Effects of lithium on the survival,growth,and reproduction of Daphniopsis tibetana Sars(Crustacea:Cladocera)

We evaluated the effects of lithium on the survival, growth, and reproduction ofD. tibetana in the laboratory. The safe concentration value was 69.3 mg/L. The time to first brood was significant lower for individuals reared in 5 and 10 mg/L （24.4 and 24.0 d, respectively） compared with individuals reared in 20, 40, or 60 mg/L. Females reared in 5 mg/L lithium produced a mean of 16.5 neonates/brood and had the highest number of broods （3.0±1.95）. The rate of egg production （a）, the intrinsic rate of increase （rm）, net reproduction rate （R0）, and finite rate of increase （2） were highest for D. tibetana reared at 5 and 10 mg/L lithium, and the duration of development was shorter than for the remaining groups. The results indicated that rearing in 5 10 mg/L lithium can accelerate the growth and reproduction ofD. tibetana.

Effect of temperature,salinity,and body length on the energy budget of Daphniopsis tibetana Sars (Cladocera: Daphniidae)

We investigated the eff ects of temperature（14,20,and 22℃）,salinity（5,10,15,20,and 25）,and body length（0.83,1.17,1.49,and 2.33 mm）on the energy budget of Daphniopsis tibetana Sars in the laboratory.The results demonstrated no diff erence in D.tibetana assimilation efficiency（AE）with values of 51.59%–56.22% at the trial temperatures.Gross growth efficiency（K1）and net growth efficiency（K2）were 28.78% and 55.71%,respectively,at 14℃.Daphniopsis tibetana energy conversion efficiency（AE,K1,and K2）was higher at salinities of 10–20,with values of 72.80%–77.31%,42.50%–50.42%,and 58.43%–65.02%,respectively.Daphniopsis tibetana energy conversion efficiency was highest when body length was 1.17–1.19 mm,with values of 83.70%–84.73%,50.11%–50.81%,and 59.13%–60.71%,respectively.The results of this study can provide a reference for large-scale cultivation use of D.tibetana in the further.

Complete Mitochondrial Genome Analysis of Daphniopsis tibetana(Branchiopoda:Diplostraca):New Insights into the Taxonomy of the Genus and Its Phylogenetic Implications for Branchiopoda

Daphniopsis tibetana is widely distributed in Xinjiang,Qinghai,Tibet of China,as well as in Russia and India,which is the dominant zooplankton in many high-altitude(4000 m)salt lakes.D.tibetana can adapt to saline waters,whereas the other species of the superorder Cladocera can only inhabit in freshwater.However,the phylogenetic status of D.tibetana in Branchiopoda remains unclear primarily because of limited mitogenome.In this study,complete mitochondrial genome sequences of D.tibetana were sequenced and annotated for the first time to obtain a comprehensive understanding of its phylogenetic status.The complete mitogenome of D.tibetana is 16196 bp in length.It contains 37 genes,including two ribosomal RNAs(12S and 16S rRNAs)genes,22 transfer RNA(tRNA)genes,13 protein-coding genes,and one non-coding region.The overall base composition is 29.6%A,33.2%T,19.0%G,and 18.2%C with a high AT bias(62.8%).Except for trnS1(GCT),most tRNAs have a typical cloverleaf secondary structure.Phylogenetic analysis based on maximum likelihood and Bayesian inference generates identical phylogenetic topology and shows the phylogenetic status of D.tibetana,which reconfirm the distinction between the genera Daphniopsis and Daphnia.Meanwhile,the class Branchiopoda is clustered into three clades(Anostraca,Notostraca,and Diplostraca)with high support values.These results provide not only a comprehensive understanding of the characteristics of D.tibetana mitogenome and its phylogenetic position in Diplostraca,but also information for future research on the phylogeny of Branchiopoda.