Research On Population Growth And Diversity Of Several Pseudodiaptomid Species

Species of Pseudodiaptomus are very common in the southeast coastal areas of China,and they play a certain role in ecosystems.However,studies on population growth and population diversity of Pseudodiaptomus are still not enough now.In this research,5 pseudodiaptomid species fed on three microalgae were used to study the effects of diets on population growth;samples of Pseudodiaptomus in the southeast coastal areas were collected,mitochondrial cytochrome oxidase subunit I(mtCOI)gene sequences were extracted and amplified to study the population diversity.The mam results are as follows:1.Population growth of Pseudodiaptomus.In dark environment at room temperature,the effects of three microalgae on 5 pseudodiaptomid species parameters,such as innate rate of increase,were studied.The results showed that different microalgae had significant effects on population growth of Pseudodiaptomus:P.bispinosus fed on Isochrysis galbana showed high level of innate rate of increase and net fecundity,which were 0.279 ind.-1·d-1 and 32.11 ind.-1 respectively;the innate rate of increase and net fecundity of P.forbesi fed on Chaetoceros mulleri were the highest in this experiment,which were 0.335 ind.-1·d-1 and 34.45 ind.-1;and the innate rate of increase and net fecundity of P.trihamatus fed on Chlorella vulgaris were relatively low,which were 0.186 ind.-1··d-1 and 13.10 ind.-1.The comparison of five species showed that under same condition,parameters such as innate rate of increase were significantly different between species:the innate rate of increase of P.forbesi was the highest,which was 0.259-0.335 ind.-1·d-1;the innate rate of increase of P.bispinosus,P.sheni and P.zhengi were less;while the innate rate of increase of P.trihamatus was the lowest,which was 0.169-0.239 ind.-1·d-1.2.Population diversity of Pseudodiaptomus.The diversity of the 6 pseudodiaptomid species populations in Xiamen Bay was high,with 307 conserved sites,262 variable sites in 569 bases,nucleotide diversity(Pi)was 0.1789,haplotype diversity(Hd)was 0.987.The difference in niche may be the reason for the coexistence of 6 pseudodiaptomid species populations in Xiamen Bay.The diversity of the 2 populations of P.annandalei in Xiamen and Zhangzhou was high,with 526 conserved sites,44 variable sites in 570 bases,nucleotide diversity(Pi)was 0.0128,haplotype diversity(Hd)was 0.969.The diversity of the 7 populations of P.forbesi in the southeast coastal areas was high,with 482 conserved sites,89 variable sites in 571 bases,nucleotide diversity(Pi)was 0.0210,haplotype diversity(Hd)was 0.954.The genetic distance,gene flow and phylogenetic tree analysis showed that the 2 populations of P.annandalei in Xiamen and Zhangzhou have already had a certain degree of genetic variation;P.forbesi in the southeast coastal areas could be divided into 3 geographical populations.