Genetic diversity and differentiation of Daphnia galeata in the middle and lower reaches of the Yangtze River, China

Abstract

Mitochondrial 16S rDNA and CO I gene were used as molecular markers for the analysis of the genetic diversity and differentiation of Daphnia galeata populations in nine water bodies in the middle and lower reaches of the Yangtze River. In the combined 16S rDNA and CO I gene sequences, 54 variable sites and 44 haplotypes were observed among 219 individuals belonging to nine D. galeata populations. Average haplotype diversity and nucleotide diversity were, respectively, 0.72% and 0.56%. The F‐statistics (FST) value of the D. galeata populations was 0.149. According to the results of the neutral test, D. galeata in the middle and lower reaches of the Yangtze River had experienced a bottleneck effect in the history. Molecular variance analysis indicated that the genetic differentiation of the D. galeata populations mainly occurred within populations (85.09%). Greater genetic differentiations of D. galeata among individuals within populations appeared in the populations from the Huaihe River basin, whereas smaller genetic differentiations occurred in the populations from the middle reaches of the Yangtze River. Strong gene flows were all observed between Group I (four populations from the middle reaches of the Yangtze River) and Group ΙΙ (three populations from the middle and lower reaches of the Yangtze River), and Group ΙΙΙ (two populations from the Huaihe River basin). The effective migration rates (M) were 851.49 from Group I to Group ΙΙ and 685.96 from Group I to Group ΙΙΙ, respectively. However, no significant relationship was observed between the genetic differentiation and geographical distance of the nine populations (r = .137, p > .05). Results suggested that the genetic differentiation of D. galeata in the water bodies in the middle and lower reaches of the Yangtze River resulted mainly from geographical isolation.

Spatial and temporal variation of genetic diversity and genetic differentiation in Daphnia galeata populations in four large reservoirs in southern China

“…It showed significant genetic differentiation along both vertical and longitudinal gradients in Rimov reservoir, Czech Republic (Seda et al, 2007;Macháček and Seda, 2008;Yin et al, 2012;Petrusek et al, 2013). D. geleata is also common in waters of tropical and subtropical China (Han et al, 2012;Liu et al, 2019;Ma et al, 2019), where it is subject to high and year-round predation pressure. To be persistent and dominant in warmer waters, D. geleata needs some ecological mechanisms to maintain its genetic diversity.…”