Explanation:
Fracking is the introduction of substances into a formation in order to increase they pore pressure and to increase natural drive of hydrocarbons.
Fracking has several environmental issues associated with it;
- Fracking leads to air pollution in case of blowout of gas pressure in formations, particles and dusts can become blasted into the environment.
- Proppants in fluids channeled into formations can lead to ground water contamination.
- In areas where fracking is done, there might be an exposure to harmful chemicals.
- Destruction of the natural habitats of animals.
Sural neuritis or sural neuralgia is the pain or injury to the sural nerve.
I'm not sure if I will answer the question you asked, as I many have interpreted it incorrectly. In natural selection, there must be variance in the gene pool, the total frequency of alleles in a population. Now, one of the organisms may have a gene that somehow helps them survive from the selective force much better compared to the others. If this does happen, over time the gene pool will narrow down to become just the genes of that organism that survived better in the first place because the rest would be taken care of by the selective force. So, the alleles and trait come from the first organisms that had the advantage over the others of its species.
When limiting factors increase, diversity in populations decreases. In this sense "limiting factors" can be anything from a lack of resources to a lack of food, meaning it's harder for the population to survive.
