| Ottelia acuminata,belongs to the genus Ottelia Pers.,a perennial submerged macrophyte of the aquatic plant family Hydrocharitaceae,with six varieties: Ottelia acuminata(Gagnep.)Dandy var.acuminata,Ottelia acuminata(Gagnep.)Dandy var.crispa H.Li,Ottelia acuminata(Gagnep.)Dandy var.lunanensis H.Li,Ottelia acuminata(Gagnep.)Dandy var.jingxiensis H.Q.Wang et S.C.Sun,Ottelia acuminata(Gagnep.)Dandy var.songmingensis Z.T.Jiang,H.Li et Z.L.Dao,Ottelia acuminata(Gagnep.)Dandy var.tonghaiensis H.Li.Ottelia acuminata is endemic and belongs to the endangered species.The existing living populations are mainly distributed in Guangxi,Sichuan,Guizhou,and Yunnan provinces with good water quality.In this study,five pairs of AFLP primers were screened in 227 individuals from five varieties of Ottelia acuminata.The genetic diversity,genetic structure,as well as the morphological characteristics of this species were analyzed to provide theoretical basis for protecting the endangered species.The main findings are as follows:1.Because the Ottelia acuminate sensitivity of the living environment,polluted lakes,wetlands destruction,herbivorous fish introduced,the influence of multiple factors such as excessive picking,Ottelia acuminate distribution range narrowed sharply,and the number of population and plant literature review found that Tonghai Qiluhu lake,Kunming Dianchi lake,Shilin Yuanhu lake,Shilin Yuehu lake,Yuxi Xingyunhu lake,Ottelia acuminate have extincted.Field when visiting survey found life polluted water discharge,riverside aquaculture development,greenhouses plant near ditches,river upstream mineral resources development,water pollution caused by the hot springs village construction,serious threat to the survival of Ottelia acuminate.In addition,artificial reclamation of the lake,the reservoir water construction also caused the number of sea rape to decrease.In recent years,with the development of Ottelia acuminate edible value,Ottelia acuminate crazy for sea fishing,accelerated the extinction rate of Ottelia acuminate,therefore the Ottelia acuminate in conservation strategies need to discuss,make,release and implementation.2.Population genetic diversity analysis with the software POPGENE found theSongming population has the lowest poplation genetic diversity(He = 0.0569).Which indicate the lowest level of genetic variability within population.Longyuandong lake,Xiagulou Village,Wenbang Village,Jinhua Town,Jianchuan County,Yunnan Province occupied the highest population genetic diversity(He =0.1134).The gene flow(Nm)among Ottelia acuminata populations is very low(Nm=0.2612),indicating that the gene flow between populations is weak and limited.The genetic differentiation coefficient among populations was high(Gst=0.4898).Long-term geographical isoloation might block the gene flow among populations.The high genetic diversity of Ottelia acuminata populations could be caused by river capture and water system differentiation.The genetic structure was used to detect the genetic differentiation of Nei.It was found that the genetic identity of the populations of Ottelia acuminata was between 0.684-0.906.The results of the Mental-test test showed that R = 0.487(P = 0.0004),indicating that the correlation between the genetic distance and the geographic distance of the population was significant.The genetic variability distribution among and within populations of O.acuminata estimated by AMOVA revealed that 69.9% of the total variation existed among populations;this value was higher than the total variation within populations(30.1%).The genetic differentiation in lower populations may be related to the environment where the Ottelia acuminata live,as well as the biological pollination and propagation system of Ottelia acuminata,the mechanism of seed spread,the conditions for seed germination,and the shorter distance among individuals.The inbreeding and recession mechanism formed by intercrossing resulted in a lower degree of genetic variation in the formation of Ottelia acuminata.3.We measured representative morphological characteristics of Ottelia acuminata,with the sampled materials.There are independent morphological characteristics traits Yunnan Province,songming County.Heilongtan Lake(SM)populations,populations at the Caohai Baijia Terminal(GW)in Weining County,Guizhou Province,and Lugu Lake(LGH),Ninglang County,Yunnan Province.Suppression is distinctly different from other populations,which partially coincides with the results of structural differentiation of populations.It is very likely that these apparent diversity are verifications of the validity of molecular analysis,and part of populations are in population structure.Differences in differentiation are not reflected in these apparent traits and may require further exploration and verification.4.The software STRUCTURE was used to infer the number of biologicallyrelevant clusters,which infer potential gene pools for O.acuminata.Principal Coordinate Analysis(PCoA)also performed using NTsys-pc software under population mode.Our results show that the Ottelia acuminata is mainly composed of three gene pools.A total of 14 populations of Ottelia acuminata consist of three major gene pools,Yunnan and Guizhou province populations.population of Yunnan province Ninglang city Lugu lake(LGH),Yunnan province Lijiang city Helongtan lake(LJ),Yunnan province Heqing city JinHua Town Helongtan lake(HQ),Yunnan province Jianchuan city Jianhu lake(JH),Yunnan province Wenbang village to Xiagulou village Longyuandong lake(LYD),Yunnan province Songming city Helongtan lake(SM),Yunnan Shilin county Changhu lake(CH),Guizhou province weining map Baijia terminal(GW)consisting of 8 in the group of the first gene pool,Jingxi county of Guangxi province,Xijin town ShangGulong Village(DB),Jingxi county Xinxu town Gengjiang village(JXX),Debao county are DuAn county Sanhe Village(JXD),DuAn map Daxing township(DA)four group consisting of the gene pool,Guangxi province Luzhai county ZhongDu village xiangshui waterfall(LZ)and Guangxi province Baishou county Yongfu village(YF)in a separate form their gene pool.In the genetic isolation analysis of geographical isolation barriers,it was found that there are different degrees of geographical distance isolation barriers among some populations.It is presumed that the geographical environment may be actively changed,and the river diversion and reversal events are frequent,which promotes gene flow among the populations of Ottelia acuminata.In the analysis of population structure,these populations belong to different water systems,and they have a geographical isolation barrier while maintaining a common gene pool.According to the changes of geographic geological events and water system differentiation,we speculated that river capture and water system differentiation formed a high degree of genetic diversity among populations of Ottelia acuminata. |
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