Professor's hypothesis may be game changer for evolutionary theory

Professor's hypothesis may be game changer for evolutionary theory

(PhysOrg.com) -- A new hypothesis posed by a University of Tennessee, Knoxville, associate professor and colleagues could be a game changer in the evolution arena. The hypothesis suggests some species are surviving by discarding genes and depending on other species to play their hand.

The groundbreaking "Black Queen Hypothesis" got its name from the game of Hearts.

In Hearts, the goal is to avoid "winning" the Queen of Spades (the Black Queen), which is worth a lot of points. Subsequently, players allow others to take the high-point card while they enjoy low-score tallies.

This same premise applies in evolution, the scientists say.

According to the hypothesis, evolution pushes microorganisms to lose essential functions when there is another species around to perform them. This idea counters popular evolutionary thinking that evolve by adding genes rather than discarding them.

"A common assumption about evolution is that it is directed toward increasing complexity," said Erik Zinser, associate professor of microbiology. "But we know from analysis of that some trend toward decreasing complexity, exhibiting a net loss of genes relative to their ancestor."

Zinser's opinion piece is published in mBio, the online open-access journal of the American Society for Microbiology. Jeffrey Morris and Richard Lenski of Michigan State University are co-authors. Morris was Zinser's doctoral student at UT.

The authors formed their theory after studying called Prochlorococcus.

"This marine microorganism continued to mystify us because it is the most common on Earth, but it is extremely difficult to grow in pure culture," Zinser said. "A major reason for this difficulty is that Prochlorococcus is very sensitive to reactive such as hydrogen peroxide and relies on other bacteria to protect them by breaking down these toxic substances for them."

Prochlorococcus had once performed this function itself, but natural selection decided it was too costly, like carrying the Queen of Spades, and discarded this ability. Instead Prochlorococcus benefits from the hard work of others within its community allowing it to concentrate its energies elsewhere—such as multiplying.

The hypothesis offers a new way of looking at complicated, interdependent communities of microorganisms.

"We know that certain microbial activities, such as scavenging, are 'leaky,' meaning their impacts extend beyond the cell and into the environment," Zinser said. "What the hypothesis suggests is that this leakiness can drive a community toward greater interdependence, even if some members are unwitting participants in this process."

This interdependence could lend itself to vulnerabilities. The scientists say the work highlights the importance of biological diversity, because if rare members are lost, "the consequences for the community could be disastrous." This would be analogous to attempting to play Hearts without the Queen of Spades.

Currently, the hypothesis is limited to , but Zinser thinks the could be extended to larger free-living organisms. All that is needed is a card which no player wants yet is crucial for the game to be played.


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The Black Queen Hypothesis: A new evolutionary theory

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Apr 04, 2012
I'm not sure about 'game changing'. It would be an interesting mechanism that helps drive a species' evolution, but it would be just another mechanism weighing in, alongside selective mating, gene drift, viral insertion, etc.

Apr 04, 2012
MO such a hypothesis is actually a component of many evolutionary models already. It's believed, that many eucaryotic organells emerged as a bacterial symbions or even endoparasites. For example chloroplasts and mitochondria in plant cells are behaving like independent bacteria in certain extent, they've their own DNA and they're even sensitive to the same antibiotics, like the common bacteria.

Apr 04, 2012
Pruning is now 'game changing' in newspeak.

Apr 04, 2012
canis familiaris has figured out that staying in the homo sapiens good graces ensures a life free of predators. hunting, and harsh elements.

Apr 04, 2012
More complex system is becoming, more fragile it is.

Apr 05, 2012
Not very surprising when you consider two truisms - use it or lose it and symbiosis (don't waste energy on functional duplication).

Apr 05, 2012
I don't understand how this is anything new at all. Humans (and other apes) lost capability of producing vitamin C cause they can get enough from the foods they eat i.e. they have outsourced the production to other species. Surely producing vitamin C is a costly effort even if it was just a small part of all energy requirements of an animal. Maybe losing vitamin C production had an effect through natural selection or maybe it didn't but the principle remains the same. I'm sure there are lots of similar examples, some with more substantial selection benefit. This hypothesis just sounds to me like something Captain Obvious would come up with.

Apr 05, 2012
This may explain our dependence on tools, gadgets and technology. Efficient system nonetheless.

Apr 05, 2012
To begin with, you can't lose something you don't have. So before losing "complexity" you have to have it, or build it in you. Same as losing weight, first you have to gain weight, then you can lose some of it. In a first step, these organisms built, through evolution, complexity and later on started shading complexity because they "figured out" they are part of a team. You can't ignore the first step, which also took millions of years, to conclude that evolution is about losing complexity.

Apr 05, 2012
Isn't this what we call commensualism,wherein two or more organisms interact to provide functions they probably used to provide for themselves. Specialization,on one level it is simplification, allows each to be more efficient and to get better at the functions it continues. in any case its a cool way of looking at the issue. The more windows we look through ,the better chance we have of finding a way in. keep at it.

Apr 07, 2012
I'm not sure about 'game changing'.

Agreed. Organisms will optimize as to their environment. If there is a factor in the environment that the organisms also provides for itself then the organism will, eventually, evolve to ditch that mechanism. Why? Because any activity costs energy/resources. If the organism doesn't have to do something then that means more resources can go to growth and reproduction.

Example: Some people have acne because of bacteria living on their skin. When you use an acne remedy then only those bacteria that have thick membranes survive (and thrive). When you stop using an acne remedy those thick-membraned bacteria are outbred by the earlier variant because they have a slower reproduction cycle (needing extra energy to manufacture thick membranes).
Whole companies have built their fortunes on understanding this (and billions of teenagers have bought their stuff foolishly thinking it could rid them of acne somehow).

Apr 08, 2012
I thought this was common sense in evolution theory... -.-
The "researcher" got his paycheck anyway.

Apr 21, 2012
I thought this was common sense in evolution theory... -.-
The "researcher" got his paycheck anyway.

Well this shows what you know!

Religiouse Trolls should be banned, why are they not?

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