How does the environment influence the effect of genes?

Question

How does the environment influence the effect of genes?

Answer 1

Many characteristics of organisms are affected by both their genes, and the environment.For example the human height; a person may inherit alleles from parents giving him the potential to grow tall; however if his diet is poor while growing up; he may not grow as tall as he could. The diet is part of the environment and has affected his height.

Another example is the E.coli bacteria which have genes that code for the production of lactose permease enzyme( allows bacteria to take up lactose), and beta galactosidase enzyme ( hydrolyses lactose to glucose and galactose).When E.coli are grown on a medium of that has glucose only they produce neither enzyme, but if they are grown on a medium containing lactose , both genes are "switched on" and the E.coli produce both enzymes. Lactose therefore is an environmental factor that induced the genes to express themselves.

Answer 2

Your question is kind of a round-about way of asking how natural selection works.

The genes that give beneficial traits in an environment tend to allow the individual to live longer and reproduce more, thereby passing on their genes.

The genes that give negative traits for the environment will increase the chance of the individual not being able to reproduce (death, no mates, etc...).

Remember, something that's bad in one environment may be very beneficial in another environment.  Here's an example:

Imagine a field of white sand with stretches of black volcanic rock.  Now picture a population of mice, black and white intermixed.  The black individuals are easily seen in the white sand, and are picked off by predators; however,  they have the advantage in the stretches of black volcanic rock, where the white mice are easily seen and picked off by predators.

The end effect, due to the environment, is that you end up with two different populations of mice.  The black one are bred out of the white sand area, and soon only white mice are born in that location.  The white mice are bred out of the locations of black volcanic rock, and soon only black mice are bred there.

Given a long enough time, these two populations, if they continue to stay separated (esp in a reproductive sense), will become two different species.