The relationship between environment, variation and selection lay the foundation for natural selection and evolution.
Genetic variations are present among species due to number of reasons like recombination or crossing over during meiosis, mutations, random fertilization etc. These factors bring changes among the members of a species. Some of the species become better adapted to survive in a particular environment whereas some are not better adapted and become extinct over a period of time. The environment selects the organisms that are best adapted to survive and hence lead to variations.
Errors would be made during DNA replications, and cells would then be unable to grow and decide. This would be a long term effect because everything is made of cells.
The correct term for on female arctic fox would be "organism". Although it should be noted that this depends somewhat on the context of the environment.
