"It is good thus to try in imagination to give to any one species an advantage over another. Probably in no single instance should we know that to do. This ought to convince us of our ignorance on the mutual relations of all organic beings; a conviction as necessary as it is difficult to acquire. All that we can do, is to keep steadily in mind that each organic being is striving to increase in a geometrical ratio; that each at some period of its life, during some season of the year, during each generation or at intervals, has to struggle for life and to suffer great destruction. When we reflect on this struggle, we may console ourselves with the full belief, that the war of nature is not incessant, that no fear is felt, that death is generally prompt, and that the vigorous, the healthy, and the happy survive and multiply." Charles Darwin, Origin of Species 2nd edition
Happy?
This passage closes the change Struggle for Existence & he was just discussing that competition is strongly within species and then varieties within species and then between closely related species. So the advantages he alludes to would be within a species or closely related species and I suppose he's is suggesting something like disease resistance, climate adaptations, better escape from predators. These are things we can think of but are these the actual causes of success and failure - that is what, at the time, we weren't sure about. And I would suggest we still are largely ignorant of genotypic differences between individuals and their consequences on fitness.
"It is good thus to try in imagination to give to any one species an advantage over another. Probably in no single instance should we know that to do. This ought to convince us of our ignorance on the mutual relations of all organic beings; a conviction as necessary as it is difficult to acquire. All that we can do, is to keep steadily in mind that each organic being is striving to increase in a geometrical ratio; that each at some period of its life, during some season of the year, during each generation or at intervals, has to struggle for life and to suffer great destruction. When we reflect on this struggle, we may console ourselves with the full belief, that the war of nature is not incessant, that no fear is felt, that death is generally prompt, and that the vigorous, the healthy, and the happy survive and multiply." Charles Darwin, Origin of Species 2nd edition
Happy?
This passage closes the change Struggle for Existence & he was just discussing that competition is strongly within species and then varieties within species and then between closely related species. So the advantages he alludes to would be within a species or closely related species and I suppose he's is suggesting something like disease resistance, climate adaptations, better escape from predators. These are things we can think of but are these the actual causes of success and failure - that is what, at the time, we weren't sure about. And I would suggest we still are largely ignorant of genotypic differences between individuals and their consequences on fitness.