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1.
The Juan Fernández Archipelago is located 667 km west of central Chile (33°S) in the Pacific Ocean. It is composed of three islands: Robinson Crusoe (ex-Masatierra), Santa Clara and Marinero Alejandro Selkirk (ex-Masafuera).The first botanical collections were made 250 years after its discovery and colonization. These studies showed the great importance of ferns in the vascular flora of the islands. Of the 53 species described up to the present, 23 are endemic (45%), with one endemic monotypic genus, Thyrsopteris, whose only species is T. elegans Kunze (Dicksoniaceae).During a period of 4 years, I have studied the flora of the islands. There has been surprisingly little change in the distribution of the ferns, considering the devastation of the angiosperm flora. Some species have even increased their abundance, especially the tree ferns. Nevertheless, the more delicate species and those with a more restricted habitat have been reduced in abundance.Ten of the endemic species (43%) are in danger of extinction, such as Asplenium macrosorum and Ophioglossum fernandezianum, four are vulnerable (17%), including Blechnum schottii and Polypodium intermedium, and nine (40%), including Pteris berteroana and Blechnum cycadifolium are not endangered.  相似文献   

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Premise of the study: Microsatellite markers were developed in Erigeron rupicola and tested by amplification in six Erigeron species endemic to the Juan Fernández Archipelago, Chile, to investigate genetic diversity and population structure. • Methods and Results: Using 454 pyrosequencing, 24 primer pairs were developed in E. rupicola, 12 of which amplified and presented polymorphism among endemic species of Erigeron in the Archipelago. Two populations from E. rupicola and E. fernandezianus were genotyped, and one to eight alleles per locus per population were detected. The expected heterozygosity ranged from 0.000 to 0.812. • Conclusions: These results indicate the utility of primers for cross-species populational studies in all endemic species of Erigeron in the Archipelago.  相似文献   

4.
Adaptive radiation is a common evolutionary phenomenon in oceanic islands. From one successful immigrant population, dispersal into different island environments and directional selection can rapidly yield a series of morphologically distinct species, each adapted to its own particular environment. Not all island immigrants, however, follow this evolutionary pathway. Others successfully arrive and establish viable populations, but they remain in the same ecological zone and only slowly diverge over millions of years. This transformational speciation, or anagenesis, is also common in oceanic archipelagos. The critical question is why do some groups radiate adaptively and others not? The Juan Fernández Islands contain 105 endemic taxa of angiosperms, 49% of which have originated by adaptive radiation (cladogenesis) and 51% by anagenesis, hence providing an opportunity to examine characteristics of taxa that have undergone both types of speciation in the same general island environment. Life form, dispersal mode, and total number of species in progenitors (genera) of endemic angiosperms in the archipelago were investigated from literature sources and compared with modes of speciation (cladogenesis vs. anagenesis). It is suggested that immigrants tending to undergo adaptive radiation are herbaceous perennial herbs, with leaky self-incompatible breeding systems, good intra-island dispersal capabilities, and flexible structural and physiological systems. Perhaps more importantly, the progenitors of adaptively radiated groups in islands are those that have already been successful in adaptations to different environments in source areas, and which have also undergone eco-geographic speciation. Evolutionary success via adaptive radiation in oceanic islands, therefore, is less a novel feature of island lineages but rather a continuation of tendency for successful adaptive speciation in lineages of continental source regions.  相似文献   

5.
Over-exploited fisheries are a common feature of the modern world and a range of solutions including area closures (marine reserves; MRs), effort reduction, gear changes, ecosystem-based management, incentives and co-management have been suggested as techniques to rebuild over-fished populations. Historic accounts of lobster (Jasus frontalis) on the Chilean Juan Fernández Archipelago indicate a high abundance at all depths (intertidal to approximately 165 m), but presently lobsters are found almost exclusively in deeper regions of their natural distribution. Fishers' ecological knowledge (FEK) tells a story of serial depletion in lobster abundance at fishing grounds located closest to the fishing port with an associated decline in catch per unit effort (CPUE) throughout recent history. We have re-constructed baselines of lobster biomass throughout human history on the archipelago using historic data, the fishery catch record and FEK to permit examination of the potential effects of MRs, effort reduction and co-management (stewardship of catch) to restore stocks. We employed a bioeconomic model using FEK, fishery catch and effort data, underwater survey information, predicted population growth and response to MR protection (no-take) to explore different management strategies and their trade-offs to restore stocks and improve catches. Our findings indicate that increased stewardship of catch coupled with 30% area closure (MR) provides the best option to reconstruct historic baselines. Based on model predictions, continued exploitation under the current management scheme is highly influenced by annual fluctuations and unsustainable. We propose a community-based co-management program to implement a MR in order to rebuild the lobster population while also providing conservation protection for marine species endemic to the Archipelago.  相似文献   

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Notes on the Poaceae of the Robinson Crusoe (Juan Fernández) Islands, Chile, Brittonia 54: 154–163. 2001.—Poaceae in the Robinson Crusoe (=Juan Fernández) Islands number 53 species in 32 genera, of which 9% of the species are endemic, 9% indigenous, and 81% adventitious. The endemic taxa (and their conservation status) are:Agrostis masafuerana (rare),Chusquea fernandeziana (not endangered),Megalachne berteroana (not endangered),M. masafuerana (not endangered), andPodophorus bromoides (extinct).Megalachne andPodophorus are endemic genera. Comparisons with Poaceae in the Bonin and Volcano Islands, Canary Islands, Galápagos Islands, and Hawaiian Islands show different levels of endemism: number of endemic taxa, respectively, 5, 10, 12, 40; percent specific endemism, 8, 6, 21, 19. No endemic genera occur.Anthoxanthum odoratum, Avena barbata andHordeum murinum are noxious weeds in the Robinson Crusoe Islands. Many adventives are shared among floras of the archipelagos, with the highest ties of Robinson Crusoe being to the Canaries (53% of total Poaceae known in Juan Fernández) and the Hawaiian Islands (47%). Low levels of adventives occur within the Bonin (5%) and Galápagos (7%) Islands. In contrast, there are many endemic genera of Asteraceae in these same archipelagos: Bonin and Volcano Islands (1), Canary Islands (8), Galápagos Islands (5), and Hawaiian Islands (6); percent of specific endemism is also higher (20, 53, 54 and 56, respectively). Hypotheses for greater levels of endemics among oceanic island Asteraceae include more efficient dispersal mechanisms by wind and birds, animal pollination systems that result in greater degrees of geographic populational genetic isolation, and a vascular cambium that offers enhanced growth-form evolutionary opportunities.  相似文献   

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Journal of Plant Research - The article Factors driving adaptive radiation in plants of oceanic islands: a case study from the Juan Fernández Archipelago, written by Koji Takayama, Daniel J....  相似文献   

8.
Phylogenetic relationships were reconstructed among chironemid fishes based on morphological and molecular (lrRNA, NADH4, S7 ribosomal protein) characters. Two sympatric species from Juan Fernández in the southeast Pacific are not sister taxa, but rather exhibit independent relationships to Australian/New Zealand chironemids. The most plausible explanation for these relationships and contemporary distributions is an Australian/New Zealand origin of the family, followed by two trans-Pacific dispersal and colonization events, facilitated by larval entrapment within the West Wind Drift. This study demonstrates that the diversity of taxa on an island can reflect multiple colonizations, rather than in situ diversification, even in the case of very small, isolated, and geologically recent islands. When taken in conjunction with studies of related taxa, our results indicate that transoceanic dispersal of temperate cirrhitoid fishes in the South Pacific has been frequent and unidirectional. Molecular estimates of divergence time between southeast Pacific chironemids and their western relatives predate the emergence of Juan Fernández, consistent with hypotheses that much of the marine nearshore faunas of young southeast Pacific islands may be the product of successive transfer from older, now submerged islands.  相似文献   

9.
The Juan Fernández and Desventuradas islands are among the few oceanic islands belonging to Chile. They possess a unique mix of tropical, subtropical, and temperate marine species, and although close to continental South America, elements of the biota have greater affinities with the central and south Pacific owing to the Humboldt Current, which creates a strong biogeographic barrier between these islands and the continent. The Juan Fernández Archipelago has ~700 people, with the major industry being the fishery for the endemic lobster, Jasus frontalis. The Desventuradas Islands are uninhabited except for a small Chilean military garrison on San Félix Island. We compared the marine biodiversity of these islands across multiple taxonomic groups. At San Ambrosio Island (SA), in Desventuradas, the laminarian kelp (Eisenia cokeri), which is limited to Desventuradas in Chile, accounted for >50% of the benthic cover at wave exposed areas, while more sheltered sites were dominated by sea urchin barrens. The benthos at Robinson Crusoe Island (RC), in the Juan Fernández Archipelago, comprised a diverse mix of macroalgae and invertebrates, a number of which are endemic to the region. The biomass of commercially targeted fishes was >2 times higher in remote sites around RC compared to sheltered locations closest to port, and overall biomass was 35% higher around SA compared to RC, likely reflecting fishing effects around RC. The number of endemic fish species was extremely high at both islands, with 87.5% of the species surveyed at RC and 72% at SA consisting of regional endemics. Remarkably, endemics accounted for 99% of the numerical abundance of fishes surveyed at RC and 96% at SA, which is the highest assemblage-level endemism known for any individual marine ecosystem on earth. Our results highlight the uniqueness and global significance of these biodiversity hotspots exposed to very different fishing pressures.  相似文献   

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We compared the geographic distribution of groups of chondrychthid fishes of two physically proximal, although geographically different, regions that include the Juan Fernández seamounts and the central Chilean continental slope, both sampled at mesopelagic and mesobenthonic depths. The ridge is in the Nazca Plate, while the slope region in on the South American Plate, and is closer to the South American continent. We found six species of Chondrichthyes for the seamounts (four orders, four families). The slope sampling produced ten species of Chondrichthyes, of which Torpedo tremens De Buen 1959, was the only species in common with the Juan Fernandez area. There are clear differences between the Chondrichthyes of the two regions. These fisheries require adequate administrative modes.  相似文献   

11.
The Juan Fernandez fur seal (Arctocephalus philippii was allegedly extremely abundant, numbering as many as 4 million prior to sealing which continued from the late 17th to the late 19th century. By the end of the sealing era the species was thought to be extinct until they were rediscovered at Alejandro Selkirk Island in 1965. Historic records would suggest that the species underwent a substantial population bottleneck as a result of commercial sealing, and from population genetic theory we predicted that the genetic variability in the species would be low. We compared the mtDNA control region sequence from 28 Juan Fernandez fur seals from two islands in the Juan Fernandez Archipelago (Chile). Contrary to expectation, we found that variation in the Juan Fernandez fur seals is not greatly reduced in comparison to other pinniped taxa, especially given the apparent severity of the bottleneck they underwent. We also determined minor, but significantly different haplotype frequencies among the populations on the two islands (Alejandro Selkirk and Robinson Crusoe Islands), but no difference in their levels of variability. Such differences may have arisen stochastically via a recent founder event from Alejandro Selkirk to Robinson Crusoe Island or subsequent genetic drift.  相似文献   

12.
A survey of the reproductive features of the angiosperm flora of the Juan Fernández Archipelago (Chile) is presented to provide a species-based review of reproduction and pollination, to identify generalizations associated with these systems, to understand the evolution of these features, and to utilize these data to promote conservation. The collection of original data was extensive, based on our own fieldwork, and was combined with data from existing literature. Data recorded include habit, sexual system, flower size, shape, and color, and the hypothesized pollination system of the first colonizers. In addition, the data on compatibility, presence and type of dichogamy, observed floral visitors, presence of floral rewards, and currently known pollination systems are summarized. Pairwise comparisons of different features are tested for statistical association. The flora is typically composed of perennials. The majority of the species have very small or small flowers. Inconspicuous flowers (i.e., a shape character describing flowers with no optical attraction) are widespread, as are dish-shaped flowers. Green is the most frequent flower color, followed by white and yellow. Most species are hermaphroditic, 9% are dioecious, and 9% are monoecious. Some 30% of the species are protandrous and 7% protogynous. Detailed studies of compatibility of about 14% of the flora indicate that 85% of these species are self-compatible (SC). Although most species studied are SC, their level of autogamy is low. Nevertheless, selfing mediated via geitonogamy is the most frequent mechanism of pollen transfer. Outcrossing is mainly achieved through dioecy and self-incompatibility (SI), promoted by dichogamy in the hermaphroditic flowers, and facilitated by wind pollination. About 55% of the species offer nectar rewards, and only 2% offer pollen rewards. Floral visitors are rare to uncommon. Two hummingbird species, one of them endemic, are considered as pollinators for 14 plant species. Flies, moths, and beetles are the native insect visitors to flowers, but they have been documented on only 11 plant species (7%). Even insect visits to these few species were rarely observed. Given the infrequent, irregular, and imprecise nature of native insect association with flowers, there is no certainty that any of the species are truly insect pollinated. Two species of introduced ants and a new endemic bee were recorded as well; however, neither is likely currently important to the pollination of the native flora species. About 9% of the extant flora is currently bird pollinated, and we hypothesize that 47% is wind pollinated. However, we propose that most of the colonizers were ancestrally either insect or wind pollinated. There is association between a number of current floral features and the hypothesized pollination of colonizers. Therefore, to a large extent the flower color, shape, and size of the extant flora may express the pollination syndromes of colonizers rather than representing extant pollination. In addition, the presence of nectar in many species of extant flora does not necessarily indicate biotic pollination. Thus, studies of the reproductive biology on oceanic island plants need to be conducted species by species before broad generalizations can be made, because the observed features can be misleading. Possible changes in the pollination system were assessed by comparison of species for which there are reliable data with the hypothesized pollination of their colonist progenitors. The wind-or bird-pollinated species have retained the pollination system of the colonizers. In other instances, species seem to bear a different pollination system: from ancestral insect systems to current hummingbird-or wind-pollination systems. The lack of alternative means of biotic pollination seems to have led in a number of instances to anemophily—in essence a default pollination system. The lack of strong selection pressure for wind pollination and the relative youth of the archipelago may help explain why the features associated with wind pollination in these species are not so obvious. Because there are many recorded extinctions of vascular plants from islands versus those from continental areas, it is imperative to invest additional effort in protecting the remaining island species. Conservation or restoration programs cannot be effective without a deep and broad understanding of the reproductive biology of the plants. In order to conserve these plants, programs must involve a combination of reproductive and environmental measures. The ultimate fate of some species may depend on preserving the plant-hummingbird relationship, including the web of organisms that affect both plant and pollinator. The populations of introduced animals and weeds must be controlled. Experimentally produced allogamous seeds would enhance diversity in restoration programs. In addition, the preservation of habitat seems to be the central challenge to indirectly protect the unique island species.  相似文献   

13.
A new genus and species of Seuratiinae is described based on adults recovered from the Juan Fernández and Kermedec Petrels (Pterodroma externa and P. neglecta) from the Juan Fernández Islands of Chile (south Pacific). Navonia pterodromae n. gen., n. sp. is distinguished from the other genera and species in Seuratiinae by the combination of the following characters: (1) cordons arising from commissures of buccal lips originating a finely denticulate collarette divided into 2 lateral lobes, and detached from underlying cuticle; (2) inconspicuous simple to bicuspid deirids; (3) presence of area rugosa; and (4) presence of a large left spicule in the male. It is also distinguished from some genera and species in this subfamily by the presence of a lateral furrow. Seuratia shipleyi was also recorded from P. externa. These are the first records of helminths in these 2 hosts and the first records of Seuratiinae from Chile.  相似文献   

14.
Major collections of the ultramafic flora of Goiás, central Brazil, were made by Brooks and co-workers in 1988 and 1990. At the time of reports on this material in 1990–1992 much of it had been identified only tentatively and incompletely, but the area was clearly interesting for taxonomic and biogeochemical reasons. Further progress has been made but still only two-thirds of the specimens are identified at the species level. Following a third collection in early 2005, we now have 800 specimens from this area, with chemical analyses of all the plants and of more than 120 representative soil samples. New species have been found, e.g., in Paspalum (Poaceae) and Pterolepis (Melastomataceae). There is a need for more taxonomic work in genera such as Cnidoscolus (Euphorbiaceae), Lippia (Verbenaceae), Turnera and Piriqueta (Turneraceae), and Vellozia (Velloziaceae). Ni hyperaccumulation (>1,000 mg/kg in dry plant matter) has now been found in a total of 79 specimens, representing more than 30 different species. Notable Ni hyperaccumulators include Pfaffia sarcophylla (Amaranthaceae), species of Justicia, Lophostachys and Ruellia (Acanthaceae), Porophyllum (Asteraceae), several species of Lippia (Verbenaceae), Turnera and Piriqueta (Turneraceae), and a possibly new Cnidoscolus (Euphorbiaceae). Ni hyperaccumulation has not been found in plants of the outcrops of Morro Feio or Crominia-Mairipotaba; it seems to be confined to the extensive layered ultramafics of Barro Alto and the Macedo-Niquelandia areas. The distribution of Ni-values in the Brazilian plant collection is different from that found in the Mediterranean and California, where there is a clear distinction between accumulator and non-accumulator plants: in Brazil the distribution is more continuous, and median Ni concentrations are much greater. An ultramafic hill just north of Niquelandia deserves to be protected because of the presence there of many of the hyperaccumulators and species probably endemic to the Goiás ultramafics.  相似文献   

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Ex situ conservation of plant germplasm, especially seed banking, is a favourable and widely used method for the conservation of plant genetic resources (PGR). The long-term conservation of these resources is fundamental for food security and plant breeding in order to stem the losses in agrobiodiversity and to meet the global challenges that agriculture is facing. The conservation and accessibility of PGR relies on their correct taxonomic labelling and on the building of a searchable database that links ex situ collections together. In the current study, we analysed the impact of taxonomic misnaming in the two major PGR databases (Genesys PGR, EURISCO), listing accessions conserved worldwide. The aim was to understand if taxonomic misnaming issues prevent PGR conservation. We chose as a case-study seed collections of accessions of the genus Citrullus (watermelon genepool), the taxonomy and nomenclature of which have been largely revised in recent times. We observed that taxonomic misnaming greatly limits PGR conservation with only 3% of the accessions listed in the databases correctly named; moreover, 28% were affected by taxonomic errors that prevent the establishment of the accessions’ taxonomic identity, with consequences on their conservation and exploitation. The existence of the problem was also confirmed by the experimental propagation of three misnamed accessions. We suggest herein a series of actions that, put in place, could solve the extant misnaming issues in the databases and prevent their reoccurrence, allowing the correct conservation and the usability by the stakeholders of all the accessions.  相似文献   

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Dialectical Anthropology - Based on fieldwork carried out between 2012 and 2015 with groups of people who protested against the government of Cristina Fernández de Kirchner and who...  相似文献   

17.
In situ study on eleven commercially important species viz;Adiantum capillus veneris L,Bergenia ciliata (Haw) Sternb,Colchicum luteum Baker,Polygonum amplexicaule D.Den,Cuminum cyminum L,Dioscorea deltoidea Wall Kunth,L Morchella esculenta L,Paeonia emodi Wall ex H Kf,Podophyllum hexandrum (Royle) Chatt & Mukh,Valeriana wallichii DC and Viola serpens Wall ex Roxb was conducted in four locations viz; Malam (1 400 to 2 000?m),Bargin (1 700 to 2 300?m),Biakand (1 500 to 2 100?m) and Shinko (2 100 to 2 700?m).The data was recorded from both protected and unprotected sites of each site.Each site had 3 altitudinal sampling point.The density, herbage coverage and fresh biomass were determined in each locations for every species.All the investigated parameters generally showed an increase of 3 to 6 times over unprotected sites in each locations.Morchella esculenta,Dioscorea deltoidea,Colchicum luteum and Podophyllum hexandrum were absent in all unprotected sites while other species had low values in these stes.The investigated parameters of Colchicum luteum,Bergenia ciliata,Paeonioa emodi,Dioscorea deltoidea and Podophyllum hexandrum generally increased with the increasing elevation.Soil analysis,soil and air temperatures were recorded for each site.The air and soil temperature were slightly higher in open areas than in the protected site and showed decrease with increasing elevation.While the soil fertility was relatively high in protected sites as compared to unprotected area.The study shows that protection promotes the growth, distribution and occurrence of medicinal plants.It is possible with the participation of local communities to conserve these resources.  相似文献   

18.
Although still in relatively good condition, the Gala´pagos Archipelago suffers from increasing human pressures. Apart from direct actions like hunting and logging, endemic plants and animals are threatened by introduced species, and in many cases the present status of the populations is not known. The conservation status of eight plant species considered endangered was studied from literature and field surveys and the main threats were determined. Each of the eight species is endemic to only one island but in some cases is also present on nearby islets. Of these eight species, one is considered extinct, one critically endangered, and the others suffer various levels of threat. As in all island systems of the world, the main threats are introduced organisms, both plants and animals. The extinct species probably disappeared owing to invasion by Lantana camara, one of the most aggressively invasive plants of the islands, and the most endangered species is threatened by goats. The remaining species seem to be regenerating well and we can expect positive results from protection efforts. Today, only one of the eight species benefits from a direct protection action.  相似文献   

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The Galápagos petrel (Pterodroma phaeopygia) is endemic to the Galápagos archipelago, where it is known to breed only on five islands. The species has been listed as critically endangered due to habitat deterioration and predation by introduced mammals. Significant morphological and behavioural differences among petrels nesting on different islands suggest that island populations may differ genetically. Furthermore, nesting phenology suggests that genetically differentiated seasonal populations may exist within at least one island. We analysed variation in six microsatellite loci and part of the mitochondrial ATPase 6/8 gene in 206 Galápagos petrels sampled from all five islands. No evidence of genetic structuring within islands was found, although statistical power was low. In contrast, significant differences occurred among island populations. For the microsatellite loci, private alleles occurred at all islands, sometimes at high frequency; global and pairwise estimates of genetic differentiation were all statistically significant; Bayesian analysis of genotypes frequencies provided strong support for three genetic populations; and most estimates of migration between populations did not differ significantly from zero. Only two ATPase haplotypes were found, but the geographic distribution of haplotypes indicated significant differentiation among populations. For conservation purposes, populations from Floreana, Santa Cruz, San Cristóbal and Santiago should be regarded as separate genetic management units. Birds from Isabela appear to be derived recently from the Santiago population, and the population on San Cristóbal appears to be a mixture of birds from other populations. However, considering ecological and behavioural differences among birds from different islands, we recommend that all five populations be protected.  相似文献   

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