Experimental Evolution: 50,000 Generations in the Life of E. coli

Air date: Wednesday, October 13, 2010, 3:00:00 PM
Time displayed is Eastern Time, Washington DC Local
Category: Wednesday Afternoon Lectures
Description: Most evolutionary studies are based either on fossils or patterns of similarity and differences among living organisms. However, evolution is an on-going process, and therefore it can also be studied experimentally in those organisms with short generations. To that end, 12 initially identical populations of E. coli have been maintained in a simple environment since 1988, during which time the cells have undergone more than 50,000 generations. Two goals of this long-term experiment have been to investigate the dynamics of evolutionary change and to examine the reproducibility of outcomes. We have quantified the extent of adaptation by natural selection, documented increasing ecological specialization over time, observed the rise of mutator phenotypes, and even seen the origin of a new function that transcends the usual definition of E. coli as a species. We have pursued genetic approaches to find the underlying mutations responsible for these changes, including several that affect major regulatory networks. We have recently sequenced complete genomes to find all of the mutations present in a temporal series of clones, and these genomic data provide new insights into the coupling of phenotypic and genomic evolution.

The NIH Director's Wednesday Afternoon Lecture Series includes weekly scientific talks by some of the top researchers in the biomedical sciences worldwide.
Author: Dr. Richard Lenski, Ph.D., Michigan State University
Runtime: 01:03:00
Permanent link: http://videocast.nih.gov/launch.asp?16192

Category:

Science & Technology

Tags:

• wals101310

[meterotronic]

@mattyoungrev3 use your other senses...........your ears...

[NorthForkFisherman]

@benthemiester E. coli is easily available. Get started. Should only take about 20 years or so.

[Njohns2007]

@wttmartin9 The experiment is not irrelevant because it was carried out multiple times. There were 12 replicate populations (all descended from a single cell) that have all been evolving independently of one another in separate flasks. Part of the uniqueness of his experiment was that you can see the repeatability of evolution and how things might differ if you were to re-wind the tape of life and play it again as Stephen Jay Gould phrased it.

[mattyoungrev3]

Very hard to read slides. Perhaps someone would be willing to edit in screen shots?

[wttmartin9]

The experiment is irrelevant and if it was carried out again it would not necessarily result in the same mutation happening again. The bottom line is that he has the bacteria that can digest citrate. These are from a species that could not use citrate. Thus they have evolved.

[benthemiester]

I know this sounds harsh but unless this Lenskis experiment can be repeated, which could have easily been done with a double blind controlled experiment it cannot be regarded a empirical.

[250ccbikes]

Oh man, that translation sub-text is a bit random at times! (Shows up particularly when he's reading from the slides).