The Wrangel Island mammoths would end up being the final survivors of a once widespread genus. In their final years, after having thrived in many parts of the world for millions of years, the very last mammoths that ever lived experienced what’s known as a mutational meltdown.
An isolated mammoth population survived an extra 6000 years past mainland mammoths… but accumulated so many negative mutations (deletions, mutations) they eventually died out too.
Minimum viable population is about 500 individuals, with 1000 to prevent negative genetic drift — only about 300 mammoths lived on Wrangel Island.
Understanding how species went extinct can help us better protect small isolated populations (e.g. cheetahs, otters) from mutational meltdown.