genetic diversity

Genetic diversity or lack thereof can have real consequences for our diets, and more importantly, for our health. 

Genetic diversity refers to both the vast numbers of different species as well as the diversity within a species. The greater the genetic diversity within a species, the greater that species' chances of long-term survival. This is because negative traits (such as inherited diseases) become widespread within a population when that population is left to reproduce only with its own members.

Source: biology online dictionary

Here, I'm talking specifically about within species diversity...

I have lived in Manhattan for five years. In that time, I have gotten used to the constant hordes of people, waiting in line for 30 minutes to buy a half gallon of milk, paying $7.00 for said half gallon of milk, and the constant smell of urine (which gets worse in the summer). (1) There is one thing, though, that I have not gotten used to - the rats. 

They lurk, hide and scurry and they are everywhere. And, it turns out they don't like to venture far from their neighborhoods. 

New work by a group at Fordham University, published in Molecular Ecology, compared the genetic makeup of 262 brown rats (Rattus norvegicus) living in Manhattan. They trapped the rats throughout Manhattan in parks and private properties in areas with evidence of rat activity. Shockingly, a...