Study On Effect Of Different Water Environment In China On The Phyletic Evolution Of Several Common Species Of Simocephalus

In the present paper,the Simocephalus collected from 9 provinces,1 municipality and 1 autonomous region in China from 2014 to 2017 are described.There were related to 41 different fresh-waters points of north and south in China.663 specimens were collected and 295 specimens were used to research.7 common species of Simocephalus in different geographical waters were identified by combining the traditional morphological identification and molecular biology techniques.The gene marker technique was used to research molecular biology of 7 common Simocephalus.We chose the partial sequence of the mitochondrial cytochrome oxidase I(COI)gene and the ribosomal small subunit 18S rDNA sequence as molecular markers.Preliminary proof showed that the phylogenetic results of species were basically consistent with morphological taxonomy.Based on the phylogenetic analysis of mitochondrial COI gene and ribosomal small subunit 18S rDNA sequence,sequence alignment and constructed different phylogenetic trees were analyzed.We found that the pH and temperature(T)of the water environment had significantly influence on phyletic evolution of Simocephalus without the impact of geographical isolation;In the study of the water environment(pH;T)of Simocephalus vetulus lived in the high altitude area of Tibet(4568.7m;4830m),the results showed that S.vetulus had estranged genetic relationship with the species of other waters,if the variation of pH and temperature in the water environment was remarkable by comparing with other water environment.It proved that the higher pH and temperature(T)had a impact on the phyletic evolution probably,however,it was uncertain whether the high altitude also had an impact on the phyletic evolution.It remains to be further studied.In the phylogenetic study of Simocephalus sibiricus Sars,the variation of temperature in water environment was not obvious,and the temperature curve showed the fluctuation at about 15?;The variation of pH was significant and pH value fluctuated in the range of 7-8.Part of S.sibiricus lived in the water environment with high pH showed more closely genetic relation.And temperature as an unstable factor effected by other factors will change at any time.Without the influence of temperature and geographical isolation,the pH of water environment may play a role in the phyletic evolution.