  >> Okay, thank you. 

 When we talk about domestication  here we're talking about genetic  change that happened in the  course of people bringing  something, in the case of  plants, into cultivation.  The cultivation by itself isn't  domestication but the genetic  change.  If we use an analogy from  animals, to go from a wolf to  all the domesticated dogs  everywhere from Poodles to  Chihuahuas to Great Danes to St.  Bernards, that was the process  of domestication that changed  wolves, genetically, into all  the variety of dogs.  So when we talk about crop  domestication, we're also  talking about genetic change  from the way things were as wild  plants to characteristics that  they have when they're  domesticated.  And often characteristics that  are very good for survival in  the wild are not the same ones  that are good for survival in  agricultural systems and also  may not be the ones that human  beings would prefer.  Such as, usually we don't want  so many toxins or unpleasant  flavors in our food.  Whereas, there are exceptions to  that, but over the course of  thousands of years people have  transformed crops from wild into  the way they are today.  So something like maize is from  what is now Mexico.  There's a lot of research on  this campus on the origins of  maize, and they've not only  identified where the original  area that maize was  domesticated, in what is now  Mexico, but they're now  studying the actual genes that  were modified in the course of  transforming the ancestor of  corn into the corn that we know  today. 

 So all of these areas around the  world are areas that we now  think different crops came from,  and in some of these areas the  diversity of those crops is  disappearing even though those  are the ones that we're, if we  need new genes for resistance to  drought, to insects or even  things that might make things  taste better, then those are the  areas where we want to go to  find those genes.  I'll just go back up, no I'll go  forward, sorry.  So back in about the, after  Vavilov and into the '60s and  '70s people began to be very  concerned about the loss of this  diversity.  They realized that as one of the  processes is that as plant  breeders come up with newer and  higher yielding varieties, if  those are taken up in the parts  of the world where those crops  first came from, sometimes that  can lead to farmers no longer  cultivating the original very  diverse crops and replacing  those with monocultures of a few  high yielding varieties.  One of the people who spoke out  about that was Garrison Wilkes,  and he likened modern plant  breeding as taking stones from  the foundation to repair the  roof.  I kind of like that analogy  because it makes it pretty easy  to see that, yes, you need to  repair your roof, but you  shouldn't take stones from the  foundation to do that.  And this quote about the end  point of genetic erosion could  be that if the last bit of seed  stock is eaten, then that  particular crop variety can go  extinct.  Obviously a lot of genetic  erosion has to have happened  before you get to this point.  So hopefully we stop it before  it gets to that point.  But these are a couple of ways  to think about the end points of  genetic erosion. 

 Well, why should we care?  One reason is that when you have  to much genetic uniformity that  can lead to huge problems of  disease.  And one of the most familiar  aspects of that or examples,  sorry, is the Irish potato  famine, and the disease called  late blight swept through  Ireland in the 1850s and wiped  out the potato crop there that  so many people had become so  dependent on.  Many, many people died of  starvation, and many, many  people came to the United  States.  It's really because of the late  blight epidemic in Ireland that  we have the Boston Celtics, that  Chicago turns their river green  on St. Patrick's Day, things  like, that because so many  people fled from that famine  to come to the United States.  Well, this disease is caused by  a water mold and it's around in  other cases but the problem in  Ireland was that they were  really pretty much growing all  over the whole country one kind  of potato.  And potatoes propagated clonally  so they're genetically identical  all over the whole country, or  nearly.  So when a disease comes through  and there's only exactly one  clone all over the place, the  diseases can really go through  very quickly.  Another example that's closer to  our own time, in the 1970s, and  in the United States, there was  a disease epidemic that really  kind of woke people up to this  problem.  It was the southern corn leaf  blight epidemic in the 1970s,  and this was a disease that  existed in the country normally  but usually wasn't that big of a  problem.  But in that year the weather  conditions were just right, very  damp and humid and it started in  Florida and then started moving  north. 

 It affected many of the  southeastern states, in  particular some of those  southern states lost half of  their farmers, and half of their  crop and half of their farmers  went bankrupt because of this  blight.  And the problem, again, was  uniformity.  Normal crop leaves up here were,  oops, that's not going to work  very well.  This is the normal leaf in this  area, and you can see that it's  only slightly affected.  But these ones over here are  maize or corn with what's called  T-cytoplasm.  And they were using that  cytoplasm all over the country  because it causes male  sterility, and it made making  the hybrids easier.  They could make their crosses  easier because they didn't have  to worry about contamination of  pollen.  So that turned out to be that  male sterile T-cytoplasm was  used all over the entire  country, and it just happened  that that T-cytoplasm was not  resistant to this disease.  So people become more aware of  the need to preserve genetic  diversity of crop plants and  started a lot of organizations  both national, international and  grassroots organizations all  came up in the 1970s,  especially, to try to preserve  more of this diversity.  So an example of how collecting  four germ plasm banks can be  useful, this was a variety of  wheat that was collected in  Turkey in 1948 by Jack Harlan,  was very miserable looking, it's  a miserable looking wheat, tall,  thin stem, lodges badly, is  susceptible to leaf rust, lacks  winter hardiness and has poor  baking qualities. 

 Why would anybody care?  Why would anybody even want to  collect this?  It's not good for anything.  Well, he collected in anyway,  put it into the USDA germ plasm  bank, and 15 years later there  was a outbreak of disease,  striped rust, and it turns out  that when they tested for  resistance to this disease, this  particular miserable looking  wheat turned out to be resistant  or tolerant to several different  wheat diseases, not just that  one, but lots of them.  So it turned out that even  though it didn't grow well and  wasn't very useful as a grain to  eat, it had a lot of resistance  that was then bred into grain  that's now used all over the  country and probably all over  the world and saves us a lot of  money.  So that's just one example of  why you would want to preserve  this diversity.  Wild plants, as well, the wild  relatives that have not yet been  domesticated are often still in  the area of origin of crops and  those ones also have contributed  a lot of resistance or, I don't  know, cotton fiber quality or  sweetness to tomatoes or various  different things like that from  wild relatives of these crops  have been bred into different  cultivated crops.  Also, many experiments are  finding now that rather than  monocultures, if you mix  different rice varieties  together, and this can be case  of other crops as well, if  they're grown in mixtures, that  can sometimes, depending on the  disease, it can sometimes mean  that the diseases move less  quickly through the crop.  Now that isn't always the case,  but if you imagine that maybe  I'm not so resistant but one of  you is if I'm infested with a  disease and then the spores are  released here and land on you,  they're not going to grow  because you're more resistant  than I am.  So if there's a mixture of  different genetic diversity in  the same fields, that can help  to slow down disease.  So those are all some of the  reasons why we care about  genetic diversity of crops and  their wild relatives.  So I'll move into what I work  on. 

 I work on this tuber crop.  It comes from the Andes, and  it's eaten and grown similarly  to a potato but it's not at all  related to potatoes.  It's a species of Oxalis.  It's in the -- family.  And so it's not at all related  but the ancient Andean people  not only domesticated the potato  and thousands of varieties but  also different tuber crops of  three other completely unrelated  plant families that are not  related to the potato and its  family or to each other.  They are completely unrelated.  So this crop, one of the things  that makes it challenging to  study is that it's octoploid,  that means it has eight sets of  chromosomes, not two like we do.  That makes studying its  evolution pretty complicated.  It's also vegetatively  propagated.  And that's similar to a potato  in many other things where you  just plant the tuber itself  rather than planting seeds, and  so each plant is genetically  identical to all the others. 

 So this crop is grown primarily  in the central Andean region, in  the highlands of the Andes of  Peru and Bolivia, especially,  and it has a very important role  there for the food security of  the people and for their crop  rotation system.  You can't grow potatoes on the  same land year after year or you  get a lot of diseases and pests.  So you have to have different  crops that you can grow on the  same land.  The potato is most important to  them, but this is probably the  second most important in many of  these areas which they grow for  their own subsistence.  So my research has looked at a  number of different angles about  this crop going all the way back  to my dissertation time.  Part of it is to look for the  origins of this crop.  And believe it or not, there's a  lot of crops that are not as  obscure as this one that people  are still learning the origins.  Because it is a polyploid, the  question of its origins isn't  just what wild species was  domesticated to transform it  into the cultivated, the  domesticated crop, but also  what's the origins of  polyploidy?  If it has eight different sets  of chromosomes usually that  means it's a hybrid, and so  which different species  contributed those genomes to the  crop.  And I've studied that in the  context of the phylogeny of  Oxala species that are closely  related to the crop.  I've also looked at different  aspects of the evolution of the  crop that continues under human  influence. 

 And part of that is to look at  what's the biological basis of  the whole classification.  That is how the farmers name and  classify their different  varieties of the crop.  And looking at humans as the  agent of dispersal because, in  this case, crop varieties are  moved by people, not by wind or  other mechanisms.  And then what then is the, as  these clones are distributed by  people, as they exchange  planting material, what is  happening to that?  What's the distribution and the  dynamics of that diversity.  Because by understanding that  that's what we need to know in  order to preserve that  diversity.  If we don't know where it is and  how it's distributed, we can't  conserve it.  So for the first parts of those  questions about the origin, I  used a number of a different  molecular data sets.  I used DNA sequencing and I used  both things that are on  the chromosomes and the nucleus,  and also different parts of the  chloroplast DNA.  Most people know that  mitochondrial DNA is inherited  only by the mother.  The same is true of the DNA or  the genome that's on the  chloroplast. 

 So we use both of those and then  a different kind of  fingerprinting.  The details are only for those  who know about those things.  So because oca has eight sets of  chromosomes, it may either have  originated by doubling of  chromosomes of one species or by  hybridization.  If it's doubling up of one  species, that's called  autopolyploid, and that means,  so pretend each of these  chromosomes is a whole set of  chromosomes, so it actually has  64, so eight sets of eight.  Each of these sets of  chromosomes will have derived  all of its genes and all of its  chromosomes from a single  diploid ancestor.  Diploid is having two sets of  chromosomes like we do.  On the other hand, if it  originated by hybridization of  several different species, then  each of its sets of chromosomes  will have originated from  ancestors, several different  ancestors.  And having eight sets of  chromosomes you could,  theoretically, have as many as  four different ancestors  originally.  There's a lot of steps missing  here.  So I traveled around, all the  way back at the time of my  dissertation I traveled around  the highlands of Peru and  Bolivia and collected a lot of  different wild species that are  related to the crop itself. 

 And used DNA sequences of two  different nuclear loci.  We're using DNA of the  chromosomes because we wanted to  have evidence of all those  different chromosome sets.  We couldn't use, for that  purpose, the plasted loci, the  chloroplast DNA because that  would only tell us which was the  mom, it wouldn't tell us who all  of those potential parents were.  So this is one of the results  from back then and I'll just say  that this is, think of it as a  family tree on its side where  these are the descendants on the  right-hand side, and on the left  you're looking at the ancestors.  So if we're looking at, I'll use  the mouse, if we're looking at  this part, we're looking at the  ancestors of all of this group  of Oxalis, and then those that  are linked closer together here  then share a more recent common  ancestor than the others.  So there's an entire group here  that was previously named the  Oxalis tuberosa alliance by some  psychologists in Argentina who  found that that group of Oxalis  were the only ones that had  eight as their base chromosome  number.  So when we talk about the  diploids would have 16  chromosomes all the way up to  oca that has 64.  Oca's not shown in here yet, but  this initial, at first I was  really only able to show that  all of this group that was  called the Oxalis tuberosa  alliance is indeed the group  from which oca comes from.  This is a much more recent  analysis, but I'm just showing  it so you can know that this is  only a very tiny part of the  genus Oxalis.  The genus actually has somewhere  between 500 and 800 species, and  this is an analysis we did more  recently with maybe about some  place between 80 and 100  different species. 

 And the part we're talking about  that oca comes from is this  group over here.  We sampled some of them there,  and that's the only part of  Oxalis where they have eight as  their base chromosome number.  So the genus is much, much  bigger, but from now on I'm only  going to be talking about one  tiny corner.  And that group, called the  Oxalis tuberosa alliance, is  found all through this northern  end, central Andes, a little bit  into Central America, and most  of them are diploid, two sets of  chromosomes, and most of them do  not have tubers.  They're related to oca, but they  do not have tubers.  However, during the time of my  dissertation I found some  populations that had small  tubers in two parts of the  Andes, in the eastern slopes of  the Andes in Bolivia and around  the area of Cusco in Peru where  there's a species called Oxalis  pes chinensis which also had  very small tubers.  So those were also included  along with cultivated oca for  the DNA analysis.  And so here's one set of results  with one of the nuclear loci.  Again, I'm only showing that one  little corner of the genus.  It was necessary to do molecular  cloning of the sequences from  oca itself, Oxalis tuberosa,  because there were multiple  sequence stripes within each  individual. 

 This is what we wanted to see.  We wanted to see multiple types  within each individual because  that meant we were seeing  evidence of all those different  ancestral genomes that came from  the different ancestral species.  So one of the ancestral  sequences of oca, which is this  tuberosa down here at the  bottom, was identical with that  of Oxalis pes chinensis, and  then two of the others of oca,  this one and this one up here,  were joined together and very  similar with the two sequences  from the wild tuber-bearing  population that I mentioned was  in Bolivia.  So that indicates, the fact that  they're coming out in three  different places on the tree and  coming out with different  species, is an indication that  indeed oca, like most  polyploids, did arise through  hybridization of multiple  different species.  And it also indicates that these  different wild tuber-bearing  ones are, according to this data  and according to this DNA  sequence data of this particular  locusts, these are the most  likely candidates as the  ancestor of oca.  Because there were three  different types and not four,  that indicates that oca may be  an autoallopolyploid which is a  kind of alloploid which has one  of its genomes represented more  than twice.  So at the time that I finished  my dissertation, this is what  seemed to be, at that time, the  simplest explanation.  That maybe oca originated by  hybridization of these two wild  tuber-bearing taxa.  And one was the one from  Bolivia.  I think that that may also be a  polyploid with something more  than two sets of chromosomes but  we don't know what. 

 Because it always had two sets,  those two different sequences.  Oxalis pes chinensis from  southern Peru, it has four sets  of chromosomes but it only ever  had one sequence from -- that  one gene.  So I think it might be an  autopolyploid itself.  But even at that time we knew  that the history might not be  this simple.  This would seem to be the  simplest explanation of that  particular set of DNA sequences,  but even at that time it might  not have been that simple.  One reason was that there was at  least one plant that I had that  didn't have that sequence.  And if this was the ancestor,  why was it missing this  sequence?  So already they were sort of  like, well there might be  something else going on.  Also, in the meantime, since  that time, we've discovered two  other areas were there are wild  tuber-bearing ones.  One is northwest Argentina  around Tucuman where there's a  species called Oxalis -- that  has these other couple of, has  all small tubers.  And then more recently another  one with small tubers on the  western slopes of the Andes in  Lima Department in Peru. 

 So we had to include those ones,  as well, because we didn't know  if those might also be the  ancestors of oca.  So I'm going it go on a little  digression here and tell you  about a different kind of work  because that will allow me to  introduce once of the other  characters in the story.  Back in 1997 I did some  ethno-botanical surveys of  farmers in three communities in  an area of Peru not far from the  ruins of Pisac.  Maybe some people who have  traveled to Peru as a tourist  might have visited those ruins.  But three communities and near  those in that area, not too far  from Cusco, where I asked the  people a lot about things having  to do with the diversity of oca,  what they called them, where  they got them, which were the  sweetest, which took longest to  cook, etc.  But part of that was looking at  the ethno-taxonomy, and what I  found there was the most  important division in their  ethno-taxonomy was the use  category.  There were a whole lot of  different colors and they all  had different names but they  were in the use category  called -- which means boiling,  essentially.  Sort of like you'd say  boiling potatoes.  These were boiling ocas.  They needed a few days to  sweeten in the sun but then you  could just cook them plain. 

 But there was this other one  that was called -- which means  sour or fermented, and that one  was only used for, it was very,  very, very sour.  It's like pucker up, like biting  into a lemon.  And it was only used for  processing by first soaking it  for several weeks in a pool, and  then drying in the hot Andean  sun and cold Andean nights,  freezing and thawing and drying  until you get this dry tubers  called khaya that will last,  basically, indefinitely.  They also make a similar product  called -- out of potatoes in the  Andes, and ethnohistorians  credit this method with the rise  of civilizations in the Andes  because it makes a tuber, which  normally has to be planted every  year and can't be stored for  long periods of time, into  something that will store and  provide food even when you have  bad, bad years.  So it can be made from other  ocas, but these really sour ones  are only used to make khaya.  And in these communities, the  people planted them separately  from the other regular ocas,  I guess I'd say.  So I started using DNA  fingerprinting, and I found that  all of the cooking varieties,  the -- varieties, separated very  distinctly from those --  varieties, the ones only for  processing.  I used a few examples of the  different wild tuber-bearing  ones and those were also  distinct.  But I was really struck by the  difference between these two use  categories.  And this molecular distinction  implied that there really was a  biological basis for the use  categories, the folk taxonomy,  and that there was some  difference in the evolutionary  history of these two use  categories. 

 With this information by itself  you couldn't really say exactly  what this difference was.  Though I suspected it might not  have as many chromosome sets  because the number of bands,  essentially the bars in the  fingerprint, that we got for  most of the ocas which was a lot  more than either the wild ones,  some of which we knew only had  four chromosome sets, or the --  variety.  So I suspected that it might  have a lower set of number or  sets of chromosomes and it turns  out, as I'll say in a moment,  that that was correct.  So why was I using this DNA  fingerprint?  And we've gone on to do that  more recently, more thoroughly.  And the questions were, were the  wild tuber-bearing varieties,  from those four different areas  in the Andes, were they distinct  from each other?  Because we didn't know that.  Are the khaya and the --  varieties are they going to also  be distinct from each other when  we use more data?  And are those four wild  tuber-bearing species or taxa,  which of them might be the  progenitor or the ancestor of  cultivated oca.  So more recently since being at  UW, we've generated a larger  data set.  A postdoc working with me, Tara,  generated these data, scored a  lot of peaks.  We included both kinds of  cultivated oca, and we used a  small number of the different  wild tuber-bearing taxa as well.  And then they analyzed those  data three different ways. 

 I'm going to just tell you about  two of them.  But first to go back to these  four different areas in the  Andes.  I want to just let you know what  we know so far of the ploidy  level or number of chromosome  sets we have.  I mentioned earlier that pes  chinensis has four sets of  chromosomes, the one in  Argentina may also based on a  very old publication that didn't  use that same name but I'm  pretty sure he's talking about  the same thing.  A master student in Peru, Kelly  Vivanco, has found that the ones  in Lima have six sets of  chromosomes.  The one that we don't know about  are still the ones in Bolivia,  though I'm pretty sure it  doesn't have only two sets of  chromosomes.  So now follow these colors and  we'll keep using those same  colors all the way through when  showing the results.  So here's one of the ways of  displaying the results of this  fingerprinting analysis with all  of these different wild ones.  So here on the right we've got  the two different varieties of  oca, the -- oca and the khaya  oca.  And here I'll mention that Kelly  Vivanco also found that at least  some of these khaya oca seemed  to have only four sets of  chromosomes. 

 So my hunch that they might have  fewer sets of chromosomes does  turn out to be correct.  It turns out that these are, you  can see that they're  non-overlapping with each other  in the results of this analysis.  The one that is are closest or  more similar, this is basically  just done on similarity and a  way to look at the similarity,  the ones that are closest to  cultivated oca are the ones from  Bolivia.  And the ones on the Oxalis -- up  on the upper right are not quite  as close.  Those, the Bolivian ones and the  ones from Argentina are not  overlapping with each other, at  least at this point, but I have  to admit that we really only  collected them from fairly  restricted areas.  >> Eve, what are the mechanisms  of hybridization that you're  considering might have mediated  the polyploidy?  Are they wild or are they human?  >> Most likely in the wild but  we don't know that yet.  And we might not ever know.  There are some crops like wheat  where some of the doubling of  chromosomes, some of the  polyploidy events happened  before domestication, and then  others, so to go from two sets  to four sets happened before  domestication and there's wild  ones with four sets.  But the bread wheat we grow with  six sets of chromosomes happened  after the four set ancestor was  already domesticated.  So I don't think we can exactly  know. 

 One way that things that can  become polyploid and was studied  also a lot on this campus was by  having the pollen or the egg  cells not reduced in all the  way.  Normally in sexual reproduction  they would go from two sets to  one set, and then the offspring  would have two sets again.  That sometimes, something  botches in the production, say,  of pollen and the pollen can  have a full set of chromosomes  when it's supposed to have only  half.  So that's one of the many ways  that things can become  polyploid.  And one thing to remember about  this is they don't all have the  same ploidy level.  So when we go to the next one,  you have to be careful about how  we interpret what we're seeing.  [INAUDIBLE]  >> Well this kind of thing,  it's really sort of arbitrary.  It takes the data that it's  given, in this case presence or  absence of particular peaks or  bands in this, they have or  don't have certain markers and  displays it in a way that sort  of shows you how similar or  different things are.  But if I excluded these two and  only showed these two, they  wouldn't be up in the corner,  you'd get a whole new display of  just these ones taking up the  whole box.  So they're really completely  arbitrary axes on that. 

 And not being a statistician I  don't think I can actually  explain it much better than  that.  So it's basically how close they  are is some measure of how  similar they are in whether they  had or didn't have certain of  these AFLP markers which I'm not  going to be able to take the  time to explain.  It's just pieces of DNA that  they share or don't share.  Yep?  >> Is there any correlation  between the selection that the  people may have made when they  were planting?  For example, what species they  planted near each other and  whether they chose largest  examples of the tubers to eat  versus using the largest ones to  plant.  >> Right.  So if they're planting smaller  ones or larger ones, if they're  doing it clonally it's not going  to make a difference because  they're all the same clone.  But in terms of what they're  planting close to each other,  that could definitely, it's not  going to necessarily affect what  the ancestry is but it affects  what's going on to this day of  how they're evolving, whether  they're able to cross breed with  each other for instance.  And that is also, but in that  case it has to not only cross  breed and form a seed but  somehow that seedling has to be  taken back up into cultivation  which is a whole other step  which may or may not happen.  At the time of when these were  domesticated thousands of years  ago we don't really know how  things were being cultivated or  necessarily where they were.  So it's kind of hard to know  that. 

 So in this case, we're just  talking about which of these  four wild tuber-bearing species  are most likely to be the  ancestor of oca and are they  distinct from each other.  And so far they seem to be  distinct.  The two populations, the  populations in two different  areas of Peru, I guess I should  say, are very distinct from each  other and also not at all  similar to oca and the other  ones.  So these are looking less like  they, so this is pes chinensis  up there, that's the one that I  earlier said might have been one  of the ancestors of oca and now  it's far enough away with this  kind of data that that's looking  less likely.  And I can say for at least right  now, the -- and the ones in  Bolivia appear that they might  be two different things and  might even be two different  species but because we've only  collected them from very  restricted areas we can't say  that yet.  I'm going to show, this is the  same data set but looked at in a  different way.  And here, if you kind of pulled  this out and looked at it, you  might start saying oh, this is  the phylogeny, this is the  ancestry.  And that's where you  particularly have to be careful  about how you interpret things  because we're not including all  of the potential members of the  group and we're only looking at  ones that have different ploidy  levels.  And so you have to be careful  when you say that the Bolivian  ones are the most similar to  these.  You've got your two different  groups of oca, and they are  staying quite distinct from each  other. 

 So that's the same when we look  at it this way.  Here are the ones from Bolivia,  and they are also closest or  most similar to oca, followed by  the ones from Argentina and the  furthest away are the two  different populations from Peru.  So you're kind of seeing the  same data, you're looking at it  is different way, you're seeing  pretty much the same thing.  One thing that stands out though  is here's this one number 284 in  the middle.  It was collected in Bolivia, but  it is, at the moment, being  loosely tied to the ones from  Argentina.  So it's not right up in the  cluster, but it's closest to the  cluster right here.  When we collected it, it was  very robust, it had relatively  large tubers and it was right  near cultivated oca.  So I thought, could this be a  hybrid between wild ones and  cultivated ones.  What is this one?  And as we added more and more  data here, it was kind of  jumping around.  Sometimes it would be with its  neighbors in Bolivia, sometimes  it would be with the -- ones and  finally it ended up being most  similar to the ones in  Argentina. 

 And that jumping around behavior  is something that hybrids tend  to as you add more data, can  jump around some.  So it might be a hybrid, but  given what it has it might not  be a hybrid with cultivated oca.  So we still don't know exactly  what the story is with number  284, but it may reappear in a  minute.  So we're now thinking that maybe  these ones in Peru are not the  ancestral ones.  The ones in Bolivia and the ones  in northwestern Argentina look  more like good candidates as the  ancestors, especially the ones  in Bolivia.  I should point out that these  ones that I've been showing all  along actually are the ones from  284 with the larger tubers.  I was actually just back in  Bolivia in February and talking  with people there about  continuing this work and we  visited that same area and they  have in greenhouses some more  that we collected from that area  so maybe we can confirm whether  that particular area is  something special about  hybridization or otherwise in  the story.  We also really need to fill in  this hole over here because I  can say that what we got, they  didn't overlap before but we  haven't really looked at the  ones in between.  If there are any in between.  I can pretty well attest to that  there are not tuber-bearing ones  in these areas over here. 

 So I'm already running through a  lot of my time.  We are also working with  chloroplast DNA, but I think I'm  going to just kind of skim  through that except for maybe  here.  This is the part that, the  chloroplast DNA is inherited  only from the mother so you  can't get evidence of all the  different ancestors that way.  What can you get is maybe which  was the seed parent, which was  the mother of the crop.  And here's some, a lot of  undergraduates have been helping  generate these data.  It's usually easier to get  chloroplast DNA than DNA from  the nucleus working.  So it's a good thing for  students to help with.  In this particular section of  the chloroplast DNA, we had oca  and four of the wild ones from  Bolivia that share two  differences that no other Oxalis  species in the entire genus  share.  That's the first piece of really  positive information that  perhaps some of the populations  from Bolivia might have been the  maternal parent of oca.  The other wild tuber-bearing  populations from central Peru  and southern Peru and the ones  from Argentina and number 284  all come out as different from  oca. 

 And so this is interesting that  number 284 actually has the  maternal type of these other  species and not similar to oca  or to the other ones in Bolivia.  Now I have to admit that we've  gotten some few other sequences  more recently, but as the  undergrads are working on this  and the story kind of breaks  apart so we're trying to see  whether we're mixed up or  whether that's really what's  going on.  But I'll at least was looking  here as if some of the ones from  Bolivia are the ones that have  the maternal type of cultivated  oca.  So it looks like as you go and  you look at different kinds of  DNA evidence you don't always  get the same story.  And polyploids are complicated  so it's not always that easy to  figure out what's going on.  But for the people in these  countries finding out which of  these ones are the ancestors  then we can start looking at  more about, once we know which  might be the ancestor, then we  can look at more detail of what  has happened to it in the  meantime.  One of the students that's  working with me is looking at  the potential selection that you  asked about, about the sourness  or sweetness and why are there  sour ones and sweet ones still  being cultivated.  There are other crops in which  toxic or unpleasant tasting  things are grown alongside of  ones that don't have those  compounds in them, and there are  reasons for that.  So she's looking at the  possibility, but it would be  really nice if we knew which of  these ancestors really is, which  of these wild populations really  is the ancestor, whether it's in  Bolivia or elsewhere, before we  try to look at the changes that  might have happened to them.  I think I'm getting close to  running out of time. 

 Is that true?  Yeah, okay.  So I'll mention a little bit  about this other work on what's  happening to oca as it evolves  under human influence up to the  present day.  And I've already talked a little  bit about biological basis of  folk classification so I'll be  mostly talking about what  happens when the people act as  agents of dispersal and affect  the distribution of these  different clones of the crop.  Many crops are vegetatively  propagated and so essentially  clonal.  Many of them are things that are  more familiar and important  around the world like potato or  banana or sugar cane.  Many of these other Andean  tubers are also vegetatively  propagated, and, of course,  also, any fruit tree that is  grafted, the grafted portion is  also clonal or vegetatively  propagated and essentially  acting as a clone.  These pictures are Andean potato  varieties.  So these vegetatively propagated  or clonal crops differ in their  evolution from seed propagated  crops.  A seed propagated crop such as  maize like here, every single  one of the kernels on every  single one of these cobs is an  unique genetic individual just  as you or I are.  And unless you have an identical  twin, there's nobody else who's  exactly like you. 

 Not much of the study of  conservation of genetic  diversity of crops is focused on  these ones that are propagated  by seed.  But if you're going to conserve  the ones that are propagated  vegetatively, that has  consequences.  They can't be put in a jar and  put away some place either on a  shelf or in liquid nitrogen the  way seed propagated crops can  be.  They either have to be  cultivated year after year in a  field or sometimes very slowly  grown in a little tube if you're  going to conserve they're  diversity.  And also even if you're going  around collecting to put these  into a germ plasm bank, your  strategies have to be different.  So it does make a difference  which way it is.  Back in the '90s, part of my  survey was asking people about  how they exchange and get new  varieties or how they give away  or trade or barter or steal  different varieties from each  other and how, potentially,  these different varieties can  move around.  They can also move, that was on  a local scale, they can also  move long distance by getting up  on trucks and going from one  city to another.  And so -- which is an  organization that works in Puno,  Peru, on different Andean crops  did market surveys and found  that many of the people who sell  these tuber crops in different  Andean cities get them and carry  them from one large city to  another across the Andes, even  across the international border  between Peru and Bolivia without  a passport, so that,  theoretically, you could have  the same exact potato or the  same exact oca being grown from  anywhere from Cusco to  Cochabamba and you could  potentially have that long  distance dispersal.  So if we want to conserve the  diversity, we have to know how  much is this happening?  How far are they going?  How is that affecting the  distribution in what is found in  one place or another?  We just go and have a potato  park in one place, is that going  to really help?  If things are really widely  distributed, that might. 

 If they're only narrowly  distributed, it might not.  So my current project, before  arriving here at UW Madison, I  was on expeditions throughout  the highlands of Peru in 2005  and 2006.  This was a collaborative project  between my former employer, the  Field Museum, current employer,  UW Madison and the Peruvian  Governmental Agricultural  Research Group, the  International Potato Center,  Ryan Epperson at Michigan State  was our statistician, we had NSF  support, and so those are all  the places where we went to  farming communities and  collected oca.  One thing to note is that  sometimes these dots look like  they're very close together, but  if you know anything about the  Andes it can be a long, long  distance up and down, back and  forth to get between two dots  that look like they're really  close together.  So one of the things we'd like  to know is what's patterning  this distribution.  One possible hypothesis, though  it's not the only one, is that  there might be a correlation  with languages.  I'm not talking about causation  here but correlation.  If people share the same dialect  of Quechua, the patterning of  dialects or different languages,  -- is spoken down here, and this  map represents the different  dialects of the Quechua  language.  Some of them in the central Peru  are so different that linguists  think they should be considered  different languages.  That might indicate where  there's more exchange between  people in many different ways. 

 There's a previous work that  looked at human genetics in  Europe and found that they could  look at allele frequencies and  use a technique, statistical  technique, called wambling that  looks for regions of abrupt  change in allele frequencies and  found that most of those regions  of abrupt change were either  geographic barriers or actually  different languages.  And maybe that isn't too much of  a surprise that people are more  likely to exchange genes and  children with people they can  talk to.  We don't yet know whether  perhaps exchange of oca might  happen in similar ways.  But that's one of the things  that we can look at.  So I traveled around with,  worked with the Peruvian  National Agriculture Research  Group.  Each of the areas of Peru  traveled with their germ plasm  coordinators, indicated here.  A whole lot of other people  traveled with us in Peru, and we  got a whole lot of help on the  travels and on the laboratory  research.  And we collected sampling  randomly from the fields.  If the people have already  harvested, we sampled randomly  from their storage areas,  whatever that might be, and then  after we did that we often did a  directed sample by looking at  how many different clones it  looked like they had by grouping  them by color and making sure  that we had representatives of  all of those so that we can use  that in the spatial statistics.  But even as we made the travels,  you could already see just by  looking at the tubers that they  were not just evenly distributed  all over the country. 

 There were certain areas like  here in the upper left.  Those are all from one family.  Just an amazing diversity of  different types, whereas, there  were other families, I think  this was in Cusco, where out of  40 tubers we really only saw two  varieties there.  And there were certain ones that  were predominate.  This one in the upper right was  predominate in a small area.  It was very common there but we  only collected it from three  different localities in central  Peru.  Whereas there were other ones  that were common and predominate  and only collected from certain  areas of southern Peru such as  this one is the next one.  These are collected from  southern Peru in the areas where  -- is spoken.  Which is kind of a little  interesting that maybe there is  a pattern with the languages.  Again, another example that was  collected from only two  different of our sample areas in  Ancash Department in Peru. 

 So what we're really seeing is  that so far we haven't  completely analyzed all this  data but I've worked and finally  gotten most of the decisions  about which ones are a clone  based on the fingerprinting and  the look of the plants and the  tubers.  We haven't done the spatial  statistics yet, but it's pretty  clear that many of them have  very narrow distributions which  really has an implication for  conserving all of this.  I doubt that all of this  diversity is really already in  the germ plasm banks of Peru or  Bolivia or the International  Potato Center.  So this really has implications  of how we're going to conserve  all of this.  Also, during our travels we got  really concerned.  While traveling with these  Peruvian agricultural  researchers from the government,  they had often been in some of   these areas before and could say  here's an area where there was  oca ten years ago, there's none  now.  So we got very, very worried  about it's conservation status  in the shorter term.  This is an area in northern Peru  where this village, really there  was only this one field that had  a relatively large amount and  diversity of oca and one old man  who was the only one who was  really growing very much oca in  this area at all.  They were now mostly growing  improved potatoes for the market  instead of growing oca for their  families.  Most people, if they had any at  all, they had just a few. 

 And here's the one gentleman  who's still growing a diversity  of oca in that area.  In the next place we went, also  in northern Peru, we tromped  around in mud all day and found  this older woman who was growing  four plants of oca.  That's all there was in this  whole area.  And this is a pattern we saw  repeated all over the place that  there were elderly people who  spouses had died, whose children  had moved to the cities and our  question was what's going to  happen?  Who are they going to pass this  diversity on to?  Who's going to keep growing it  after they're gone?  So we got very worried that  instead of thinking about, oh,  I'm helping conserve the  diversity of oca for the  long-term, we really got worry  about the short-term.  Why?  Well one of the reasons is this  pest, the oca weevil.  These larvae infest the tubers  and make them so infested that  people, they're only good for  feeding pigs and people are not  growing this anymore.  Another is those improved  potatoes that people are  growing.  Sometimes there's unintended  consequences of development  projects.  So people advise people to raise  dairy cattle instead of crops,  and that's, some of the areas  where we couldn't find any oca  where there had been 10 or 15  years ago it's because they were  just growing oats and pasture  for the cows and not really  growing crops anymore.  There are efforts to try to  promote diversity of these  crops. 

 There's these fairs in many  different parts of the Andes  where there's competitions for  who has the greatest diversity  of different crops and trying to  promote the use and conservation  of traditional crops.  And there are some areas like  here in southern Peru, Cuyo Cuyo  near the Bolivian border, where  it's very famous for oca in the  past.  These are terraces that were  built before the time of the  Incas and had been continuously  cultivated in this area.  They're actually all over this  entire valley.  And this area still has lots of  oca.  It's big, it's healthy, it still  has a lot of diversity, but I've  been in this community twice,  separated by nearly 10 years,  and there's enormous changes  taking place.  And so it's questionable to what  extent the next generation is  going to continue this tradition  of growing such a diversity of  oca in this area.  So those are some of our  concerns and some of our  research, and I'm hoping that  all of this investigation is  going to be able to be used by  people in the Andes to conserve  the diversity of these crops for  the future.  And I thank you.  (applause)