... how that so labouring ye ought to support the weak, and to remember the words of the Lord Jesus, how he said, It is more blessed to give than to receive. Acts 20:35
"Evolution is onward and upward, right? Competition between individuals leads to the fittest surviving, right? Not so fast, says Jason B. Wolf of the Department of Ecology and Evolutionary Biology at the University of Tennessee...
There’s an influence that puts the brakes on this “traditional paradigm”, and that is the influence of indirect genetic effects (IGEs). Most evolutionary biologists focus on the direct genetic effects (DGEs): i.e., how an organism’s body (phenotype) is the direct result of its genes (genotype). But that cannot be the whole picture, because social interactions and even the environment can cause phenotypic effects that are heritable. Thus, they can influence evolution.
Wolf studied the pupa size of fruit flies as a measure of fitness. His results supported a model that took IGEs into account, and found that IGEs fight against the effects of DGEs; that is, “competition enforces the negative covariance between IGEs and DGEs.” He explains:
indirect genetic effects, he found that IGEs cancel out about half the fitness gains of the direct genetic effects. This is in addition to the constraint due to antagonistic pleiotropy, where genes on the same chromosome must evolve together or else no net evolution occurs.
But IGEs are expected to put more brakes on selection the more competition increases. The effect is more severe when the individuals are related. “The diminished response to selection caused by the antagonistic counterevolution of IGEs,” he summarizes, “and the further diminution expected when interactions are among relatives can be viewed as a constraint on phenotypic evolution.”
Q: How widespread is this braking effect?
A: He notes in conclusion:
--Charles Darwin was deeply influenced by this idea.
--It contributed to his theory of natural selection: competition leads to the survival of the fittest.
A great deal of intellectual, political and philosophical baggage soon became attached to this assumed law of nature: competition drives the fittest to bigger and better things.
--Wolf now seems to be saying that competition actually inhibits increases in fitness from becoming established in a population. His paper is entitled, “Genetic architecture and evolutionary constraint when the environment contains genes." CEH
"Evolution is onward and upward, right? Competition between individuals leads to the fittest surviving, right? Not so fast, says Jason B. Wolf of the Department of Ecology and Evolutionary Biology at the University of Tennessee...
There’s an influence that puts the brakes on this “traditional paradigm”, and that is the influence of indirect genetic effects (IGEs). Most evolutionary biologists focus on the direct genetic effects (DGEs): i.e., how an organism’s body (phenotype) is the direct result of its genes (genotype). But that cannot be the whole picture, because social interactions and even the environment can cause phenotypic effects that are heritable. Thus, they can influence evolution.
Wolf studied the pupa size of fruit flies as a measure of fitness. His results supported a model that took IGEs into account, and found that IGEs fight against the effects of DGEs; that is, “competition enforces the negative covariance between IGEs and DGEs.” He explains:
For example, if we were to select the largest individuals in a generation, they would on average also be the most competitive individuals. These individuals would have a set of genotypes that, under the current social conditions, make individuals large, and selection would therefore produce a genetic change in the population. However, the progeny of these individuals would find themselves in a more competitive environment, because they all inherited genes from the most competitive individuals in the previous generation. Thus, this new generation would not be as large as we would have expected based on the size of their parents, because they are experiencing a different social
environment.
As an analogy, we can view body size evolving on a treadmill, where every step forward is accompanied by movement backward due to the associated negative changes in the environment. The result is that, depending on the speed of the treadmill, the trait either remains where it started or does not move as far as expected [Dickerson (48) referred to this as “slippage” on the treadmill]. When describing his fundamental theorem of natural selection, Fisher (47) recognized this process as the critical reason why populations do not continue to evolve to higher states of fitness (or character values) despite widespread recurrent directional selection. However, his intuition that these effects would exist and be potentially important had not been previously demonstrated.From his experiments watching pupa size evolve with and without
But IGEs are expected to put more brakes on selection the more competition increases. The effect is more severe when the individuals are related. “The diminished response to selection caused by the antagonistic counterevolution of IGEs,” he summarizes, “and the further diminution expected when interactions are among relatives can be viewed as a constraint on phenotypic evolution.”
Q: How widespread is this braking effect?
A: He notes in conclusion:
Because interactions between individuals are ubiquitous, the opportunity for phenotypic effects of these interactions, and thus IGEs, is considerable….In the early 1800’s, Thomas Malthus proposed the principle that fecundity outpaces food supply, so that there is always competition for resources.
--Charles Darwin was deeply influenced by this idea.
--It contributed to his theory of natural selection: competition leads to the survival of the fittest.
A great deal of intellectual, political and philosophical baggage soon became attached to this assumed law of nature: competition drives the fittest to bigger and better things.
--Wolf now seems to be saying that competition actually inhibits increases in fitness from becoming established in a population. His paper is entitled, “Genetic architecture and evolutionary constraint when the environment contains genes." CEH