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1.
本文对狭义小奥德蘑属Oudemansiella s. str.的概念做了修订,在修订后的属中,狭义干蘑属Xerula s. str.的物种不纳入其中。在狭义小奥德蘑属下,提出了一个包含4个组O. sect. Oudemansiella、Mucidula、Dactylosporina 和 Radicatae的新系统。小奥德蘑组sect. Oudemansiella包括热带至南温带的一些物种,如新热带小奥德蘑O. platensis、澳洲小奥德蘑O. australis、旧热带小奥德蘑O. canarii和宽褶小奥德蘑O. crassifolia,这些物种的菌盖表皮为粘栅栏型,由菌丝组成,但其中常夹杂有链状排列的膨大细胞。粘蘑组sect. Mucidula包含北半球温带至亚热带的一些物种,如粘小奥德蘑O. mucida、网褶小奥德蘑O. venosolamellata和近粘小奥德蘑O. submucida,其菌盖表皮为粘子实层-栅栏型,由近棒状的顶端膨大细胞组成。小奥德蘑组和粘蘑组的物种,在外形和小生境上有相似之处,其担子果皆生于地表外的腐木上,菌柄上有或无菌环。刺孢组sect. Dactylosporina包含中南美洲那些孢子表面有指状凸起的物种。长根组sect. Radicatae由长根小奥德蘑O. radicata及其近缘种为代表,是该属中最大的组,包括该属其他三组之外的所有种。北美的O. americana、欧洲的O. caussei 和东亚的O. hongoi曾被置于小奥德蘑属中的白毛组O. sect. Albotomentosae或干蘑属的亮毛组X. sect. Hyalosetae,在本系统中它们没有纳入小奥德蘑属,因为它们可能代表一个单独的属。本文还提出了1新等级、32个新组合和1个新名称。  相似文献   

2.
Despite the global importance of New Zealands invertebrates, relatively little is known about them and their relationships with plants and plant communities in native habitats. Invertebrate diversity was examined by beating randomly chosen shrubs of the species Olearia bullata (Asteraceae) and Coprosma propinqua(Rubiaceae). Invertebrate taxon richness was assessed initially using morphospecies, which were identified subsequently by expert taxonomists. Though the taxon richness of invertebrates recorded from O. bullata was not significantly higher than that on C. propinqua (except for the orders Diptera and Hemiptera), there was a clear indication that O. bullata hosts a higher diversity of invertebrates. Mean number of taxa per shrub for O. bullata was higher in all cases (except Coleoptera), and so was the maximum number of taxa per shrub. Overall, O. bullata yielded 115 invertebrate taxa compared with 93 for C. propinqua. Moreover, 50 invertebrate taxa were restricted to O. bullata compared with 28 for C. propinqua. Since at least ten species of Oleariaare threatened or uncommon, this could be cause for concern with respect to the maintenance of invertebrate diversity. Therefore, sites where Oleariaspecies are still present are likely to be of significance for invertebrate conservation.  相似文献   

3.
Carex sect. Spirostachyae comprises 25 species displaying the centre of diversity in Eurasia. Phylogenetic analysis of the ITS nrDNA region of 20 species of sect. Spirostachyae, six species of sect. Ceratocystis, five species of sect. Elatae, and eight outgroup species reveals that neither sect. Spirostachyae nor sect. Elatae is monophyletic. With the exclusion of Carex cretica, the 19 species of sect. Spirostachyae studied form a clade with the five species of tropical-subtropical sect. Elatae. Taxonomy of the core Spirostachyae is not only mostly in agreement with our phylogenetic hypothesis, but also with ecological and new cytogenetic results. Two main groups with different chromosome numbers and edaphic preferences are identified in the core Spirostachyae. One includes primarily acidophilous species with high chromosome numbers (2n=(64)68–84), whereas the other one includes mainly basophilous species with lower chromosome numbers (2n=60–74(75)). Chromosome-number variation is extremely different in the core Spirostachyae, showing great stability in some widespread species (e.g. Carex extensa) but an active chromosome evolution – faster chromosomal rearrangements, fusion and fission events than ITS nucleotide substitutions – in more restricted species (e.g. Carex troodi). Biogeography of the two amphiatlantic pairs of species reveals two independent colonizations of South America from the European continent. The geographical barrier of the Strait of Gibraltar has played different roles in the course of evolution of this section, acting as an effective barrier to gene flow in one case (Carex helodes) but as a limited barrier or recent separation in two others (Carex distans, Carex punctata).  相似文献   

4.
Phylogenetic relationships are inferred from nuclear ribosomal internal transcribed spacer sequences for species belonging to Sophora sect. Edwardsia from South America, New Zealand, Lord Howe Island, Hawai'i, La Réunion, Easter Island, and Raivavae Island (French Polynesia). Results support the monophyly of sect. Edwardsia , but relationships among the species from this section are poorly resolved due to most species having identical sequences. The origin of Sophora sect. Edwardsia is discussed, as competing hypotheses have proposed the group originated in South America from a North American ancestor, or in the north-west Pacific. We suggest sect. Edwardsia may have arisen in the north-west Pacific from a Eurasian ancestor.  © The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 435–441.  相似文献   

5.
All known populations of the nationally critical tree daisy, Olearia gardneri, were studied using AFLP markers. With fewer than 160 individual plants, Olearia gardneri is the third-rarest tree in New Zealand and a good model with which to study evolutionary process in fragmented endangered plants. Genetic variation was at similar levels to other long-lived tree species in New Zealand and also as in other studies to date had poor correspondence between genetic and geographic distance. Genetic factors such as inbreeding depression and the loss of genetic diversity might lower fitness and have substantial consequences for evolution and survival of rare threatened plants. Due to the decline of this species in recent times it is imperative that conservation measures are undertaken, including revegetation. Despite considerable emphasis on “eco-sourcing” in plant recovery programmes there is strong evidence that this may not be the best strategy for O. gardneri due to breeding system and population size considerations.  相似文献   

6.
Quantitative information on large scale spatial patterns of biodiversity remains poor, especially for pelagic systems. In this paper the regional diversity of procellariiforms is mapped worldwide at the species level. These seabirds do not display a conventional latitudinal gradient of decreasing species richness towards high latitudes, but rather are most speciose between 37° and 59°S in all ocean basins. Based on data for foraging ranges, areas with the highest species richness and the most species with smaller range sizes are all found in the vicinity of New Zealand and its sub-Antarctic islands. In contrast, data for breeding ranges show islands in the southern Indian and Atlantic oceans to have the highest number of breeding species, while these islands and New Zealand have the most species with smaller range sizes. No northern hemisphere regions are amongst the top ten grid cells for foraging and breeding species richness, although Hawaii has the highest species richness of procellariilforms north of the equator. Northern Baja California. Madeira, the Canary islands, and the west coast of South America are all important sites of narrow endemism in the northern hemisphere. High species richness and narrow endemism coincide with areas of significant longline fishing activity in the southern hemisphere. Near-minimum sets based on one and three representations demonstrate that if all procellariiform species are to be retained, large areas of the ocean and almost all breeding sites require conservation.  相似文献   

7.
8.
The life cycles of many African species of tiger beetles (Insecta: Coleoptera: Cicindelidae) exhibit pronounced seasonality, with adult emergence and reproductive activity closely associated with seasonal rains. Anecdotal reports have suggested that adults of certain riverine tiger beetle species may be active during the dry season near perennial water sources. To test this hypothesis, fifteen sites along three perennial rivers in Kruger National Park, South Africa, were surveyed for tiger beetles in early September, 2006. Thirteen sites yielded adult beetles, with six species represented [ Chaetodera regalis (Dejean), Cylindera disjuncta (Dejean), Habrodera nilotica (Dejean), Lophyra neglecta intermediola (Horn), Lophyridia fimbriata imperatrix (Srnka), and Myriochile melancholica (Fabricius)]. Microhabitat associations of adults of all six species and ovipositional/larval substrates of five of the six species are reported, along with observations on predatory and reproductive behaviours and the possible presence of an anti-predator chemical defence in C. regalis and L. fimbriata imperatrix .  相似文献   

9.
A new species of Nageia, Nageia maomingensis sp. nov., is described from the Late Eocene of Maoming Basin, Guangdong Province, South China. According to its cuticular characteristics, the present fossil species is assigned to N. sect. Dammaroideae, showing the most resemblance to the extant species N. motleyi (Parl.) de Laub. At present, this section is mainly distributed in the Pacific islands region from South Asia to New Guinea. The discovery of N. maomingensis demonstrates that plants of this section inhabited South China at least by the Eocene. The distribution and living habitat of extant N. sect. Dammaroideae imply that South China was warmer during the Late Eocene than today, and may represent one of the centers for early diversification of Nageia and its section Dammaroideae during the Eocene. In addition, we postulate that plants of sect. Dammaroideae migrated southward in response to climate cooling after the Eocene.  相似文献   

10.
The success of restoration plantings in restoring indigenous forest vascular plant and ground invertebrate biodiversity was assessed on previously grass-covered sites in the eastern South Island, New Zealand. The composition and structure of grassland, three different aged restoration plantings (12, 30, and 35 years old), a naturally regenerating forest (100 years old), and a remnant of the original old-growth forest of the area were measured. The restoration plantings are dominated by the native tree Olearia paniculata, which is not indigenous to the study area. Despite this, indigenous forest invertebrate and plant species are present in all three restoration sites and with increasing age the restoration sites become compositionally more similar to the naturally regenerating and mature forest sites. In particular the regenerating vegetation of the restoration sites is very similar floristically to the regenerating vegetation of the naturally regenerating and mature forest sites, despite marked differences in the current canopy vegetation reflecting the presence of the planted O. paniculata. The presence of regeneration in all three restoration sites indicates that the functional processes that initiate regeneration, such as dispersal, are present. The majority of regenerating tree species (71%) are bird dispersed and it is clear that birds play an important role in the recolonization of plant species at these sites despite the absence of edible fruit attractive to frugivorous birds on O. paniculata, a wind-dispersed species. The strong correlations between plant and invertebrate community composition and study-site age (r = 0.80, ?0.24, ?0.68 for plants, beetles, and spiders, respectively) suggest that the restoration site plant and invertebrate communities are undergoing change in the direction of the naturally regenerating and mature forest communities. Without restoration, colonization of grassland by forest plants is very slow in the study area and the restoration plantings studied here have been successful because they have considerably accelerated the return to forest at these sites.  相似文献   

11.
Using an exhaustive data compilation, Iberian vascular plant species richness in 50 times 50 UTM grid cells was regressed against 24 explanatory variables (spatial, geographical, topographical, geological, climatic, land use and environmental diversity variables) using Generalized Linear Models and partial regression analysis in order to ascertain the relative contribution of primary, heterogeneous and spatially structured variables. The species richness variation accounted for by these variables is reasonably high (65% of total deviance). Little less than half of this variation is accounted for spatially structured variables. A purely spatial component of variation is hardly significant. The most significant variables are those related to altitude, and particularly maximum altitude, whose cubic response reflects the occurrence of the maximum number of species at the highest altitudes. This result highlighted the importance of Iberian mountains as hotspots of diversity and the relevance of large and small scale historical factors in contemporary plant distribution patterns. Climatic or energy-related variables contributed little, whereas geological (calcareous and acid rocks) and, to a lesser extent, environmental heterogeneity variables (land use diversity and altitude range) seem to be more important.  相似文献   

12.
Japan is considered a global hot spot of biodiversity. With regard to species diversity, insects are no exception. To date, more than 32,000 insect species have been identified in Japan, while around 100,000 species of insects are estimated to inhabit this country. In this paper, we outline background factors having contributed to diversification of Japanese insects. Of course, the high degree of Japanese insect diversity is the result of many complex factors. In addition to the humid Asian monsoon climate and the extensive latitudinal gradient of habitats, the extremely complex geological history has contributed as an important factor to generate and maintain the high species diversity and endemism. In particular, the independent origins of northeastern and southwestern Japan from the Eurasian continent have greatly contributed to the diverse composition of Japanese insect fauna. To highlight the importance of this process, we introduce some case studies and previously published papers focusing on several insect groups with low dispersal ability. Those cases indicate that the geological history of Japan has played an important role in the differentiation of Japanese insect species. Besides such geological factors, climatic and ecological factors in combination have contributed to the formation of Japanese insect fauna in complicated ways and produced its particularly high degree of biodiversity. The knowledge compiled here will provide useful information for future studies aiming to understand more deeply the processes of speciation and faunal formation of Japanese insects.  相似文献   

13.
Summary This paper reports the number of plant species on circumscribed fynbos areas (gamma diversity), ranging in size from 0.27 km2 (a site with 364 species) to 471 km2 (2351 species). The composition of the floras of four of these sites was analysed to measure delta diversity, the change in flora from one site to the next. Maximum gamma diversity values fitted a species-area curve log S=2.69+0.25 log A. Gamma diversity is apparently higher than in any of the world's biogeographic zones except perhaps the tropical rain forest, and in other South African sites of areas around 1.0 km2, which have about as many species. High delta diversities are reflected in differences between fynbos floras of 50 to 70 %, in spite of relative proximity; this degree of diversity is apparently unmatched anywhere. The results support the conventional view that fynbos plant diversity is partly a consequence of the peculiar geography of the zone, and of palaeo-climatic change, which have favoured geographic speciation.This paper would not have been possible without the conscientious work of staff at Jonkershoek, especially that of R.A. Haynes and E.F. Kruger. The information on the floras of each area studied here has been built up through decades of field work by various collectors. Identifications of the many difficult taxa are due to taxonomists at the National Herbarium, at the Compton Herbarium, Kirstenbosch and at the Bolus Herbarium, University of Cape Town. M. F. Thompson and E. E. Esterhuysen contributed materially in this respect.Paper presented at the Annual Congress of the South African Association of Botanists, Stellenbosch, January 1979.This work is based partly on the results of the conservation research programme of the South African Department of Forestry and the Botanical Research Institute's programme on fynbos phytosociology, and is published with permission of our respective heads of Departments.  相似文献   

14.
We compiled herbarium specimen data to provide an improved characterization of geographic patterns of diversity using indices of species diversity and floristic similarity based on rarefaction principles. A dataset of 3650 georeferenced plant specimens belonging to Orchidaceae and Rubiaceae endemic to Atlantic Central Africa was assembled to assess species composition per half‐degree or one‐degree grid cells. Local diversity was measured by the expected number of species (Sk) per grid cell found in subsamples of increasing size and compared with raw species richness (SR). A nearly unbiased estimator of the effective number of species per grid cell was also used, allowing quantification of ratios of ‘true diversity’ between grid cells. Species turnover was measured using a presence/absence‐based similarity index (Sørensen) and an abundance‐based index that corrects for sampling bias (NNESS). Our results confirm that the coastal region of Cameroon is more diverse in endemic species than those more inland. The southern part of this coastal forest is, however, as diverse as the more intensively inventoried northern part, and should also be recognized as an important center of endemism. A strong congruence between Sørensen and NNESS similarity matrices lead to similar delimitations of floristic units. Hence, heterogeneous sampling seems to confer more bias when measuring patterns of local diversity using raw species richness than species turnover using Sørensen index. Overall, we argue that subsampling methods represent a useful way to assess diversity gradients using herbarium specimens while correcting for heterogeneous sampling effort. Abstract in French is available in the online version of this article.  相似文献   

15.
16.
Abstract  Caliothrips fasciatus is native to the USA and western Mexico and overwintering adults are regular contaminants in the 'navel' of navel oranges exported from California, USA to Australia, New Zealand and elsewhere. Due to the long history of regular interceptions of C. fasciatus in Australia, a survey for this thrips was undertaken around airports, seaports, public recreational parks and major agricultural areas in the states of Queensland, New South Wales, Victoria, South Australia and Western Australia to determine whether C. fasciatus has successfully invaded Australia. Host plants that are known to support populations of C. fasciatus , such as various annual and perennial agricultural crops, urban ornamentals and weeds along with native Australian flora, were sampled for this thrips. A total of 4675 thrips specimens encompassing at least 76 species from a minimum of 47 genera, and three families were collected from at least 159 plant species in 67 families. Caliothrips striatopterus was collected in Queensland, but the target species, C. fasciatus , was not found anywhere. An undescribed genus of Thripidae, Panchaetothripinae, was collected from ornamental Grevillea (var. Robyn Gordon) at Perth (Western Australia) Domestic Airport, and is considered to be a native Australian species. This survey has provided valuable information on the background diversity of thrips species associated with various native and exotic plant species around major ports of entry and exit for four of five states in Australia. We suggest that the major reason C. fasciatus has not established in Australia is due to high adult mortality in navels that are kept at low storage temperatures (2.78°C) during an 18- to 24-day transit period from California to Australia.  相似文献   

17.
Sect. Calceolaria (= Aposecos) of Calceolaria (Scrophulariaceae) in NW South America is revised, and the other species of the section are briefly discussed. The section comprises annual herbs with somewhat succulent stems and leaf–blades that are usually pinnately dissected (pinnatifid). Four species are recognized in the investigated area, viz. C. mexicana, C. tenuis, C. tripartita , and C. chelidonioides , and their chromosome numbers are reported (2n = 32, 60, 64, and 60 respectively). The basic number in sect. Calceolaria is x = 8. Two new combinations are made, viz. C. mexicana ssp. prostrata (Kränzlin) Molau and C. mexicana ssp. perijensis (Pennell) Molau. The species of sect. Calceolaria are intersterile and facultatively autogamous, and each species comprises numerous pure lines, some of which may be morphologically discernible.
In the appendices, chromosome numbers are listed and the occurrence of elaiophores in all NW South American species of Calceolaria is indicated. The chromosome numbers of C. crenata ssp. australis, C. adenanthera, C. gossypina, C. semiconnata, C. stricta, C. sericea , and C. comosa (all 2n = 36) have not previously been reported. A revised key to the sections of Calceolaria in NW South America is also provided.  相似文献   

18.
Abstract.  A total of 246 marine bryozoan species was recorded within an area of the south-west Atlantic between 35° and 56°S, and between the coast of Argentina and 50°W. The distribution pattern of benthic stations surveyed during the most important cruises in the area shows that the sampling effort has been biased towards southern shelf areas off Santa Cruz and Tierra del Fuego, as well as around the Malvinas (Falkland) islands. The littoral zone, Patagonian gulfs and the continental shelf off Chubut, Río Negro and Buenos Aires state received less attention, and should be surveyed more intensively in the future. Only 2% of the species can be regarded as non-indigenous, all of them inhabiting biofouling communities in harbour environments. With the exception of some thoroughly surveyed localities, the number of species recorded for different areas of the coast, shelf and slope is estimated to be just a small fraction of the actual number of species present. A distinct diversity gradient was found, with species-rich stations located only in the southern shelf. Highest diversity occurred in shelf areas dominated by coarse sediments, and along a high-productivity shelf-break front. A remarkable decrease in species richness was found in inner and middle shelf areas off Chubut, Río Negro and Buenos Aires state. This pattern may be related to the Pacific origin of the Magellanic fauna, since the diversity of bryozoans is higher in the Pacific than in the Atlantic Ocean. The trend of species richness is, however, overemphasized by the fact that the least diverse faunistic assemblage occurs in areas where surveys have been relatively less frequent. An up-to-date checklist of species recorded for the study area is included.  相似文献   

19.
Plant species coexistence in cliff habitats   总被引:1,自引:0,他引:1  
An ecological analysis of the ledge and crevice vegetation of cliffs in north-east Ireland was carried out using a sampling programme based on multivariate land classification. The composition of the vegetation was shown to be determined primarily by distance from the sea, elevation and rock type. The chemical composition and physical structure of the cliffs, together with environmental gradients associated with aspect, elevation and nearness to the sea provide a wide range of habitats in which plants coexist. Certain types of cliff vegetation contained associations of species with a contrasting ecology, such as arctic–montane, maritime, woodland, calcicole and calcifuge plants. The positions of these species in ordination space were found to be unique but overlapping. A model is described to account for these observations. It proposes that species dominance in cliff habitats is prevented by factors such as physical disturbance and that plants are able to coexist in cliff habitats which meet their common environmental tolerances and preferences. The model predicts that cliff habitats with the greatest diversity of species are likely to be subject to less extremes of environmental variability. These habitats include inland sites with nutrient enrichment by sea spray, north-facing sites, seepage sites, base-rich sites, low elevation sites and sites with a heterogeneous physical structure.  相似文献   

20.
Fourteen native species of Linum are recognized in southern Africa, all of which belong to sect. Linopsis. Four are commonly accepted species; four were described more than a century ago but have not been recognized in recent treatments; six are newly described. Thirteen species are endemic; one ranges as far north as Angola and Tanzania. Among the new species two are heterostylous, the first described for the genus from this region.
The section Linopsis ranges broadly from the Mediterranean region to southern Africa and to both North and South America. The occurrence in the Mediterranean region of species exhibiting such features as heterostyly and chromosome numbers of 2n = 18 or 20, the only diploids known in the section, seems to indicate that in that region are to be found the most primitive species of the section. The close similarity between species of southern Africa and a number of South American and North American species appears to place the southern African species in an intermediate evolutionary position with respect to the Old and New World species of the section.  相似文献   

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