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1.
The Juan Fernández Archipelago is located 667 km (about 360 nautical miles) west of central Chile (33° S). It is composed of three islands: Robinson Crusoe, Santa Clara and Alejandro Selkirk. Since its discovery in 1574, the islands have been exposed to strong anthropogenic disturbance as a product of colonization. The vascular flora presents a high degree of endemism. Among the Magnoliophyta, 68% of the species are endemic, 15% of the genera and the monotypic family, Lactoridaceae, has only one species, Lactoris fernandeziana, Phil., which is found exclusively on Robinson Crusoe island. This species is a shrub which has been catalogued as extremely rare. More than 960 individuals of Lactoris fernandeziana, over 30 cm in height, were found in 14 localities. The height structure of the individuals suggests a species in recovery. In germination tests under experimental conditions the species shows a light requirement; seedling establishment was difficult and all individuals died within six months. Results are discussed in the light of the conservation measures undertaken by the administration of the Juan Fernández Archipelago National Park. Further studies on the population dynamics and the genetic structure of L. fernandeziana are needed to assure its conservation.  相似文献   

2.
Sixteen populations and 89 individuals of Lactoris fernandeziana were examined for variation in intersimple sequence repeat (ISSR) banding patterns. The species is a rare endemic of Masatierra Island in the Juan Fernández Archipelago, and is the only member of the endemic family Lactoridaceae. Five populations showed a single genotype whereas the other 11 populations had from two to 16 multilocus genotypes. Over 73% of the ISSR diversity occurred across populations, with only about 27% within populations. Diversity among populations results from the presence of different subsets of loci within each population rather than unique loci within populations; only two populations displayed novel loci, with one and three in each. Levels of differentiation at ISSR loci among populations are not correlated with geographic distance on Masatierra; rather, the pattern of variation is mosaic. The presence of differentiated local populations is concordant with the geitonogamous breeding system of the species and suggests low levels of long distance pollen or seed dispersal. The mosaic pattern of ISSR variation on Masatierra may result, in part, from drift and inbreeding in small populations following fragmentation of a once more continuous distribution of Lactoris with the formation of canyons by erosion. Also, the generation of new ISSR loci by mutation could occur with rare, sporadic gene flow among populations accounting for the mosaic pattern of variation and the paucity of unique alleles within populations. The ISSR results for Lactoris suggest that studies of morphological, ecological and physiological features may elucidate differentiation among populations of L. fernandeziana . Field studies have demonstrated that plants occur both in the dense forest understory and in the full sunlight in forest openings.  相似文献   

3.
Morphological and ITS sequence divergence were assessed between the two presently recognized taxa of the endemic genusCuminia (Lamiaceae), on Masatierra of the Juan Fernandez Islands. Morphological studies were based on leaf morphology of 51 individuals. Individuals ofC. fernandezia have narrow and lanceolate leaves with cuneate to acute bases and apices, whereas individuals ofC. eriantha have broadly ovate leaves with rounded bases and acute to obtuse apices. The two taxa can also be distinguished by the presence of pubescence.Cuminia eriantha has hairs on the leaves, young stems, floral peduncles, calyx, and corolla. Alternatively,C. fernandezia is glabrous except for tuft hairs on the nodes, and hairs on calyx teeth and corolla tubes. The ITS 1 and 2 regions of the five plants ofCuminia sequenced are a total of 451 bp long. All plants have identical ITS-1 but pubescent and glabrous plants are consistently different in ITS-2 sequence, revealing 1.3% total sequence divergence between the species. Both morphological and molecular data support the taxonomic recognition of two taxa, and the small but consistent differences appear to justify species status for the two entities. The pubescent populations representC. eriantha and the glabrous ones areC. fernandezia. It is hypothesized that the species diverged from a common ancestral immigrant to the islands, when Masatierra was much larger and more ecologically diverse than it now is. The two taxa seem to maintain their identities with no evidence of hybridization, even though they often grow in close proximity to one other on the island. Each population consists only of glabrous or pubescent plants, with no mixed population detected.  相似文献   

4.
Lactoridaceae are a monotypic family confined to Masatierra Island, Juan Fernández Archipelago, in the Pacific Ocean. It grows in the understorey of a subtropical montane rain forest. Lactoridaceae most probably originated in southern South Africa in the Cretaceous, with the oldest records in the Turonian–Campanian, and reached its widest palaeogeographical distribution by the Maastrichtian, extending into Australia, India, Antarctica, and North and South America. In this paper, we report a new fossil find of lactoridaceous tetrads from the early Miocene of eastern Patagonia, southern South America. This record is the youngest and geographically one of the closest to the extant Lactoris distribution area. Patagonian fossil material shows greater similarities to extant L. fernandeziana Phil. than to any other described morphotaxon. The family may have migrated into South America, either via Africa (through the Atlantic Ocean) or Antarctica, by the Maastrichtian, growing in eastern Patagonia up to the early Miocene. Arid conditions established in this region by the middle–late Miocene onwards would have determined the restriction of forests to the western lands. Lactoridaceae may have followed a similar migration pattern towards the Pacific coast of South America. The shifting of Lactoridaceae towards Masatierra Island would have occurred in the last 4 Myr by long‐distance dispersal events (perhaps by birds). © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 41–50.  相似文献   

5.
Random Amplified Polymorphic DNA (RAPD) markers were used to measure genetic diversity within and divergence among species of Dendroseris (Asteraceae: Lactuceae), a genus endemic to the Juan Fernandez Islands, Chile. Results were compared to previous studies employing allozymes. For five of the species, RAPD banding patterns distinguished all individuals examined, and different mutilocus genotypes were found even in species exhibiting no allozyme diversity. RAPD band diversities ranged from 0.003 to 0.022 within species; >90% of total diversity was among species and <10% within them. Relative levels of allozyme and RAPD diversity were similar for some species, particularly those with highest and lowest diversities, but overall there was no significant correlation. Relationships inferred from a neighbor-joining tree generated from RAPD bands were similar to results obtained from morphology, chloroplast DNA (cpDNA) restriction site mutations, and sequences from the internal transcribed spacer regions of nuclear ribosomal DNA (ITS), but somewhat better resolution was achieved. Relationships shown by allozymes differed from trees based on other data; this ostensibly is a result of the sharing of ancestral alleles and the absence of alleles generated subsequent to speciation. Dendroseris represents an example where RAPD markers, because of their greater variability, provide a useful alternative to allozymes for assessing diversity in rare species endemic to oceanic islands and for resolving relationships among the species.  相似文献   

6.
The phylogenetic relationships of the fossil orussid taxa Mesorussus taimyrensis and Minyorussus luzzi are examined by analysing them together with a large data set compiled previously for the extant Orussidae. The fossils are placed in an unresolved trichotomy with the extant Orussidae. The phylogeny is used for evaluating the hypothesis that the ancestors of the family had reduced body size; the results of this analysis are inconclusive. The biogeographical history of the Orussidae is explored. The common ancestor of the family was probably widespread, the initial splitting events taking place prior to or coinciding with the separation of Laurasia from Gondwana. Later putative vicariance events can be correlated with the gradual breakup of Gondwana. However, the biogeographical history of the Orussidae is dominated by speciation within regions and dispersal. The minimum age of the common ancestor of the Orussidae is >180 Myr when estimated from the biogeographical pattern, >95 Myr when estimated from the phylogenetic position of the fossils; the earlier date is considered to be the most likely.  © 2004 The Linnean Society of London , Biological Journal of the Linnean Society , 2004, 82 , 139–160.  相似文献   

7.
Ferinestrix vorax is an extinct mustelid carnivoran of enigmatic relationships, known from a partial mandible and femur collected from the 3.2‐ and 3.6‐Myr‐old deposits of Hagerman Fossil Beds National Monument, Idaho, USA. Here, we report Ferinestrix rapax sp. nov. based on 80 remains of skull and dentition from a 3.1–3.6‐Myr‐old deposit of Udunga, Transbaikal, Russia. We demonstrate that Ferinestrix is a stem genus of the badger subfamily Melinae. This genus is distinctly larger and more carnivorous than any other total‐clade meline. We show that Ferinestrix originated in Asia and immigrated to North America no later than at the early (Zanclean) to late (Piacenzian) Pliocene transition, and that the North American F. vorax and Asian F. rapax underwent parallel evolution toward increased carnivory. © 2013 The Linnean Society of London, Zoological Journal of the Linnean Society, 2013, 167 , 208–226.  相似文献   

8.
张奠湘  陈德昭   《广西植物》1994,(1):11-15
羊蹄甲属厚盘组作为一个分类实体包含有约18个种,本组植物主要分布于中国南部及中南半岛等地,其中很多种类在其分布区内地理替代现象相当明显。对此组的分支系统学研究,一方面有助于对本组种类系统进化关系的理解,另一方面又为对热带亚热带亚洲大陆各区系之间关系。的理解提供帮助,为本地区的分支生物地理学研究提供材料.本文用30个形态及叶脉脉序性状对厚盘组进行了分支分析.云南羊蹄甲被选作外类群,内类。群包括龙须藤亚组及攀援羊蹄甲亚组的所有18个种。分析产生了8个最简约的分支图。分析还表明攀援羊蹄甲单独作为一个亚组是不可取的,厚盘组的分类及生物地理学需要进一步的研究.  相似文献   

9.
10.
Hexabathynella is the only cosmopolitan genus of the order Bathynellacea (Crustacea). The known species number 18, found in Europe (9), Africa (1), South America (2), North America (3) and Australia and New Zealand (3). Phylogenetic analysis suggests that the least derived species are those from South America and the most derived those from the Iberian Peninsula, North America and Australia. The five species with the most plesiomorphic characters occur in salt or brackish water, which supports a marine origin for the genus. Phylogenetic and biogeographical analyses suggest that the distribution of the genus can be explained by dispersion and a double vicariant biogeographical model based on plate tectonics and the evolution of the Tethys during the Mesozoic and Cenozoic.  © 2003 The Linnean Society of London . Biological Journal of the Linnean Society , 2003, 78 , 457–466.  相似文献   

11.
The phylogenetic relationships of the genera in the geometrid tribe Scopulini (Lepidoptera: Sterrhinae) were examined using 141 characters of adult morphology and ecology. The study material included 92 species, representing all previously recognized genera and covering the morphological variation and full geographical range of the tribe. The cladistic analysis resulted in 20 equally parsimonious trees and a strict consensus cladogram based on these was well resolved. A majority of the recovered synapomorphic characters have been used previously in the taxonomy of the tribe. However, many novel characters were found in the sclerotized structures of the thorax. Many previously recognized genera were found to be nonmonophyletic and based on the present revised, synapomorphy-based classification, the number of recovered genera is reduced considerably. Twenty new generic synonyms and 90 new or revived species combinations are proposed. Seven genera are considered valid, with the large genus Scopula Schrank including over 85% of all species in the tribe. The taxonomic history of the tribe is reviewed and the problems of earlier classifications are discussed. A key to the genera is presented, although an informal diagnosis is preferred. All recognized genera are illustrated and a revised world checklist of the Scopulini is presented.  © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society , 2005, 143 , 473−530.  相似文献   

12.
The phylogeny of the Vitrinidae is reconstructed in a cladistic analysis based on characters of the genitalia, the copulation behaviour and the radula. The genera with an atrial stimulator turned out to be the earliest branches of the Vitrinidae, whereas the genera with a glandula amatoria form a monophyletic, taxonomically apomorphic group. The differences between the proposed phylogeny and previous hypotheses are discussed. The ancestral areas of the Vitrinidae and its sister group, the limacoid slugs Boettgerillidae–Limacidae–Agriolimacidae, are estimated using weighted ancestral area analysis. The Vitrinidae and the limacoid slugs might have originated by a vicariance event between Central Europe and the Near East. © 2002 The Linnean Society of London. Zoological Journal of the Linnean Society , 2002, 134 , 347–358.  相似文献   

13.
Cladistic and biogeographic analyses of the genus Farrodes are presented. Two species groups are delineated within Farrodes: F. caribbianus and F. bimaculatus. Three species formerly placed in other genera– Thraulus caribbianus Traver, Thraulus roundsi Traver and Homothraulus maculatus (Needham & Murphy)–are transferred to Farrodes. The species of the F. caribbianus species group are revised. Three new species are described: F. savagei from Venezuela, F. maya and F. mexicanus from Mexico. Keys to separate the two species groups of Farrodes and the species of the F caribbianus species group are provided. Successive cladistic analyses were carried out on both adult and nymphal characters using Hennig86 and CLADOS. The matrix was composed of all available data (nymphal characters were missing for some species), from nymphal and adult stages separately and on taxa represented by both adult and nymphal characters. Species of the genera Simothraulopsis and Homothraulus (components of the Farrodes lineage) were included in the analyses, and Ecuaphkbia was used as the outgroup. Results of the four analyses are compatible. The historical biogeography of Farrodes , with a distribution from nordiern Argentina to southern Texas, is analysed using the program COMPONENT. Areas of endemism are established, and some of their relationships compared with those of other groups available in the literature.  相似文献   

14.
Phylogenetic evidence for the herbaceous origin of angiosperms   总被引:7,自引:0,他引:7  
The ancestral angiosperm is commonly interpreted as an arborescent to shrubby magnolialean with large, multiparted, complex flowers. We examined this hypothesis using a phylogenetic analysis of new and reevaluated characters polarizabled with outgroup comparison. Our cladistic analysis of basal angiosperms placed the nonmagnolialeanChloranthaceae andPiperaceae at the bottom of the tree. We further inferred the probable ancestral states of characters not polarizable with outgroup comparison by examining their distribution among taxa at the base of our cladogram. The sum of ancestral character states suggests that the protoangiosperm was a diminutive, rhizomatous to scrambling perennial herb, with small, simple flowers.  相似文献   

15.
A molecular phylogenetic analysis recovers a pattern consistent with a drift vicariance scenario for the origin of Greater Antillean cichlids. This phylogeny, based on mitochondrial and nuclear genes, reveals that clades on different geographic regions diverged concurrently with the geological separation of these areas. Middle America was initially colonized by South American cichlids in the Cretaceous, most probably through the Cretaceous Island Arc. The separation of Greater Antillean cichlids and their mainland Middle American relatives was caused by a drift vicariance event that took place when the islands became separated from Yucatan in the Eocene. Greater Antillean cichlids are monophyletic and do not have close South American relatives. Therefore, the alternative hypothesis that these cichlids migrated via an Oligocene landbridge from South America is falsified. A marine dispersal hypothesis is not employed because the drift vicariance hypothesis is better able to explain the biogeographic patterns, both temporal and phylogenetic.  相似文献   

16.
Systematics and phylogeny of the Aglajidae (Opisthobranchia: Mollusca)   总被引:3,自引:0,他引:3  
The generic limits within the Aglajidae are reviewed and modified, based on the study of 21 species. Navanax Pilsbry, 1895 is reinstated as a genus distinct from Aglaja. The generic placement of several species is altered from previous works. An evaluation of morphological characters suggests that each of six genera has distinctive external morphology. The systematic value of twelve characters is critically reviewed. The evolutionary relationships of the Aglajidae and its genera to other philinacean familes are discussed.  相似文献   

17.
Alitocoris Sailer, 1950, consists of four valid species described from Central America. In a recent cladistic analysis of Ochlerini, the genus was considered paraphyletic in the Herrichella Distant, 1911, group of taxa. The present study provides a cladistic analysis of the Herrichella clade, using 88 morphological characters and 40 taxa representing 21 genera of Ochlerini, including all known species of Alitocoris plus 16 new species. Outgroups included Eritrachys bituberculata Ruckes, 1959, Phereclus pluto Stål, 1862, and Adoxoplatys comis Breddin, 1903, with the last used for rooting. The cladistic analysis was conducted using TNT under heuristic searches and implied weighting of characters; 11 K‐values calculated for an average character fit ranged from 50 to 90% of a perfectly hierarchical character. The results corroborated the paraphyly of Alitocoris, calling for changes in the classification of the genus with the proposition of three new genera for two, three, and ten species, respectively, that will be described elsewhere. Alitocoris is redescribed and a key for the species is presented. Alitocoris brunneus, Alitocoris maculosus, and Alitocoris parvus are removed from the genus, and the new species Alitocoris grandis sp. nov. , Alitocoris lateralis sp. nov. , and Alitocoris ornatus sp. nov. are described. © 2013 The Linnean Society of London  相似文献   

18.
Recent morphometric and breeding studies of diatoms show that the present species classification is too coarse and hides significant diversity. Many species are subdivided into phenodemes, which often differ in cell size, shape, stria density and pattern, but may also have different ultrastructural features. In raphid diatoms these can include the form of the raphe endings, details of the pore occlusions, and the structure of the girdle, while chloroplast structure can also vary. The phenodemes can be sympatric or allopatric. In Sellaphora pupula and other species, sympatric phenodemes are reproductively isolated. It is recommended that such demes are recognized as separate species; the total number of diatom species worldwide may thus be at least 2 × 105. Use of a fine-grained classification reveals that many diatom species may be endemics, some restricted to a single lake or catchment, others to wider areas. Environmental impact assessments and conservation strategies must begin to take account of endemism and rarity among microscopic algae and protists.  相似文献   

19.
The Resedaceae, containing 6 genera and ca. 85 species, are widely distributed in the Old World, with a major center of species diversity in the Mediterranean basin. Phylogenetic analyses of ITS and plastid trnL-trnF sequences of 66 species from all genera of the Resedaceae reveal (1) monophyly of the family, in congruence with preliminary phylogenetic studies; (2) molecular support for the traditional morphological subdivision of the Resedaceae into three tribes according to ovary and placentation types, and carpel number; (3) two monophyletic genera (Caylusea, Sesamoides), and one natural group (core Reseda), which includes the remaining four genera of the family (Ochradenus, Oligomeris, Randonia, Reseda); (4) a monophyletic origin for four of the six taxonomic sections recognized within Reseda (Leucoreseda, Luteola, Glaucoreseda, Phyteuma). Our results lead us to interpret an increment of the basic chromosome number in the family from x=5 to x=6 in at least two independent instances, and a broad representation of polyploids in multiple lineages across phylogenies, including association between octoploids and alien invasion in many parts of the world. Species diversity, endemism number, phylogenetic relationships and sequence divergence in Resedaceae suggest two major centers of differentiation, one in the western Mediterranean, and the other in the eastern Mediterranean and SW Asia. Two independent colonization events to the Canary Islands from Africa are indicated for the two Canarian Reseda endemics.  相似文献   

20.
Homology, biogeography and areas of endemism   总被引:1,自引:1,他引:0  
Hypotheses of biogeographic homology constitute the basis of historical biogeography. Primary biogeographic homology refers to a conjecture on a common biogeographic history, and secondary biogeographic homology refers to the cladistic test of the formerly recognized homology. Panbiogeography deals with the former, through the recognition of generalized tracks and areas of endemism, whereas cladistic biogeography deals with the latter, through the generation of general area cladograms. A historical biogeographic analysis may include both approaches, in a two‐stage analysis.  相似文献   

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