How did birds get their wings? Bacteria may provide a clue, say scientists

May 6, 2016, University of Oxford
Pseudomonas aeruginosa
Gram-stained P. aeruginosa bacteria (pink-red rods) Credit: Wikipedia

How did birds get their wings? Bacteria may provide a clue, say scientists

The evolution of major novel traits - characteristics such as wings, flowers, horns or limbs - has long been known to play a key role in allowing organisms to exploit new opportunities in their surroundings.

What's still up for debate, though, is how these important augmentations come about from a genetic point of view.

New research from an international team of evolutionary biologists, led by the University of Oxford, has used to show that acquiring duplicate copies of genes can provide a 'template' allowing organisms to develop new attributes from redundant copies of existing genes.

Gene duplication has been proposed as playing a key role in innovation since the 1970s, but these findings add important empirical evidence to support this theory.

The study, which involved collaboration with researchers from the University of Zurich, is published in the journal PLOS Genetics.

Professor Craig MacLean, a Wellcome Trust Research Fellow in the Department of Zoology at Oxford University, said: 'The appearance of novel traits, such as wings and flowers, has played a key role in the evolution of biological diversity. However, it is usually difficult to understand the actual genetic changes that drive these evolutionary innovations.

'We have taken advantage of a simple bacterial model system, where bacteria evolve the ability to eat new food sources, to overcome this obstacle.'

The researchers allowed 380 populations of Pseudomonas aeruginosa bacteria to evolve novel metabolic traits such as the ability to degrade new sugars. This gave the researchers the opportunity to witness evolution happening in real-time.

After 30 days of evolution, they sequenced the genomes of bacteria that had evolved novel metabolic traits. They found that mutations mainly affected genes involved in transcription and metabolism, and that novelty tended to evolve through mutations in pre-existing duplicated genes in the P. aeruginosa genome.

Duplication drives novelty because genetic redundancy provided by duplication allows bacteria to evolve new metabolic functions without compromising existing functions. These findings suggest that past duplication events might be important for future innovations.

Professor MacLean added: 'The key insight of our study is that having redundant copies of genes provides bacteria with a template for evolving new traits without sacrificing existing traits. In other words, redundant genes allow bacteria to have their cake and eat it.

'In higher organisms like animals and plants, duplicate genes arise from spontaneous duplication of existing genes. In contrast, bacteria tend to acquire duplicate from neighbouring bacterial cells through horizontal gene transfer, which is the bacterial equivalent of sex.

'These findings provide important empirical evidence to support the role of gene duplication in evolutionary innovation, and they suggest that it may be possible to predict the ability of pathogenic bacteria to evolve clinically important traits, such as virulence and antibiotic resistance.'

Explore further: The secret behind the power of bacterial sex discovered

More information: Macarena Toll-Riera et al, The Genomic Basis of Evolutionary Innovation in Pseudomonas aeruginosa, PLOS Genetics (2016). DOI: 10.1371/journal.pgen.1006005

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humy
3.7 / 5 (3) May 06, 2016
" New research....has used bacteria to show that acquiring duplicate copies of genes can provide a 'template' allowing organisms to develop new attributes from redundant copies of existing genes.
...
these findings add important empirical evidence to support this theory. "

I fail to see why we NEED "empirical evidence" to support a said 'theory' that is mainly a matter of deduction as opposed to something that really requires empirical evidence. We already know that mutations consisting of gene duplication are common place thus it would be a huge scientific mystery if none of those copies of genes could then ever further mutate and evolve to develop new functions. What natural barrier could possibly exist to block this from happening? Unless someone can come up with a plausible theoretical example of such a natural barrier or until if or when we have evidence to the contrary, the default scientific assumption should be this almost certainly can happen.

cgsperling
5 / 5 (4) May 06, 2016
It does seem obvious, since almost all human innovation proceeds by copying something that exists and modifying it. But it never hurts to confirm and document it as it happens, so as to confirm that natural mutation and selection forces really do have the power to innovate.
torbjorn_b_g_larsson
5 / 5 (3) May 06, 2016
This may be why bacterial sex evolved in the first place. Not to share genes that were fit in a certain environment, but to produce a buffer of gene duplicates to meet environmental problems by evolving new fit genes.

@humy: Testing maps to the logic that philosophers once labeled "deductive". [C.f. Popper.] And testing is the platform that science needs to weed out "deductions" that doesn't happen for one reason or other. [C.f. flogiston.]
humy
5 / 5 (1) May 06, 2016

@humy: Testing maps to the logic that philosophers once labeled "deductive". [C.f. Popper.] And testing is the platform that science needs to weed out "deductions" that doesn't happen for one reason or other. [C.f. flogiston.]


The deduction in this case are based on assumptions that are extremely difficult to refute and seem extremely unlikely to be false, such as there exists mutations etc. Not that I think it does any harm to check such deduction with hard empirical evidence ( just in case ) . All I am saying here is that, in this particular case, there is no noteworthy need for such an empirical check since the premises of the deduction are already pretty much well verified with no reasonable scientific doubt and the fact that it has now been empirically verified is rather unsurprising.
torbjorn_b_g_larsson
5 / 5 (1) May 07, 2016
Well, I noted why scientists always test all predictions ('deductions'). I guess they know best.

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