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1.
Elizabeth S. Allman James H. Degnan John A. Rhodes 《Journal of mathematical biology》2011,62(6):833-862
Gene trees are evolutionary trees representing the ancestry of genes sampled from multiple populations. Species trees represent
populations of individuals—each with many genes—splitting into new populations or species. The coalescent process, which models
ancestry of gene copies within populations, is often used to model the probability distribution of gene trees given a fixed
species tree. This multispecies coalescent model provides a framework for phylogeneticists to infer species trees from gene
trees using maximum likelihood or Bayesian approaches. Because the coalescent models a branching process over time, all trees
are typically assumed to be rooted in this setting. Often, however, gene trees inferred by traditional phylogenetic methods
are unrooted. We investigate probabilities of unrooted gene trees under the multispecies coalescent model. We show that when
there are four species with one gene sampled per species, the distribution of unrooted gene tree topologies identifies the
unrooted species tree topology and some, but not all, information in the species tree edges (branch lengths). The location
of the root on the species tree is not identifiable in this situation. However, for 5 or more species with one gene sampled
per species, we show that the distribution of unrooted gene tree topologies identifies the rooted species tree topology and
all its internal branch lengths. The length of any pendant branch leading to a leaf of the species tree is also identifiable
for any species from which more than one gene is sampled. 相似文献
2.
W. B. RUDMAN 《Zoological Journal of the Linnean Society》1977,61(4):351-397
Six species of Hypselodoris and three species of Chromodoris axe described from the coast of East Africa. Three species of Hypselodoris and one species of Chromodoris are new species. Two species of Chromodoris from the tropical West Pacific are also described. The eleven species fall into three groups of similarly coloured species.
Hypselodoris nigrostriata and a new species of Hypselodoris are compared with H. infucata, H. festiva, H. obscura and two unnamed species from the literature. It is concluded that all these are distinct species.
H. nigrolineata and two new species, are compared with H. lineata and H. hilaris and all are considered distinct.
H. regina, Chromodoris quadricolor, C. africana, C. elisabethina, C. magnified and a new species of Chromodoris, are compared with C. westraliensis and two unnamed species from the literature. All these species are considered distinct.
All other names for forms falling into these three colour groups are considered synonyms of one or other of the above named species. Full synonymies are given. 相似文献
Hypselodoris nigrostriata and a new species of Hypselodoris are compared with H. infucata, H. festiva, H. obscura and two unnamed species from the literature. It is concluded that all these are distinct species.
H. nigrolineata and two new species, are compared with H. lineata and H. hilaris and all are considered distinct.
H. regina, Chromodoris quadricolor, C. africana, C. elisabethina, C. magnified and a new species of Chromodoris, are compared with C. westraliensis and two unnamed species from the literature. All these species are considered distinct.
All other names for forms falling into these three colour groups are considered synonyms of one or other of the above named species. Full synonymies are given. 相似文献
3.
Mediterranean hydromedusae can be classified in several categories: common species, widely distributed throughout the Mediterranean and rare species reported from the Pacific, Indian or Atlantic Oceans; seasonal species comprising cold-season species with a boreal affinity and warm-season species with a hot to temperate affinity; neritic and mid-ocean species; surface species and meso-, infra-, and bathypelagic species. Holoplanktonic species are known to be associated with stable hydrological conditions (offshore waters, deep waters, summer and winter homothermy), whereas meroplanktonic species are more likely to be found in more disturbed hydrological conditions (coastal waters, surface waters, spring and autumn periods of temperature fluctuation). A general pattern of medusa distribution is established based upon comparative study throughout the Mediterranean. 相似文献
4.
KEVIN DE QUEIROZ 《Biological journal of the Linnean Society. Linnean Society of London》2011,103(1):19-35
Charles Darwin introduced a novel idea into the concept of species, namely that species are branches in the lines of descent (segments of population lineages). In addition to this novel evolutionary component, Darwin's species concept also retained an older taxonomic component, namely the view that the species category is a taxonomic rank; moreover, he adopted amount of difference as a criterion for ranking lineages as species. Subsequent biologists retained both components of Darwin's species concept, although they replaced Darwin's ranking criterion with ranking criteria that either are more objectively defined or relate more directly to the biological bases of lineage separation and divergence. Numerous alternative ranking criteria were proposed, resulting in a proliferation of species definitions and a controversy concerning the concept of species. That controversy can be resolved by distinguishing more explicitly between the theoretical concept of species and the operational criteria that are used to apply the concept in practice. By viewing the various alternative ranking criteria as operational indicators of lineage separation rather than necessary properties of species, the conflicts among competing species concepts are eliminated, resulting in a unified concept of species. A brief examination of the history of biology reveals that an important shift related to the unified species concept has been emerging ever since Darwin reformulated the concept of species with an evolutionary basis. The species category is effectively being decoupled from the hierarchy of taxonomic ranks and transferred to the hierarchy of biological organization. Published 2011. This article is a US Government work and is in the public domain in the USA. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 19–35. 相似文献
5.
Cytological characters of four species in Syncalathium (Asteraceae: Lactuceae), a small genus with six identified species endemic to alpine scree of the Sino-Himalayan region, are surveyed in this report. Three species ( Syncalathium pilosum, Syncalathium chrysocephalum, and Syncalathium disciforme ) are examined for the first time. Combined with our previous counts, five species have been cytologically investigated from the genus and the results indicated that all species are diploid with the basic somatic chromosome number of x=8. The karyotype asymmetry of Syncalathium souliei is 2A, distinct from the other four species of 1 A, and the remaining species are divided into two subgroups with different karyotypes, consistent with their morphological features. The significance of the cytological evolution of Syncalathium is briefly discussed. 相似文献
6.
江西省资溪县马头山蕨类植物区系 总被引:1,自引:0,他引:1
马头山蕨类植物区系由 3 0科 62属 1 42种组成。区系地理成份复杂 ,科属的地理成份以热带亚热带性质为主。主要的科是鳞毛蕨科 (2 5种 )、水龙骨科 (1 8种 )、金星蕨科 (1 5种 )、卷柏科 (1 1种 )、蹄盖蕨科 (1 1种 ) ,5科占总种数 5 6.3 4%。主要的属是鳞毛蕨属 (1 6种 )、卷柏属 (1 1种 )、凤尾蕨属 (8种 )、铁角蕨属 (8种 )、复叶耳蕨属 (5种 )、假瘤蕨属 (4种 )占总种数 3 6.62 %。马头山蕨类植物区系属的地理成份可分为 8个 ,主要是泛热带 (1 9属 )、热带亚洲 (7属 )、世界广布 (1 9属 )成份 ,占总属数 72 .5 8%。而种的地理成份则以亚热带山地成份为主 ,本区东亚成份突出 ,加上中国特有成份共占总种数的 66.2 1 %。显然应是东亚植物区系的一部分。掌叶假瘤蕨为江西省首次发现。 相似文献
7.
Mark Ridley 《Biology & philosophy》1989,4(1):1-16
The correct explanation of why species, in evolutionary theory, are individuals and not classes is the cladistic species concept. The cladistic species concept defines species as the group of organisms between two speciation events, or between one speciation event and one extinction event, or (for living species) that are descended from a speciation event. It is a theoretical concept, and therefore has the virtue of distinguishing clearly the theoretical nature of species from the practical criteria by which species may be recognized at any one time. Ecological or biological (reproductive) criteria may help in the practical recognition of species. Ecological and biological species concepts are also needed to explain why cladistic species exist as distinct lineages, and to explain what exactly takes place during a speciation event. The ecological and biological species concepts work only as sub-theories of the cladistic species concept and if taken by themselves independently of cladism they are liable to blunder. The biological species concept neither provides a better explanation of species indivudualism than the ecological species concept, nor, taken by itself, can the biological species concept even be reconciled with species individualism. Taking the individuality of species seriously requires subordinating the biological, to the cladistic, species concept. 相似文献
8.
Fang Zhen-Fu 《植物分类学报:英文版》1987,25(4):307-313
1. The distribution of Salix species among the continents. There are about
526 species of Salix in the world, most of which are distributed in the Northern Hemisphere
with only a few species in the Southern Hemisphere. In Asia, there are about 375 species, making up 71.29 percent of the total in the world, including 328 endemics; in Europe, about 114
species, 21.67 percent with 73 endemics; in North America, about 91 species, 17.3 percent with
71 endemics; in Africa, about 8 species, 1.5 percent, with 6 endemics. Only one species occurs
in South America. Asia, Europe and North America have 8 species in common (excluding 4
cultivated species). There are 34 common species between Asia and Europe, 14 both between
Europe and North America and between Asia and North America, 2 between Asia and Africa.
Acording to the Continental Drift Theory, the natural circumstances which promoted speciation
and protected newly originated and old species were created by the orogenic movement of the
Himalayas in the middle and late Tertiary. Besides, the air temperature was a little higher in
Asia than in Europe and North America (except its west part) and the dominant glaciers were
mountainous in Asia during the glacial epoch in the Quaternary Period. Then willows of Europe moved southwards to Asia. During the interglacial period they moved in opposite direction. Such a to-and-fro willow migration between Asia and Europe and between and North
America occurred so often that it resulted in the diversity of willow species in Asia. Those
species of willows common among the continents belong to the Arctic flora.
2. The multistaminal willows are of the primitive group in Salix. Asia has 28 species of
multistaminal willows, but Europe has only one which is also found in Asia. These 28 species
are divided into two groups, “northern type” and “southern type”, according to morphology of
the ovary. The boundary between the two forms in distribution is at 40°N. The multistaminal willows from south Asia, Africa and South America are very similar to each other and
may have mutually communicated between these continents in the Middle or Late Cretaceous
Period. The southern type willows in south Asia are similar to the North American multistaminal willows but a few species. The Asian southern type willows spreaded all over the continents of Europe, Asia and North America through the communication between them before the
Quaternany Period. Nevertheless, it is possible that the willows growing in North America
immigranted through the middle America from South America. The Asian northern type multistaminal willows may have originated during the ice period.
The multistaminal willows are more closed to populars in features of sexual organs. They
are more primitive than the willows with 1-3 stamens and the most primitive ones in the genus.
3. The center of origin and development of willows Based on the above discussion it is reasonable to say that the region between 20°-40°N in East Asia is the center of the origin and
differentiation of multistaminal willows. It covers Southern and Southwestern China and northern Indo-China Pennisula. 相似文献
9.
J. T. ATWOOD N. H. WILLIAMS F.L.S. 《Botanical journal of the Linnean Society. Linnean Society of London》1979,78(3):141-156
Epidermal cells from adaxial leaf surfaces of 42 species of Paphiopedilum and 6 species of Phragmipedium were surveyed with the SEM. The surfaces of the cells are flat to papillose and often have various sculpturing patterns. To designate two orders of papilla size the terms 'macropapilla' and 'micropapilla' are proposed. Species exhibiting unornamented flat to macropapillose epidermal cells appear to be correlated with high light environments, whereas those species exhibiting micoropapillae and various degrees of sculpturing appear to be correlated with low light environments. Sculpturing features are often characteristic of a single species, but they may vary considerably between species. Epidermal characters are of some utility in identifying sterile plants which are otherwise indistinguishable. 相似文献
10.
We used data on the world's woodpeckers to test for patterns in the geographic distributions of a single group of closely related species. The frequency distribution of woodpecker geographic range sizes is approximately lognormal. Most variation in range sizes is explained by differences between species within genera; that is, range size seems to be an evolutionarily labile trait. The largest woodpecker ranges are found in Eurasia, both when absolute differences are compared and when range size is measured as a proportion of estimated available habitat. Notably, there is a negative relationship between the mean range sizes attained by species in a genus or tribe in South America and the mean ranges attained by species in the same tribe or genus in North America. Large-bodied species tend to be more widely distributed and to live at higher latitudes, but both tendencies disappear if the taxonomic relatedness of species is controlled for. Species living at high latitudes also tend to be more widely distributed. This relationship seems largely due to the effect of North American woodpeckers, which show it even when the taxonomic relatedness of species is controlled. Small continents generally have more woodpecker species than do large ones. Woodpecker geographic range sizes are smaller the more woodpecker species inhabit an area. Species show less overlap in their geographic ranges with species of similar than with species of dissimilar body size. The implications of these results for our understanding of patterns in geographic range sizes are discussed. 相似文献
11.
Leonard Finkelman 《Biology & philosophy》2018,33(5-6):32
Developments in genetic engineering may soon allow biologists to clone organisms from extinct species. The process, dubbed “de-extinction,” has been publicized as a means to bring extinct species back to life. For theorists and philosophers of biology, the process also suggests a thought experiment for the ongoing “species problem”: given a species concept, would a clone be classified in the extinct species? Previous analyses have answered this question in the context of specific de-extinction technologies or particular species concepts. The thought experiment is given more comprehensive treatment here. Given the products of three de-extinction technologies, twenty-two species concepts are “tested” to see which are consistent with the idea that species may be resurrected. The ensuing discussion considers whether or not de-extinction is a conceptually coherent research program and, if so, whether or not its development may contribute to a resolution of the species problem. Ultimately, theorists must face a choice: they may revise their commitments to species concepts (if those concepts are inconsistent with de-extinction) or they may recognize de-extinction as a means to make progress in the species problem. 相似文献
12.
Peatlands, with organic soils, are usually dominated by one or a few species. Above and belowground ecological processes are regulated by the characteristics of the dominant species in the peat. Understanding how these species relate to climatic or water chemistry gradients will help to predict the fate of those ecosystems under current climate change. The patterns of abundance and occurrence of 12 major peat-forming species from different structural plant groups were quantified along gradients of elevation, precipitation, and water chemistry. The species were distributed in four major structural groups: cushion plants, true mosses, sedges, and Sphagnum mosses. A response curve for each species was built with Generalized Additive Models. Niche breadths, species tolerances, and species optima were estimated using bootstrap resampling. Our results showed that species were limited in their elevational ranges; Sphagnum species were biased toward low to intermediate elevations, sedges, and true mosses to intermediate elevations and cushion plants to very high elevations. Sphagnum species were more likely to occur in sites with low precipitation, while sedges preferred wet sites. Sphagnum species preferred habitats with acidic pH. The species tolerances and optimum distributions are an indication to the vulnerability of the species to changes in their environment. Species with limited tolerances are more vulnerable, such as the narrow elevational distribution of cushion plants or the low pH and narrow tolerances observed for Sphagnum species. Climate and hydrological changes will very possibly affect the distribution of those species forcing changes on ecosystem functioning. 相似文献
13.
《Harmful algae》2016
The cyanobacterium Cylindrospermopsis raciborskii is a widespread species increasingly being recorded in freshwater systems around the world. It is of particular concern because strains in some geographic areas are capable of producing toxins with implications for human and animal health. Studies of this species have increased rapidly in the last two decades, especially in the southern hemisphere where toxic strains are prevalent. A clearer picture is emerging of the strategies adopted by this species to bloom and out-compete other species. This species has a high level of flexibility with respect to light and nutrients, with higher temperatures and carbon dioxide also promoting growth. There are two types of toxins produced by C. raciborskii: cylindrospermopsins (CYNs) and saxitoxins (STXs). The toxins CYNs are constitutively produced irrespective of environmental conditions and the ecological or physiological role is unclear, while STXs appear to serve as protection against high salinity and/or water hardness. It is also apparent that strains of this species can vary substantially in their physiological responses to environmental conditions, including CYNs production, and this may explain discrepancies in findings from studies in different geographical areas. The combination of a flexible strategy with respect to environmental conditions, and variability in strain response makes it a challenging species to manage. Our ability to improve bloom prediction will rely on a more detailed understanding of the complex physiology of this species. 相似文献
14.
Lang Kai-Yung 《植物分类学报:英文版》1985,23(6):418-428
The Gongga Mountain Region, located on the eastern fringe of QinghaiXizang Plateau and at the north-eastern end of Hengduan Mountains, is one of the
well-known large mountain areas in Sichuan Province. There are forty five high peaks
with the elavation of 6000 m or over in the area, among which the Gongga Mountain
is the highest one, with its summit being at the altitude of 7556 m, whereas the Dadu
River Valley in the eastern part of the area is only 1150 m above sea level; The relative height in the region is thus about 6400 m.
As we know so far the orchids in Gongga Mountain Region comprise 34 genera and
75 species with 1 variety, of which 12 species are epiphytes, 59 species with 1 variety
terrestrials and 4 species saprophytes (Table 1.).
I. The geographical distribution in the Gongga Mountain Region.
The vertical distribution of the orchids in the area.
Eastern flank: There are 39 species with I variety of orchids at 1150-2300
(-2400) m alt. in the subtropical evergreen broadleaf forest zone, of which 12 species,
such as Bulbophyllum andersonii, Dendrobium hancockii, Otochilus porrecta, etc., are
epiphytic (including a semiepiphyte, Pleione bulbocodioides), 25 species with 1 variety,
such as Bletilla formosana, Calanthe davidii, Cypripedium henryi, etc., are terrestrial,
and 2 species are saprophytic (i.e. Gastrodia elata and Neottia listeroides), the upper
limit of the real epiphytic orchids is 1800 m alt. At the altitude 2300(-2400)-3600
(-3800) m, in the coniferous forest zone, found are 23 species, including 20 terrestrial
species with 1 variety, such as Amitostigma gonggashanicum, Calanthe fimbriata, Coeloglossum viride, etc., 2 saprophytic species (Neottia acuminata and Risleya atropurpurea) and one semiepiphytic species. There are only 2 terrestrial species (i.e. Cypripedium tibeticum and Orchis chusua) at 3600(-3800)-4000m alt., in alpine shrub zone,
the upper limit of the terrestrial orchids being 4000 m alt. At 4000-4400 m alt., in
alpine meadow zone no orchids have so far been found.
Western flank: There are 14 species of orchids, such as Habenaria limprichtii,
Hemipilia flabellata, Satyrium ciliatum, etc., at 2300-2800 m alt., in the river valley
shrub zone, and they all belong to the terrestrial orchids. At the altitude of 28003800m, in the coniferous forest zone found are 19 species of orchids, among which 18
species are terrestrial (such as Amitostigma monanthum, Cephalanthera longifolia, Peristylus coeloceras, etc.) and one is saprophytic. There are only 4 species of terrestrial
orchids (i.e. Cypripedium tibeticum, Gymnadenia orchidis, Orchis chusua and O. diantha) at 3800-4800 m alt., in the alpine shrub-meadow zone, the upper limit of vertical
distribution of terrestrial orchids being 4400 m alt. Twelve species here are common
to the eastern flank.
II. The floristic composition of orchids in Gongga Mountain Region.
1. Twenty three species, belonging to 13 genera, are widespread in Whole EastAsian Region.
2. Eight species, belonging to 8 genera, are the elements of the Sino-Japanese
Subregion.
3. Forty one species with 1 variety, belonging to 24 genera, are the elements of
the Sino-Himalayan Subregion, more than five times the elements of the Sino-Japanese
Subregion.
4. The floristic features of the orchids in the area.
(1) The floristic elements are mainly temperate and subtropical ones.
(2) The life form is mostly terrestrial.
(3) The species endemic to China are prolific (35 species with 1 variety, belonging to 18 genera, are endemic to China, and 26 species with 1 variety are distributed
in south-western China and its adjacent region; Amitostigma gonggashanicum is endemic
to the area).
The floristic composition of orchids in the area is characterized by the dominance
of terrestrial species and temperate and subtropical East-Asian elements, though with
a few Indo-African tropical elements (such as genus Satyrium (1 species) ).
In conclusion, it may be considered that the species of orchids are abundant and
floristic elements are comparatively complex in the Gongga Mountain Region. 相似文献
15.
《农业工程》2019,39(6):443-450
Pakistan has rich history of indigenous folk medicine, and of the 6000 species of higher plants found in the country 12% are used in medicinal formulations. This immensely important knowledge of folk practices to cure different ailments has been learned after centuries and is mostly verbally communicated. Therefore, a field study was designed to investigate the plant biodiversity and accumulate the indigenous knowledge about the uses of plants of Tehsil Oghi, District Mansehra, Pakistan. A total of 141 local inhabitants were interviewed through a structured questionnaire followed by multivariate approaches to evaluate the data based on the Principle Component Analysis (PCA) and Detrended Correspondence Analysis (DCA). Plants specimen were preserved, mounted and labeled on the herbarium sheets, cataloged and deposited for voucher numbers in Herbarium, Government Post Graduate College, Mansehra, Pakistan. In present study, a total 104 species belonging to 88 genera and 54 families were recorded from the study area; herbaceous growth form dominated the study area with 56 species, followed by trees with 30 species and shrubs 14 species. Among all 54 families, Rosaceae species were dominant with 12 species, followed by Asteraceae with 8 species. Out of the reported 104 species, 94 plant species are medicinal, 22 plant species are edible fruits, 37 plant species are fuel wood, 24 plant species are timber wood, 38 plant species are fuel wood, 9 plant species are vegetables, while 34 plant species are ornamental. The present study revealed the importance of the flora of this unexplored area and also provides the baseline study for future biological, phytochemical and pharmacological experimentations. 相似文献
16.
Large‐scale biodiversity maps are essential to macroecology. However, between‐region comparisons can be more useful if patterns of observed species richness are supplemented by variations in dark diversity – the absent portion of the species pool. We aim to quantify and map plant diversity across Europe by using a measure that accounts for both observed and dark diversity. To do this we need to delimit suitable species pools, and evaluate the potential and limitation of a large‐scale dataset. We used Atlas Florae Europaeae (ca 20% of European plant species mapped within 50 × 50 km grid cells) and defined for each grid cell several species pools by applying various geographical and environmental filters: geographic species pool (number of species within 500 km radius), biogeographic species pool (additionally incorporating species distribution patterns, i.e. dispersion fields), site‐specific species pool (additionally integrating environmental preferences of species based on species co‐occurrence). We integrated dark diversity and observed diversity at a relative scale to calculate the completeness of site diversity: logistic expression of observed and dark diversity. We tested whether our results are robust against regional variation in data availability. We used independent regional databases to test if Atlas Florae Europaeae is a representative subset of total species richness. Environmental filtering was the most influential determinant of species pool size with more species filtered out in southern Europe. Both observed and dark diversity adhered to the well‐known latitudinal gradient, but completeness of site diversity varied throughout Europe with no latitudinal trend. Dark diversity patterns were fairly insensitive to variations in regional sampling intensity. Atlas Florae Europaeae represented well the total variation in plant diversity. In summary, dark diversity and completeness of site diversity add valuable information to broad‐scale diversity patterns since observed diversity is expressed at a relative scale. 相似文献
17.
A. L. Lvovsky 《Entomological Review》2013,93(4):422-431
The Palaearctic fauna of broad-winged moths (Oecophoridae with the subfamilies Oecophorinae, Pleurotinae, and Deuterogoniinae) comprises 47 genera and 329 species. The number of species rapidly increases from north to south, from 19 species in the Euro-Siberian taiga Region to 149 in the Mediterranean Region, but the Scythian steppe Region (30 species) and Sethian desert Region (49 species) have relatively poor faunas because the majority of oecophorid species are trophically associated with arboreal plants. The proper desert species are very rare among Oecophoridae moths, and the majority of species in the Sethian desert Region occur in the mountains. The number of endemic species is also greater in southern regions; it amounts for more than half of the total number of species in the Hesperian and Orthrian evergreen forest regions and in the Sethian desert Region. The faunas of European (62 species) and Far Eastern (67 species) deciduous forests comprise close numbers of species but are very different, having only 5 species in common. This fact indicates their long isolation. The Oecophoridae are represented in the Palaearctic mainly by the genera with a small number of species, except for 2 genera, Pleurota (100 species) and Promalactis (85 species). The distribution patterns of these genera are opposite: the species of Pleurota are numerous in the south of West Europe and in North Africa, their number quickly decreasing from west to east and only 2 species being present in China (Wang, 2006). The species of Promalactis are numerous in Southeast Asia, their number quickly decreasing from east to west: 3 species occur in Tibet and only 1, P. splendidella (Amsel, 1935), in Israel and Turkey. 相似文献
18.
2419 freshwater fishes from the Sudan were examined for helminth parasites and found to harbour one monogenean species, 15 species of adult digenetic trematodes, three species of larval trematodes, 16 species of adult cestodes, 13 species of adult nematodes, two species of larval nematodes and three species of acanthocephalans. Four species of adults and four species of larval worms are recorded for the first time in the Sudan and 30 new hosts are listed. The intensity of infestation of each species, the host-specificity and the variations in the infestation of fishes are discussed. The helminth fauna of the Sudan is compared with that of other African countries. 相似文献
19.
通过查阅相关文献并进行统计,确认湖北特有种子植物共计129种,无特有属分布。129种植物隶属于45科92属,其中含4种以上的科共有10个,含特有种最多的科为蔷薇科,共有7属15种。特有种以草本植物占绝对优势,藤本植物最少。按地理分区,可将129种植物归入5个区,其中包含种类最多的为大巴山区(仅神农架地区至少就有17种),大别山区和幕府山区的特有种极少。基于湖北与湿地、森林植被有关的自然保护区和特有植物的模式产地进行作图,结果显示,保护区的分布范围和密度与特有植物的分布基本重合,说明绝大部分特有种在保护区内都能得到有效地保护。 相似文献
20.
De Wet J Slippers B Preisig O Wingfield BD Wingfield MJ 《Molecular phylogenetics and evolution》2008,46(1):116-126
Three anamorph genera of the Botryosphaeriaceae namely Diplodia, Lasiodiplodia and Dothiorella have typically dark, ovoid conidia with thick walls, and are consequently difficult to distinguish from each other. These genera are well-known pathogens of especially pine species. We generated a multiple gene genealogy to resolve the phylogenetic relationships of Botryosphaeriaceae with dark conidial anamorphs, and mapped host associations based on this phylogeny. The multiple gene genealogy separated Diplodia, Lasiodiplodia and Dothiorella and it revealed trends in the patterns of host association. The data set was expanded to include more lineages of the Botryosphaeriaceae, and included all isolates from different host species for which ITS sequence data are available. Results indicate that Diplodia species occur mainly on gymnosperms, with a few species on both gymnosperms and angiosperms. Lasiodiplodia species occur equally on both gymnosperms and angiosperms, Dothiorella species are restricted to angiosperms and Neofusicoccum species occur mainly on angiosperms with rare reports on Southern Hemisphere gymnosperms. Botryosphaeria species with Fusicoccum anamorphs occur mostly on angiosperms with rare reports on gymnosperms. Ancestral state reconstruction suggests that a putative ancestor of the Botryosphaeriaceae most likely evolved on the angiosperms. Another interesting observation was that both host generalist and specialist species were observed in all the lineages of the Botryosphaeriaceae, with little evidence of host associated co-evolution. 相似文献