At what level of organization (cell, tissue, organism, population, community...) does evolution occur?

Question

At what level of organization (cell, tissue, organism, population, community...) does evolution occur?

Answer 1

It occurs at the population level.  It cannot occur in an organism (or anything less) because there needs to be generations and variation for natural selection to choose from. In other words evolution acts upon the phenotype. It also does not happen at the community level because evolution does not have the same effect on multiple populations.

Population is the correct answer.

Also for verification: "Evolution occurs when there are changes in the frequencies of alleles within a population of interbreeding organisms" - wiki

Answer 2

I'm gunna go the other extreme and argue that it occurs at the subcellular level. DNA evolves and this is what is subject to variability and selection in that fitter DNA is passed on more.

Answer 3

It is usually at the organism level.  Macro evolution is above organism level though.

Answer 4

Organisms do not evolve by themselves, organisms evolve with the population.