Antlers, Plumes, and Evolutionary Fitness... My Little Theory

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Offline AndroidNeox

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Since Darwin, biologists have puzzled at the profligacy of sexual and dominance displays of many species. Moose & deer antlers. Peacock tails. Magpie bower collections. Countless examples.

A commonality of these displays is that they entail significant cost to the individual. Not just the cost to create the display, but the cost to live while maintaining the display.

I have a possible explanation for how these seemingly pointless characteristics can improve the fitness of the entire species when the environment suddenly turns bad.

For example, carrying a huge rack of antlers makes every aspect of life harder for a buck: growing them, carrying the weight, moving through forest, etc. The buck must be stronger, faster, better coordinated, and have better stamina. He must be a superior specimen.

This enhancement of a broad range of characteristics will require fine tuning of a broad range of genes.

Suppose that the genetics of the display trait are not widely distributed through the genome. Suppose they are, functionally, tightly linked. They can be enhanced or suppressed with few and or simple mutations.

In times of extreme stress, the individuals with elaborate displays would tend to be culled. However, the remainder of the species, even though they don't express the display characteristics, will still benefit from the broad range of genetic fine tuning that the previously dominant males required in order to sustain their elaborate display.

When (not if) life suddenly gets hard, this improved genome helps the species survive, albeit the individuals carrying the best displays would have a significant disadvantage. In the hardest of times, one might expect the display trait to be suppressed to a practical degree (e.g. purely functional antlers) or even completely disappear (peacocks might survive severe hardship best with camouflage and small tails).

In this way, the genome of the entire species could be continuously fine tuned to a degree beyond that necessary for currently prevailing circumstances.