The Fantastic Four First Steps’ ending and post-credits scenes explained. Doctor Doom's MCU debut teased as Robert Downey Jr ...

The arrival of a certain villain is teased in the post-credits scene of The Fantastic Four: First Steps, but what does it mean for the wider MCU?

Ultimately, the dark-haired mice predominate. The shorter the breeding season, the faster the change occurs. With pocket mice, which produce large litters twice a year, it can occur very quickly.