What is the significance of the units of selection problem in evolutionary biology?

Answer 1

That question cannot be answered well in this space. It's a very large debate about how evolution functions.

If you want a very technical discussion, here's one from Stanford Univ.'s website.

http://plato.stanford.edu/entries/selection-units/#1

But here's the basic rub--evolution means survivals of the fittest, right? But fittest what? Gene? Individual? Population? What unit does evolution favor? The answer will affect your description of the process of evolution.

Go to Wikipedia for a more casual explanation that still contains a great deal of information.

http://en.wikipedia.org/wiki/Unit_of_selection

Answer 2

One of the questions for evolution is to determine at what level, exactly, are environmental forces shaping the adaptation of life. Possible answers to this question are different units of selection.

For example, the gene level is one possible unit of selection. Genes, of course, produce enzymes which ultimately build an organism. And if an organism has a hard time surviving because some gene is producing wacky chemistry, it seems reasonable to believe that selection will weed it out.

But there are lots of other levels of organization too - cells, individuals, groups, and even whole species. And there could just as easily be arguments that any of these is the base unit on which selection primarily acts. Altruism, for example, is a behaviour where one individual harms their own survival to aid another's. There is no single gene for it, and it's only observed and relevant when you get to groups and species.

Various biologists have come forward to declare that one particular unit of selection is far more important than the others. Personally, I think they're all important in different amounts according to different environments and circumstances.

Answer 3

As an evolutionary biologist I have been partial to the gene as the unit of selection and the whole organism concept. I am 56 years old and have yet to make up my mind.