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
USS Delphinus (AF-24) USS Delphinus (AF-24) USS Delphinus (AF-24) was built in 1915 as by Workman Clark and Co., Ltd., Belfast, Northern Ireland; acquired by the U.S. Navy 11 August 1942; and commissioned the same day as "San Mateo", Lieutenant O. M. Mikkelsen, USNR, in command. She was assigned the name "Delphinus" on 22 August 1942. Departing San Francisco, California, 12 September 1942, "Delphinus" arrived at Auckland, New Zealand, 4 October. She operated from this base until the end of 1945, carrying chilled and frozen provisions to forward bases in the South Pacific and to the Society, Fiji, and Samoan Islands. After calling