| Biodiversity is a growing concern for governments and the public,with its basic object of protecting various species.Species classification and a reasonable delimitation of various taxa are the foundation of research,species conservation,and the sustainable use of biodiversity.Carex,the largest genus in the family Cyperaceae,has about 2000 widely distributed species occupying various habitats,and its morphology-based taxonomy is notoriously difficult to master.Carex filipes complex,which belongs to sect.Paniceae,is mainly distributed in the China-Japan Forest Subkingdom of East Asia.Historically,the species delimitation in C.filipes complex included diverse taxa,with the taxonomy of the complex complicated by an insufficient mastery of the morphological variation and limited research methods available.Based on a wide range of population sampling,an evaluation of morphological variation,niche differentiation,phylogeny,and population genetics,we conducted an integrative taxonomy and biogeography study of C.filipes complex,which aimed to provide a reasonable species delimitation,and to analyze the process of population differentiation and speciation under broader spatio-temporal conditions.All these will also help researchers to deeply understand the speciation and maintenance mechanism in the Sino-Japan Forest Subkingdom of East Asia.Studies on the biogeography of sects.Paniceae and Confertiflorae,two sections being richness in East Asia,detected the diversification of shallow lineages in the genus Carex.The main results are as follows.Combining the sequences of two n DNA sequences（ETS and ITS）and three cp DNA sequences(mat K、rpl32-trn L（UAG）,and trn L-F),the phylogeny of C.filipes complex,together with sects.Paniceae and Confertiflorae s.l.,was reconstructed,which revealed that two sections and the complex were monophyletic.The origin of sect.Paniceae occurred in the mid to Late-Miocene（ca.9.49 Ma）in East Asia,after which part of the section spread to the W Palearctic.Some of the species spread to eastern North America through North Atlantic land bridges or long-distance dispersal ca.6.35 Ma,and the modern pattern of distribution has experienced multiple independent dispersal events.Most species of sects.Paniceae and Confertiflorae s.l.diverged at the end of the Pliocene and Pleistocene,which may be related to the global cooling of the Late Tertiary,as well as the climatic oscillations,geographical heterogeneity,and sea level fluctuations of the Quaternary.The opinion that the diversification rate of shallow lineages of Carex in East Asia is low was challenged.In Carex filipes complex,the two monophyletic groups,C.baohuashanica and C.sp.from East China,were sister groups.Carex sparsinux from central China and C.arakiana and C.rouyana formed another monophyletic group.The complex has originated in eastern China and diverged in the Pliocene（3.73 Ma）species in Japan originated from China and were due to two independent dispersal events through the East China Sea land.Speciation in complex was driven by changing geology and climate of the Quaternary.Based on the observation of 14 morphological characters of 347 individuals in 32populations,as well as the micro-morphology of nutlets from 30 populations,the variation of all characters was analyzed and the taxonomic implications were evaluated.The different populations in species were significantly different in morphological characters,such as culm height,length of utricles,staminate spikes,pistillate spikes,and utricle density per spike,and those differences were more significant among species than among populations.Presence/absence of stolons and the basal sheath color were also different among species.Species in the complex could be recognized using a combination of the above-mentioned characters,whereas the micro-morphology of nutlets was consistent among populations or species.Niche equivalency and similarity tests revealed that the niches of C.sp.from the Yellow Mount and C.rouyana from South Japan were significantly equivalent and similar,whereas the others were significantly inequivalent.Precipitation of driest month and precipitation seasonality were two principal factors which drive the niche divergence between C.arakiana and its relatives.In the niche divergence of C.baohuashanica and C.sp.,annual mean temperature and min temperature of the coldest month contributed the most to the niche divergence.The genetic diversity and the structure of the complex detected by 18 EST-SSR loci revealed all species in the complex had a selfing mating system,and the levels of selfing in C.sp.and C.rouyana were lower than in other taxa in the complex.Both pollen and seed flow occurred in C.sp.and C.rouyana,which led to a lower level of genetic differentiation than in the species with only seed-based gene flow（C.baohuashanica,C.filipes,C.arakiana and C.rouyana）.STRUCTURE analysis,PCo A and UPGMA analysis based on Nei’s distance indicated the recognition of six independent species.Thirty-three haplotypes were detected from 330 individuals of 32 populations in C.filipes complex,using two cp DNA sequences(rpl32-trn L（UAG）and trn L-F).AMOVA analysis showed a considerably high level of genetic differentiation was present among population and species in this complex,and the complex had an extremely significant phylogeographic structure（NST>GST,p<0.01）.A network of haplotypes and BEAST analysis revealed that the complex started to diverge in the Pliocene（3.73 Ma）.The mountains at the boundary between the Second and Third ladders may act as dispersal barriers and have led to the divergence of the central and eastern lineages.Followed by the initial divergence,C.sparsinux entered the eastern part of China along the Wuling and Nanling mountains.The divergence among species and lineages was influenced by a combination of geology and climate,and could also be the result of adaptive evolution.Based on the evidence from phylogeny,morphology,niches and population genetics,seven species including two new species were recognized in Carex filipes complex,they are C.filipes,C.arakiana,C.baohuashanica,C.sinoneglecta,C.jinzhaiensis,C.sparsinux and C.rouyana. |
