Evolutionary biology vs. evolved biology

Once, during a medical exam, the doctor asked me what I did. I said I was an evolutionary biologist, to which he replied, "oh, so not a creation biologist?" His tone of voice made it clear he thought it was funny that I had to specify evolutionary, as though a biologist in Berkeley could possibly not believe in evolution. Considering where his hands were at the time, I didn't stop to explain to him what the term "evolutionary biologist" means. Every biologist knows, or should, that Theodosius Dobzhansky wrote, "Nothing in biology makes sense except in the light of evolution." The vast majority of biologists, of all disciplines not only know about evolution, but accept it as a necessary part of any complete explanation for the things they study. But a large portion of biologists don't regularly think about evolution; it is not the part of the explanation they are interested in. A large (and I think increasing) proportion of biologists study the interactions of atoms, molecules, organelles, genes, cells, etc. And while they may connect their work to evolution in some way, they are not basically asking questions about evolution, but about the details of the proximate mechanisms which make organisms work. That these mechanisms are the result of evolution is often not particularly relevant to the present question.

An example: A couple of years ago I attended a workshop on bioinformatics in aging research. There was a dinner the night before the talks started, and the bioinformaticist organizing the workshop asked me about my training and research. I said, "well I study the evolution of demographic patterns, particularly how constraints on natural selection lead observed demographic patterns to differ from the predictions of evolutionary theory." He replied, "Oh, but you are also trained in biology?" What he meant by this, I discovered, was that I also had some training in the molecular nuts and bolts that to him are biology. Evolution is a process that shapes biology, but in his view, and I think the view of many of the people there, does not in itself count as biology. Asking him if he ever incorporated evolution into his work, he explained that he had, comparing how networks of gene interactions differed between fruit fly and nematode. Fair enough, comparative biology is surely the study of evolution, but his approach to it required no technique or concept from evolutionary theory. He produces good and useful science, and gives no more daily thought to evolution than I give to promoter regions. I am certain that he would not be offended to be described as a good biologist who believes in evolution, but is not an evolutionary biologist.

A definition from wikipedia: "Evolutionary biology is a sub-field of biology concerned with the study of the evolutionary processes that have given rise to the diversity of life." This is somewhat too narrow in my view, but it is close enough given that it is past my bedtime.

This has all come to mind because of the post I wrote yesterday, about weeds evolving resistance to Monsanto's best-selling herbicide, and the failure of Monsanto's biologists to predict this. A good friend of mine, who is deeply knowledgeable about matters environmental and agricultural, responded by asking how Monsanto's biologists could have failed to predict the apparently obvious facts I was pointing out unless they were A, Tools; B, Fools; or C, having their results manipulated by suits. This is a reasonable and interesting question, and I'll venture an answer. My guess is that they were neither A nor B, and that C went on but was not a major factor. Monsanto did have an enormous financial stake in convincing regulators that weeds would not evolve resistance to Roundup, but they also had an enormous stake in having weeds actually not evolve resistance to Roundup.  So my guess is they honestly thought it was a highly unlikely outcome.

Why did they think so, despite being smart, honest biologists? Because they weren't trained in, or primarily thinking about, evolution as it occurs in nature. They were plant geneticist and bioengineers, spending many years and countless millions of dollars to unravel the finest details of how Roundup kills plants and how to build a crop that will have resistance to it (without passing that resistance on to its offspring). That was an enormous challenge, and their success was unprecedented. They had achieved what many, even within their own company, must have thought was an impossible SciFi dream.

Surely someone was assigned to think deeply about the problem of whether weeds would evolve resistance, but surely that someone had been involved in the project for years, and was so wrapped up in the grotesque details of the genetic magic they had just achieved that no perspective was possible. In other words, they couldn't see the field for the soybeans. A person highly trained in artificial selection, and used to that way of thinking, will think of the evolution of weed resistance in those terms, despite the fact that natural selection has inherent advantages.

In hindsight, their logical errors are obvious, probably even to them. In foresight, reasonable and well intentioned people frequently fail to think of highly relevant and potentially obvious things. This is particularly likely if those things require a perspective they don't possess, doubly particularly if they are thinking deeply about the problem from a very different perspective. Monsanto had many biologists who knew about evolution, used a particular type of evolution as a tool, and thought about evolution. But my guess is they didn't have any evolutionary biologists.

Skipping that hard middle part

The part of science I like best is the coming up with questions part. The part where I ask something someone else has never asked before (or at least I don't yet know that they did) and brainstorm together a plan about how the question could be answered. But my second favorite part is writing rough drafts. I like the rough drafts in particular because I can let the ideas flow, without getting hung up on making sure I have exactly the right reference or my font is just the one the journal prefers. In other words, it is writing without the impeding mechanical details.

I can do lab work, I can program a simulation, I can edit bibliography formats in citation management software, and all those other jobs that require extensive attention to details beyond the scientific concepts. But by preference I'm really a concept guy. If I had collaborators who wanted to do every part of the process between the planning and writing the rough draft, I'd be thrilled.

This is why I'm writing a Forum piece, to submit to a journal that responded positively to my pre-submission inquiry. (A positive response means they are willing to look at it, not that they promise to publish it.) Their Forum section is designed for short papers of about a 1000 words, in which the author makes a relatively simple point or poses a question without a lot of new data. I've finished a rough draft of 1100 words in the last two days. Now comes the less fun part of editing it for clarity, making sure all the papers I cite actually say what I claim they say, getting feedback from colleagues and editing it again. A more adulterated and repetitive form of creativity. Still, I think I would be inclined to write more papers in this format, as it makes a nice compact project.

Jon Asks: 2

In the Laura Ingalls Wilder book The Long Winter, Laura's father says that you can predict the severity of a winter by observing the thickness of muskrat nests in the summer. Muskrats, he says, will build thicker nests during the summer if the following winter is going to be relatively colder, and vice versa with thinner nests and relatively warmer winters. Has this folk wisdom been investigated? Is it true? And if so, where can I get my own muskrat colony?

I can't find anything on Google Scholar or Web of Science indicating that anyone has published anything about muskrats and weather prediction, other than this:

Man's natural craving for advance knowledge of coming weather extends thousands of years back of any attempts at scientific weather forecasting. Realizing that he has not the necessary foresight himself, he has imagined animals to be endowed with some peculiar sense which enables them to know, weeks or months ahead, what the weather will be. Thus a large group of animal weather proverbs has come into existence. Millions of people believe that the thickness of fur on a muskrat, or the number of nuts stored by a squirrel, or a supposedly early migration of certain birds, indicates a severe winter. Yet it is certain that animals have no such foresight.

from: Robert DeC. Ward. 1926. The Present Status of Long-Range Weather Forecasting
Proceedings of the American Philosophical Society,Vol. 65, No. 1, pp. 1-14

He provides no evidence to show that they don't, he is just certain. Note that the version you mention has to do with the thickness of the wall of the house, while the version Ward mentions has to do with the thicknesss of their fur. The fur hypothesis would be easier to test, if you were a muskrat hunter. I am frankly doubtful whether he or anyone else has done the work that would be needed to convincingly either story. You would have to measure the wall thickness of bunches of muskrat houses (or the pelt of many muskrats) in the summer. You would have to do this every year for quite a few years in order to make a convincing analysis of the relationship between wall thickness and hardness of winter. You would probably also want to measure various features of the microclimate, the muskrats behavior and physiology, and the local ecology, in order to get some sense of what the mechanism was. You probably would want to measure the pelts and the houses, just to make sure you were measuring the right thing. This is one limitation to testing folk-wisdom. There are often several versions, and it is hard to know if you are testing the right one unless you test all of them, and then you increase your chances of finding a strong correlation just by chance. My best guess is that there is some, but not a lot of, truth to either version of the story. Certainly they could pick up on whatever cues are available that the winter is going to be hard. But like most weather prediction, they probably aren't very accurate, at least not months in advance.

Jon Asks: 1

I've read that fungi are the only organisms that can degrade the longer-chain fibers in wood, such as lignin, and that without saprobic fungi the world would be blanketed in dead, undecayed trees. I see on Wikipedia that it is not literally true that no bacteria can degrade lignins, however, by Wiki's account, it does seem that no known bacteria are very good at it. (http://en.wikipedia.org/wiki/Ligninase) So why would that be the evolutionary case? Bacteria have evolved to break down pretty much everything else on the planet (roughly speaking), and wood has been around for something like 350+ million years. Why would they be such second-rate degraders when it comes to lignin?

This is an interesting question, but not one I can give a very satisfying answer to. Explanations of why something didn't evolve are always fairly speculative. Why no six legged tigers? Why no live-birthing birds? Why no Ents?

So why no lignin devouring bacteria? If they can do it poorly, why not well? Maybe it isn't worth their while to invest in that capacity, as they are always outcompeted by the fungi who can already do it? Maybe they can rely on the fungi to make the enzymes, and then they can just mooch. Perhaps the process of making the necessary enzymes requires separate cellular compartments, which bacteria lack. Maybe the necessary mutations just never occurred, and so couldn't be selected for. Certainly I don't know.

Binning Algorithms for Metagenomic Sequencing

One of my assistants, SM, who is at least as smart as me and twice as hard working, wrote to ask my advice.

SM: Do you know of any good binning algorithms for metagenomic sequencing?
DL: Huh? What does, "binning algorithms for metagenomic sequencing," mean?

SM has not given me an answer. Either she assumes I am joking, and actually do know (which I don't) or she assumes it would take far too long to explain it to me (which I will pretend to resent.) So now I shall try to reckon out what "binning algorithms for metagenomic sequencing" means on my own.

Metagenomics, according to my sources (Wikipedia) "is the study of genetic material recovered directly from environmental samples." So, you take a pinch of garden dirt, extract all the DNA in it and then set out to study it in some way. You are metagenomisizing.

Sequencing, in the context of genetics, means figuring out the sequence of DNA bases (A's, T's, G's and C's) that make up part of the genome of an organism. So metagenomic sequencing presumably is taking the DNA from your pinch of dirt, then trying to figure out the sequence of DNA bases that made up all the genomes of all the organisms whose DNA are jumbled together in that dirt. A pinch of dirt, I am guessing, has DNA from hundreds of types of bacteria, a huge number of types of fungi, various protozoans and whatever else has dropped seeds, pollen, poo, tissue or hair in that vicinity in the recent past. And much of that DNA isn't going to be whole chromosomes, but whatever bits and pieces are still mostly intact after all that pooing and shedding and biodegrading. You'll have a real mishmash.

This, I suspect, is where the "binning algorithm" comes in. Binning is any process where you have a large number of elements and you want to separate them into a smaller number of categories. A binning algorithm would be a set of rules one uses to make those decisions on categorization. In the context of metagenomics, I'm guessing that each bin represents a species. You have a snippet of DNA and you need to assign it to an organism, so you don't just think that every bit of DNA is another organism, and you want to get a sense of how much representation you have of each species. So the set of rules you use to assign snippets of DNA extracted from your pinch of dirt to different species is your Binning Algorithms for Metagenomic Sequencing. I think.
My friend DS works on this kind of stuff. I'll write to him and ask.

UPDATE:
I wrote to SM and DS and asked:
Will one of you tell me what "binning algorithms for metagenomic sequencing" means?
I know what each word means, but I could come up with three or four very different guesses as to what the whole phrase means. What does each bin represent?

DS writes: [Bins represent] Taxa. In metagenomic sequencing, you get a soup of reads from all the strains of microbes present in your sample. "Binning" is the process of trying to guess which species each read comes from (or genus, or kingdom for that matter).

All methods in the literature so far are "supervised", meaning that you can only assign a read to a taxon bin if you know something about that taxon in advance (e.g., you have an isolate genome). However, environmental samples may contain previously unknown taxa: new bacterial divisions are still being discovered fairly rapidly, and at the strain level of course nearly everything is novel. A supervised binning process ought to throw up its hands at sequences from novel taxa, since they don't match any known bins. An "unsupervised" process would create new bins on the fly, in order to lump together reads that seem to be related to each other, independent of reference sequences. No published methods do that yet, though.

The accuracy of binning varies dramatically depending on the complexity of the community, the read length, the phylogenetic resolution you're asking for, and many other parameters.

Hope this helps,

-ds

Reader JTE asks:

Q:What does

two individuals with the same genotypes, except for those genes determining sex (which is some species don't exist, where sex is environmentally determined),

mean?

A: I'm glad you asked.

It means that if I had one missing or dysfunctional gene on my Y chromosome (or was XX instead of XY), I would be phenotypically female, but the rest of my genome would be the same as it is now. A great many aspect of my physical, chemical, social and mental being (my phenotype) have been altered by the effects of this one gene, which acts as a sex switch. Switch on maleness, and a whole bunch of aspects of phenotype are altered. Don't switch it on, and you get a different phenotype.

In some species, there are no X and Y chromosomes, or anything equivalent, to act as a sex switch. Instead, whether an individual develops as a male or a female is determined by the environmental conditions which prevail at a certain point in development. In alligators for example, there is no genetic determination of sex. Instead, if the temperature around the egg is above a certain temperature at a certain point in development, the alligator becomes one sex (I think male, but I don't actually remember). If it is ?colder? than that temperature, you get a female alligator. Many of the aspects of the switch are the same, only the first step of the switch is very different.

So my colleague was pondering the fact that two individuals with similar, or even identical, genotypes can have importantly different phenotypes, based on the action of this switch. This means that whether this switch is on or off can greatly affect the actions of other genes, and therefore the effects those other genes have on the survival and reproductive success of the organism.