 Genome sequences done in 2013 revealed that the Yangtze River dolphin , or " baiji " ( Lipotes vexillifer ) , lacks single nucleotide polymorphisms in their genome . After reconstructing the history of the baiji genome for this dolphin species , researchers found that the major decrease in genetic diversity occurred most likely due to a bottleneck event during the last deglaciation event . During this time period , sea levels were rising while global temperatures were 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 . 
