1,356,084 research outputs found
Tracking Invasion Histories in the Sea: Facing Complex Scenarios Using Multilocus Data
No full textIn recent years, new analytical tools have allowed researchers to extract historical information contained in molecular data, which has fundamentally transformed our understanding of processes ruling biological invasions. However, the use of these new analytical tools has been largely restricted to studies of terrestrial organisms despite the growing recognition that the sea contains ecosystems that are amongst the most heavily affected by biological invasions, and that marine invasion histories are often remarkably complex. Here, we studied the routes of invasion and colonisation histories of an invasive marine invertebrate Microcosmus squamiger (Ascidiacea) using microsatellite loci, mitochondrial DNA sequence data and 11 worldwide populations. Discriminant analysis of principal components, clustering methods and approximate Bayesian computation (ABC) methods showed that the most likely source of the introduced populations was a single admixture event that involved populations from two genetically differentiated ancestral regions - the western and eastern coasts of Australia. The ABC analyses revealed that colonisation of the introduced range of M. squamiger consisted of a series of non-independent introductions along the coastlines of Africa, North America and Europe. Furthermore, we inferred that the sequence of colonisation across continents was in line with historical taxonomic records - first the Mediterranean Sea and South Africa from an unsampled ancestral population, followed by sequential introductions in California and, more recently, the NE Atlantic Ocean. We revealed the most likely invasion history for world populations of M. squamiger, which is broadly characterized by the presence of multiple ancestral sources and non-independent introductions within the introduced range. The results presented here illustrate the complexity of marine invasion routes and identify a cause-effect relationship between human-mediated transport and the success of widespread marine non-indigenous species, which benefit from stepping-stone invasions and admixture processes involving different sources for the spread and expansion of their range
Polyzoa iosune Turon & Lopez-Legentil
No full textPolyzoa iosune Turon & López-Legentil Fig. 10 Localities: 6 N. Holotype: a colony has been designated as the holotype and deposited in the Museo Nacional de Historia Natural de Chile (code MNHNCL TUN- 15001). Two other colonies (paratypes) are kept at the Biological Collections Room of the Universidad Católica del Norte (SCBUCN 3962). Several colonies of this new species have been found in the lower intertidal in the Coquimbo area. They form thick carpets by the union side by side of elongated zooids, reaching 17 mm in height. A single colony may cover hundreds of square centimetres. The tunic is of a clear brownish colour, and the siphons are pigmented in red. Small zooids appear in between larger ones, attached to their tunics. Thick stolons are found at the basis of the colony. The tunic is thin but firm. The zooids have a weekly muscular body wall that allows the observation of some internal features. There is an inner oral velum and about 16 tentacles (big and medium size). The aperture of the neural gland is oval-vertical. There are 7 longitudinal vessels to the right and 4 (sometimes 5) to the left. Parastigmatic vessels cut the stigmata (up to 10 per mesh). Sometimes there are 2 and even 3 parastigmatic vessels between two consecutive transverse vessels. The digestive system forms an open primary loop, with a long and straight intestine reaching anteriorly towards the atrial siphon and ending in a smooth anus. The stomach has 12–16 folds and a pyloric caecum. There are several endocarps (6–8) attached to the body wall at each side, round or elongated. Up to 18 gonads can be found on the right hand side, forming a row adjacent to the endostyle. The gonads are hermaphrodite and elongated. The male portion is basal and forms most of the gonad, and the female portion lies distally and apically. There is a short and wide oviduct opening distally with a scalloped aperture, and a long and thin subterminal spermduct. To the left there are only 5–7 hermaphrodite gonads between the endostyle and the ascending intestine. Some zooids brood larvae in the peribranchial cavity. The larval trunk length is up to 0.65 mm. When mature, the larvae feature a ring of tubular anterior ampullae (6–7 pairs), three conical adhesive papillae, and a single pigmented spot. Remarks. Monniot (1970) established a tabular key for the known species of Polyzoa. None matches the characters observed in the Chilean specimens. In particular, the number of longitudinal vessels falls within the variability of P. minor alone (Monniot 1973), a different species in terms of size, colony form, number of gonads and larval morphology. The only species featuring zooids joined together and of the size found here is P. opuntia, but it has consistently 8 longitudinal vessels per side, among other differences. On the other hand, and based on the COI sequences obtained here, P. iosune forms a well-suported clade (Neighbour Joining tree, results not shown), sister to the clade of P. opuntia sequences, with which it features 8–9 % sequence differentiation. Species described more recently such as P. e xi g ua and P. nodosa (Kott 1990), or P. atlantica (Sanamyan et al. 2009) are all clearly different in colony and zooid size and shape, as well as in internal features. Derivatio nominis: this species is dedicated to María Jesús Uriz, colleague, friend, and great sponge specialist. Iosune (María Jesús in basc language) is here used as substantive in apposition.Published as part of Turon, Xavier, Cañete, Juan I., Sellanes, Javier, Rocha, Rosana M. & López-Legentil, Susanna, 2016, Ascidian fauna (Tunicata, Ascidiacea) of subantarctic and temperate regions of Chile, pp. 151-180 in Zootaxa 4093 (2) on pages 168-169, DOI: 10.11646/zootaxa.4093.2.1, http://zenodo.org/record/26766
A chart of Turon Bay and Island of Callao or Campello, Cochin China [cartographic material] /
No full textManuscript map of Dà Nãng Bay in Vietnam and nearby islands. Depths shown by soundings.; "Soundings expd in fathoms".; Pencilled bar scale.; Turon Bay charts were used as the basis for the engraving of plate 3 in Sir George Leonard Staunton's "An authentic account of an embassy from the King of Great Britain to the Emperor of China" published in 1797.; Also available online http://nla.gov.au/nla.map-rm4619.Chart of Turon Bay, Cochin China and Island of Callao or Campell
Tough adults, frail babies: an analysis of stress sensitivity across early life-history stages of widely introduced marine invertebrates
No full textAll ontogenetic stages of a life cycle are exposed to environmental conditions so that population persistence depends on the performance of both adults and offspring. Most studies analysing the influence of abiotic conditions on species performance have focussed on adults, while studies covering early life-history stages remain rare. We investigated the responses of early stages of two widely introduced ascidians, Styela plicata and Microcosmus squamiger, to different abiotic conditions. Stressors mimicked conditions in the habitats where both species can be found in their distributional ranges and responses were related to the selection potential of their populations by analysing their genetic diversity. Four developmental stages (egg fertilisation, larval development, settlement, metamorphosis) were studied after exposure to high temperature (30°C), low salinities (26 and 22 ) and high copper concentrations (25, 50 and 100 µg/L). Although most stressors effectively led to failure of complete development (fertilisation through metamorphosis), fertilisation and larval development were the most sensitive stages. All the studied stressors affected the development of both species, though responses differed with stage and stressor. S. plicata was overall more resistant to copper, and some stages of M. squamiger to low salinities. No relationship was found between parental genetic composition and responses to stressors. We conclude that successful development can be prevented at several life-history stages, and therefore, it is essential to consider multiple stages when assessing species' abilities to tolerate stress. Moreover, we found that early development of these species cannot be completed under conditions prevailing where adults live. These populations must therefore recruit from elsewhere or reproduce during temporal windows of more benign conditions. Alternatively, novel strategies or behaviours that increase overall reproductive success might be responsible for ensuring population survival
Turon Harbour, Cochin China [cartographic material] /
No full textManuscript map of Dà Nãng Harbor in Vietnam showing low tides and anchorage points. Relief shown by hachures.; Pencilled bar scale.; Turon Bay charts were used as the basis for the engraving of plate 3 in Sir George Leonard Staunton's "An authentic account of an embassy from the King of Great Britain to the Emperor of China" published in 1797.; Also available online http://nla.gov.au/nla.map-rm4621
Provincia de Gerona
No full text1 manuscrit. Probablement delineat per Joan Turon i Algans per a la Diputació de Girona. - Paper tela.1:400 00043 x 56 c
Provincia de Gerona
No full text1 manuscrit. Probablement delineat per Joan Turon i Algans per a la Diputació de Girona. - Paper tela.1:400 00043 x 56 c
Characterization and analysis of conduction welded thermoplastic composite joints considering the influence of manufacturing
No full texthermoplastic composite welding is a key technology that can help to make the aviation industry more sustainable, while at the same time enable high-volume production and cost-efficient manufacturing. In this work, characterization, testing and analysis of thermoplastic composite conduction welded joints is performed while accounting for the influence of the manufacturing process. Test specimens are designed from welds of a half a meter long welding tool that is developed to weld the stiffened structures of the next-generation thermoplastic composite fuselage. In the design, special attention is paid to the weldability of the laminates, while ensuring fracture occurs only at the welded interface. Two specimen configurations are evaluated for the Double Cantilever Beam and End-Notched Flexure characterization tests. Moreover, Single Lap-Shear specimens are tested in tension and in three-point-bending. Finally, the characterized material properties are introduced in finite element analyses to demonstrate that the cohesive zone modeling approach can be used to conservatively predict the strength of these welded joints. New insights are obtained in the relation between the manufacturing process, the quality of the weld and the mechanical properties of the joints, which are significantly different compared to autoclave consolidated composites
Turon River at Sofala Bathurst district, NSW
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/232578Black and white photograph.
Previous group titled: Australia Today rural scenes photographs NSW 1930s.
Stamp on verso: This photograph may be reproduced or published free of charge on condition same is acknowledged to NSW Government Printer. Written in pencil on verso: No. 9584259150
Item: [1979.0162.02378] "Turon River at Sofala Bathurst district, NSW
DOES FIRMNESS OF CONVICTION CAUSE OBJECTIVISM ABOUT A MORAL ISSUE?
No full text(Statement of Responsibility) by David Turon(Thesis) Thesis (B.A.) -- New College of Florida, 2013(Electronic Access) RESTRICTED TO NCF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE(Bibliography) Includes bibliographical references.(Source of Description) This bibliographic record is available under the Creative Commons CC0 public domain dedication. The New College of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.(Local) Faculty Sponsor: Graham, Steve
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