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The monotypic genus Eremotropa Andres (Monotropoideae, Ericaceae) is endemic to central Yunnan. It was first described by Andres in 1953, and was subsequently treated as a synonym of Monotropastrum Andres (1987); however, the phylogenetic placement of this genus has not, to date, been investigated. In this study, phylogenetic analyses were undertaken using DNA sequences from the nuclear internal transcribed spacer from all species of Monotropoideae available in GenBank. Comparative morphological studies on Eremotropa, Monotropastrum, and Monotropa L. were also carried out. The molecular phylogenetic evidence suggests that Eremotropa is sister to a clade formed by Monotropa and the remaining species of Monotropastrum, thus rendering Monotropastrum not monophyletic. Morphologically, Eremotropa differs from Monotropastrum in plant color, inflorescence type, length of the style, and size of the baccate fruit. Consequently, molecular and morphological evidence supports the resurrection of Eremotropa, which contains only one species, E. sciaphila Andres, as distinct from Monotropastrum. 相似文献
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Background and Aims
Peripheral populations of plant species are often characterized by low levels of genetic diversity as a result of genetic drift, restricted gene flow, inbreeding and asexual reproduction. These effects can be exacerbated where range-edge populations are fragmented. The main aim of the present study was to assess the levels of genetic diversity in remnant populations of Hypopitys monotropa (syn. Monotropa hypopitys; yellow bird''s nest) at the edge of the species'' European range in Northern Ireland, since these remnant populations are small and highly fragmented.Methods
Every plant found through surveys of 21 extant populations was genotyped for eight microsatellite loci to estimate levels and patterns of genetic diversity and clonality.Key Results
Levels of genetic diversity were relatively high in the populations studied, and the incidence of clonal reproduction was generally low, with a mean of only 14·45 % of clonal individuals. Clones were small and highly spatially structured. Levels of inbreeding, however, were high.Conclusions
The observed low levels of clonality suggest that the majority of genets in the populations of H. monotropa studied are fertile and that reproduction is predominantly sexual. As the species is highly self-compatible, it is likely that the high levels of inbreeding observed in the populations in the present study are the result of self-pollination, particularly given the small numbers of individuals in most of the patches. Given this extent of inbreeding, further genetic monitoring would be advisable to ensure that genetic diversity is maintained. 相似文献3.
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《Fungal Ecology》2016
Few studies of tripartite mycoheterotrophic systems have examined ecological specificity across broad geographic ranges or addressed autotrophic host specificity. Pterospora andromedea was selected as an ideal candidate to examine ecological specificity of a mycoheterotrophic system as it is widely distributed, has been shown to have high levels of symbiont specificity with Rhizopogon subgenus Amylopogon, and is found with several autotrophic hosts. Pairs of P. andromedea + Rhizopogon spp. samples were co-collected across North America and were sequenced using trnL and ITS, respectively. Bayesian phylogenetic reconstructions between the co-collected taxa were used to examine ecological specificity, and for subsequent tests for autotroph specificity. P. andromedea lineages exhibited both high specificity and relaxed specificity for fungal symbionts and autotrophic hosts across the geographic landscape under allopatric and sympatric conditions. This strong evidence for geographic mosaics of specificity in mycoheterotrophic systems is an important future consideration in determining the evolutionary ecology of mycoheterotrophs. 相似文献
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Hideki Takahashi 《Journal of plant research》1987,100(4):385-405
A palynological survey, including LM, SEM and TEM is presented for eight genera, nine species and 76 samples of the Monotropoideae
which is composed of 10 genera and 13 species. On the basis of the aperture number and shape, the following six pollen types
are recognized: 1) 3-colp(oroid) ate—Allotropa, 2) 2-colpor(oid)ate—Monotropsis andHemitomes, 3) 4-colpor(oid)ate—Pterospora, Sarcodes andPleuricospora, 4) 2- and 3-colpor(oid)ate—Monotropa hypopitys, 5) 3-colporate and-porate —Monotropa uniflora, 6) 3- to 4- porate—Monotropastrum humile. Relationships among taxa within the Monotropoideae are illustrated on the palynological characters including the aperture
type, exine sculpture and structure. Both pollen grains with two and four apertures have evolved independently from pollen
grains with three apertures, according to the infraspecific variation of aperture numbers and the usual occurrence of three-aperturate
pollen grains in the Ericaceae. 3-colp(oroid)ate pollen ofAllotropa is the most primitive and occupies an isolated position in the subfamily, on the other hand 3- to 4-porate pollen ofMonotropastrum humile is most advanced in the subfamily, probably even in the Ericaceae. A reduced sexine inMonotropastrum humile appears to be a specialized pollen character. Infraspecific geographical difference in palynological characters is revealed
in two species ofMonotropa for the first time.M. hypopitys is basically characterized by pollen grains with two apertures in the New World vs. three apertures in the Old World.M. uniflora is basically characterized by 3-porate pollen in the New World vs. 3-colporate in the Old World. In both species pollen grains
with more primitive characters usually occur in the Old World. 相似文献
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