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1.
Understanding the factors driving the diet breadth of phytophagous insects remains one of the main questions in ecological research. In this study we explored the diet breadth and plant-insect associations in the plume moth Lioptilodes friasi Vargas & Parra (Lepidoptera: Pterophoridae). This phytophagous insect was originally described in association with a single host species, Haplopappus foliosus (Asteraceae), a native shrub of the Chilean Mediterranean matorral. In order to address the breadth of host plant choice, we surveyed other Haplopappus species growing along the elevation gradient of central Chile from sea level to 2600 m. We were able to obtain L. friasi adults from five additional Haplopappus species: Haplopappus chrysantemifolius and Haplopappus decurrens from the coastal zone, Haplopappus multifolius and Haplopappus schumanii from the mid-elevation zone, and Haplopappus scrobiculatus at high elevation. Our results demonstrate that the genus-specialized endophagous herbivore L. friasi has a wider distribution and climatic tolerance than previously described. Its biogeographical range extends from the lowland coastal habitats up to the Andean subnival level. We propose that shared flower phenotypic traits such as morphology and chemical composition may have allowed the colonization of closely related Haplopappus species in central Chile, the expansion of which is limited by the harsh high elevation conditions.  相似文献   

2.
Cycas debaoensis is a critically endangered cycad species endemic to China. This species is found on two kinds of habitats according to the edaphic differences, sand and karst. A previous chloroplast DNA (cpDNA) study indicated that C. debaoensis had low genetic variation within populations and high genetic differentiation among populations. Because maternally inherited cpDNA does not fully characterize genetic structure of the species, we screened seven low-copy nuclear genes and 17 nuclear microsatellite loci to detect the nuclear genetic diversity, differentiation, and the population structure of C. debaoensis. The nuclear genes revealed higher level of genetic diversity. There were both the same and region-specific haplotypes or alleles between the karst and sand regions. Nuclear gene flow among all the populations was much greater than that of cpDNA, which indicated that pollen-mediated gene flow was much greater than seed-mediated gene flow. This promoted low nuclear genetic differentiation among populations of C. debaoensis. The study suggests that both genetic and anthropogenic disturbances have resulted in the critically endangered status of C. debaoensis.  相似文献   

3.
Zygophyllum xanthoxylon, a desert species, displaying a broad east–west continuous distribution pattern in arid Northwestern China, can be considered as a model species to investigate the biogeographical history of this region. We sequenced two chloroplast DNA spacers (psbK-psbI and rpl32-trnL) in 226 individuals from 31 populations to explore the phylogeographical structure. Median-joining network was constructed and analysis of AMOVA, SMOVA, neutrality tests and distribution analysis were used to examine genetic structure and potential range expansion. Using species distribution modeling, the geographical distribution of Z. xanthoxylon was modeled during the present and at the Last Glacial Maximum (LGM). Among 26 haplotypes, one was widely distributed, but most was restricted to either the eastern or western region. The populations with the highest levels of haplotype diversity were found in the Tianshan Mountains and its surroundings in the west, and the Helan Mountains and Alxa Plateau in the east. AMOVA and SAMOVA showed that over all populations, the species lacks phylogeographical structure, which is speculated to be the result of its specific biology. Neutrality tests and mismatch distribution analysis support past range expansions of the species. Comparing the current distribution to those cold and dry conditions in LGM, Z. xanthoxylon had a shrunken and more fragmented range during LGM. Based on the evidences from phylogeographical patterns, distribution of genetic variability, and paleodistribution modeling, Z. xanthoxylon is speculated most likely to have originated from the east and migrated westward via the Hexi Corridor.  相似文献   

4.
The species/lineage delimitation and possible hybridization/introgression are prerequisites in the management of invasive organism. Phragmites australis invaded diverse habitats and displaced the native lineages in North America as a consequence of the introduction from the Eurasia. Such species threatened the biodiversity safety of the invaded regions, in particular the biodiversity hot spots. Southwest (SW) China is a biodiversity hot spot with the occurrence of Phragmites species, both native and introduced. However, the genetic identity of Phragmites species in this biodiversity hot spot remains unclear, hampering effective ecological managements. In this study, we explored the phylogenetic lineages of Phragmites species in SW China. A total of 44 accessions sampled across SW China were analyzed using two chloroplast DNA (cpDNA) markers and amplified fragment length polymorphisms. Two genetic lineages were recovered, i.e., (1) the tropical lineage which primarily consisted of native Phragmites species represented by cpDNA haplotypes I, Q, and U in relatively low altitude and (2) the common lineage including native species at higher elevations in the Hengduan Mountains as well as artificially planted species represented by cpDNA haplotype P. The between-lineage hybridization was suggested for five analyzed accessions collected from either natural or artificial habitats. The putative hybrids might have originated from the maternal native tropical lineages and paternal introduced common lineage. Our results suggest the likelihood of introgressive hybridizations in SW China and thus provided implications for future research and ecological management.  相似文献   

5.
Eight pairs of chloroplast DNA (cpDNA) universal primers selected from 34 pairs were used to assess the genetic diversity of 132 pear accessions in Northern China. Among them, six amplified cpDNA fragments showed genetic diversity. A total of 24 variable sites, including 1 singleton variable site and 23 parsimony informative sites, as well as 21 insertion-deletion fragments, were obtained from the combined cpDNA sequences (5309–5535 bp). Two trnL-trnF-487 haplotypes, five trnL-trnF-413 haplotypes, five rbcL haplotypes, six trnS-psbC haplotypes, eight accD-psaI haplotypes and 12 rps16-trnQ haplotypes were identified among the individuals. Twenty-one haplotypes were identified based on the combined fragments. The values of nucleotide diversity (Pi), average number of nucleotide differences (k) and haplotype diversity (Hd) were 0.00070, 3.56408 and 0.7960, respectively. No statistical significance was detected in Tajima’s D test. Remarkably, the important cpDNA haplotypes and their representing accessions were identified clearly in this study. H_19 was considered as one of the ancient haplotypes and was a divergent centre. H_16 was the most common haplotype of the wild accessions. H_2 was the haplotype representing the most pear germplasm resources (46 cultivars and two wild Ussurian Pear accessions), followed by haplotype H_5 (30 cultivars, two wild Ussurian Pear accessions and four sand pears in outgroups) representing the cultivars ‘Dangshan Suli’ and ‘Yali’, which harbour the largest and the second largest cultivation areas in China. More importantly, this study demonstrated, for the first time, the supposed evolution routes of Pyrus based on cpDNA divergence in the background of pear phylogeny in Northern China.  相似文献   

6.
In this study, we assessed geographic patterns of genetic variations in nuclear and chloroplast genomes of two related native oaks in Japan, Quercus aliena and Q. serrata, in order to facilitate development of genetic guidelines for transfer of planting stocks for each species. A total of 12 populations of Q. aliena and 44 populations of Q. serrata were analyzed in this study. Genotyping of nuclear microsatellites in Q. aliena was done with only nine populations (n = 212) due to limited numbers of individuals in two populations, while all 12 populations (n = 89) were used in sequencing chloroplast DNA (cpDNA). In Q. serrata, 43 populations (n = 1032) were genotyped by nuclear microsatellite markers, while cpDNA of 44 populations (n = 350) was sequenced. As anticipated, geographic patterns detected in the variations of Q. aliena’s nuclear genome and its chloroplast haplotype distribution clearly distinguished northern and southern groups of populations. However, those of Q. serrata were inconsistent. The geographic distribution of its chloroplast haplotypes tends to show the predicted differentiation between northern and southern lineages, but geographic signals in the genetic structure of its nuclear microsatellites are weak. Therefore, treating northern and southern regions of Japan as genetically distinct transferrable zones for planting stocks is highly warranted for Q. aliena. For Q. serrata, the strong NE-SW geographic structure of cpDNA should be considered.  相似文献   

7.
Saussurea involucrata (Asteraceae) is a medicinal and second-degree national priority endangered plant that is mainly distributed in the high latitude region of the western Tianshan Mountains. The population is fragmented and isolated, and extensive human impact merits a suitable and specific conservation strategy, which can be compiled based on the genetic diversity, population structure, and demographic history. Phylogeographic studies were conducted on a total of five natural populations and 150 individuals were sampled. Data from three cpDNA intergenic spacer regions (trnL-F, matK, and ndhF-rpl32) and nrDNA ITS sequences showed that twelve haplotypes in cpDNA and five haplotypes in nrDNA indicated high genetic diversity among populations sampled (H T?=?0.820 and 0.756) and within populations sampled (H S?=?0.792 and 0.721). Additionally, the high genetic diversity did not mirror genetic structure in either cpDNA (F ST?=?0.03153, G ST?>?N ST, p?<?0.05) or nrDNA (F ST?=?0.03666, meaningless G ST and N ST). Two groups (north and south) were determined for a SAMOVA analysis. Based on this analysis, the demographic history was conducted with a Bayesian Skyline Plot and Isolation with Migration analysis, which showed sustainable and stable extension without a marked bottleneck. Divergence time was indicated at c. 6.25 Mya (90%HPD: 15.30–0.22 Mya) in the Miocene, which is consistent with the formation of the Kelasu section of Tianshan. The southern populations in the Bayanbulak and Gonglu regions require additional attention and transplanting would be an effective way to restore rare cpDNA haplotypes, increase effective population size, and migration rate. Our results suggested that in situ conservation of S. involucrata in western Tianshan should be the main strategy for protection and recovery of the species.  相似文献   

8.
Hymenonema (Compositae, tribe Cichorieae) together with the genera Catananche, Gundelia, and Scolymus forms the subtribe Scolyminae. It is endemic to Greece and consists of two species, Hymenonema laconicum and Hymenonema graecum, which occur in the south Peloponnisos and central Aegean area, respectively. The present contribution aims at a phylogenetic reconstruction of evolutionary relationships among the 12 species of the subtribe, focusing on the temporal and spatial framework for its evolution. The phylogenetic relationships among the members of Scolyminae were inferred from molecular data based on the multi-copy region of the nrDNA internal transcribed spacers ITS1 and ITS2, two intergenic spacers of the cpDNA (trnL-trnF, rpl32-trnL), and one single-copy nuclear region (D10). The gene trees were reconstructed using Bayesian phylogenetic methods. All gene trees support the monophyly of Hymenonema and the sister-group relationship with the genus Scolymus. The further sister-group relationship of this group (HymenonemaScolymus) with Catananche is also supported by nrDNA and cpDNA analyses. Finally, a species tree (inferred in a Bayesian coalescent framework) was reconstructed and dates the divergence time between the two Hymenonema species to the Pleistocene (around 1.3 Ma ago). Maximum likelihood-based biogeographical reconstructions suggest a Miocene (pre-Messinian) differentiation of the subtribe on the northern Tethyan platform, followed by Miocene/Pliocene dispersal events to the western Mediterranean and North-African platforms and final, small-scale vicariance events within the genera in the Pleistocene.  相似文献   

9.
We here present a molecular phylogenetic analysis of cultivated Zanthoxylum species which have a long history of cultivation both for economic and for chemical values in China. Three cpDNA markers, including matK, rbcL, and trnL-F, were sequenced, with the goals of untangling phylogenetic relationships and inferring biogeographic origin and patterns of distribution among Zanthoxylum species. Based on three cpDNA markers, 19 haplotypes with 64 polymorphic sites in Zanthoxylum provenances were identified in our study. A low genetic differentiation (G ST ?=?0.271, N ST ?=?0.373) was observed within Zanthoxylum provenances. Based on phylogenetic tree and haplotype network, all 19 haplotypes were grouped into six clusters. Our results also supported the hypothesis that the so-called “Green Huajiao” belongs to the species Zanthoxylum armatum rather than Zanthoxylum schinifolium. The results also revealed that haplotypes of two cultivated species, Zanthoxylum bungeanum and Z. armatum, most probably diverged during the Late Miocene. Ancestral area reconstruction indicated that cultivated Zanthoxylum species experienced multiple long-distance dispersal events and several vicariance events and the ancestors of Zanthoxylum first colonized Yunnan and Guizhou provinces (D). Accordingly, the current disjunct distribution of Z. bungeanum and Z. armatum may represent long-distance dispersal of ancestors popularly named “Dahongpao” and “Qinghuajiao,” respectively. It is concluded that cpDNA markers may provide a new conceptual and practical opportunity to evaluate genetic diversity and to identify local cultivars of Zanthoxylum, making it a valuable source to include into potential breeding programs.  相似文献   

10.
Crossability relationships between Scots pine (Pinus sylvestris L.) and mountain dwarf pine (Pinus mugo Turra) was studied, using artificial pollination approach. Partial compatibility of the reciprocal crossings of these species was proved experimentally, validating the idea of a spontaneous formation of their hybrid swarms under natural conditions. The hybrids were validated using organellar DNA markers and nuclear DNA microsatellites. Based on the percentage of filled seeds, the interspecific crossings were less efficient than the intraspecific cross-pollinations of P. sylvestris and P. mugo individuals. Both species were found to intercross readily with individuals of their putative hybrid swarm, P. mugo exhibiting a higher hybridological affinity towards putatively hybrid individuals than P. sylvestris. Validation of the hybrids confirmed the paternal inheritance of chloroplast DNA (cpDNA) in the combination P. sylvestris × P. mugo only. Surprisingly, in the reciprocal crossing P. mugo × P. sylvestris, maternal inheritance of cpDNA was revealed. Obtained results offer a new insight into the direction and intensity of gene flow within the hybrid swarms of Scots pine and mountain dwarf pine.  相似文献   

11.
The opposite modes of chloroplast DNA (cpDNA) inheritance were found to operate in the reciprocal crossings of Scots pine (Pinus sylvestris L.) and mountain dwarf pine (Pinus mugo Turra). The crossings were found to be partially compatible. In P. sylvestris × P. mugo crossing, the paternal transmission of cpDNA to the offspring takes place corroborating the generally acknowledged concept of the paternal cpDNA inheritance in gymnosperms. On the contrary, in P. mugo × P. sylvestris crossing the seed progeny exhibited P. mugo haplotype of the mother tree deviating conspicuously from the above concept. In the open pollination offspring of the putatively hybrid individuals of the Scots and mountain dwarf pines, a biparental inheritance of cpDNA was revealed in mother tree with P. mugo haplotype indicating a loosened control of the maternal inheritance of cpDNA in the putative hybrids. Implications and impacts of this finding for further studies are discussed.  相似文献   

12.
Polyploidization has long been recognized as one of the most important driving forces of plant evolution. Aconitum subgenus Lycoctonum (Ranunculaceae) has a wide distribution range and well-known background of polyploidy, thereby providing a potentially valuable model to explore polyploid origin and evolutionary history. However, the phylogeny of subg. Lycoctonum has not yet been completely resolved. In the current study, 29 species including diploid, tetraploid and hexaploid species were sampled in subg. Lycoctonum. Using four cpDNA regions (ndhF-trnL, psbA-trnH, psbD-trnT and trnT-L) and two nrDNA regions (internal transcribed spacer, ITS, and external transcribed spacer, ETS), phylogenetic relationship was first reconstructed for the polyploid species within subg. Lycoctonum. In combination with nuclear diversification rate estimation, cpDNA haplotype network, ancestral area reconstruction as well as morphological and karyotypic evidence, potential origin and divergence time were further assessed among the polyploid species. Hybridization was inferred for A. angustius and A. finetianum was suggested to be the potential maternal progenitor, due to their close phylogenetic relationship, highly similar morphologies and overlapping distribution range. Local origin was inferred for tetraploids in the Hengduan Mountains (HDM) with eight groups of chromosomes of four homeologous, which diverged approximately 3.00 Ma in the same period of the orogeny of the HDM. The hexaploid A. apetalum was inferred to suffer from geographical isolation due to the formation of the Qinghai–Tibetan Plateau (QTP) and the HDM. Hybridization and heterogeneous habitats in the HDM were suggested to play an important role in the polyploidization in subg. Lycoctonum.  相似文献   

13.
Phragmites australis is a perennial grass that has invaded wetlands of the northeastern United States over the past century. The Hudson River Estuary and surrounding watersheds are no exception in that populations of P. australis have spread dramatically along its shores and tributaries in the past 40 years. Recent studies have shown that genetically variable populations of P. australis can spread by seed dispersal in addition to clonal mechanisms. It is important to characterize the genetic variation of Hudson River populations as part of a management strategy for this species to determine the mechanisms by which its spreads and colonizes new habitats, particularly those with frequent anthropogenic disturbances. The goals of this study were to quantify levels of genetic variation and structuring in Hudson River populations of P. australis using microsatellite DNA analysis. A total of 354 culms of P. australis were collected from nine locations ranging from Albany, New York to Staten Island, New York in the summers of 2004 (N = 174) and 2011 (N = 180). Microsatellite data from eight loci indicated that the Hudson River Estuary has some of the highest levels of genetic variation of all U. S. Atlantic Coast regions containing P. australis. Gene diversity (Hs) across all loci in the 2004 collection was 0.45 (±0.02) and that of the 2011 collection was 0.47 (±0.07). Patches within sample sites were rarely monoclonal and had multiple genetic phenotypes. Moran’s Identity tests indicated that individuals within a patch were closely related, whereas little genetic relatedness was evident among individuals from sample sites >1 km apart. Spatial structuring was also not evident in autospatial correlation and principle coordinate analyses. These findings suggest that genetic diversity is maintained within stands by sexual reproduction and that seeds are important in dispersal of P. australis across the Hudson River Estuary. Ample habitats are available for establishment of new Phragmites stands due to high levels of anthropogenic disturbance from populations living along the Estuary. Wildlife managers should focus on monitoring habitats that provide seedbed for Phragmites and promote land use practices that prevent soil disturbance and establishment of new stands.  相似文献   

14.
Subtropical East Asia harbours a large plant diversity that is often attributed to allopatric speciation in this topographically complex region characterized by a relative climate stability. Here, we use observations of Platycarya, a widespread subtropical Asian tree genus, to explore the consequences of past climate stability on species’ evolutionary history in subtropical China. This genus has a controversial taxonomy: while it is now prevailingly treated as monotypic, two species have been originally described, Platycarya strobilacea and P. longipes. Previous information from species distribution models, fossil pollen data and genetic data based on chloroplast DNA (cpDNA) were integrated with newly obtained genetic data from the two putative species. We used both cpDNA (psbA-trnH and trnL-F intergenic spacers, including a partial trnL gene sequence) and nuclear markers. The latter included sequences of the internal transcribed spacer region (ITS1–5.8S–ITS2) of the nuclear ribosomal DNA and random genomic single nucleotide polymorphisms. Using these nuclear genetic markers, we found interspecific genetic divergence fitting with the ‘two species’ scenario and geographically structured intraspecific variation. Using cpDNA markers, we also found geographically structured intraspecific variation. Despite deep inter- and intraspecific genetic divergence, we detected genetic admixture in southwest China. Overall, our findings of genetic divergence within Platycarya support the hypothesis of allopatric speciation. However, episodes of population interconnection were identified, at least in southwest China, suggesting that the genus has had a dynamic population history.  相似文献   

15.
We typify and clarify the nomenclature and identity of three species originally described in the fern genus Pellaea. We find Pellaea bongardiana to be illegitimate and recognize it as a synonym of Ormopteris riedelii (= P. riedelii). We also consider Pellaea brasiliensis to be a synonym of O. riedelii. The phylogenetic position of Pellaea flavescens, recently combined in Ormopteris (as O. flavescens), is discussed, and a key to all species of Ormopteris in Brazil is provided.  相似文献   

16.
The disjunct occurrence of Pedicularis exaltata in the White Carpathians (Czech Republic), isolated by more than 500 km from the nearest populations in the Eastern Carpathians, has been considered one of the mysteries of the Western Carpathian flora. We used molecular methods (AFLP, ITS and cpDNA sequencing) to reconstruct a possible scenario of the evolution of P. exaltata and its closely related congener P. hacquetii and to evaluate their differentiation. We paid particular attention to the origin of the isolated population in the White Carpathians. We also analysed the vegetation composition at the sampling sites to characterize the habitat preferences of the Pedicularis species and compare different sites. The pattern of molecular variability does not support a species boundary between P. exaltata and P. hacquetii. These assumed species should be merged into one bearing the name Pedicularis hacquetii following the priority rule, as also proposed by several early morphology-based taxonomic studies. The cpDNA variability pattern supports an evolutionary scenario involving a distribution centre (refugium) in the Eastern Carpathians from which the species expanded to the more westerly parts of its extant geographical range. Low population differentiation in AFLPs, high gene diversity and high DW index in isolated populations indicate that this expansion was contiguous rather than based on long-distance dispersal. Under such a scenario, the White Carpathian population is considered one of isolated relict populations scattered throughout the Carpathians and the East European Plain. A complete phylogeographic reconstruction of P. hacquetii s.l., however, requires ancient DNA analysis of herbarium specimens of nowadays extinct populations of the East European Plain. Extant habitats of P. hacquetii s.l. consist of species-rich dry-mesic to mesic (sub)montane grasslands and subalpine tall-herb growths, which may be relics of vegetation widespread in the late Glacial/early Holocene, when the contiguous expansion of the species possibly proceeded. The analysis of species with high fidelity to P. hacquetii s.l. throughout its range indicated that middle altitudes of south-western White Carpathians belong to the regions most suitable for the taxon within the Czech Republic and Slovakia. We found no support for the late introduction/long-distance dispersal scenarios and consider the relic survival scenario most parsimonious for the White Carpathians.  相似文献   

17.
The plasticity in clonal architecture may enable plants to effectively respond to environmental constraints and to enhance species ecological niche breadth but its role in plant tolerance to water flow is poorly documented. The present study was carried out to determine whether the clonal architecture varies with respect to water flow in 10 species of the genus Potamogeton colonizing habitats differing by flow conditions. For these 10 species, the traits describing clonal architecture were measured on individuals sampled in natural sites and plasticity in clonal architecture was examined in a common garden growth experiment. The clonal growth architecture did not vary significantly in the species which inhabit either standing (P. lucens, P. natans, and P. pusillus) or running water (P. amblyphyllus and P. berchtoldii). However, the species inhabiting both standing as well as running waters (P. crispus, P. nodosus, P. pectinatus, P. perfoliatus, and P. wrightii) showed considerable and significant variation in clonal growth architecture across these habitats. Transplantation experiment revealed that clonal architecture observed between the plants under different conditions is plastic and not due to genetic differentiation. The present study demonstrated that plasticity in the clonal architecture may enable these species to inhabit stressful conditions of flowing water.  相似文献   

18.
Glacial relicts have been regionally more common in glacial than in recent times. A rigorous assessment of which species are indeed glacial relicts is extremely difficult because direct evidence is untraceable or equivocal for many species. We aimed to identify species of the Western Carpathian flora (vascular plants, bryophytes and terrestrial lichens) that display apparent biogeographical and ecological symptoms, suggesting a wider regional or supra-regional distribution during glacial times, or at least before the middle-Holocene climate optimum. We worked with the premise that exemplary relict species should tolerate continental and/or arctic climates, should have large distribution ranges with disjunctions, being regionally rare and ecologically conservative nowadays, should be associated with habitats that occurred during glacial times (tundra, steppe, peatland, open coniferous forest) and should display a restriction of ecological niches in the study region. The assessed species were primarily those with boreo-continental or artcic-alpine distribution. We demonstrated a conspicuous gradient of glacial-relict symptoms, with Carex vaginata, Betula nana, Trichophorum pumilum, Nephroma arcticum, Saxifraga hirculus and Cladonia stellaris topping the ranking. Based on the arbitrary ranking, 289 taxa can be considered high-probability relicts. For only a minority of them, there are any phylogeographical and/or palaeoecological data available from the study area. Biogeographical and ecological symptoms of 144 taxa suggest that they retreated rapidly after the Last Glacial Maximum whereas other species probably retreated later. The first principal component of biogeographical symptoms sorted species from circumpolar arctic-alpine species of acidic peatlands and wet tundra to strongly continental species of steppe, steppe-tundra and mineral-rich fens. This differentiation may mirror the altitudinal zonation of glacial vegetation in the Western Carpathians.  相似文献   

19.
The Japanese Lepisorus thunbergianus complex contains diploid and tetraploid races of L. thunbergianus and a hexaploid species, L. mikawanus. Here, we performed molecular phylogenetic analysis on this complex to delimit species and to elucidate the evolutionary origins of tetraploid and hexaploid species. Chloroplast DNA (cpDNA) phylogeny supported the monophyly of the complex. Based on a single-copy nuclear gene (PgiC) tree, the tetraploid L. thunbergianus samples could be classified into two variants: an allotetraploid of hybrid origin between diploid L. thunbergianus and Japanese L. angustus and another allotetraploid of hybrid origin between diploid L. thunbergianus and an unknown diploid race of L. tosaensis. These variants can be recognized morphologically and distinguished from their parent species. Hence, here we described these allopolyploids as new species, L. nigripes and L. kuratae, respectively. The hexaploid species L. mikawanus has three types of PgiC alleles, each of which was derived from diploid L. thunbergianus, L. tosaensis, and Japanese L. angustus, while cpDNA shows that it is included in Japanese L. thunbergianus clade. Based on the cpDNA phylogeny and PgiC nucleotide sequences, we therefore concluded that L. mikawanus is an allohexaploid that originated through hybridization between tetraploid species, L. nigripes and an unknown ancestral diploid race of L. tosaensis.  相似文献   

20.
Rosa praelucens is a critically endangered decaploid alpine rose with an extremely narrow geographic distribution in Northwestern Yunnan, China. We sampled almost all the extant individuals (527 individuals in 31 natural locations and 56 individuals preserved in three local living collections) to assess the genetic variation and to probe the genetic connectivity among the individuals and populations based on three cpDNA intergenic spacers and six fluorescent amplified fragment length polymorphism (AFLP) markers. The morphological traits from seven populations were also measured. R. praelucens exhibited high levels of morphological variation, genetic diversity, and differentiation. The extant individuals were clustered into eight groups in neighbor-net networks, and subsequent Bayesian analysis assigned them into three larger gene pools, both in accordance with their morphological traits, especially flower color. The living collections embraced two private cpDNA haplotypes and included three out of the species’ total eight AFLP genotypes. Rhizome clonal growth, decaploid, and mixed breeding system may largely contribute to high genetic diversity and differentiation in R. praelucens. We concluded that the endangered status of R. praelucens may mainly be due to habitat fragmentation and loss and inherent reproductive difficulties, rather than low genetic diversity. The populations contributing higher cpDNA genetic diversity, representing more AFLP genotypes, and encompassing private cpDNA haplotypes should be given conservation priority by creating plant-micro reserves. The living collections should also be targeted for further ex situ conservation, population recovery, and reintroduction of R. praelucens plants.  相似文献   

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