To be clear, being fit in this case refers to a species being best suited for their specific environment. So a species beginning to die off because the environment they adapted to over a very long time was suddenly and drastically changed makes perfect sense.
Survival of the fittest means the ones most suited for their environment survive enough to pass on their genes. When the environment changes (a new predator moves in, humans tear down your habitat to build condos, the ocean heats up so you don't have enough food for everyone, etc) only the members of your species that can handle the new condition will survive to pass down their genes.
Maybe as oceans warm, the remaining crabs will evolve to survive their changing environment better. Or maybe they will go extinct because they can no longer compete with species that are better suited for the warmer oceans. Either way survival of the fittest still applies 100% whether the cause is climate change or some other evolutionary pressure.
Does that clear up why it makes no sense to say that this somehow proves Darwin wrong?
This is about species as a whole and their physical characteristics. All humans are the same species and religion is a social construct, so that does not apply. Eugenics =/= Darwinism and it is intellectually dishonest to equate the two.
Also, there is nothing about winners and losers in Darwinism. It is simply an observation about the natural world. The world is always changing and is never static. Those who can handle the change will make babies and pass on whatever quality they have that makes them suited for their current environment. In the future, that quality may or may not be selected for. Or maybe you have a quality that is not beneficial for your environment, but is not harmful for your survival either, thus it may continue to be passed down (e.g. my shitty eyesight that was passed down, but with correction doesn't impact my survival).
I'm genuinely not sure if you are a troll and trying to be intentionally argumentative or what...
But your argument is that the entire theory of evolution is proven wrong by crabs dying en masse because of climate change, because humans are racist and commit genocides against each other? Or did you just move the goal posts on this discussion about crabs and try to call me racist in the process for shits and giggles? Like you took such a hard turn in the discussion and the only logic is that you are probably gish galloping the discussion and it would be a waste of energy to continue.
This is not what he's talking about. We are apex evolutions but we are also the biggest waste of space and have caused the most amount of damage ever done by a single species.