American Black Bear

American black bear is the smallest but most common bear seed in North America. People tend to think that bears are extremely dangerous, especially for humans. In fact, the bear is a harmless creature and has a very kind attitude. Compared to all other kinds of bears, the American black bear is in the middle of the size. It is smaller than Polar bear but bigger than lazy bear. Asian black bears differ in size depending on their position in the world, gender, the amount of food available, the timing, and their genetics. The ancestors of American black bear and Asian black bear are separated from Sun Bear 4.58 mya. Then American black bear was separated from Asian black bear 4.08 mya. The fossil of the early American black bear was in the port of Kennedy, Pennsylvania, very similar to Asian seeds, but later specimens grew to the size of Grizzlies. From the Holocene to the present, the size of American black bear seems to shrink, but it is controversial for these fossil sample age. Cons istent with phylogenetic contradiction and D statistics, the DFOIL statistics found a gene flow between the ancestors of American black bear / brown bear / polar bear cactus and Asian black bears (FIG. 4, Table 1). Euroria bear overlaps with other bear species geographically and is widely distributed like Asian black bear. It was found in the fossil layer of 2.5 Ma - 1.0 Ma1, 31 in Europe. The broad geographical distribution will explain the almost equally strong gene flow from Asian black bear seen in D statistics to Brown bear (Supplementary Figure 14). Finally, there is a gene flow signal between America and Asian black bear. Gene flow can occur on the US side or Asian side of the Bering Strait, consistent with intra-species mitochondrial capture 2 (Figure 3). Most of weak gene flow signals are shown in Figure 1.