首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Aim I analysed distributional and phylogenetic information on weevils (Coleoptera: Curculionidae) from the Falklands, and integrated it with molecular, palaeontological and geological information to infer a geobiotic scenario. Location Falkland Islands (Islas Malvinas). Methods The panbiogeographical analysis was based on data on 23 Falkland species and their related taxa from southern South America. For the cladistic biogeographical analysis I analysed six weevil taxa for which phylogenetic hypotheses are available (the generic groups Cylydrorhinus, Strangaliodes and Falklandius, and the genera Antarctobius, Germainiellus and Puranius). Results from this analysis were compared with previous regionalizations. Cenocrons (sets of taxa that share the same biogeographical history) were identified by considering temporal information provided by fossils and molecular clocks. Finally, a geobiotic scenario was proposed by integrating the available information. Results Six generalized tracks were detected: Maule–Valdivian forests, Magellanic forest, Magellanic moorland, Falkland Islands, Magellanic forest–Magellanic moorland, and Magellanic forest–Falkland Islands. A node was identified in the Magellanic forest, based on the overlap of two generalized tracks. A single general area cladogram was obtained, implying the following sequence: (Magellanic moorland (Maule–Valdivian forests (Magellanic forest, Falkland Islands))). The Falklands are classified here as a biogeographical province in the Austral realm, Andean region and Subantarctic subregion. Falkland weevils seem to belong to a single Subantarctic cenocron. The sequence of events deduced implies the following steps: development of the Subantarctic biota in southern South America, arrival of the Falkland crustal block from South Africa in the Early Cretaceous, geodispersal of the Subantarctic cenocron from southern South America to the Falklands during the Early Oligocene, vicariance of the Magellanic moorland, vicariance of the Maule–Valdivian forests, and final vicariance between the Magellanic forest and the Falkland Islands. Main conclusions The biotic components identified support the connection of the Falkland weevils with the Magellanic forest. Falkland weevils belong to a single cenocron, dated to at least the Early Oligocene, when geodispersal from southern South America may have occurred. An older African cenocron may have been replaced completely by the Subantarctic one when the proto‐Falklands made contact with the Patagonian continental shelf. A geobiotic scenario implying vicariance events related to sea‐level variations could explain the distributional patterns analysed herein.  相似文献   

2.
All crested penguins present a unique reversed hatching asynchrony: the larger second-laid egg (B-egg) hatches before the smaller first-laid egg (A-egg). Although both eggs often hatch, the A-chick generally dies of starvation within days after hatching. However, within rockhopper penguins, the population at the Falkland Islands is unique in that some birds manage to raise both chicks. Although it has been suggested that the egg size dimorphism between A- and B-eggs may explain how long both eggs and chicks survive, this hypothesis has never been explicitly tested. We expect that both eggs are retained longer in the less dimorphic clutches than in the more dimorphic ones. In this paper, we have compiled egg measurements for three rockhopper penguin species (Eudyptes chrysocome, E. filholi and E. moseleyi) in order to compare the intra-clutch egg size dimorphism among these species. Furthermore, we have collected new data to compare egg size dimorphism between two populations of E. chrysocome (Falkland Islands versus Staten Island). A-egg volumes are more variable between species and populations than B-egg volumes. E. chrysocome and especially the population from the Falkland Islands produces the largest A-eggs and the least dimorphic eggs. Nevertheless, as differences in A-egg volumes between species and between the populations of Falkland Islands and Staten Island are stronger and more significant than differences in egg dimorphism, we suggest that A-egg volume, more than egg dimorphism, could be one of the factors influencing the prevalence of twins. A large A-egg and/or reduced egg dimorphism is probably necessary to enable rockhopper penguins to raise two chicks, but other reasons may also be involved which enable them to keep both eggs and chicks.  相似文献   

3.
Abstract

This article presents a comprehensive inventory of the urban vascular flora of the town of Palermo. The data were gathered from extensive field collections, from specimens kept in different herbaria, and publications of the last 30?years. The floristic catalogue includes all the vascular plants that occur spontaneously within the urban area. Thirteen taxa are endemic to Sicily and one of these, Clinopodium raimondoi, is exclusive to Palermo’s area. The inventory comprises 1052 taxa belonging to 119 families and 225 genera, and contains 170 taxa non-native to the Italian flora.  相似文献   

4.
The Falkland Islands wolf Dusicyon australis is an extinct canid that was once the only endemic terrestrial mammal to inhabit the Falkland Islands. There is still a puzzling picture of the morphological adaptations of this wolf that quickly evolved from its mainland fossil ancestor: Dusicyon avus. We employ a geometric morphometric approach to identify patterns of skull shape variation in extant canids and Dusicyon spp. The Falkland Islands wolf and its fossil ancestor show a more carnivorous feeding morphology than other South American foxes, and they cluster morphologically with jackals. This supports convergence in skull shape between Dusicyon and Old World canids, although the convergence is not as strong as that exhibited by their sister hyper‐ and hypocarnivorous taxa.  相似文献   

5.
Antarctic terrestrial ecosystems currently include very few non-native species, due to the continent’s extreme isolation from other landmasses. However, the indigenous biota is vulnerable to human-mediated introductions of non-native species. In December 2005, four construction vehicles were imported by contractors to the British Antarctic Survey’s (BAS) Rothera Research Station (Antarctic Peninsula) from the Falkland Islands and South Georgia (South Atlantic) on board RRS James Clark Ross. The vehicles were contaminated with >132 kg of non-Antarctic soil that contained viable non-native angiosperms, bryophytes, micro-invertebrates, nematodes, fungi, bacteria, and c. 40,000 seeds and numerous moss propagules. The incident was a significant contravention of BAS operating procedures, the UK Antarctic Act (1994) and the Protocol on Environmental Protection to the Antarctic Treaty (1998), which all prohibit the introduction of non-native species to Antarctica without an appropriate permit. The introduction of this diverse range of species poses a significant threat to local biodiversity should any of the species become established, particularly as the biota of sub-Antarctic South Georgia is likely to include many species with appropriate pre-adaptations facilitating the colonisation of more extreme Antarctic environments. Once the incident was discovered, the imported soil was removed immediately from Antarctica and destroyed. Vehicle cleaning and transportation guidelines have been revised to enhance the biosecurity of BAS operations, and to minimise the risk of similar incidents occurring.  相似文献   

6.
ABSTRACT

The results of a floristic study of benthic marine macroalgae on rocky substrata from the Tremiti Islands (Adriatic Sea) are presented. The list of taxa at specific and infraspecific level consists of 226 Rhodophyceae, 59 Fucophyceae and 36 Chlorophyceae. Of these 321 taxa, 147 are newly reported from the Tremiti Islands. Data on the reproductive phenology of each species, and comments on some species of particular interest are also given.  相似文献   

7.
Michael B.  Usher 《Journal of Zoology》1983,200(4):571-582
A collection of 55 spiders, which was made on Beauchêne Island, Falkland Islands archipelago, in December 1980, contains seven species. Three of these are known from the main body of the Falkland Islands, one is a new subspecies of a species previously known from Patagonia and Tierra del Fuego, and the remaining three are endemic to Beauchêne Island. New taxa described are Auximus fuegianus bransfieldi nssp. and Emmenomma beauchenicum n.sp.  相似文献   

8.
Abstract

Prevention and early detection are considered to be the most effective means of managing non-native invasive species that have serious ecological and economic impacts. Consequently, the study of those taxa that are still in an early stage of invasion but are highly likely to spread and to have a significant adverse impact in future is becoming an increasingly important issue in both the research on and management of invasive species. In Italy, one such species is Arctotheca calendula (L.) Levyns, a herbaceous plant of the Asteraceae family that is native to South Africa. Here, we present an overview of current knowledge on the distribution and potential impacts of this species in Italy, and we outline some features that are crucial to understanding and preventing its invasive spread.  相似文献   

9.
Gentoo penguins (Pygoscelis papua) are found across the Southern Ocean with a circumpolar distribution and notable genetic and morphological variation across their geographic range. Whether this geographic variation represents species‐level diversity has yet to be investigated in an integrative taxonomic framework. Here, we show that four distinct populations of gentoo penguins (Iles Kerguelen, Falkland Islands, South Georgia, and South Shetlands/Western Antarctic Peninsula) are genetically and morphologically distinct from one another. We present here a revised taxonomic treatment including formal nomenclatural changes. We suggest the designation of four species of gentoo penguin: P. papua in the Falkland Islands, P. ellsworthi in the South Shetland Islands/Western Antarctic Peninsula, P. taeniata in Iles Kerguelen, and a new gentoo species P. poncetii, described herein, in South Georgia. These findings of cryptic diversity add to many other such findings across the avian tree of life in recent years. Our results further highlight the importance of reassessing species boundaries as methodological advances are made, particularly for taxa of conservation concern. We recommend reassessment by the IUCN of each species, particularly P. taeniata and P. poncetii, which both show evidence of decline.  相似文献   

10.
The European earwig (Forficula auricularia) is an invasive species in the Falkland Islands, causing considerable problems for local horticulture, as well threatening indigenous ecosystems. To assess the potential of a classical biological control introduction two parasitoid fly species, Triarthria setipennis and Ocytata pallipes (Diptera: Tachinidae), were collected from sites in southern and northern England and then tested for their suitability as earwig biological controls at Egham, UK. Both species had previously been introduced into North America for earwig control however little is known of their long-term efficacy and host specificity. Host range tests including both target and non-target species were done. As there are no native Dermaptera on the Falkland Islands, tests were restricted to the field cricket Gryllus assimilis and the Dubia cockroach Blaptica dubia, as representatives of insect orders phylogenetically closely related to earwigs. A second cricket species (Gryllus bimaculatus) was included in an egg-depositing experiment for O. pallipes. Both tachinid species successfully parasitised and emerged from earwigs under laboratory conditions but no signs of parasitisation and development were observed in either the cricket or cockroach.  相似文献   

11.
《Journal of bryology》2013,35(4):287-291
Abstract

Mnioloma fuscum, a liverwort species known to date primarily from tropical-montane regions, is reported for New Zealand for the first time. Its occurrence in New Zealand is unexpected as the next nearest known site is believed to be the Solomon Islands, some 3500 km distant. The occurrence of Mnioloma fuscum in New Zealand highlights the contribution tropical regions have made to the composition of New Zealand's hepatic flora.  相似文献   

12.
13.
The continental coasts and remote islands in the high-latitude Southern Hemisphere, including the subantarctic region, are characterized by many endemic species, high abundance of taxa, and intermediate levels of biodiversity. The macroalgal flora of these locations has received relatively little attention. Filamentous green algae are prolific in the intertidal of southern islands, but the taxonomy, distribution, and evolutionary history of these taxa are yet to be fully explored, mostly due to the difficulty of access to some of these locations. In this study, we examined specimens of the order Cladophorales from various locations in the high-latitude Southern Hemisphere including the subantarctic (the Auckland Islands, Bounty Islands, Campbell Island, Macquarie Island, and Kerguelen Islands), as well as mainland New Zealand, the Chatham Islands, Chile, and Tasmania. The analyses of the rDNA sequences of the samples revealed the existence of two new clades in a phylogeny of the Cladophoraceae. One of these clades is described as the novel genus Vandenhoekia gen. nov., which contains three species that are branched or unbranched. The amended genus Rama is reinstated to accommodate the other clade, and contains four species, including the Northern Hemisphere “Cladophora rupestris.” In Rama both branched and unbranched morphologies are found. It is remarkable that gross morphology is not a predictor for generic affiliations in these algae. This study illustrates that much can still be learned about diversity in the Cladophorales and highlights the importance of new collections, especially in novel locations.  相似文献   

14.
Black-browed albatrosses Thalassarche melanophris are currently classified as globally endangered. The most important populations of this species are believed to be declining due to, amongst other factors, unsustainable levels of incidental mortality in fishing gear. However, detailed demographic data are lacking for several critical populations, including the largest of all, nesting in the Falkland Islands. Here, we present data from the first Falkland Islands detailed demographic study (at New Island) and show that, from 2003 to 2009, the mean adult survival probability was 0.942 (95% CI: 0.930–0.952). Nesting frequency of adults is amongst the highest recorded for Thalassarche albatrosses and breeding success (0.564 chicks per egg) is within normal values. The nesting population in the intensively studied plots experienced an increase of 4% per year from 2004 to 2009. These results indicate that the Falklands population may not be as threatened as previously supposed, although studies from more sites and a longer time series are needed to confirm or refute this. The high survival rates may partly reflect recent efforts to mitigate bycatch made by the Falkland Islands and other fisheries in the region. The reinforcement of such initiatives may be critical to buffer the black-browed albatross population against ecosystem shifts and natural disasters (such as harmful algal blooms) that will likely become more frequent with ongoing global changes.  相似文献   

15.
DEVONIAN TRILOBITES FROM THE FALKLAND ISLANDS   总被引:1,自引:0,他引:1  
Abstract:  New trilobite material is described from the Fox Bay Formation (Lower Devonian; Pragian) of the Falkland Islands (South Atlantic). The fossils were collected from many localities in both East and West Falkland and represent the first significant collection of trilobites from East Falkland. The trilobites belong to three higher taxa: Proetida (the first proetid record in these islands); Homalonotidae, Burmeisteria Salter, 1865; and Calmoniidae, including Bainella Rennie, 1930 and Metacryphaeus Reed, 1907. All of the forms except proetids have now been found in both East and West Falkland.  相似文献   

16.
Aim To address the biogeographical enigma of why guanacos (Lama guanicoe) are in the Falkland Islands we investigated the following questions: (1) What was the origin of the introduced guanacos? (2) What were the initial population sizes? (3) Why are they found only on one island? and (4) Who was John Hamilton and what role did he play? Location The Falkland Islands are located in the South Atlantic Ocean 600 km east of Patagonia at the southern end of South America. While dominated by East and West Falkland Islands, the archipelago is composed of some 750 islands. Sedge and Staats Islands, two small outlying islands of West Falkland, are the focus of this paper. Methods Historical information was collected from known relevant documents housed at the Falkland Islands Government Archives in Stanley, and personal interviews conducted with past and present residents of West Falklands. Research expeditions were made to Staats Island in 1999, 2002 and 2003 to assess the guanaco population size, distribution and social structure. Results Guanacos were unsuccessfully introduced in 1862 to East Falkland south of Mt Pleasant where Prince Alfred hunted them in 1871. John Hamilton, Scottish immigrant to the Falklands and Patagonia of southern Argentina and Chile, was the driving force in the introduction of guanacos from the region of Rio Gallegos, Argentina during the 1930s. The guanaco was one of several wildlife species he introduced, however, only the guanaco, Patagonia grey fox (Dusicyon griseus) and perhaps the sea otter (Lutra felina) survive. Hamilton's acting agent, Jimmy Miller, imported four shipments totalling 26 guanacos from 1934 to 1939. In 1934 the Falkland Government authorized Miller to introduce guanacos to Sedge Island, all 11 of which disappeared. Whether intentional or accidental, 15 guanacos were taken to Staats Island, an islet of 500 ha on the western edge of the archipelago. Historically, guanacos are unexpected on Staats Island because documentation authorizing their introduction is unknown. Guanaco numbers have fluctuated widely on Staats Island for 65 years primarily due to culling. In 1959 the population was dangerously close to extirpation, but today 400 thrive there. A severely reduced gene pool and genetic bottlenecking were suggested by recent field studies, revealing preliminary evidence of deleterious consequences of inbreeding. Main conclusions John Hamilton, spirited and visionary Scottish immigrant to the Falklands in the early 1880s, was responsible for the introduction of guanacos into the Falkland Islands. While there are some gaps in the historical events, the enigma of how and why guanacos were introduced to a single island in the South Atlantic Ocean is understood. Today, Staats Island, as a closed system, is a rare natural experiment in progress. It offers unique opportunities for addressing advanced questions in ungulate population, behavioural and genetic ecology. The population potentially also represents breeding stock for farming the guanaco's highly valuable wool on other islands. Thus, among his many efforts to practice land stewardship and promote economic diversity through the introduction of Patagonian wildlife, a remaining legacy of John Hamilton to the Falkland Islands is unmistakably the guanacos of Staats Island.  相似文献   

17.
Abstract

Chromosome number knowledge of the Italian vascular flora is stored in the online database Chrobase.it, which includes 6723 records, referable to 3428 taxa, 2799 accepted species and subspecies (about 35% of the national flora), and 3410 different chromosome countings (cytotypes). Appropriate queries to Chrobase.it allowed us to calculate mean, modal and median chromosome numbers for the Italian vascular flora, for geographical subgroups (islands, south, centre, north) and for selected orders, families and genera. Chromosome number data were available for 41 out of 55 orders (74%) and 107 out of 428 families (67%), represented by 664 out of 1297 genera (51%). The most studied administrative regions are Sicily (844 taxa), Tuscany (592 taxa), and Sardinia (390 taxa), while the most studied families are Asteraceae (465 taxa), Fabaceae (266 taxa), Brassicaceae (158 taxa), and Poaceae (144 taxa). Chromosome numbers range from 2n = 6, occurring in several species of Hypochaeris (Asteraceae), to 2n = 240, occurring in Ophioglossum (Ophioglossaceae), Dryopteris (Dryopteridaceae) and Arenaria (Caryophyllaceae) (mode is 2n = 18, and median is 2n = 24). Chromosome number variability was analyzed by frequencies (linear plots) and ANOVA, resulting in significant differences among geographical groups (mean chromosome number increasing from islands-south to centre-north) and selected taxa. B-chromosomes occur in 5.3% of data (148 taxa) and their number is not significantly different among geographical areas, while they occur only in 14 orders, 17 families, and 56 genera. The number of B-chromosomes ranges from 1 to 13 (mode = 1, median = 2).  相似文献   

18.
ABSTRACT

A revision of Gastrocopta from the Galápagos Islands (Ecuador) is made. Four new species from Pinzón, Santa Cruz and Floreana Islands are described; species previously known are redescribed and new locations are added. Gastrocopta (Gastrocopta) reibischi is revalidated through new records from Floreana, Isabela and San Bartolomé Islands. Shell shape and the number, morphology and disposition of the apertural barriers support the discrimination of the taxa. The species have cylindrical to pupoid shells; the number of apertural barriers – differentiated as lamellae, folds and nodulae – varies between 4 and 11, almost completely occluding the aperture in the more complex cases. These structures are: angular-parietal, infraparietal, supracolumellar, columellar, subcolumellar lamellae, and supernumerary, basal, infrapalatal, lower-palatal, interpalatal, upper-palatal and suprapalatal folds. In addition to this classic scheme, a supernumerary fold and a nodule are added. Calcareous concretions – pustulae – are found in several species, mainly located in the peristome. The aulacognathous jaw and radular dentition formulae of Gastrocopta (Gastrocopta) clausa and Gastrocopta (Gastrocopta) munita, are described and photographed for the first time.  相似文献   

19.
Summary

The Lichen flora of Rhum is described with emphasis on its ecology. In general, the 387 species represent a fine example of eu-oceanic assemblages and contain many taxa typical of western Britain. The margins of freshwater lochs hold particularly rich communities; the flora of the serpentine is singular for its narrow range of species. There is some evidence that existing fragments of woodland have continuity with the ancient forest. Lecanactis plocina is reported new to Scotland.  相似文献   

20.
The flora of the Pitcairn Islands: a review   总被引:1,自引:0,他引:1  
vascular plant flora of the Pitcairn Islands, south-central Pacific Ocean, is described based on extensive new collections made in 1991 and previously published records. Two vascular plants occur on Ducie Atoll; one (Pemphis acidula) is a new record. Sixty-three native vascular plants occur on Henderson, of which nine are endemic; Canavalia rosea, Operculina lurpethum, Psilotum nudum and Solanum americanum are new records for the island. Oeno Atoll has 16 native vascular plants; the single endemic (Bidens hendersonensis var. oenoensis) was not found in 1991 despite careful searches. Triumfetta procumbens was new for Oeno. Sixty-six native vascular plants have now been recorded from Pitcairn Island, there are two endemic ferns and seven endemic angiosperms in this number. A number of non-native taxa were new to Pitcairn. Some of the previously described taxa could not be found on Pitcairn, probably because they are very rare and only a small amount of time was spent collecting on Pitcairn. Many of the Pitcairn taxa are threatened by the spread of introduced species, especially Syzygium jambos.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

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