> it may be merely selection of a pre-existing color variant that already widely found in nature... very dark / black frogs which are already found in nature, m

> it may be merely selection of a pre-existing color variant that already widely found in nature... very dark / black frogs which are already found in nature, may have just reproduced better If this variant is being selected for preferentially, that's evolution: "Typically, we think of biological evolution as changes in gene frequency within a population over time – if, say, birds with genes that produce wide beaks went from being rare to being common over multiple generations." https://evolution.berkeley.edu/evolution-101/mechanisms-the-processes-of-evolution/descent-with-modification/ https://evolution.berkeley.edu/evolution-101/mechanisms-the-...