Why where the Galapagos Turtles different from the mainland turtles if they shared a common ancestor?​

Speciation! Speciation occurs when a single species becomes two or more separate populations by a geographical barrier. This changes each population’s environment which forces them to adapt. Eventually these populations will become so different from each other that they will not be able to interbreed populations and create fertile offspring. This is what makes them different species, but they still share a common ancestor.

It allows water to resist freezing and thawing cycle.