Question: Worker: Which animal which is white in winter and brown in summer lives throughout the Arctic and can trace its roots to an extinct animal that lived in the Himalayas?
Related documents: [0]  [DOC] The Arctic fox ("Vulpes lagopus"), also known as the white fox, polar fox, or snow fox, is a small fox native to the Arctic regions of the Northern Hemisphere and common throughout the Arctic tundra biome. It is well adapted to living in cold environments. It has a deep thick fur which is brown in summer and white in winter. Its body length ranges from 46 to , with a generally rounded body shape to minimize the escape of body heat. [END] 
[1]  [DOC] Vulpes qiuzhudingi is an extinct species of fox found in the Himalayas. It was primarily carnivorous. The fossils, dating from between 5.08 and 3.60 million years ago, were found in the Zanda Basin and Kunlun Mountains of Tibet. It was named after Qiu Zhuding, a paleontologist from the Chinese Academy of Sciences. The species is believed to be the ancestor of "Vulpes lagopus", the modern Arctic fox, which would support the "Out of Tibet" theory: namely, that a number of current arctic species trace their ancestry to species originally from the Tibetan Plateau. [END] 
Answer: 
Arctic fox
Arctic fox