Evolution of cetaceans decreasing. Other historical climate events can be correlated and matched with the genome history of the Yangtze River dolphin as well. This shows how global and local climate change can drastically affect a genome, leading to changes in fitness, survival, and evolution of a species. The European population of common dolphins ("Delphinus delphis") in the Mediterranean have differentiated into two types: eastern and western. According to a 2012 study, this seems to be due to a recent bottleneck as well, which drastically decreased the size of the eastern Mediterranean population. Also, the lack of population structure between the western and
Hydrus (legendary creature) Hydrus (legendary creature) The Hydrus (also known as "Enhydros, Enidros, Hildris, Hydra, Idra, Idres, Ydre, Ydris", and "Ydrus") is a creature from Medieval bestiaries. They were said to be found in the Nile River. While in the Nile, a crocodile would roll the hydrus in the mud before eating the smaller creature. However, once inside the crocodile's stomach, the hydrus would burst free from the stomach lining. In medieval Christian tradition, this bursting free from the crocodile became an emblem of the resurrection of Christ bursting free from Hell. There is considerable confusion in applying the name hydrus and its