Richard Lenski's Experiment on E. Coli Bacteria
Richard Lenski’s experiment on E. coli bacteria
🪫 A funny example that evolutionists have used as evidence of evolution is Richard Lenski’s experiment on E. coli bacteria .
They found that the bacteria’s rate of reproduction increased over generations,
and they said, “Boom! Evidence of evolution!”
🪫 They discovered that these bacteria had deteriorated, not evolved.
Their ability to digest ribose sugar had been abolished.
Instead, they had lost part of their DNA, which made them copy less,
and thus reproduce faster.
🚗 A real-life example to illustrate this:
If you had a car that was about to run out of fuel mid-trip, and you had luggage,
what would you do?
You might remove parts of the car and throw away the luggage
so you could reach your destination with less fuel,
since it would be less of a burden on the engine.
🪫 The same thing happened with bacteria:
they lost part of their genome, so they copied less of it,
and so their rate of reproduction would be faster.
🧬 Twelve populations of Escherichia coli B all lost d-ribose catabolic function during 2,000 generations of evolution in minimal glucose medium.
We sought to identify the population genetic processes and molecular genetic events that caused these rapid and parallel losses.
Seven independent Rbs− mutants were isolated,
and their competitive fitnesses were measured relative to that of their Rbs+ progenitor .
These Rbs− mutants were all about 1 to 2% more fit than the progenitor.
A fluctuation test revealed an unusually high mutation rate —
about 5 × 10⁻⁵ per cell generation — from Rbs+ to Rbs− ,
which contributed to rapid fixation.
🪫 Seven independent Rbs− mutants were isolated,
and their competitive fitness relative to their Rbs+ ancestors was measured.
All of these Rbs− mutants were approximately 1 to 2% more fit than the ancestor.
A fluctuation test revealed an unusually high rate —
approximately 5 × 10⁻⁵ per cell generation —
of mutation from Rbs+ to Rbs− , contributing to rapid fixation.
The genome deletion rate was also significant,
ranging from 0.9% to 3.5% of the genome size .
Some species even have genome deletions as high as 8% , as reported in the study.
Then they say this is evolution!
🧬 We analyzed both the optical maps and the genome sequences
to estimate the genome size of each evolved clone sampled at 40,000 generations.
- Genome size was reduced in 10 of the 12 clones ,
by amounts ranging from 0.9% to 3.5% of the ancestral genome size (Fig. 1).
However:
🪫 The clones from populations Ara+4 and Ara+5 showed slight increases in genome size —
0.8% and 0.3% , respectively —
that resulted from duplications,
including one encompassing ~4% of the genome (~180 kbp) in Ara+4 .
The overall tendency toward reduced genome size reflected the fact that large deletions were much more common than large duplications.
📌 Before we end the article:
Note that the percentage of the increase in the genome is due to excess duplications (excess repeats),
as written in the study.
🪫 No new information was added to drive the rate of division.
📎 https://pmc.ncbi.nlm.nih.gov/articles/PMC99500/
📎 https://journals.asm.org/doi/10.1128/mbio.01377-14#fig1