Mice: Mammalian Pioneers
These small mammals would serve as crucial research subjects for understanding how larger animals might eventually adapt to Mars. They reproduce quickly (20-day gestation) with 5-10 pups per litter, enabling rapid studies of genetic adaptation. Space station experiments showed 10% bone density reduction in similar gravity conditions, requiring dietary supplements or other countermeasures. Ethical concerns about their welfare would necessitate carefully designed habitats with enrichment features.