Caused by sexual contact are more difficult to treat..
Gene duplication, mutation, or other processes can produce new genes and alleles and increase genetic variation. New genetic variation can be created within generations in a population, so a population with rapid reproduction rates will probably have high genetic variation.
I think for your distilled water of 1 it would look like 27.8 +/- 5 because you can go 5 above or below your average and 2 would be 27.8 +/- 10 because you can go 2 times below or above your average?
Insufficient nutrient, lack of water, no sunlight, climate change, pollution