Is
evolution fairly predictable? A new study with E. coli suggests yes,
forming the same solutions for the same problems in different
populations.
Researchers started the experiment with 3
populations of E. coli. The bacteria in each population were
generalists, competing for two different foods: glucose and acetate.
After 1,200 generations, each population had split into two types, each
specialised physiologically to either
glucose or acetate. After analysing bacteria at 16 points over its
evolution, the team found significant similarity in the changes that had
occurred.
"In all three populations it seems to be more or
less the same core set of genes that are causing the two phenotypes that
we see... In a few cases, it's even the exact same genetic change,"
Matthew Herron (University of Montana) said. “There are about 4.5
million nucleotides in the E. coli genome. Finding in four cases that
the exact same change had happened independently in different
populations was intriguing.”
The team suggested that one
particular form of selection, negative frequency dependence, played an
important part. As the population of one type of specialised bacteria
increases the amount of resources for them will decrease, giving
bacteria who specialise in the alternate food an advantage.
Of
course, there are important counterpoints. Bacteria such as E. coli
produce asexually, so it may not be wise to extrapolate from these
findings how sexually-reproducing organisms evolve. The large
populations of bacteria may make their evolution more predictable than
that of more dispersed species. The E. coli populations were also
evolving in a stable environment, which could have an effect on any
predictability.
To read the paper: http://bit.ly/12QFjdc
Photo credit: Mattosaurus, 2009.
http://www.nature.com/news/
http://www.sciencedaily.com/
http://www.redorbit.com/news/
http://www.eurekalert.org/
Is
evolution fairly predictable? A new study with E. coli suggests yes,
forming the same solutions for the same problems in different
populations.
Researchers started the experiment with 3 populations of E. coli. The bacteria in each population were generalists, competing for two different foods: glucose and acetate. After 1,200 generations, each population had split into two types, each specialised physiologically to either glucose or acetate. After analysing bacteria at 16 points over its evolution, the team found significant similarity in the changes that had occurred.
"In all three populations it seems to be more or less the same core set of genes that are causing the two phenotypes that we see... In a few cases, it's even the exact same genetic change," Matthew Herron (University of Montana) said. “There are about 4.5 million nucleotides in the E. coli genome. Finding in four cases that the exact same change had happened independently in different populations was intriguing.”
The team suggested that one particular form of selection, negative frequency dependence, played an important part. As the population of one type of specialised bacteria increases the amount of resources for them will decrease, giving bacteria who specialise in the alternate food an advantage.
Of course, there are important counterpoints. Bacteria such as E. coli produce asexually, so it may not be wise to extrapolate from these findings how sexually-reproducing organisms evolve. The large populations of bacteria may make their evolution more predictable than that of more dispersed species. The E. coli populations were also evolving in a stable environment, which could have an effect on any predictability.
To read the paper: http://bit.ly/12QFjdc
Photo credit: Mattosaurus, 2009.
http://www.nature.com/news/
http://www.sciencedaily.com/
http://www.redorbit.com/news/
http://www.eurekalert.org/
Researchers started the experiment with 3 populations of E. coli. The bacteria in each population were generalists, competing for two different foods: glucose and acetate. After 1,200 generations, each population had split into two types, each specialised physiologically to either glucose or acetate. After analysing bacteria at 16 points over its evolution, the team found significant similarity in the changes that had occurred.
"In all three populations it seems to be more or less the same core set of genes that are causing the two phenotypes that we see... In a few cases, it's even the exact same genetic change," Matthew Herron (University of Montana) said. “There are about 4.5 million nucleotides in the E. coli genome. Finding in four cases that the exact same change had happened independently in different populations was intriguing.”
The team suggested that one particular form of selection, negative frequency dependence, played an important part. As the population of one type of specialised bacteria increases the amount of resources for them will decrease, giving bacteria who specialise in the alternate food an advantage.
Of course, there are important counterpoints. Bacteria such as E. coli produce asexually, so it may not be wise to extrapolate from these findings how sexually-reproducing organisms evolve. The large populations of bacteria may make their evolution more predictable than that of more dispersed species. The E. coli populations were also evolving in a stable environment, which could have an effect on any predictability.
To read the paper: http://bit.ly/12QFjdc
Photo credit: Mattosaurus, 2009.
http://www.nature.com/news/
http://www.sciencedaily.com/
http://www.redorbit.com/news/
http://www.eurekalert.org/
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