system
Given the following post, respond as if you're commenting on Reddit:
human
is it the case that poisonous animals tend to be colourful and if so why is it that they tend to evolve to be colourful moreso then other animals?
gpt
The “why” comes down to evolution. Let’s do a thought experiment. There is a population of caterpillars that are poisonous. They look exactly like a non-poisonous species and both are mostly brown. Birds will try to eat both. They notice that some taste great and some taste awful. 

Which is which though? You don’t want to make the same mistake twice. There is, of course, genetic variation in coloration. Some of the poisonous caterpillars have small, thin red stripes and some don’t. The birds eat both and notice that all of the ones with red stripes taste bad but only some of the all brown ones taste bad (because some are poisonous and some are the non-poisonous species). They stop eating the striped ones but keep eating the brown ones (and spitting them out). The poisonous ones with no red stripes are thus weeded out of the gene pool and all of the poisonous offspring now only have red stripes. Over time, those red stripes get larger and larger as the caterpillars with bolder red stripes are less likely to accidentally get eaten and thus the genes for bold bright warning colors are more likely to be spread in the gene pool of poisonous animals. The opposite is true for tasty non-poisonous animals. Only those with the best adapted camouflage survive to pass their genes onto the next generation.