首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
A revised infrageneric classification of Nothofagus (Fagaceae)   总被引:1,自引:0,他引:1  
HILL, R. S. & READ, J., 1991. A revised infrageneric classification of Nothofagus (Fagaceae). An examination of cupule morphology, leaf architecture and cuticular morphology of Nothofagus species demonstrates that the existing infrageneric classifications are inaccurate. Four subgenera are proposed, based on these characteristics as well as other morphological information. This analysis indicates that the traditional pollen groupings of Nothofagus closely reflect the infrageneric taxonomy. It is hypothesized that deciduousness is primitive in Nothofagus , and the evergreen habit has arisen more than once, and therefore the deciduous or evergreen habit is invalid as a primary taxonomic character.  相似文献   

2.
The invertebrates directly associated with the southern hemisphere tree genus Nothofagus are described and discussed in terms of their organization into guilds and attributes of their hostplants. Using literature records, comparisons are made of the guild composition between host species and provenances; a full invertebrate-hostplant list is appended. Sap-sucking Homoptera are particularly diverse and usually host-species specific whereas defoliating insects seem less prevalent and less specific. Few seed-eating insects are reported. Some provenances and hostplants exhibit local radiations in certain taxa, such as Eriococcidae in New Zealand, Notophorina psyllids in South America and scolytid beetles on N. dombeyi. Environmental stresses such as drought, disturbance and landslips, can induce outbreaks of certain scale insects and borers, affecting the dynamics of the forest. Generally, however, the influence of invertebrates appears benign, but occasional large-scale defoliation is observed on N. solandri var. cliffortioides, N. moorei, N. antarctica and N. pumilio. Collectively this fauna has two elements: a geographically recurrent Gondwanic element, usually monophagous, and a provenance-specific element (often polyphagous) locally recruited following vicariance of the host genus. The fauna of Nothofagus can be in stark contrast to that of adjacent forest types. In Australia, the insect profile of Nothofagus has more in common with fagaceous trees on other continents than the more recent Eucalyptus forests which surround it. There is almost no evidence of fauna transfer from Nothofagus to Eucalyptus. Relative to New Zealand, the Australian Nothofagus fauna is depauperate and may reflect truncation in Pleistocene glaciations. Typically low insect populations on these trees may partly explain the limited range of insectivorous birds and spiders observed in Australia. Much more data on the phytophagous insects of this biome is needed for comparative purposes. The fauna of the montane tropical subgenus Brassospora pollen group is almost unknown but could hold the key to the origin of fagaceous insect communities more generally. The conservation value of remaining Nothofagus forests is enhanced by recognition of their co-adapted fauna, some of which are arranged in stable functional groups likely to give valuable insight into invertebrate-hostplant interactions originating in the Cretaceous. Elucidation of its role in the processes of these unique forests remains a fertile field for endeavour in the future.  相似文献   

3.
4.
The genus Rhanteriopsis Rauschert, belonging to the f/iula–group of the Asteraceae–Inuleae, is monographed in a study based on herbarium material. Rhanteriopsis has a disjunct distribution with a westerly occurrence in Lebanon and Syria and an easterly distribution in Iran and Iraq along the Iranian border. Eour species are recognized: R. hombvcina (Boiss. & Hausskn.) Rauschert, R. lanuginosa (DC.) Rauschert, R. microcephala (Boiss.) Rauschert and R. puberula (Boiss. & Hausskn.) Rauschert. The morphology and phytogeography of the genus are discussed, a cladogram is proposed and a taxonomic treatment is provided.  相似文献   

5.
The North African genus Perralderia (Asteraceae-Inuleae-Inulinae) is revised. Three species and two subspecies are recognized. The systematic position, phylogeny and biogeography of the genus are also discussed.  相似文献   

6.
Gross anatomical characters of all 18 species of Littorina are used to construct a phylogenetic hypothesis for the genus, by the method of cladistic analysis. The resulting cladogram suggests that of the four subgenera of Littorina, one (Littorina) is paraphyletic. It is uncertain whether the genus Mainwaringia should be included in Littorina. It is shown that the non-planktotrophic Littorina species in the northern Atlantic comprise a monophyletic group, with the sister-species L. kurila and/or L. subrotundata in the northern Pacific. Invasion of the Atlantic by a minimum of two Pacific species, across the Arctic migration route established during the late Cenozoic, is sufficient to account for the modern distribution of the subgenera Littorina and Neritrema. The importance of the cladogram as a basis for hypotheses of adaptation is illustrated by a discussion of spawn and development in Littorina.  相似文献   

7.
WIKLUND, A., 1986. The genus Rhanterium (Aateraceae: Inuleae) . This revision of the genus Rhanterium Desf. of the /nu/a-group in the Asteraceae: Inuleae, subtribe Inulinae, is based on studies of herbarium material. The genus is distributed over western North Africa, the Arabian peninsula, Iraq and Iran. Three species are recognized: R. adpressum Coss. & Durieu, R. epapposum Oliver and R. suaveolens Desf. A fourth previously accepted species, R. intermedium Coss. & Durieu ex Pomel, is here considered to be composed of hybrids between R. adpressum and R. suaveolens. A laxonomical recognition of these hybrids is not found to be justified. The morphology, phylogeny and phytogeography of the species are discussed and a cladogram of the genus is proposed.  相似文献   

8.
Abstract: The genus Nothofagus in New Zealand and Australia exhibits strong mast seeding (i.e. highly variable seed crops between years). Seed crop variation is synchronized within and between species over large spatial scales, and results in greatly increased wind pollination efficiency which could provide a selective benefit favouring the maintenance of mast seeding. However, the null hypothesis (that plants simply match their reproductive effort to the variable resources available each year) has not been tested in Nothofagus. Here we use a 33‐year dataset on seedfall and wood ring increments for 19 individual Nothofagus truncata trees at Orongorongo, New Zealand, to test for the presence of switching (exaggeration of seedfall variability by diverting resources into, then out of, reproduction). A generalized least squares model explained 40.7% of the variance in standardized ring widths, using six weather variables (absolute minimum temperatures in March (lag 0) April (lag 0 and lag 1), May (lag 0) and rainfall in November and February (lag 0) ) and seedfall. Seedfall had a negative relationship with the current year's ring widths even after controlling for all significant weather variables. This shows that switching is occurring in N. truncata within individuals among years, and therefore that masting in this species is the result of selective forces such as increased wind pollination efficiency. As this result has been demonstrated for very few masting species, we call for this test to be applied more widely.  相似文献   

9.
BPA(broks parsimony analysis)是历史生物地理学研究的重要分析方法之一,包括初级BPA和二级BPA。前者主要用于寻找共同格局,后者是对网状进化格局的解释。本文详细介绍了二级BPA的分析方法,并就BPA与其它历史生物地理学/支序学派的研究方法进行了区别。  相似文献   

10.
The suggestion that Trigonobalanus excelsa reached Colombia by migration from south-east Asia via the Bering land-bridge is criticized. The distribution of Trigonobalanus can be more simply explained by the disruption and drift of the former Pacific continent and the peninsula of West Gondwanaland. All but the New Guinea species of Nothofagus remain on the drifted fragments of the Gondwana peninsula, the original home of the family. Drift accounts for the present disjunct distribution of related Nothofagus species in the Southern hemisphere, but topoclines in characters of the fructifications and of the leaves linking New Zealand, New Caledonia and New Guinea indicate the overland migration route into the Pacific continent. Diversification of the family occurred in Pacifica before that continent was disrupted in the late Jurassic. With the formation of Eurasia, a topocline in leaf characters developed in Fagus along the migration route from China to Western Europe. Absence of topoclines involving the Bering land-bridge indicate that this bridge played no significant part in the dispersal of the Fagaceae. Shedding of the fruits of Glossopteris before the development of an embryo draws attention to the primitive character of delay in fertilization found in Nothofagus.  相似文献   

11.
The distributional patterns of the seven species of Rhizoprionodon were analysed using the panbiogeographical method of track analysis. The individual tracks of Rhizoprionodon suggest that the genus is mainly an Indian–Atlantic Ocean group. Five generalized tracks were found: (1) Caribbean, defined by R. porosus and R. terraenovae; (2) eastern coast of South America, defined by R. porosus and R. lalandei; (3) Indian Ocean, defined by R. acutus and R. oligolinx; (4) north‐western Australia, defined by R. acutus, R. oligolinx and R. taylori; (5) north‐north‐eastern Australia, defined by R. acutus and R. taylori. Only R. longurio was not included in any generalized track, and its distribution is restricted to the eastern Pacific Ocean. Two biogeographical nodes were found at the intersection of the generalized tracks 1 and 2 (Caribbean Sea) and generalized tracks 4 and 5 (north Australia). The generalized tracks overlap with those found in several unrelated marine taxa. Overall, the generalized tracks are associated with warm currents. The biogeographical nodes found (Caribbean and Australian) are coincident with the global distribution of mangroves.  相似文献   

12.
Abstract Although positive interactions among plants are believed to be common in primary succession, they have rarely been demonstrated on glacial moraines. In Patagonia, the prostrate shrub Empetrum rubrum is dominant in early succession in recently deglaciated valleys, eventually being replaced by the small tree Nothofagus antarctica. This study experimentally evaluates the effects of E. rubrum shrubs on density, biomass, growth and survival of N. antarctica seedlings. The initial density of the seedlings was significantly higher under the canopy of Empetrum than in open areas. A removal experiment was performed to evaluate the influence of Empetrum on survival and growth of seedlings that germinated naturally beneath the canopy of this species. The shrub cover was removed from half of a sample of randomly selected seedlings, and left intact above the remainder. One year later, seedlings with an intact cover of E. rubrum showed significantly higher survival, growth and leaf number than seedlings which had been exposed. The results suggest that the presence of E. rubrum facilitates the establishment of N. antarctica in post‐glacial succession, mainly as a result of more favourable microclimatic conditions under the shrub canopy.  相似文献   

13.
The karyotypes of ten species of Holcoglossum (Orchidaceae), a highly endangered and diversified genus from China, were investigated to study the infrageneric relationships, biogeography, and speciation patterns in the Hengduan Mountains. The karyotype formulae of the studied species are as follows: 2 n  = 38 = 20m + 18sm in H. subulifolium , 2 n  = 38 = 22m + 16sm in H. amesianum , 2 n  = 38 = 26m + 12sm (6 SAT) in H. lingulatum , 2 n  = 38 = 26m + 12sm in H. wangii , 2 n  = 38 = 10m + 28sm in H. kimballianum , 2 n  = 38 = 14m + 22sm + 2st in H. flavescens , 2 n  = 38 = 24m + 12sm + 2st in H. rupestre , 2 n  = 38 = 14m + 20sm + 4st in H. sinicum , 2 n  = 38 = 16m + 14sm + 8st in H. weixiense , and 2 n  = 76 in H. tsii . The karyotypes of two tropical species, H. amesianum and H. subulifolium , are the most primitive in the genus, whereas those of four temperate alpine species, H. sinicum , H. rupestre , H. weixiense , and H. flavescens , are more advanced. H. tsii is a tetraploid and H. rupestr e may be one of its ancestors. The low frequency of polyploidy in Holcoglossum in the Hengduan Mountains region supports the conclusion that chromosome stasis during rapid speciation is common there.  © 2007 The Linnean Society of London. Botanical Journal of the Linnean Society , 2007, 154 , 283–288.  相似文献   

14.
15.
南水青冈属及壳斗科其他属花粉壁超微结构比较研究   总被引:5,自引:1,他引:5  
对主要分布于南美和新西兰的南水青冈属Nothofagus 花粉外壁的超微结构进行了观察和研究, 同时与壳斗科其他属花粉外壁的结构进行比较,结果表明,南水青冈属花粉外壁的厚度、结构、萌发孔类 型以及花粉外壁表面的纹饰与壳斗科其他属花粉外壁的超微结构存在明显差别。主要表现为:南水青 冈属花粉外壁的柱状层和内层发育差,为颗粒状;基层和覆盖层无分化结构;覆盖层上为刺状纹饰;萌发 孔为5~8沟。壳斗科其他属花粉外壁的小柱发育好,形成明显的柱状层;覆盖层和基层常具一定的结 构;花粉表面较光滑,或为波状、颗粒或瘤状纹饰;内层发育较好;多数花粉具3孔沟,少数为3沟或3拟 孔沟。本研究认为南水青冈属花粉外壁的结构属于较原始类型,支持kuprianova等将南水青冈属独立为南壳斗科。  相似文献   

16.
WIKLUND, A., 1992. The genus Cynara L. (Asteraceae-Cardueae). This study includes a taxonomic revision of the genus Cynara. Eight species and four subspecies are recognized, viz. C. algarbiensis, C. auranitica, C. baetica including subsp. baetica and subsp. maroccana (formerly known as C. hystrix), C. cardunculus including subsp. cardunculus and subsp. flavescens, C. cornigera, C. cyrenaica, C. humilis (formerly sometimes in the genus Bourgaea) and C. syriaca. The cultivated artichoke (formerly C. scolymus) and cardoon are both included in C. cardunculus. One species, C. tournefortii , is excluded from Cynara. A cladistic study of the genus is also undertaken and its morphology, anatomy and phytogeography are discussed.  相似文献   

17.
The genus Nothofagus is mainly distributed in South America and New Zealand. The present paper describes its pollen exine ultrastructure and compares the exine ultrastructure with that of the other genera of Fagaceae. The pollen grains were examined using ultrathin sectioning technique under transmission electron microscope. The study shows that the pollen exine ultrastructure of Nothofagus differs from that of the other genera of Fagaceae by its exine structure and thickness, type of aperture, and ornamentation. The pollen exine of Nothofagus is thin and possesses granular bacules, regular foot layer and tectum, spinulate ornamentation, and the endexine is usually visible at poral area, and 5~8 colpate. The pollen exine of the other genera of Fagaceae possesses entire bacules, irregular foot layer and tectum, granulate and tuberculate ornamentation, thicker endexine, and is 3-colporate ( 3-colpate or 3-colporoidate). The pollen exine ultrastructure of Nothofagus may belong to primitive type. The pollen exine ultrastructure data support Kuprianova’s opinion that Nothofagus should be separated from Fagaceae and established as a monogenetic family, i.e. Nothofa-gaceae.  相似文献   

18.
Five Thermocyclops species were found in Uzbekistan: T. crassus, T. dybowskii, T. rylovi, T. taihokuensis, and T. vermifer. The last species has been for the first time recorded in the region. The data on morphology, variability and distribution of these species in Uzbekistan are given. A key to determine to the five species is proposed.  相似文献   

19.
The morphology and architecture of young Nothofagus pumilio plants growing as understorey and in a cleared area were assessed. Length, number of internodes, presence of branches and apex condition were registered for each growth unit (GU) in the sampled plant. GUs were grouped according to branching order and age of the bearing axis. Understorey plants were seven years old and had a short trunk bearing 2–3 orders of branches; all of their most recent GUs were horizontal and of comparable size. Plants growing in the cleared area were 10–16 years old and had a vigorous vertical and dominant trunk bearing 4–5 orders of less vigorous, horizontal branches. Plants from the cleared area showed signs of having had comparable-size GUs in all of their axes at a younger stage of growth. N. pumilio plants appear to start their growth with the production of short GUs in all of their axes irrespective of the light conditions. In contrast, the development of a vertical, vigorous trunk, seems to be restricted to plants growing in open environments.  相似文献   

20.
Revision of the Neotropical fern genus Danaea (Marattiaceae) has resulted in the recognition of ten new species, which are here for the first time presented to the scientific audience. Morphological and molecular data suggest that the genus consists of three monophyletic subgenera that are circumscribed here. A key is provided to aid species identification. The geographical ranges of the species are summarized and discussed with regard to speciation. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 163 , 360–385.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号