Genetic Bottle-Necking

I was looking in the freezer while preparing supper and found that I had both haddock and salmon. Before choosing one I looked at the nutrition to confirm my suspicion--the salmon had about four grams of fat per serving while the haddock only had 1. But the fat in salmon is "good", polyunsaturated omega 3 fat and since it had four times as much as the haddock the salmon seemed to be a superior choice. But then I got to thinking about the micro-nutrition--the minerals and vitamins that aren't listed on the back of the package. Although one food may seem superior to the other both foods fill slightly different dietary niches. After looking it up I found that haddock is higher in magnesium than salmon, which is a valuable mineral in aiding the body in recovery. The most important part of any diet is diversity and to make sure a broad range of foods are consumed. If I could get all my daily calories from peanut butter sandwiches I would probably eat them from dawn to dusk but clearly that wouldn't work, I would soon become very sick which a cornucopia of deficiencies.
   And then I remembered a term which was a frequent theme in an evolution class I took last spring, "genetic bottle-necking". If you are unfamiliar with the term it is basically the tendency for an allele to become fixed in a small population by means of genetic drift. To me this seems to the perfect analogy, if you start comparing all similar foods together and eliminating the food which is deemed "worse", you are in essence removing an allele from your dietary gene pool which in turn reduces the chances have hitting all major micro-nutrients.
 
   ...I ate the haddock.