The theory is proposed in The Black Queen Hypothesis: Evolution of Dependencies through Adaptive Gene Loss J. Jeffrey Morrisa, Richard E. Lenskia, and Erik R. Zinserc
In the context of evolution, the BQH posits that certain genes, or more broadly, biological functions, are analogous to the queen of spades. Such functions are costly and therefore undesirable, leading to a selective advantage for organisms that stop performing them. At the same time, the function must provide an indispensable public good, necessitating its retention by at least a subset of the individuals in the community — after all, one cannot play Hearts without a queen of spades.
Gene loss can provide a selective advantage by conserving an organism’s limiting resources, provided the gene’s function is dispensable. Many vital genetic functions are leaky, thereby unavoidably producing public goods that are available to the entire community. Such leaky functions are thus dispensable for individuals, provided they are not lost entirely from the community. The BQH predicts that the loss of a costly, leaky function is selectively favored at the individual level and will proceed until the production of public goods is just sufficient to support the equilibrium community;
But what about the counterbalancing effects of group selection? Most evolutionary selection among social creatures occurs at the group/tribe level not the individual. Afterall - it's not only the leader of the pack who mates, they just mate first. Improves the odds yes, but doesn't exclude others - therefore a QOS can continue to survive in the group to the extent that it makes the group successful.
ReplyDeleteRight. I wasn't clear. The BQH applies to species, not individuals. And it was developed in the context of bacteria.
ReplyDeleteimagine a cesspool of bacteria. One species drops the gene for metabololic function X. They can no longer make X. But the rest of the bacterial species can. Since cells are leaky, the environment is still full of X from the other producers. And our species has a slight evolutionary advantage since it no longer spends its resources making X.
It is a bit like the free rider problem, taken to extremes. Just as in Hearts, the last person stuck with the black queen (spades) cannot get rid of it (as this is suicide), and everyone else gets a free ride.