Magnesium Sulphate Monohydrate
Any characteristic, whether a physical trait, a behaviour, a physiological adaptation etc can make an organism more or less likely to survive in a particular environment.
A dark colour could help a rabbit survive if it lives in a dark forest, because predators can't see it so well, but it would be less likely to survive in the arctic, where the environment is all white and it would show up.
In terms of the characteristics, think about: does it help the organism get food? Does it help protect the organism from predators? If it does, that organism is more likely to survive, and pass the characteristic on to it's offspring. If a bacterium has a characteristic of not being killed by antibiotics, this will help it to survive and breed.
I want to say individuals more so than entire populations. That being said it's because the entire populations of living things are able to evolve and move forward through slow evolution.
Answer: the actual size of the population is relatively small.
Explanation:
In relatively small populations, the phenomenon of genetic drift significantly may change the frequencies of the alleles in that population. This consequently affect the genetic structure of the population in context.
Whereas big populations doesn't significantly feel the shakings of this phenomenon because her effects are small and insignificant.
