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?

full_context: Document 1: Arctic fox: 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.
Document 2: Silver fox (animal): The silver fox is a melanistic form of red fox ("Vulpes vulpes"). Silver foxes display a great deal of pelt variation: some are completely black except for a white coloration on the tip of the tail, some are bluish-grey, and some may have a cinereous color on the sides. Historically, silver foxes were among the most valued furbearers, and their skins were frequently worn by nobles in Russia, Western Europe, and China. Wild silver foxes do not naturally reproduce exclusively with members of the same coat morph and can be littermates with the common red variety, though captive populations bred for their fur are almost exclusively mated with members of the same color.
Document 3: Lemming: A lemming is a small rodent usually found in or near the Arctic in tundra biomes. Lemmings are subnivean animals. They make up the subfamily Arvicolinae (also known as Microtinae) together with voles and muskrats, which forms part of the superfamily Muroidea, which also includes rats, mice, hamsters, and gerbils.
Document 4: Vulpes qiuzhudingi: 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.
Document 5: Dhole: The dhole /dəʊl/ ("Cuon alpinus") is a canid native to Central, South and Southeast Asia. Other English names for the species include Asiatic wild dog, Indian wild dog, whistling dog, red dog, and mountain wolf. It is genetically close to species within the genus "Canis", though its skull is convex rather than concave in profile, it lacks a third lower molar and the upper molars sport only a single cusp as opposed to two to four. During the Pleistocene, the dhole ranged throughout Asia, Europe and North America but became restricted to its historical range 12,000–18,000 years ago.
Document 6: Ezo red fox: The Ezo red fox ("Vulpes vulpes schrencki") is a subspecies of red fox widely distributed in the northern hemisphere. They live in Hokkaido, Sakhalin and surrounding islands in Japan.
Document 7: Kwäday Dän Ts'ìnchi: Kwäday Dän Ts'ìnchi (meaning "Long Ago Person Found" in Southern Tutchone), or Canadian Ice Man, is a naturally mummified body found in Tatshenshini-Alsek Park in British Columbia, Canada, by a group of hunters in 1999. Radiocarbon dating of artifacts found with the body placed the age of the body at between 300 and 550 years. The find was comparable in condition and scientific value to Ötzi the Iceman, remains dating to 3300 BC that were found in the Ötztal Alps in 1991.
Document 8: Cape fox: The Cape fox ("Vulpes chama"), also called the cama fox or the silver-backed fox, is a small fox.
Document 9: Mountain hare: The mountain hare ("Lepus timidus"), also known as blue hare, tundra hare, variable hare, white hare, snow hare, alpine hare, and Irish hare, is a Palearctic hare that is largely adapted to polar and mountainous habitats.
Document 10: Blanford's fox: Blanford's fox ("Vulpes cana"), is a small fox found in certain regions of the Middle East and Central Asia.
Document 11: Red fox: The red fox ("Vulpes vulpes"), largest of the true foxes, has the greatest geographic range of all members of the Carnivora order, being present across the entire Northern Hemisphere from the Arctic Circle to North Africa, North America and Eurasia. It is listed as least concern by the IUCN. Its range has increased alongside human expansion, having been introduced to Australia, where it is considered harmful to native mammals and bird populations. Due to its presence in Australia, it is included among the list of the "world's 100 worst invasive species".
Document 12: Arabian red fox: The Arabian red fox ("Vulpes vulpes arabica") is a subspecies of the red fox native to Arabia, specifically Dhofar and Al Hajar Mountains in Oman and they are also found in UAE, Syria, Jordan, Palestine, and Israel to Saudi Arabia and Yemen. The Arabian red fox is similar in color to the common red fox. However, it is more adapted to desert life than its parent species. The fox's ears are much larger, and its body is much smaller than that of the red fox.
Document 13: Canis falconeri: In Eurasia during the Middle Pleistocene, Canis falconeri gave rise to the hypercarnivore genus "Xenocyon", which then gave rise to genus Cuon (the dhole) and genus Lycaon (the African hunting dog). Just before the appearance of "C. dirus", North America was invaded by genus "Xenocyon" that was as large as "C. dirus" and more hypercarnivorous. The fossil record shows them as rare and it is assumed that they could not compete with the newly derived "C. dirus". The large wolf "C. antonii" from late Pliocene to early Pleistocene China was assessed as being a variation within "C. chihliensis", and the large wolf "C. falconeri" occurred abruptly in Europe in the Early Pleistocene, perhaps representing a westward extension of "C. antonii".
Document 14: Xenocyon: Xenocyon ("strange wolf") is an extinct subgenus of "Canis". The group includes "Canis (Xenocyon) africanus", "Canis (Xenocyon) antonii", and "Canis (Xenocyon) falconeri" that gave rise to "Canis (Xenocyon) lycanoides". The hypercarnivore "Xenocyon" gave rise to the modern dhole and the African hunting dog.
Document 15: Crab-eating fox: The crab-eating fox ("Cerdocyon thous"), also known as the forest fox, wood fox, or Maikong, is an extant species of medium-sized canid endemic to the central part of South America, and which appeared during the Pliocene epoch. Like South American foxes, which are in the genus "Lycalopex", it is not closely related to true foxes: "Cerdocyon" comes from the Greek words "kerdo" (meaning fox) and "cyon" (dog) referring to the dog-and fox-like characteristics of this animal.
ground_truth: Arctic fox