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EVOLUTIONARY DIVERSIFICATION OF AUSTRALIAN GALL-INDUCING THRIPSMcLeish, Michael John, mcleish@sanbi.org January 2007 (has links)
This work further elucidates processes involved in promoting and
sustaining evolutionary diversification within the gall-inducing thrips
that specialise on Australian Acacia. A phylogenetic approach was taken
to determine modes of diversification available to these insects. The
extension and revision of the gall-thrips phylogeny is central to the
work and primarily focuses on cryptic populations of the Kladothrips
rugosus and Kladothrips waterhousei species complexes. Parallel
diversification, where the radiation of the K. rugosus and K.
waterhousei lineages broadly mirror one another, offered a rare
opportunity to test hypotheses of coevolution between gall-thrips and
their Acacia hosts. In the absence of a reliable host Acacia phylogeny,
indirect inference of insect/plant cospeciation can be arrived at as
these two complexes share the same set of host species. The expectation
is that if the phylogenies for the gall-thrips complexes show a
significant level of concordance, then cospeciation between insect and
host-plant can be inferred. Results indicate that the K. rugosus species
complex comprise populations at species level. A significant level of
phylogenetic concordance between the two species complexes is consistent
with gall-thrips lineages tracking the diversification of their Acacia
hosts. Given the less than strict form of insect/host cospeciation,
factors impacting host diversification become important to gall-thrips
diversification. Gall-thrips radiated over a period during the expansion
of the Australian arid-zone. Cycles of host range expansion and
fragmentation during the Quaternary could have played a major role in
gall-thrips diversity. An interesting feature of resourse sharing
amongst the K. rugosus and K. waterhousei complex members is the
apparent absence of competitive exclusion between them. The persistence
of this sympatry over millions of years is an unusual feature and merits
further investigation.
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Regulation of Hydrogen Peroxide in the Human AirwayForteza, Radia 05 December 2008 (has links)
In airway epithelia, lactoperoxidase (LPO) constitutes an important anti-microbial system to protect the host against infection and inflammation. LPO uses hydrogen peroxide and thiocyanate anion to form the biocidal compound, hypothiocyanite. The rate-limiting factor is hydrogen peroxide substrate availability. This study was conducted to identify the major source of hydrogen peroxide and to characterize its regulation in the human airway. Two homologues of the phagocytic NADPH oxidase, Duox1 and Duox2, were shown to be highly expressed and functional in human airway epithelial cells re-differentiated at the air liquid interface (ALI). Duox activity is regulated by intracellular calcium concentration via its two EF-hand motifs. A rise of intracellular calcium concentration exhibited kinetics that correlated with increase of Duox-generated hydrogen peroxide production, which was inhibited by DPI, a NADPH oxidase inhibitor. Additionally, the involvement of Duox activity in the LPO system was investigated. Bacterial products such as flagellin or inflammatory mediators were used to challenge ALI cultures. As a result, mRNAs from Duox2, LPO and DUOXA2, but not Duox1, were up-regulated in response to stimuli. This study provided new information about the regulation of the anti-microbial LPO system in innate immune host defense.
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Bycatch and Discarding under Species InteractionsChen, Hsi-wen 25 June 2010 (has links)
By-catch is an unavoidable problem in fishery, and the occurrence of by-catch may lead to the phenomenon of discarding. Discarding of non-targeted species will not only result in the losses in economic, but may also damage the resource stock. As the interaction between species exists, the economic costs and the degree of damage derive from by-catch and discarding will become increasingly complicated.
The research will start from the assumption of possible interactions between species, investigating that under different interactions between species, the possible influence to the optimal decision of fishermen and resource stocks.
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Bacteria in Ballast Water: The Shipping Industry's Contributions to the Transport and Distribution of Microbial Species in TexasNeyland, Elizabeth B. 2009 August 1900 (has links)
The transportation of organisms in the ballast water of cargo ships has been recognized as a source of invasive species despite current control measures. Pathogenic bacteria in the ballast tank have been studied but the total diversity of the ballast tank bacterial community has not been examined. This study is the first to characterize the total bacterial community within a ballast tank by constructing a clone library from a ballast water sample from a cargo ship in the Port of Houston, amplified ribosomal rDNA restriction analysis (ARDRA) and phylogenetic analysis. Bacterial communities in Texas ports and bays were also examined using denaturing gradient gel electrophoresis (DGGE), looking at both temporal and spatial variations for effects of deballasting activity.
This ballast tank bacterial community had a high level of diversity (95%) with the clone library only representing 40% of the total community of the tank. Most probable originating habitats of the ballast bacteria were: marine pelagic (40%), estuarine (37%), coastal (6%), freshwater (3%) and other (14%), even though this ballast tank was exchanged with pelagic water. Predominate groups were alpha- and gammaproteobacteria, a few betaproteobacteria and bacteriodetes, and one each of verrucomicrobia, planctomycetes and actinobacteria, but no pathogens were detected. The data reveals a ballast tank that consists of half marine-pelagic, half port bacteria, revealing a low efficacy of exchange control methods and potentially invasive bacteria.
The bacterial communities of five ships that exchanged ballast water in the Pacific Ocean shared on average 50% similarity. Two ships that exchanged ballast water in temperate latitudes were more similar than three other ships that exchanged in tropical latitudes, showing a correlation between location of exchange and community similarity.
The bacterial communities of the Ports of Houston and Galveston exhibit stable, seasonal successions over one year. The port and bay systems of Texas exhibited spatial variations in bacterial communities related to salinity levels. Both experiments did not show evidence of community disruption by deballasting activities. This study shows that ballast water is a viable vector for invasive bacterial transport, although impact on Texas estuarine systems seems minimal.
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Green-tree retention and ectomycorrhiza legacies : the spatial influences of retention trees on mycorrhiza community structure and diversity /Stockdale, Christopher A. January 2000 (has links)
Thesis (M.S.)--Oregon State University, 2001. / Typescript (photocopy). Includes bibliographical references (leaves 67-78). Also available on the World Wide Web.
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Bestämd eller obestämd form : En studie i bestämdhet bland svenskstuderande i PolenQureshi, Karl January 2015 (has links)
Syftet med denna uppsats är att undersöka bruket av bestämdhet bland svenskstuderande i Polen och försöka utröna hur och i vilken grad deras bruk avviker från normen. För att få en holistisk bild av fenomenet har även normriktiga former tagits i beaktning. Metoden som tillämpas är en felanalys som har till syfte att studera felfrekvensen samt orsakerna till fenomenet genom att samtliga nominalfraser, med ett substantiv som huvudord, excerperas ur det primära materialet, bestående av 24 studentuppsatser. Dessa studeras och analyseras sedan för att kunna ge en enhetlig bild av fenomenet. Resultatet visar att studenterna överlag klarar att producera normriktiga fraser både avseende form och funktion. Bland de normriktiga nominalfraserna dominerar lexikaliserade fraser samt fraser som innehåller olika typer av attribut. Bland de avvikande nominalfraserna dominerar fraser med anaforisk samt svagt referentiell betydelse. Dessutom visar resultatet att studenterna gärna använder sig av en strategi som går ut på att kopiera satser och fraser redan givna i uppgiftens instruktioner, vilket i likhet med lexikaliserade fraser påverkar utfallet då studenterna oftast inte behöver ta hänsyn till substantivets böjning.
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Systematics of the Archiborborinae (Diptera: Sphaeroceridae)Kits, Joel 29 September 2011 (has links)
The Archiborborinae comprise a diverse clade of flies in the family Sphaeroceridae. This thesis presents the first phylogenetic analysis and a thorough taxonomic revision of the subfamily. The phylogenetic revision includes morphological data from all species, and molecular data from a subset of 21 ingroup species. Although the group here treated as the Archiborborinae has been traditionally treated as a tribe within the subfamily Copromyzinae, analysis of morphological, molecular, and combined datasets supports the monophyly of the Archiborborinae and shows that the Archiborborinae and Copromyzinae are not sister taxa. The Copromyzinae are more closely related to the Sphaerocerinae and possibly to the enigmatic genus Pycnopota than they are to the Archiborborinae. The elevation of the clade to subfamily rank is supported on the basis of this evidence. Basal relationships within the Archiborborinae are difficult to resolve, but the phylogenetic evidence generally supports a division of the subfamily into the following 8 genera: Antrops Enderlein 1909, Penola Richards 1941, Frutillaria Richards 1961, Boreantrops gen. nov., Coloantrops gen. nov., Maculantrops gen. nov., Photantrops gen. nov., and Poecilantrops gen. nov. The genus Archiborborus, until recently a paraphyletic assemblage including most of the described species in the subfamily, is treated as a junior synonym of Antrops (syn. nov.) All genera are described and a generic key is provided. A total of 122 species, including 25 previously described and 89 new, are fully described and illustrated; another 8 new species are diagnosed but not formally named.
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A MULTIGENE APPROACH FOR INVESTIGATING DNA BARCODE LINEAGES IN PROVISIONAL CRYPTIC SPECIES OF LEPIDOPTERA IN COSTA RICABertrand, Claudia 04 May 2012 (has links)
DNA barcoding has illuminated genetically distinct lineages within what appears to be one morphological species. For example, a large-scale DNA barcode analysis of Lepidoptera in the Área de Conservación Guanacaste has revealed that 8% of the morphospecies show more than one DNA barcode lineage. To assess the evolutionary significance of five of these lineages I conducted further molecular analyses by sequencing mitochondrial cytochrome b, nuclear Elongation Factor 1α and ribosomal Internal Transcribed Spacer 2, and compare their gene phylogenies with the provisional species tree hypothesized by DNA barcode genetic distances.
Both mitochondrial and nuclear markers support the existence of three cryptic species in one of the five cases. Morphological and ecological correlates are still lacking to understand the origin of this divergence. The lack of corroboration between markers in the four remaining species either suggests that the chosen nuclear markers have not diverged since speciation, or there has been recent hybridization between lineages. In one case, hybridization is strongly suggested. / Natural Sciences and Engineering Research Council of Canada, Genome Canada through the Ontario Genomics Institute
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Hybridization and the Typological ParadigmCarlson, Charles 2011 December 1900 (has links)
The presence of parasites in a population has an impact on mate choice and has substantial evolutionary significance. A relatively unexplored aspect of this dynamic is whether or not the presence of parasites increases the likelihood of hybridization events, which also have a significant role in ecological adaptation. One explanation of increased hybridization in some areas and not others is that stress from parasites results in selection for an increase of novel genotypes. Two swordtail species Xiphophorus birchmanni and Xiphophorus malinche maintain an active hybrid zone. The patterns of hybridization are unique in that they do not match up directly with expectations. We set out to test whether or not individuals can sense, using chemical cues, whether conspecifics in their immediate vicinity have high parasite loads and also whether this has an effect on mating and association behavior toward both conspecific and hybrid mates. Our hypothesis being that females will have greater association times with hybrid/heterospecific mates if conscpecifics are heavily parasitized. We found that females exposed to parasitized males had a weaker preference for conspecific odor than those exposed to unparasitized males, both relative to a water control and relative to hybrids.
The empirical investigation described above is coupled with a historical and philosophical discussion of some of the issues surrounding the acceptance and understanding of the concept of hybridization. This discussion takes as its major themes: an analysis of the role that social views have on the formation of scientific hypothesis; the lag between epochal change in the scientific community and the assimilation of the consequences into social beliefs; the survival of hierarchical and teleological thinking in our concept of species and purity; and the failures of contemporary evolutionary theory to provide satisfactory explanations about the meaning and upshot of hybridization. Two specific misconceptions about hybridization are addressed. First, that hybridization clashes with the belief in kinds/types/species having separate and pure identities. Secondly, the teleological view that reads purpose into nature and places all instances of variation on a hierarchical scale; the top and bottom of which are determined by estimated closeness to the predetermined perfection of a type.
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Patterns of availability and use of resources by otters (Lutra lutra L.) in southwest PortugalBeja, Pedro Rui January 1995 (has links)
The use of resources by otters (<I>Lutra lutra</I> L.) living along coasts and streams in Southwest Portugal was described, and related to their spatial and temporal patterns of availability. The use of freshwater along coasts was inferred from the spatial distribution of spraints, and from radio-tracking. Spraints were mostly concentrated at the mouth of streams that provided freshwater throughout the dry season, and where rest-sites were found within dense thickets of brambles. Rest-sites were considered a scarce resource, because they seemed to be associated with the few permanent sources of freshwater. Along the coast prey availability was highest in winter and lowest in later summer and autumn. The corkwing wrasse was the dominant prey, and the seasonal variation in diet was primarily related to fluctuations in its abundance: wrasse were consumed when they were most abundant, other prey being taken to compensate for lows in their availability. In streams there were large year-to-year fluctuations in fish abundance, and these were related to the severity of summer droughts. Spring was probably the period of maximum prey abundance. Eels and crayfish were the dominant prey, but cyprinids, toads and frogs were also important seasonally. Prey were consumed relative to availability, except eels, which were consumed less than expected during the peak abundance of crayfish. Crayfish and eels were more associated in spraints that expected by chance. The introduction of the American crayfish to Iberia contributed to increase food abundance from spring to early autumn. Breeding of otters occurred seasonally, but births were earlier on the coast (October-December) than inland (January-March), most probably as a consequence of the seasonal patterns of food availability. Litter sizes inland were larger than on the coast. Differences between otter habitats in Southwest Portugal and elsewhere were discussed. A conservation strategy for otters in this region was developed.
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