There numerous of them but some of them would be contaminated soil which can be followed with altered soil chemistry that contains fewer soil organisms that are essential. The third one would be surface runoff due to extensively modified hydrology of the area.
Answer:
Smaller populations have a greater chance of having one allele expressed disproportionately.
Explanation:
Genetic drift corresponds to a drastic casual alteration of the natural order, reaching the genotypic concentration of one or several species, not preliminarily involving natural selection factors, but caused by sudden events. Such phenomenon is characterized by the occurrence of ecological catastrophes, for example: earthquakes, tsunamis, tornadoes, floods, burnings, avalanches and other processes, affecting a large population contingent. Thus limiting the genetic content of a particular group, restricted to the prevailing individuals.
In this situation, with low variability, differentiated individuals will experience a more significant selection pressure in relation to the ascending lineage, which minimized the achievements of selection due to the high number of living individuals. In this scenario, smaller populations will have a greater chance of having a disproportionately expressed allele as the number of members is reduced. We can also see this effect if by using a coin we imagine that heads and tails are two alleles in a population and each coin toss represents one member of that population.

<em>The next time you wake in the middle of the night and need to make a trip to the kitchen or the restroom, cover one of your eyes with your hand before turning on any lights. You'll save the night vision (a.k.a. Sharingan) in that eye. The effect is trippy.</em>
to digest food in order to get nutrients.