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Asking for a Skeptic Friend

I sometimes get email from people asking, in one way or another, whether our long-term evolution experiment (LTEE) with E. coli provides evidence of evolution writ large – new species, new information, or something of that sort. I try to answer these questions by providing some examples of what we’ve seen change, and by putting the LTEE into context. Here’s one such email:

Hi Professor Lenski,

I have a quick question. I’m asking because I am having a discussion with someone who is skeptical of evolution. The question is: Over the 50,000 generations of e-coli has any of the e-coli evolved into something else or is it still e-coli?

I am a non-religious person who likes to think of myself as an adherent to science but I am not sure how to respond to my skeptic-friend.

Thank you!

And here’s my reply:

Hello —-,

50,000 generations, for these bacteria, took place in a matter of ~25 years. They have changed in many (mostly small) ways, and remained the same in many other respects, just as one expects from evolutionary theory. Although these are somewhat technical articles, I have attached 3 PDFs that describe some of the changes that we have seen.

Wiser et al. (2013) document the process of adaptation by natural selection, which has led to the improved competitive fitness of the bacteria relative to their ancestors.

Blount et al. (2012) describe the genetic changes that led one population (out of the 12 in the experiment) to evolve a new capacity to grow on an alternative source of carbon and energy.

Tenaillon et al. (2016) describe changes that have occurred across all 12 populations in their genomes (DNA sequences), which have caused all of them to become more and more dissimilar to their ancestor as time marches on.

Best wishes,

     Richard

Although these articles were written for other scientists, they make three big points that I hope almost anyone with an open mind can understand.

  • We see organisms adapting to their environment, as evidenced by increased competitiveness relative to their ancestors.
  • Against this backdrop of more or less gradual improvement, we occasionally see much bigger changes.
  • And at the level of their genomes, we see the bacteria becoming more and more different from their ancestors.

In these fundamental respects, evolution in these flasks works in much the same way that evolution works in nature. Of course, the scales of time and space are vastly greater in nature than they are in the lab, and natural environments are far more complex and variable than is the simple one in the LTEE. But the core processes of mutation, drift, and natural selection give rise to evolution in the LTEE, just as they do (along with sex and other forms of gene exchange) in nature.

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Evolving Fun and Games

Science isn’t always fun and games. But sometimes it is!

This guest post is by Terry Soule, a computer scientist, and Barrie Robison, a biologist, both on the faculty at the University of Idaho. The BEACON Center for the Study of Evolution in Action brings together biologists, computer scientists, and engineers to illuminate and harness the power of evolution as an on-going process.

With BEACON’s support, Terry and Barrie have developed a video game, called Darwin’s Demons, where you must fight off enemies that are evolving to defeat your best efforts!

Feel free to comment here.  However, please send any technical queries via email to Terry (tsoule@cs.uidaho.edu) and/or Barrie (brobison@uidaho.edu).

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Thanks to BEACON’s support, Polymorphic Games has created the evolutionary video game Darwin’s Demons, and placed it on the Steam website as part of the greenlight process.

Darwin’s Demons adds an evolutionary component and modern flair to an arcade classic.  Darwin’s Demons models biological evolution using enemies with digital genomes. Enemies acquire fitness by being the most aggressive, accurate, and longest lived, and only the most fit enemies pass their genomes to the next generation. The result? The creatures you found hardest to kill have all the babies, making each generation more challenging than the last!

The game includes in-game graphs for tracking evolution, displays the most fit enemies from each wave, and has an experiment mode where you can set parameters like the mutation rate, fitness function, etc.  It also dumps all of the evolutionary data to a file.  So, there are opportunities for experiments on user driven evolution if anyone is interested.  (We are more than happy to share the code and/or make simple modifications for controlled experiments.)

If you get the opportunity please try out the demo (downloadable at either of the sites listed above, with Windows, MAC, and Linux versions), vote for us on Steam, and send us comments, suggestions, or ideas for future directions and collaborations.

Thanks,

— Terry Soule (tsoule@cs.uidaho.edu), Computer Science, UI

— Barrie Robison (brobison@uidaho.edu), Biological Sciences, UI

 

Darwin's Demons

[Darwin’s Demons: image from the Polymorphic Games website]

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Evolution Education in Action

This entry is a guest post by my MSU colleague Jim Smith. Jim is one of the PIs on an NSF-supported project to develop Avida-ED as a tool for learning about evolution in action and the nature and practice of science. (Besides Jim’s work with Avida-ED, many readers will be interested in Evo-Ed, a project where he and colleagues have developed teaching and learning materials organized around six case studies of evolution that integrate knowledge of the genetic, biochemical, physiological, and ecological processes at work.) Here is Jim’s report on the Avida-ED professional-development workshop that was recently held here at MSU.

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This past week, we had the pleasure of working together in a 2.5 day workshop with a group of biology faculty from across the country who are interested in evolution education.  As a part of our work in the NSF-funded Active LENS project, and as members of the BEACON NSF Science and Technology Center at Michigan State, our focus in this workshop was finding ways to incorporate the digital evolution software program, Avida-ED, into Biology course offerings.  Avida-ED allows students to understand evolution as an empirical science, where things can be studied and discovered via manipulative experiments, rather than solely as an historical science consisting mainly of observation and deep inference.

This Active-LENS Workshop brought together 20 biology teaching faculty over the course of 2.5 days to build lessons for their courses that incorporate Avida-ED.  On Day 1, we heard presentations from: Rob Pennock, who outlined what Avida-ED is, how it came to be, and why it is important; Rich Lenski, who introduced the group to his 28-year 65,000 generation long-term experimental evolution project and also described how the research platform, Avida, was used to evolve organisms with complex features; and Charles Ofria, who gave us a tour under the hood of Avida-ED, showing us how the program works on a computational level.

Avidian replicating

An Avidian and its offspring (with mutations) in Avida-ED.

In between these presentations, workshop participants were introduced to a new browser-based version of Avida-ED that is in its final stages of development.  Software developer Diane Blackwood is now “squashing bugs” in this beta version of Avida-ED (3.0), which will be released later this month.  Jim Smith then led the workshop participants through three hands-on exercises that allowed them to see first-hand how Avida-ED could be used in an educational setting to address specific misconceptions that students have about evolutionary processes.  For example, some students think that selection causes the mutations that are advantageous, so one exercise explores whether mutations that confer a beneficial trait arise sooner when selection favors the mutation than when it does not. We also introduced the participants to some independent research projects that our Introductory Cell and Molecular Biology students carried out using Avida-ED.

On Day 2, participants started on their journeys to develop their own Avida-ED lessons and spent most of the day doing so.  This was perhaps the most interesting and challenging part of the workshop, given that the participants came to us from a wide range of institutions and instructional settings.  Thus, each participant had his/her own set of opportunities and challenges to consider during the lesson planning sessions.

In conjunction with, and in between, bouts of lesson planning, Jim Smith introduced participants to and/or reminded them about how to use backward design to plan instruction.  In addition, Mike Wiser presented data showing how he has been using Avida to study fundamental research questions in evolutionary biology, and also presented results of research he has been doing as a member of our team to study impacts of the use of Avida-ED in educational settings.  Moshe Khurgel, who participated in last year’s Active-LENS workshop, described his Avida-ED implementation at Bridgewater College (VA) this past year, and provided the participants with a great set of tips and things to consider as they developed their own curricular pieces.  Louise Mead rounded out the set of presentations on Day 2 by providing participants with some basics on how to assess student learning, and how the work done by the participants would fit into the overall Discipline Based Education Research (DBER) goals of the Avida-ED team.

The big payoff came on Day 3, when each participant team presented their ideas for implementation of Avida-ED into their courses.  These were great! Projects that were presented ranged from the use of Avida-ED in a case-based framework utilizing oil spill remediation to explore how (and when) genetic variation arises in populations (Introductory Cell and Molecular Biology, Kristin Parent and Michaela TerAvest, Michigan State), to using Avida-ED to explore concepts in phylogenetics and compete organisms directly against each other in a March Madness framework (300-level Microbiology Lab, Greg Lang and Sean Buskirk, Lehigh University), to using Avida-ED to explore environmental effects on species diversity (300-level Ecology course, Kellie Kuhn and David Westmoreland, Air Force Academy). Many other creative and innovative ideas were presented by the other participants.

Events such as this 2.5 day workshop are true highlights of an academic life. Working with dedicated faculty who are motivated and energized by the prospect of creating excellent learning experiences for their students is a real pleasure.  It also gives one hope for the future of American science.

The best news is that we will be doing this 2.5 day workshop again next year. Sound like fun? If so, give one of us a shout (I’m at jimsmith@msu.edu), and we’ll see what we can do to have you join the group in the summer of 2017!

— Jim Smith

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Representing Science to My Representative

My research is funded by the National Science Foundation, including the BEACON Center for the Study of Evolution in Action. BEACON is one of a dozen or so NSF Science and Technology Centers. Today, our Representative in the US Congress, Mike Bishop, came to BEACON for 40 minutes to discuss our center—what we do, what impacts our work has, and so forth.

It was something of a “fire hose” for Mr. Bishop, with several presenters trying to convey a lot of information very quickly.  However, he was engaged and asked thoughtful questions.  I think he left with an understanding of the importance of scientific and engineering research, including how fundamental curiosity-driven research can lead to applications.

I had 10 minutes to show him my lab and explain what we do and why.  When I make a short presentation like this one, I often write out a version in advance.  I don’t read it or memorize it by any means. However, writing it out helps get my thoughts in order—removing details that aren’t important, ordering ideas into a narrative, reminding me of what I most want to convey.

I’m sure I was not as clear or coherent as the text that follows.  I offer it here because it conveys the points I tried to make in the few minutes that I had as a representative of science speaking with a representative of the people.

~~~~~~~~~~~

I want to show you one of the experiments in my lab.  We call it the long-term evolution experiment. It’s an unusual experiment because it’s been running for over 27 years.  And we keep it going because it’s been a scientific goldmine leading to new discoveries about how bacteria change over time.

It’s important that we understand bacteria and how they evolve for many reasons. Bacteria are best known because some of them can cause dangerous infections. But many of them protect us against infections—if our guts were not filled with harmless bacteria, then the dangerous ones would have a much easier time getting established in our bodies. Some bacteria also provide nitrogen to plants and perform other essential functions in the environment, including degrading some of the wastes that we produce.  And some bacteria are the workhorses of biotechnology.

To give one example of why bacterial evolution is so important:  If bacteria didn’t evolve, we would have defeated nearly all the pathogenic bacteria on Earth with antibiotics.  But they do evolve and become resistant to our drugs, and so the pharmaceutical industry has to spend billions of dollars trying to keep up with the evolving bacteria and viruses by developing new drugs to treat infections.

It’s possible to see evolution-in-action in bacteria, like we do here, for several reasons.

  • Their populations are huge.  The number of bacteria in just one of these little flasks is comparable to number of people in the United States.
  • They grow really fast.  Every day, there are about 7 generations of bacteria in each of the flasks.  So each day we see the great-great-great-great-great grandkids, so to speak, of the bacteria that were in our flasks yesterday. After 27 years, the experiment has run for over 63,000 generations.
  • And one more important thing about bacteria. We can freeze them and bring them back to life, and so we’ve got a frozen fossil record of the experiment.

When I started the experiment in 1988, there was no human genome project, and not even a single bacterial genome had been sequenced.  Now we go into our freezers and sequence the bacterial genomes to see how their DNA is changing over time.

The work we’ve done in this curiosity-driven experiment has inspired others who are using similar ideas and approaches to understand the rates and mechanisms of how bacteria evolve.

I’ll give two quick examples that show how our NSF-supported fundamental science gets translated into applications that are important for security and health.

First, you remember the anthrax letter attacks on Congress that occurred right after the 9/11 attacks. In the first few days after the anthrax attacks, I was contacted by the Defense Threat Reduction Agency for advice on how to identify the source of the strain used in that bioterrorism, and how to distinguish it from other related strains. And in the months that followed, I was asked for and provided advice to the FBI and other agencies investigating the attacks. Tracking the source of microbes in outbreaks—whether natural or terroristic in origin—requires understanding how they change over time.

Second, my colleague Prof. Martha Mulks studies bacteria that colonize the lungs of people with cystic fibrosis (CF).  There are about 30,000 people with this disease in the US alone.  It’s an inherited disease that makes people susceptible to lung infections and, unfortunately, those infections kill many kids and young adults with CF.  Some of the bacteria that infect the diseased lungs are not pathogens to most of us—they’re bacteria that live in soil and on plants, but when they get into the lungs of CF patients they evolve and adapt to that new environment. They also evolve resistance to the antibiotics that are meant to get rid of them. How exactly the various bacteria change to become better adapted to the CF lung environment is not known. Luckily, though, Martha Mulks and other foresighted scientists and clinicians have kept frozen samples of these bacteria over the years—just like we’ve done with the long-term experiment I described a moment ago. Now the BEACON Center is supporting work by a graduate student, Elizabeth Baird, who will analyze the DNA from old and new samples and apply some of the same approaches and methods that we’ve used and developed for the laboratory experiment to see how the bacteria have changed—how they have become resistant to antibiotics and otherwise adapted to the environment of the lungs of people who suffer from cystic fibrosis.

The bottom line is that the fundamental, curiosity-driven research that the National Science Foundation supports is also an engine for future applications—often ones that we may not even have dreamed of—as well as a training ground for the talented and dedicated young people who you can see working all around us in this lab and throughout the BEACON Center.

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Rep. Mike Bishop (MI-08) and me in the lab.  [Photo: Danielle Whitaker, MSU.]

Rep Mike Bishop and me in lab, 14 Oct 2015

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63,000 Strong

Ever wonder about those big numbers posted in a window in that tall building on the east side of Farm Lane, across from the entrance to the MSU Dairy Store?

Right now, the digits read 63000. That’s the number of generations in an experiment that’s been running in my lab for over a quarter century.

We call it the LTEE, which stands for the Long-Term Evolution Experiment. There are 12 populations of E. coli bacteria in the experiment, and they all started from the same strain.

Every day—weekends and holidays included—a member of my team takes 1% of the cells in each population and puts them in a flask with fresh food. Over the next 24 hours, the population grows 100-fold and then runs out of food. These dilutions and renewals go on day after day, week after week, month after month, year after year, decade after decade. I hope the experiment will continue long after I’m gone, so that someday someone can write “and century after century.”

Bacteria grow by binary fission: 1 cell makes 2 cells, 2 cells make 4, 4 make 8, etc. So the 100-fold growth in the fresh medium represents about 6.6 doublings, or generations, every day. (There’ve been some interruptions since the LTEE began in 1988, but not many.)

Now consider a bacterial cell that gets a mutation in its DNA that lets it acquire more food and grow a little faster. That cell will leave more descendants than its competitors—that’s adaptation by natural selection. Over time, the bacteria are becoming stronger and fitter in their flask-worlds.

By watching the 12 populations evolve, we can answer questions about the dynamics and repeatability of evolution in a group of organisms—bacteria—that are essential for life on Earth as well as important players in health and disease. We measure the growth rates of the bacteria, we sequence their DNA, and we see just how much evolution can achieve even in short order.

Oh, about the sign. Zachary Blount is a talented postdoc who works on this project, and he likes to have fun with science. He put up the window display which, if you look closely, has a picture of Charles Darwin on the left, “The E. coli Long-Term Evolution Experiment” over the number, and “Generations and Counting” to the right. Every 1,000 generations or so, Zack updates the sign.

63K window

[Photo credit: Zachary D. Blount]

Note:   This piece first appeared at eastlansing.org after an invitation from Alice Dreger to explain the numbers in the window to our community.

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Tiny Things that Live in Little Bottles

As I mentioned in my previous post, it can be a fun challenge to explain your scientific research to people who aren’t scientists.

A week or so ago I came across a website that challenges you to explain something complicated using only the thousand most commonly used words.

So here’s my effort about our long-term evolution experiment with E. coli:

My team works with really tiny things that live in little bottles. We watch the tiny things change over time – over a really long time. The tiny things that do the best have learned to eat their food faster and faster, before the other guys can eat their lunch, so to say.  Well, the tiny things don’t really learn, but it’s kind of like learning – and even better, the best ones pass along what they learned to their kids.  A really cool guy came up with the idea of how this works more than a hundred years ago. My team’s work shows he got it pretty much right. But there’s a lot of stuff he didn’t know, and we’re figuring that out, too.

Several other biologists followed up including Nicole King, Graham Coop, and Josie Chandler (the links are to the simple-words-only descriptions of their own research).

Give it a try, and add your contributions in the comments below!

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Through the Wormhole with Science Communication

As a scientist, I spend a lot of my time trying to communicate subtle ideas and complex results to other scientists who, to a first approximation, share my interests and vocabulary. When I’m not doing that, I also spend a fair bit of time teaching students who are learning about science and, in some cases, trying to become scientists.

But it can be fun and interesting to step outside the usual communication channels by trying to explain our scientific research to people who aren’t scientists or students.

Last fall, I was invited to explain our research on the show Through the Wormhole with Morgan Freeman. The show’s director Tony Lund spoke with me at length by phone, asking questions about scientific concepts, our work, my personal interests, etc.

Based on our conversation, Tony came up with several ideas for scenes to film, both inside and outside the lab. The people in my lab group organized the props and materials that we would need to film the scenes, and several of them also had cameo roles in the various scenes.

Tony then came to MSU, along with veteran cameraman Max Miller. They spent over 12 hours with me, filming scenes in a studio and the lab, and asking countless questions on and off camera. I was impressed by the combination of creativity and attention to detail they brought to this work. For me, it was both exciting and exhausting.

Tony then had to take the hours of film and edit it all down to just a few minutes, while adding interesting visuals and preparing the script for the distinctive style and perspective of the show’s host and narrator, Morgan Freeman.

You can see the fruit of everyone’s labor here, in this four-minute segment: Evolution is Like Poker.  (Or here on youtube.)

My lab’s portion of the show ran a bit longer than this clip, but this is the bulk of it. A lot of time and effort went into making those few minutes of the show, but I think it was well worth it. I understand the show has over a million viewers, and I hope some of them will have a better understanding of evolution, our place in nature, and the joy of science.

So thanks Tony Lund, Max Miller, Morgan Freeman, Kim Ward in MSU’s communication office, everyone who helped with logistics and production, and all the members of the team, past and present, who have kept the LTEE going … and going … and going.

 

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