Contemporary theory includes the writings of Stephen Gould. Evolution of large populations is known to be slow, but there is no theory that forbids rapid evolution in founder populations.
Contemporary evolutionary theory essentially says that organisms adapt to meet the demands of their environment. It’s very hard to tack down a time frame with it. I personally believe evolution increases as population values decrease, based on evidence I’ve seen. These findings do not shatter contemporary evolutionary beliefs, because a time frame for evolution is not standardized. There are multiple theories on how long evolution takes or what specifically speeds an evolutionary step.
‘punctuated equilibrium’ the idea that evolution remains relatively stable for long periods then rapidly adapts under stressors has been kicked around for sometime.