Love Daléns team in Stockholm (they are basically on the other side of the road from us) have sequenced and published much mammoth DNA, and not least from Wrangel. Rogers and Slatkin used some of that data and just recently published a super-interesting study (here is a popular version of the paper , and here is the actual paper) on the genetic melt-down in the last of these beasts. Wrangel sustained a small population of mammoths for millenias after they went extinct on mainland-Siberia. But for every generation the inbreeding increased, and the last once on Wrangel expressed some heavy inbreeding-depression. These were some sick mammoths that lived off the coast of Siberia a few thousand years ago. The study is interesting not least because it shows what heavy inbreeding can do to a species, a good piece of knowledge to keep in mind when we are discussing conservational measures for some of the mammals that are on the brink of extinction today.