Genetic diversity and phylogeography of Daphnia similoides sinensis located in the middle and lower reaches of the Yangtze River

: Geographical patterns, climate, and environmental change have important influences on the distribution and spread of aquatic organisms. However, the relationships between the geographical pattern and phylogenetics of Daphnia as well as environmental change are not well known. The genetic diversity and phylogeography of seven D. similoides sinensis populations located in the middle and lower reaches of the Yangtze River were investigated based on the combination of mitochondrial (COI gene) and nuclear (14 microsatellite primers) markers. Based on the mitochondrial gene markers, D. similoides sinensis from the middle and lower reaches of the Yangtze River had one ancestral haplotype and two evolutionary clades. In addition, D. similoides sinensis population deviated from neutral evolution, showing signs of a bottleneck effect followed by population expansion. Based on the microsatellite markers, the seven D. similoides sinensis populations formed three main groups. The dendrogram (NJ/ME) showed that D. similoides sinensis based on the mitochondrial genes marker were obviously clustered two main clades, whereas there were three clades based on the microsatellite markers. Our results suggested that the habitat fragmentation due to the barrier of the dams and sluices promoted the genetic differentiation and phylogeography of D. similoides sinensis populations in the middle and lower reaches of the Yangtze River.