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1.
Climate change is forcing many plant species to shift their range in search of adequate environmental conditions, being localized endemic species particularly at risk on mountain summits. The Pantepui biogeographic province, a set of flat-topped mountain summits (called tepuis) of northern South America, contains both high plant diversity and a high degree of endemism. Previous studies based on warming projections for the area suggested that half of the Pantepui endemic flora would disappear due to habitat loss by 2100. In this study, we selected one of the best-explored tepuis, Roraima-tepui, to establish the baseline of diversity and endemism for comparisons with historical data and future monitoring surveys, aimed at testing the hypothesis of upward migration of plants in response to global warming. We also analysed floristic and physiognomic features of the Eastern Tepui Chain (ETC, the mountain range where Roraima is located), and the phytogeographic patterns of both the ETC and Pantepui. The Roraima summit contains 227 species, including 44 new records, 13 exotic species (some of them with high invasive potential), and at least one species new to science. At the ETC level, Roraima is the tepui with highest species richness and degree of endemism, and shows a relatively high floristic similarity with Kukenán and Ilú. Herbaceous species dominate over shrubs on these tepuis, Tramen and Maringma, whereas on Yuruaní, Karaurín and Uei, they reach similar abundances. At the Pantepui level, endemic species have highly localized distribution patterns (17% local endemics). Conservation opportunities are evaluated in light of these results.  相似文献   

2.
The alpha-diversity of trees found in the region of Manaus, Brazil is among the highest recorded for one-hectare plots in Amazonia or any tropical forest. Based on a survey of the distributions of 2541 Neotropical tree species, we analyzed the geographic distribution of 364 species of terra firme forest trees that occur in the region and that are not edaphic specialists. Fifteen distinct distribution patterns were recognized for trees occurring in Manaus. The great majority of species (84.9%) have continuous, somewhat restricted distributions, 35 (9.6%) show broad distributions and 20 species (5.5%) show disjunction between Amazonia and Eastern Brazil. A remarkable 150 (41.2%) of these species showed the region of Manaus as one of their distribution limits. Using the same pool of 2541 species distributions, the percentage of species with a distribution limit in Manaus was compared with that for other localities known to be centers of botanical collection. The null hypothesis that the difference in proportion of species with distribution limits among these localities and Manaus is insignificant was rejected. We conclude that the results are not an artifact of collecting density, that Manaus is indeed a crossroads of distinct phytogeographic regions, and that this explains part of the high species diversity of trees in the region of Manaus. A number of scenarios proposed for the Pleistocene in Amazonia postulate some degree of fragmentation of Amazonian forests or at least populations. As much as these theories may conflict with each other in some respects, they are compatible with the concept of Manaus as a region of re-convergence of isolated or disrupted floras and faunas. The significance of the vicinity of Manaus in the history of the Amazon flora and its current status as a repository for surprisingly high tree diversity highlights the need to make this region a conservation priority.  相似文献   

3.
Chile is home to 23 species of Bromeliaceae, including 2 subspecies and 4 varieties. Twenty species are endemic to the country. We examined 883 herbarium specimens from 27 herbaria for our treatment of the Bromeliaceae for the “Flora de Chile”. These data and field observations resulted in a comprehensive database that we used to generate distribution maps for each species. We applied ecological niche modelling to reveal distribution areas and centers of Bromeliaceae diversity. We further analysed the collecting dates of the herbarium specimens to assess possible changes in species abundance. In this study we assess the conservation status of the bromeliad species in Chile. IUCN categories were assigned to the 27 bromeliad taxa as follows: Critically endangered: 4, Endangered: 6, Vulnerable: 11, Near threatened: 2, Least concern: 4. No species has become “Extinct” up to now. We also put forth a hypothesis about their biogeographic history.  相似文献   

4.
Abstract

The aim of this article was to test the way in which geographical factors influence island floras in the Mediterranean basin, using ferns as target organisms, and the islands surrounding Sicily as location. A matrix with presence/absence data concerning fern taxa in the 16 islands studied was compiled. Cluster analysis, principal co-ordinates analysis (PCoA), principal components analysis (PCA) and a Bayesian analysis were performed. For each island, the total number of fern taxa was regressed against three factors: island area, island elevation and isolation. All the analyses pointed to affinities between islands according to their different geological composition, independently from their geographic position. A clear positive island species/area relationship (ISAR) was shown only for the volcanic islands. The island species/(area×elevation) relationship (ISAER), on the contrary, was unsatisfactory. The main features of interest are the following: (1) the clear division of the islands into two groups, volcanic vs. sedimentary; (2) the floristic richness of the volcanic compared to sedimentary islands and (3) the uniqueness of the pteridophyte flora of Pantelleria. This seems to demonstrate that the lower number of taxa in the islands farthest away from the “mainland” (Sicily, Tunisia) is not due to isolation, but due to another factor, probably habitat availability.  相似文献   

5.
Parsimony analysis of endemicity (PAE) was used to analyse the distributional patterns of 124 species of Mexican gymnosperms, using two different sample units: grid-cells and biogeographical provinces. PAE analyses were based on distributional data from herbarium specimens and specialized literature. Two data matrices were constructed for 60 grid-cells of 2° and 14 biogeographical provinces. The analysis of the 2° grid-cell matrix led to 7084 cladograms. The strict consensus cladogram showed several clades equivalent to the results obtained with the biogeographical provinces. Three clades agree with some principal regions of distribution of Mexican pines, previously identified by several authors, located at the northern portion of the Baja California peninsula, the Sierra Madre Occidental, and the Sierra Madre Oriental. These areas represent important centres of species diversity and endemism for Mexican gymnosperms. The analysis of the province matrix led to two most parsimonious cladograms, which only differed in the position of the Sierra Madre Occidental province. The iterative procedure PAE with progressive character elimination was applied to identify generalized tracks, where clades of provinces were considered equivalent to generalized tracks, and each time a cladogram was obtained, species defining its clades were deleted and a new run was undertaken. We found five generalized tracks, mainly located in montane provinces. The distribution patterns of gymnosperms agree with the existence of several Mexican biogeographical provinces, and a different historical biogeography of the Mexican peninsulas from the rest of the country is evident.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 405–417.  相似文献   

6.
We analysed pappus characters in 31 of the c. 34 accepted Leontopodium spp. (edelweiss). Micromorphological pappus character states were useful for discriminating between individual species and intrageneric groups. The pappus differs in number, length, breadth, surface structure, colour and the tips of the bristles. Several features characterize single species, for example a unique fan‐like tip that is only found in L. franchetii. Leontopodium section Nobilia is supported by unusual pappus characters. Experimental evidence shows that the pappus of Leontopodium, previously thought to be caducous, is well suited for wind dispersal of the fruit. One clear trend is that species growing in sparsely vegetated, high‐altitude regions often have more numerous and longer pappus bristles, particularly on the female flowers.  相似文献   

7.
Quantitative and qualitative data are given for samples of mature wood of all eight species of woody Asteraceae, representing three tribes, of St Helena I. The quantitative features of all except one species are clearly mesomorphic, corresponding to their mesic central ridge habitats. Commidendrum rugosum has more xeromorphic wood features and occurs in dry lowland sites. Commidendrum species are alike in their small vessel pits and abundant axial parenchyma. Melanodendrum agrees with Commidendrum in having fibre dimorphism and homogeneous type II rays. The short fibres in both genera are storied and transitional to axial parenchyma. Elongate crystals occur in ray cells of only two species of Commidendrum , suggesting that they are closely related. Wood of Commidendrum and Melanodendrum is similar to that of the shrubby genus Felicia , thought closely related to Commidendrum on molecular bases. Commidendrum and Melanodendrum have probably increased in woodiness on St Helena, but are derived from shrubby ancestors like today's species of Felicia. Petrobium wood is paedomorphic and indistinguishable from that of Bidens , from which Petrobium is likely derived. The two senecionid species (Senecio leucadendron = Pladaroxylon leucadendron; and Senecio redivivus = Lachanodes arborea , formerly Lachanodes prenanthiflord) also show paedomorphic wood. Wood of the various St Helena Asteraceae is consonant with relationship to African or South American ancestors that reached St Helena via long distance dispersal. Derivation from genera of Pacific islands or Austromalesian regions is considered less likely. However, DNA evidence is needed to clarify origins, times of colonization on St Helena and divergence from closest relatives, and the nature of evolutionary patterns.  相似文献   

8.
Biogeographical patterns of distribution of 74 species of Asteraceae that inhabit mainly the temperate forests of eastern Mexico were studied usingtrack analysis. Five generalized tracks were identified and conservation areas proposed based on degree of complexity of floristic patterns (Luna et al., 1999) and biotic richness. The northern part of the Sierra Madre Oriental harbours a high concentration of narrowly restricted species. In this area there are four track nodes that coincide with the Mexican priority terrestrial regions (RTPs) proposed by the Comisión Nacional para el Conocimiento y Uso de la Biodiversidad (CONABIO) and with previously identified areas of importance for bird conservation (AICAs). Two more nodes are found in the central and southern part of the Sierra. With the gathered information, we propose particular selected species of Asteraceae to be included in the Mexican areas of endangered species (NOM).  相似文献   

9.
Amazon parrots (Genus Amazona) are among the most recognizable and imperiled of all birds. Several hypotheses regarding the evolutionary history of Amazona are investigated using a combined phylogenetic analysis of DNA sequence data from six partitions including mitochondrial (COI, 12S, and 16S) and nuclear (beta-fibint7, RP40, and TROP) regions. The results demonstrate that Amazona is not monophyletic with respect to the placement of the Yellow-faced parrot (Amazona xanthops), as first implied by. In addition, the analysis corroborates previous studies suggesting a Neotropical short-tailed parrot genus as sister to Amazona. At a finer level, the phylogeny resolves the Greater Antillean endemic species as constituting a monophyletic group, including the Central American Amazona albifrons, while further revealing a paraphyletic history for the extant Amazon species of the Lesser Antilles. The reconstructed phylogeny provides further insights into the mainland sources of the Antillean Amazona, reveals areas of taxonomic uncertainty within the genus, and presents historical information that may be included in conservation priority-setting for Amazon parrots.  相似文献   

10.
The purpose of this study was to examine the composition, distribution, ecology, and conservation status of the Atlantic elements of the Swiss flora. About 195 Atlantic and 80 Mediterranean–Atlantic vascular plant species of the European flora have been used as the basis for our analysis. The complete list of 3,143 taxa has been used as the reference for the Swiss flora. The distributions of the species are illustrated in coincidence maps based on the computer database of the Data Centre of the Swiss Flora in Geneva, Switzerland. Our study demonstrates clearly that the Atlantic flora of Europe requires a new biogeographical appraisal. The Swiss flora comprises 66 Atlantic and Mediterranean–Atlantic taxa, which are taxonomically and ecologically highly diverse. Switzerland contains 44% of all European Sub-Atlantic plants. This confirms the Sub-Atlantic geographical position of Switzerland. Only one Eu-Atlantic species growing in Switzerland, Vicia orobus, can be classified as native with certainty. This species is critically endangered and merits the highest conservation priority. Although a very alpine country, Switzerland has a relatively large number of Mediterranean–Atlantic species. The Atlantic and Mediterranean–Atlantic plants are a very threatened group in Switzerland, with wetland plants the most imperilled ecological group. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

11.
Gypothamnium and Oxyphyllum (Asteraceae) are two monotypic genera endemic to the Atacama Desert of northern Chile. We performed a phylogenetic analysis using published sequences of the plastid rbcL and ndhF genes, the trnLtrnF region and the nuclear ribosomal internal transcribed spacer (ITS) to assess the systematic placement of the two genera within Mutisioideae. On the basis of the phylogenetic results, we constructed area cladograms to explore the biogeographical relationships and origin of the genera. The phylogenetic analysis showed that Gypothamnium is closely related to Aphylloclados, Plazia, Urmenetia, Lycoseris and Onoseris, whereas Oxyphyllum is closely related to Leucheria, Moscharia, Polyachyrus and, with low support, Jungia. These results do not differ substantially from those proposed in previous treatments based on morphological characters. The biogeographical analysis suggests that Gypothamnium in the coastal Atacama Desert is related to taxa that are currently distributed in eastern subtropical South America and in the Puna. Oxyphyllum may have originated from central Chile and other areas in southern South America, but its sister group (Leucheria + Polyachyrus) also reaches the Puna and the coastal Atacama Desert. Both groups show ancestral affinities with elements currently distributed in north‐western South America and Mesoamerica. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 32–51.  相似文献   

12.
13.
Lithophyllum species in the Mediterranean Sea function as algal bioconstructors, contributing to the formation of biogenic habitats such as coralligenous concretions. In such habitats, thalli of Lithophyllum, consisting of crusts or lamellae with entire or lobed margins, have been variously referred to as either one species, L. stictiforme, or two species, L. stictiforme and L. cabiochiae, in the recent literature. We investigated species diversity and phylogenetic relationships in these algae by sequencing three markers (psbA and rbcL genes, cox2,3 spacer), in conjunction with methods for algorithmic delimitation of species (ABGD and GMYC). Mediterranean subtidal Lithophyllum belong to a well‐supported lineage, hereby called the L. stictiforme complex, which also includes two species described from the Atlantic, L. lobatum and L. searlesii. Our results indicate that the L. stictiforme complex consists of at least 13 species. Among the Mediterranean species, some are widely distributed and span most of the western and central Mediterranean, whereas others appear to be restricted to specific localities. These patterns are interpreted as possibly resulting from allopatric speciation events that took place during the Messinian Salinity Crisis and subsequent glacial periods. A partial rbcL sequence from the lectotype of L. stictiforme unambiguously indicates that this name applies to the most common subtidal Lithophyllum in the central Mediterranean. We agree with recent treatments that considered L. cabiochiae and L. stictiforme conspecific. The diversity of Lithophyllum in Mediterranean coralligenous habitats has been substantially underestimated, and future work on these and other Mediterranean corallines should use identifications based on DNA sequences.  相似文献   

14.
The results of a study on pollen morphology of the species of the genus Ptilostemon growing in Italy: Ptilostemon niveus, P. greuteri, P. gnaphaloides, P. casabonae, P. strictus, P. stellatus by light and scanning electron microscopy were presented and discussed including in relation to their taxonomic position. The exine shows two different ornamentation patterns: echinae and scabrae. This last ornamentation pattern together with other features was previously described in the genus Ptilostemon. Of 6 species analysed, P. stellatus is the only one that shows a scabrate ornamentation of exine. Two pollen types were recognized through the exine ornamentation, length of ectocolpus and polar outline: P. stellatus type and P. niveus type. A multivariate analysis (principal component analysis and linear discriminant analysis) was carried out with the aim of examining potential morphological characters which could be used to identify taxa. The data suggest that several characteristics can be used to delimit the species in particular the exine ornamentation. The results of our studies support the actually subgeneric classification, and several features of the pollen grains analysed seem to have a palynoecological role and an important taxonomic significance. A dichotomous key based on palynological data is also given.  相似文献   

15.
There is still no clear consensus on how to relate geographical variation in the morphology and genetics of the globally widespread wildcat Felis silvestris to its taxonomy and systematics. Reconstructing the dynamic biogeography of the wildcat provides insight into how current geographical patterns of morphological and molecular variation may have developed. A geographical information system was used to infer climate-change influences using a deduced distribution model (DDM) to reconstruct the wildcat's geographical distribution at four points in time from the Last Glacial Maximum [LGM; 18 000 years before present ( bp )] until today. The DDM for 9000  bp , when mean global temperatures were 2 °C more than today, provides insight into how current global warming will affect the wildcat's distribution 50–100 years into future. Modelled distributions were assessed against known geographical barriers or unsuitable habitats, which may have separated populations and led to known morphological and genetic divergence. The DDMtoday corresponds well with known contemporary wildcat distribution records, except where wildcats would be expected to be excluded (e.g. high human population densities, potential competitors, inaccessible islands). The DDMtoday also corresponds closely with the results of recent studies on skull morphometrics and phylogeography, which support hypothesized colonizations of Africa and Asia from Europe during the late Pleistocene. Although DDM palaeo-distributions are more uncertain, they correspond to expected dramatic declines in northern Eurasia during the LGM, and significant distributional decline in central Asia, the Sahara and southern Africa, owing to increased aridity during climate cooling. From the DDM9000 model moderate global warming is hypothesized to impact minimally on wildcats, except in the Middle East and south-west Asia.  相似文献   

16.
Ostrea chilensis (Küster, 1844), the flat oyster, is native to Chile and New Zealand. In Chile, it occurs in a few natural beds, from the northern part of Chiloé Island (41 ºS) to the Guaitecas Archipelago (45 ºS). This bivalve is slow growing, broods its young, and has very limited dispersal potential. The Ostrea chilensis fishery has been over-exploited for a number of decades such that in some locations oysters no longer exist. The aim of this study was to study the genetic diversity of the Chilean flat oyster along its natural distribution to quantify the possible impact of the dredge fishery on wild populations. The genetic structure and diversity of Ostrea chilensis from six natural beds with different histories of fishing activity were estimated. Based on mitochondrial (Cytb) and nuclear (ITS1) DNA sequence variation, our results provide evidence that genetic diversity is different among populations with recent history of wild dredge fishery efforts. We discuss the possible causes of these results. Ultimately, such new information may be used to develop and apply new management measures to promote the sustainable use of this valuable marine resource.  相似文献   

17.
Currently 177 vascular plant species are known or presumed to be obligately associated with water in Peru. Their composition and diversity were surveyed in relationship to their distributions among the natural regions of Peru. Despite considerable aridity, the coastal plains of Peru have important aquatic ecosystems, including marshes in river deltas and mangroves in the far north, near the border with Ecuador; 70 species of aquatic plants are found in this coastal region. The Andean highlands include a great variety of wetlands, plus lakes and rivers; 62 species are found, including eight species of Isoetes, some of which are potentially threatened by extinction. The Amazon region of Peru includes both steep montane rivers in the headwaters and wide floodplains formed by meandering rivers in the lowlands; 102 species are found distributed among these ecosystems, although many additional species are semi-aquatic. Research and conservation strategies for Peru's aquatic plants need to take into account these important regional differences.  相似文献   

18.
19.
A cytogenetic study of 62 populations of Santolina pectinata in Spain shows the existence of two ploidy levels. The diploid cytotypes with 2 n  = 18 occupy the eastern Betic mountains, and the tetraploid cytotypes with 2 n  = 36 are located on the spurs of the Iberian System. The former show a much wider ecological spectrum than the latter. Mixed cytotypes were observed in two diploid populations, with one tetraploid in each, showing different karyotypes. Three trisomic individuals were detected, one in a diploid population and the other two in a tetraploid population. Also, three hypotetraploid individuals were detected in a tetraploid population. Polyploidy is shown to be spontaneous and recurrent, promoting partial sterility in the pollen. Structural chromosomal changes, principally translocations, and local speciation through autopolyploidy are the principal factors in the evolution and diversification of this species.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 657–667.  相似文献   

20.
The genus Syrphetodes Broun is revised to include a total of 13 species. Most of the species are restricted in their distributions, are rarely collected and have been attributed conservation status in New Zealand. Eleven species are described as new: three from Northland (S. relictus sp.n ., Te Paki; S. insularis sp.n. , Three Kings Islands; S. magnus sp.n. , Hokianga), one from the central North Island (S. obtusus sp.n. ), one from Central Otago (S. nunni sp.n. , Waikaia Bush), and seven from the southern Alps (S. cirrhopogon sp.n. , Aspiring National Park; S. occiduus sp.n. , Westland; S. melanopogon sp.n. , Mt Dewar, Paparoa Range; S. defectus sp.n. , northern Paparoa Range; S. marrisi sp.n. , Mt Domett, Northwest Nelson; S. carinatus sp.n. , Victoria Range). Eleven synonymies are proposed: S. crenatus Broun (= S. dorsalis Broun, syn.n .), S. marginatus Pascoe (= S. bullatus Sharp, syn.n. ; S. sylvius Broun, syn.n. ; S. cordipennis Broun, syn.n. ; S. punctatus Broun, syn.n. ; S. simplex Broun, syn.n. ; S. nodosalis Broun, syn.n. ; S. truncatus Broun, syn.n. ; S. variegatus Broun, syn.n. ; S. pensus Broun, syn.n. ; S. thoracicus Broun, syn.n. ). The phylogenetic relationships among the species were reconstructed using morphological (25 adult characters) and DNA sequence (nuclear 28S rDNA and mitochondrial cytochrome c oxidase subunit I) data. A morphological analysis rooted with Trachyderastes resulted in a split between lowland and high‐altitude species and a well‐supported group from Northland. Molecular trees rooted with representatives of Trachyderastes Kaszab (New Caledonia), Meryx Latrielle (Australia), Ulodes Erichson (Australia) and three New Zealand genera (Arthopus Sharp, Brouniphylax Strand, Exohadrus Broun) resulted in the following tree: ((Ulodes, Brouniphylax) (Exohadrus, Arthopus)) (Syrphetodes (Meryx, Trachyderastes)). Species relationships within Syrphetodes included a strongly supported northern North Island clade and an alpine clade either as sister taxon to S. crenatus and S. marginatus or sister remaining lowland lineages. Combined phylogenetic analyses also showed paritial congruence with separate partitions. The distributions of the lowland species, in particular those from the North Island, correspond to islands that existed in the Pliocene. The alpine, black‐coloured lineage, found above the treeline, is monophyletic based on several characters (e.g. lack of abdominal flanges and reduced scalation) and, in some reconstructions, the tan‐coloured S. cirrhopogon is sister taxon to the remaining black‐coloured species. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:697E68E8‐EE90‐46C1‐A009‐78A794E0EF4F .  相似文献   

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