Post by brobear on Apr 8, 2021 3:16:17 GMT -5
online.sfsu.edu/bholzman/courses/Spring99Projects/panda.htm
It has been debated that whether the giant pandas belong to the bear family, the raccoon family, or another family including only the giant pandas and the lesser pandas (the red pandas). Yet that to which family the giant pandas belong remains a mystery. Although today�s giant pandas feed almost completely on bamboo, they are in fact carnivores. Carnivores� ancestors are miacids that is small weasel-like, forest-dwelling animals. About thirty-five million years ago, some of the miacids developed into the earliest dogs, the canids. The canids further branched off to evolved into different animals. About twenty-five million years ago, some of the canids �diverged away from chasing and killing prey to� procyonids, the early ancestors of the raccoons that originated in North American and spread to South America. Another branch of procyonids that were the ancestors of the lesser pandas spread to the Himalayan region. Several million years after these procyonids evolved into these animals, some other canids began to evolve into much larger animals that they became the bears. They originated in the Northern Hemisphere and spread southward to southern Asia and South America except Africa. (Collins 1973) See figure 1.
Whether the giant pandas and the lesser pandas are related to each other or not is another unsolved issue. Some biologist consider the two pandas are not related claiming their similarities come from convergent evolution. They place the lesser panda into the raccoon family, the Procyonidae, and the giant panda into the bear family, the Ursidae. Other biologists consider the two pandas are relatives having the same evolutionary root. Some of them place both pandas into a separate family while the rest put them into the raccoons�. In 1985, Stephen O�Brien and his coworkers conducted DNA hybridization tests in which proteins from both pandas, bears, and raccoons were compared. In their publication, they concluded that the giant panda is a bear and the lesser panda is a raccoon. However, another investigation conducted in the same year after this one concluded that �the two pandas are more alike than are either giant panda and bear or lesser panda and raccoon." In 1989, O�Brien performed another experiment and the conclusion further confirmed the one he made in 1985. Yet in 1991, Zhang Yaping and Shi Liming came up with a conclusion based on the analysis of mitochondrial DNA from the two pandas, Asiatic Black bear, and sun bear. It said that the giant panda is more closely related to the lesser panda than to the bears and the similarities between the two pandas are the result of convergent evolution. (Schaller 1993)
It has been debated that whether the giant pandas belong to the bear family, the raccoon family, or another family including only the giant pandas and the lesser pandas (the red pandas). Yet that to which family the giant pandas belong remains a mystery. Although today�s giant pandas feed almost completely on bamboo, they are in fact carnivores. Carnivores� ancestors are miacids that is small weasel-like, forest-dwelling animals. About thirty-five million years ago, some of the miacids developed into the earliest dogs, the canids. The canids further branched off to evolved into different animals. About twenty-five million years ago, some of the canids �diverged away from chasing and killing prey to� procyonids, the early ancestors of the raccoons that originated in North American and spread to South America. Another branch of procyonids that were the ancestors of the lesser pandas spread to the Himalayan region. Several million years after these procyonids evolved into these animals, some other canids began to evolve into much larger animals that they became the bears. They originated in the Northern Hemisphere and spread southward to southern Asia and South America except Africa. (Collins 1973) See figure 1.
Whether the giant pandas and the lesser pandas are related to each other or not is another unsolved issue. Some biologist consider the two pandas are not related claiming their similarities come from convergent evolution. They place the lesser panda into the raccoon family, the Procyonidae, and the giant panda into the bear family, the Ursidae. Other biologists consider the two pandas are relatives having the same evolutionary root. Some of them place both pandas into a separate family while the rest put them into the raccoons�. In 1985, Stephen O�Brien and his coworkers conducted DNA hybridization tests in which proteins from both pandas, bears, and raccoons were compared. In their publication, they concluded that the giant panda is a bear and the lesser panda is a raccoon. However, another investigation conducted in the same year after this one concluded that �the two pandas are more alike than are either giant panda and bear or lesser panda and raccoon." In 1989, O�Brien performed another experiment and the conclusion further confirmed the one he made in 1985. Yet in 1991, Zhang Yaping and Shi Liming came up with a conclusion based on the analysis of mitochondrial DNA from the two pandas, Asiatic Black bear, and sun bear. It said that the giant panda is more closely related to the lesser panda than to the bears and the similarities between the two pandas are the result of convergent evolution. (Schaller 1993)