Dissertations / Theses on the topic 'Rarity'
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1
Pritt, Jeremy Joseph. "Defining rarity and determining the mechanisms of rarity for North American freshwater fishes." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/31696.
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Conserving rare species and protecting biodiversity depends on sound information on the nature of rarity. Rarity is multidimensional, presenting the need for a quantitative classification scheme by which to label species as rare or common. I defined rarity for freshwater fishes based on the range extents, habitat breadths, and site abundance and examined the relationship between these dimensions of rarity and imperilment. Imperiled fishes were most often rare by all three dimensions, whereas undesignated species were most often common by all three dimensions. Next, I examined the effect of sampling intensity on observed rarity of stream fish using different numerical and proportional rarity criteria and found that increasing sampling intensity increased the number of species labelled as rare with proportional criteria but did not affect the number of species labelled as rare with numerical criteria. Additional electrofishing passes within a fixed reach increases the likelihood of detecting rare and endemic species. A tradeoff between information collected and sampling resources should be carefully considered in the context of objectives when sampling for rare species. Finally, I examined the effect of regional and watershed habitat variables, biotic interaction variables, and instream habitat variables, on the rare or common status on 23 North American freshwater fishes. I also compared biological and reproductive traits among species classified into the rarity framework. Rarity was successfully explained in 19 of the 23 species and I found that regional and watershed habitat variables were the most important predictors of rarity. I also found that species large body size, high fecundity, and long age at maturity were generally more common by range extent and site abundance while those species that did not guard nests were more frequently rare by site abundance. These results indicate that large-scale variables can be used to successfully predict species rarity and rare fishes differ in their biology and reproduction from common fishes.Master of Science
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Johnson, Jana Joan. "Butterflies, rarity, and conservation practices." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1692119141&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Dalrymple, Sarah. "Rarity and conservation of Melampyrum sylvaticum." Thesis, University of Aberdeen, 2006. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=128181.
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Melampyrum sylvaticum (small cow-wheat) is a hemiparasitic annual of boreal-montane regions of Europe. The Species Action Plan recommended that in addition to protecting extant populations, by 2010 there should be an additional five populations that have been created with the aim of enhancing greater genetic diversity of the species. Consequently this project was set up in order to provide the ecological knowledge required to meet such targets. There are various management options available to conservationists looking to prevent Melampyrum sylvaticum’s extinction from the UK but from the results of this project it is clear that some methods have drawbacks that should preclude their use. Population augmentation with seeds from other populations is not advised due to the risk of genetic ‘swamping’ or outbreeding depression. Seed amplification would avoid these problems but may introduce different complications by artificially promoting certain genotypes within a population. Population expansion by mimicking ant dispersal is recommended as a way of minimizing density dependent mortality in larger populations but is not suitable in smaller populations. Seed translocation to unoccupied sites is therefore, the best option but the exact details of seed-sourcing and sowing should be guided by the results of the Species Recovery Project in order to avoid predicted limitations. The long-term outlook for M. sylvaticum will depend entirely on whether populations can be created that operate as part of a functioning ecosystem (including pollinating and seed-dispersing insects) with enough demographic and genetic stability to survive predicted climate change.
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Webb, Thomas James. "Evolutionary causes and consequences of rarity." Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251266.
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Lennard, Christopher James. "The causes of avian extinction and rarity." Master's thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/20042.
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Bibliography: pages 144-153.Biological extinction rates have escalated by as much as 1000 times the background extinction rate over the last 1500 years, causing concern over the long-term survival of many species. Avian extinctions since 1600 have been well documented relative to other taxa, as have current levels of avian threat. This study analyses avian extinctions post-1600 and current threats in an attempt to develop some predictive capacity about which avian taxa should be awarded the highest conservation priority. Analyses performed include examinations of the causes of avian extinction and threat, geographical location of extinct and threatened species, prehistoric and historical extinction rates, endemicity, migration, bird body size and phylogenetic diversity. An analysis dealing with historical and phylogenetic aspects of endangered and critically threatened species was performed, from which the world's most threatened species were identified. Factors which were the primary cause of historical extinctions are generally not the primary factors threatening today's extant avifauna. Whilst introduced predators and exploitation were primary causes of historical extinctions, habitat destruction poses the greatest threat to extant birds. Species predisposed to extinction typically have restricted ranges, and, compounded by habitat loss, these ranges are becoming more restricted. This has resulted in mainland-dwelling species becoming as prone to extinction as island-dwelling species have been historically. Introduced predators, however, do still threaten many of the world's most threatened species and their potential effects are highlighted in the phylogenetic analysis. Already, many extinctions may be inevitable over the next 25 years as a result of habitat loss. The magnitude of extinctions across all animal and plant species in the next few decades could be comparable with that of previous mass extinctions unless immediate conservation action is taken. However, future conservation efforts will have to be prioritized, and this study is intended as a contribution towards such a prioritization exercise.
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Hoffsten, Per-Ola. "Rarity in boreal stream insects : patterns, causes and consequences /." Doctoral thesis, Umeå University, Ecology and Environmental Science, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-142.
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Patterns of site occupancy among boreal stream insects were studied in central Sweden with focus on sparsely distributed species and the role of dispersal and niche limitations.
In the study of dispersal limitation, I found that effects of an extraordinarily harsh winter in small to medium-sized streams were strongest in sites located in small streams and far from lake outlets. Species richness and the total abundance of macroinvertebrates and trout returned to pre-disturbance levels after three years. However, some species showed slow recolonization and the proportion of holoaquatic taxa was still reduced after three years. In a second study, I found a positive correlation between site occupancy in stream caddisflies and morphological traits associated with fast and energy-efficient flight, whereas specialized spring caddisflies showed a negative correlation to these traits compared to stream species. This suggested that streams, but not springs, select for strong dispersal ability in caddisflies. In a survey of springs in central Sweden, hydrogeology was found to be a useful predictor of the occurrence of spring specialists. Two of these, Crunoecia irrorata Curtis and Parachiona picicornis (Pictet), were found exclusively in glaciofluvial springs, characterized by a stable discharge and temperature. Less specialized members of the spring fauna (i.e. species also occurring in streams, ponds or lakes) also occurred in moraine and limestone springs characterized by more unstable conditions.
Niche limitations were studied by contrasting large-scale distributions of closely related rare and common stoneflies. Differences in temperature requirements in the juvenile stages and life cycles suggested that the rare species, Isogenus nubecula Newman, was restricted by a limited tolerance to low stream temperatures, whereas the two common species, Isoperla grammatica (Poda) and Diura nanseni (Kempny), appeared to have a broader tolerance to climatic conditions in the study area. In a second study of niche limitations, macroinvertebrate assemblages in 88 streams in Central Sweden showed a nested distribution pattern. Most species deviating from expected distributions occurred in small streams, indicating competitive exclusion from species-rich sites, predator avoidance, or specialization to unique habitat features of small streams. In the last paper, the longitudinal distribution of filter-feeding caddisflies in a lake-outlet stream demonstrated patterns concordant to feeding specialization.
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Xiang, Lan. "Interesting Association Rules Mining Based on Improved Rarity Algorithm." Thesis, Mittuniversitetet, Avdelningen för informationssystem och -teknologi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-35320.
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With the rapid development of science and technology, our society has been in the big data era. In human activities, we produce a lot of data in every second and every minute, what contain much information. Then, how to select the useful information from those complicated data is a significant issue. So the association rules mining, a technique of mining patterns or associations between itemsets, comes into being. And this technique aims to find some important associations in data to get useful knowledge. Nowadays, most scholars at home and abroad focus on the frequent pattern mining. However, it is undeniable that the rare pattern mining also plays an important role in many areas, such as the medical, financial, and scientific field. Comparing with frequent pattern mining, studying rare pattern mining is more valuable, because it tends to find unknown, unexpected, and more interesting rules. But the study of rare pattern mining is little difficult because of the scarcity of data used for verifying rules. In the frequent pattern mining, there are two general algorithms of discovering frequent itemsets, i.e., Apriori, the earliest algorithm which is proposed by R.Agrawal in 1994, and FP-Tree, the improved algorithm which reduced the time complexity. And in rare pattern mining, there are also two algorithms, Arima and Rarity, what are similar to Apriori and FP-Tree algorithms, but they still exist some problems, for example, Arima is time-consuming because of repeatedly scanning the large database, and Rarity is space-consuming because of the establishment of the full-combination tree. Therefore, based on the Rarity algorithm, this report presents an improved method to efficiently discover interesting association rules among rare itemsets and aims to get a balance between time and space. It is a top-down strategy which uses the graph structure to indicate all combinations of existing items, defines pattern matrix to record itemsets, and combines the hash table to accelerate calculation process. This method decreases both the time cost and the space cost when comparing with Arima, and reduces the space waste to solve the problem of Rarity, but its searching time of mining rare itemsets is more than Rarity, and we verified the feasibility of this algorithm only on abstract and small databases. Thus in the future, on the one hand, we will continue improving our method to explore how to decrease the searching time in the process and adjust the hash function to optimize the space utilization. And on the other hand, we will apply our method to actual large databases, such as the clinical database of the diabetic patients to mine association rules in diabetic complications.
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Rustage, Sarah Elizabeth. "Correlates of rarity in UK bumblebee (Bombus spp.) populations." Thesis, University of Plymouth, 2015. http://hdl.handle.net/10026.1/3372.
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The decline of bumblebee (Bombus spp.) populations in the UK and worldwide has been well reported. It has been generally assumed that such declines result in the genetic impoverishment of some species, potentially leading to reduced fitness and increased extinction risk. This study tested the fundamental assumption linking population fragmentation with fitness, in a model system of two Bombus species native to the UK. Bombus monticola has declined significantly in range across the UK in recent years and occupies fragmented upland areas, while Bombus pratorum has remained abundant and widespread over many habitat types. The effects of genetic diversity on fitness have been addressed in wild Bombus species, but this is the first study to explicitly compare data from species of differing levels of population connectivity and hence test the assumptions of traditional population genetic theory. As genetic diversity has often been linked with immunocompetence, aspects of the innate immune response were quantified, together with parasite load. These empirical measures of fitness showed lower than expected variability between the two study species, and no evidence was found to support the theory of lower fitness in fragmented populations. However, the considerable variability between sample sites in both species for all parameters measured raised interesting questions as to the underlying evolutionary processes; it is postulated that B. monticola populations may maintain a higher than expected Ne, despite their fragmented distribution. This study also provided methodological developments. An alternative method for the quantification of wing wear as a proxy for age was proposed, which could be easily applied to other Bombus species and possibly adapted for use in other flying insects. In addition possible sources of error in AFLP analysis were highlighted which have not been adequately discussed in the current literature, namely the effects of sample storage. Given the utility of AFLPs for non-model species, this is an important avenue for future research, and would be applicable to studies in other systems. Overall, the data presented here emphasise the challenges of studying fitness in wild populations, and underline the requirement for research into the fundamental principles underlying many assumptions made by conservation genetic theory.
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Pilgrim, Emma Susan. "The ecology of rarity : an experimental study using arable weeds." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404578.
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Simmons, Mark Trevor. "Vegetation, diversity and rarity on the Cape Peninsula, South Africa." Master's thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/9668.
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Bibliography: leaves 93-107.The Cape Peninsula, (471 km²) with over 2285 vascular plant species, is characterised by the combination of a diversity of habitats supporting a mosaic of vegetation types. This study attempts to describe and explain some of the determinants of species pattern and distribution. The first part of this thesis compares a simple vegetation classification, derived from visual examination of dominant species and environmental characteristics, with the result of a multivariate classification derived from the analysis of an extensive database (835 plots, 833 species). This rapid system of classification of fynbos showed an 81 similarity with Two-Way Analysis (TWA) classification. Detrended Correspondence Analysis (DCA) and Colonial Analysis (CCA) were used to relate floristic variation to environmental factors. These analyses revealed that altitude, rainfall and soil fertility were the principle environmental factors explaining species distribution.
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Handley, Richard John. "Determinants of rarity in a dioecious annual macrophyte, Najas marina L." Thesis, University of East Anglia, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327542.
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Walker, Jonathan S. "Feeding ecology and rarity of frugivorous birds in tropical rain forest." Thesis, Manchester Metropolitan University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400944.
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Giles, Mark. "Patterns of Species Rarity as a Driving Mechanism for Species Richness Gradients." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40587.
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Broad scale geographic variation in species diversity correlates with environmental variables in most taxa, but a mechanistic understanding of this relationship has remained elusive. More than a half-century ago, F.W. Preston observed that the number of individuals per species in species assemblages is log-normally distributed (with two parameters: the total number of individuals, I, and the number of individuals of the rarest species, m). Here, we show that ϕ, a proxy for m, is correlated with environmental variables in several datasets of trees, birds, fish, and invertebrates. Moreover, variation in species richness is more strongly related to this measure of rarity than to environment. In all the datasets we examined, structural equation models are consistent with the hypothesis that environmental variables affect species richness principally by affecting rarity, which in turn affects richness. We propose that geographic variation in the ability of species to persist at low densities provides a possible unifying explanation for global gradients of species richness. Our findings may have important implications regarding Earth’s biodiversity, highlighting the rarest species as those most at-risk but also important indicators for the ongoing consequences of climate change.
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Rebelo, Anthony G. "The preservation of the Cape flora : status, causes of rarity, ideals and priorities." Doctoral thesis, University of Cape Town, 1992. http://hdl.handle.net/11427/14229.
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Includes bibliographies.The Cape Floristic Region (CFR), covering 90 000 km2, comprises one of the world's six floral kingdoms. With 8600 species, of which 68 per cent are endemic, it ranks amongst the richest of temperate and tropical floras. Although 19 per cent of the CFR occurs in nature reserves, by far the majority of the preserved area comprises Mountain Fynbos. Only 0.5 and 3 per cent of the original extent of Renoster Shrub/and Lowland Fynbos is preserved, respectively. In this study Fynbos vegetation is identified as the richest habitat for Red Data Book (RDB) plant, freshwater fish, amphibian, butterfly, and reptile species in southern Africa. The greater Cape Town metropolitan area is identified as containing by far the highest richness of RDB plant, butterfly, reptile and amphibian species in the CFR Thus, this area ranks globally as one of the most urgent conservation priorities. The study also illustrates that previously used methods for evaluating priority conservation areas have under-rated species-poor areas containing a high proportion of RDB species. By collecting for species richness, a far more realistic picture of threatened areas can be obtained from RDB taxa. This study predicts, using a priori hypotheses based on ecological traits, and finds, that seed dispersal and regeneration strategies are most strongly correlated with rarity, most specifically with distributional area. Using distributional data for the Proteaceae, this study estimates that 95 per cent of all vascular plant species in Fynbos can be preserved in 16 per cent of the area. It also identifies the sites that require preservation if the maximum protection of floral diversity is to be realized. Two null models for evaluating the efficiency of a spatial configuration of reserves are proposed. Utilizing an iterating selection procedure, this study explores various algorithms, based on species richness and rarity, to construct ideal reserve configurations. This study provides the first empirical confirmation that the ideal approach to designing a reserve configuration is to identify areas of high endemism and richness in distinctive vegetation types within particular biogeographical regions. Thus, this study pioneers the use of RDB data to identify priority conservation regions, provides one of the first assessments of the causes of rarity in plants and establishes useful null models and algorithms for the identification and testing of ideal reserve locations in the design of integrated reserve networks. Not only does this study contribute towards theoretical reserve selection procedures, but it provides one of the most advanced frameworks for the preservation of a top conservation priority in the world, the CFR.
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Mugodo, James, and n/a. "Plant species rarity and data restriction influence the prediction success of species distribution models." University of Canberra. Resource, Environmental & Heritage Sciences, 2002. http://erl.canberra.edu.au./public/adt-AUC20050530.112801.
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There is a growing need for accurate distribution data for both common and rare plant
species for conservation planning and ecological research purposes. A database of more than
500 observations for nine tree species with different ecological and geographical
distributions and a range of frequencies of occurrence in south-eastern New South Wales
(Australia) was used to compare the predictive performance of logistic regression models,
generalised additive models (GAMs) and classification tree models (CTMs) using different
data restriction regimes and several model-building strategies. Environmental variables
(mean annual rainfall, mean summer rainfall, mean winter rainfall, mean annual temperature,
mean maximum summer temperature, mean minimum winter temperature, mean daily
radiation, mean daily summer radiation, mean daily June radiation, lithology and
topography) were used to model the distribution of each of the plant species in the study
area.
Model predictive performance was measured as the area under the curve of a receiver
operating characteristic (ROC) plot. The initial predictive performance of logistic regression
models and generalised additive models (GAMs) using unrestricted, temperature restricted,
major gradient restricted and climatic domain restricted data gave results that were contrary
to current practice in species distribution modelling. Although climatic domain restriction
has been used in other studies, it was found to produce models that had the lowest predictive
performance. The performance of domain restricted models was significantly (p = 0.007)
inferior to the performance of major gradient restricted models when the predictions of the
models were confined to the climatic domain of the species. Furthermore, the effect of data
restriction on model predictive performance was found to depend on the species as shown by
a significant interaction between species and data restriction treatment (p = 0.013). As found
in other studies however, the predictive performance of GAM was significantly (p = 0.003)
better than that of logistic regression. The superiority of GAM over logistic regression was
unaffected by different data restriction regimes and was not significantly different within
species.
The logistic regression models used in the initial performance comparisons were based on
models developed using the forward selection procedure in a rigorous-fitting model-building
framework that was designed to produce parsimonious models. The rigorous-fitting modelbuilding
framework involved testing for the significant reduction in model deviance (p =
0.05) and significance of the parameter estimates (p = 0.05). The size of the parameter
estimates and their standard errors were inspected because large estimates and/or standard
errors are an indication of model degradation from overfilling or effecls such as mullicollinearily.
For additional variables to be included in a model, they had to contribule
significantly (p = 0.025) to the model prediclive performance. An attempt to improve the
performance of species distribution models using logistic regression models in a rigorousfitting
model-building framework, the backward elimination procedure was employed for
model selection, bul it yielded models with reduced performance.
A liberal-filling model-building framework that used significant model deviance reduction at
p = 0.05 (low significance models) and 0.00001 (high significance models) levels as the
major criterion for variable selection was employed for the development of logistic
regression models using the forward selection and backward elimination procedures. Liberal
filling yielded models that had a significantly greater predictive performance than the
rigorous-fitting logistic regression models (p = 0.0006). The predictive performance of the
former models was comparable to that of GAM and classification tree models (CTMs). The
low significance liberal-filling models had a much larger number of variables than the high
significance liberal-fitting models, but with no significant increase in predictive
performance. To develop liberal-filling CTMs, the tree shrinking program in S-PLUS was
used to produce a number of trees of differenl sizes (subtrees) by optimally reducing the size
of a full CTM for a given species. The 10-fold cross-validated model deviance for the
subtrees was plotted against the size of the subtree as a means of selecting an appropriate
tree size. In contrast to liberal-fitting logistic regression, liberal-fitting CTMs had poor predictive performance.
Species geographical range and species prevalence within the study area were used to
categorise the tree species into different distributional forms. These were then used, to
compare the effect of plant species rarity on the predictive performance of logistic regression
models, GAMs and CTMs. The distributional forms included restricted and rare (RR)
species (Eucalyptus paliformis and Eucalyptus kybeanensis), restricted and common (RC)
species (Eucalyptus delegatensis, Eucryphia moorei and Eucalyptus fraxinoides),
widespread and rare (WR) species (Eucalyptus data) and widespread and common (WC)
species (Eucalyptus sieberi, Eucalyptus pauciflora and Eucalyptus fastigata). There were
significant differences (p = 0.076) in predictive performance among the distributional forms
for the logistic regression and GAM. The predictive performance for the WR distributional
form was significantly lower than the performance for the other plant species distributional
forms. The predictive performance for the RC and RR distributional forms was significantly
greater than the performance for the WC distributional form. The trend in model predictive
performance among plant species distributional forms was similar for CTMs except that the
CTMs had poor predictive performance for the RR distributional form.
This study shows the importance of data restriction to model predictive performance with
major gradient data restriction being recommended for consistently high performance. Given
the appropriate model selection strategy, logistic regression, GAM and CTM have similar
predictive performance. Logistic regression requires a high significance liberal-fitting
strategy to both maximise its predictive performance and to select a relatively small model
that could be useful for framing future ecological hypotheses about the distribution of
individual plant species. The results for the modelling of plant species for conservation
purposes were encouraging since logistic regression and GAM performed well for the
restricted and rare species, which are usually of greater conservation concern.
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Hopkins, Graham Wyn. "Rarity of tree aphids with particular reference to the birch aphid Monaphis antennata (Kaltenbach)." Thesis, University of East Anglia, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338048.
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Henfield, Malik S. ""I am a rarity in my school" hidden obstacles for African Americans in gifted education /." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1155752723.
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Mills, Michelle Holland. "Correlates of rarity in the flora of North America : life histories, habitats, and geographic distributions /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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McKenna, David J. "Demographic and ecological indicators of rarity in a suite of obligate-seeding Persoonia (Proteaceae) shrubs." Access electronically, 2007. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20080131.142010/index.html.
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Martin, Lynn. "Factors contributing to the rarity and threatened status of the Large Copper butterfly (Lycaena dispar batavus)." Thesis, Keele University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341238.
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The Large Copper butterfly, Lycaena dispar, is extinct in Britain and rapidly declining in the rest of Europe, due predominantly to loss of its wetland habitats. In the Netherlands the sub-species L. d. batavus is at the edge of its range in Northern Europe and, as with most marginal butterflies, has more specialised food plant and habitat requirements than the core populations of L. d. ruti/us. The aim of this study was to investigate some of the reasons for its continuing rarity, particularly looking at the reasons for its specialisation on Rumex hydrolapathum in a fen land habitat, whilst L. d. ruti/us is more generalist and utilises a range of Rumex species. Laboratory experiments reveal that L. d. batavus has retained its ability to feed on other Rumex species, without detriment to their overall survival and can utilise these alternative host plants more efficiently than their natural host plant. This indicates that plant chemistry is not responsible for their lack of utilisation in the wild. Field experiments have also shown these potential hosts can support larvae, throughout each of their larval stages, to maturity within a natural habitat, with no significant differences in survival rates compared with R. hydrolapathum. Investigations into adult female oviposition preferences were undertaken. Females showed a willingness to oviposit on alternative Rumex and expressed no preference for any particular plant species. There are plans to re-establish L. dispar into Britain in the near future, dependent upon the location of a suitable donor population. Allozyme electrophoresis work on L. dispar and several of its captive colonies, has revealed that the wild Dutch, and one captive population, have sufficiently high levels of genetic diversity that may enable a reestablishment programme to go ahead with a captive colony, if necessary.
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Cioffi, Rebekah Katie Elizabeth. "Understanding rarity and latitudinal range relationships in European diving beetles (Dytiscidae) using metabolic plasticity and immunocompetence." Thesis, University of Plymouth, 2017. http://hdl.handle.net/10026.1/9480.
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Whilst the geographical range of species is a fundamental unit of macroecology and a leading predictor of extinction risk, the evolutionary dynamics of species’ ranges remain poorly understood. In some aquatic beetles, thermal niche has been shown to be related to both the relative range size and position of congeners but whether other physiological niche parameters play a role is unknown. Here, immunocompetence and metabolic plasticity were related to biogeography in these insects. Immunocompetence was first compared within a rare-common pair of Hydroporus species, finding species-specific immunity, which was affected by sex and acclimation time in the laboratory, with no clear relationship with rarity. This relationship was explored further in Deronectes species, whilst controlling for sex and acclimation time. Southern, narrow-ranging species had higher phenoloxidase (PO) activity, lower parasite load and antimicrobial peptide (AMP) activity that was stronger against Gram-negative Bacteria but weaker against Gram-positive Bacteria than their wider-ranging counterparts. As both of these studies found that PO activity did not positively correlate with encapsulation or AMP activity as reported in the literature, the pathway was investigated further in Tribolium castaneum. The data showed that the assumptions of the widely-used PO assay were violated, with differential activity between PO-driven reactions in melanin synthesis and different substrates used by larvae and adults. Future work should be wary of using the PO assay as a marker of potential melanin production and take into account the developmental requirements for melanin at different life stages. The relationship between metabolic plasticity and range was then assessed in Deronectes, finding that southerly species had more marked changes in glucose and protein content under elevated temperature stress than their northerly counterparts. Glucose content was also significantly positively correlated to lipid content, indicating that the energetics of species exhibiting differing range sizes may warrant future study. As the results from Hydroporus suggested that there may be trade-offs between immune defence and metabolism, the data on metabolic plasticity and immunocompetence in a sub-sample of Deronectes species were combined with thermal physiology, dispersal ability, body size and phylogenetic relatedness to assess which of these best explained variation in range size and position. Whilst variation in range extent and position were explained in part by thermal physiology, aspects of metabolic plasticity and immunocompetence also appeared to be important. This thesis provides one of the first indications that immunocompetence and metabolic plasticity may be related to geographical range and suggests parameters that may be worthy of exploration in other taxa.
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Yenni, Glenda Marie. "Self-limitation as an explanation for species' relative abundances and the long-term persistence of rare species." DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/1958.
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Much of ecological theory describes species interactions. These interactions often play an important theoretical role in facilitating coexistence. In particular, rarity in ecological communities, though often observed, provides a significant challenge to theoretical and empirical ecologists alike. I use a plant community model to simulate the effect of stronger negative frequency dependence on the long-term persistence of the rare species in a simulated community. This strong self-limitation produces long persistence times for the rare competitor, which otherwise succumb quickly to stochastic extinction. The results suggest that the mechanism causing species to be rare in this case is the same mechanism allowing those species to persist. To determine if ecological communities generally show the theoretical pattern, I estimate the strength of frequency-dependent population dynamics using species abundance data from 90 communities across a broad range of environments and taxonomic groups. In approximately half of the analyzed communities, rare species showed disproportionately strong negative frequency dependence. In particular, a pattern of increasing frequency dependence with decreasing relative abundance was seen in these communities, signaling the importance of this mechanism for rare species specifically. Insight into the special population dynamics of rare species will inform conservation efforts in response to climate change and other disturbance. Further difficulties in the detection of theoretical patterns in ecological data may be a result of the ecological currency used. Though ecologists typically use abundance data to test theories, energy use is another ecological currency that may be more relevant in some cases. In particular when detecting patterns that are a result of species interactions, the currency used should be the one in which those interactions actually operate. I compare the results of using abundance and energy use to detect two processes with well-defined expectations. The first is a description of population dynamics, the above described relationship between relative abundance and self-limitation. The second, compensatory dynamics, is a description of community-level dynamics. I find that the currency used alters the results, and thus the species-level implications. It does not, however, alter the overall pattern that would have theoretical implications. Results in both currencies support the pattern of strong self-limitation for persistent rare species.
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Munagani, Indira Priya Darshini. "Mining Rare Features in Fingerprints using Core points and Triplet-based Features." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/24784.
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A fingerprint matching algorithm with a novel set of matching parameters based on core points and triangular descriptors is proposed to discover rarity in fingerprints. The algorithm uses a mathematical and statistical approach to discover rare features in fingerprints which provides scientific validation for both ten-print and latent fingerprint evidence. A feature is considered rare if it is statistically uncommon; that is, the rare feature should be unique among N (N>100) randomly sampled prints. A rare feature in a fingerprint has higher discriminatory power when it is identified in a print (latent or otherwise). In the case of latent fingerprint matching, the enhanced discriminatory power from the rare features can help in delivering a confident court judgment. In addition to mining the rare features, a parallel algorithm for fingerprint matching on GPUs is also proposed to reduce the run-time of fingerprint matching on larger databases. Results show that 1) matching algorithm is useful in eliminating false matches. 2) each of the 30 fingerprints randomly selected to mine rare features have a small set of highly distinctive statistically rare features some of whose occurrence is one in 1000 fingerprints. 3) the parallel algorithm implemented on GPUs for larger databases is around 40 times faster than the sequential algorithm.Master of Science
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Knapp, Sonja. "Plant biodiversity in urbanized areas analyses of plant functional traits in space and time, plant rarity and phylogenetic diversity." Wiesbaden Vieweg + Teubner, 2009. http://d-nb.info/995192685/04.
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McCue, Kimberlie A. "The ecological genetics of rarity : a study of genetic structure, inbreeding and seed bank dynamics in a rare annual plant /." free to MU campus, to others for purchase, 1997. http://wwwlib.umi.com/cr/mo/fullcit?p9841324.
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Line, Eric R. "Effects of Landscape Aggregation and Landscape Conversion on Bird Diversity in Ohio from 2013-2017." Bowling Green State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1621604319860423.
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Kilani, Asma. "Le rôle des restrictions temporelles de vente sur l'évaluation de l'offre et l'intention d'achat : analyse par méthode des scénarios." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAB014/document.
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Le rôle des restrictions de vente sur l’évaluation de l’offre et l’intention d’achat reste controversé. La littérature marketing est divisée à ce sujet et met en avant différents cadres conceptuels et théories susceptibles d’expliquer les effets de ces restrictions. Face à ce manque d’unanimité dans la littérature et dans un contexte où la rentabilité des promotions de vente n’est pas établie, cette thèse vise une meilleure compréhension de l’impact des limites temporelles sur l’évaluation d’une offre promotionnelle de vente et l’intention d’achat du consommateur. Cette étude a été réalisée à l’aide d’une méthodologie mixte, basée sur une étude exploratoire, et une étude quantitative conduite selon la méthode des vignettes. Les résultats soulignent un comportement ambivalent des consommateurs face aux restrictions temporelles et mettent en évidence un rôle modérateur de la marque pouvant atténuer la perception des inconvénients dans le cadre d’une restriction temporelle de venteThe role of the sales restrictions on the evaluation of the offer and the intention of purchase still stays controversial. The marketing literature is divided over the subject and sets up different conceptual frames and theories explaining the effects of these restrictions. Facing the lack of unanimity in literature, in a context where the rentability of sales promotions is not established, this thesis aims to a better comprehension of the impact of the temporal limits on the evaluation of a promotional sales offer and the intention of the consumer's purchase. This survey was made through a mixed methodology made by an exploratoring study lead by focus groups and by a quantitative study lead by the scanario method. The results of our explorating survey underline an ambivalent behaviour versus the temporal restriction of sales. Our empiric study reveals a moderating role of the brand able to limit the perception of the drawbacks in the space of the time restrictions of sales
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Müller, Gregor Simon [Verfasser]. "Testing the relative roles of competition and plant-soil feedback in explaining commonness and rarity of alien and native plant species / Gregor Simon Müller." Konstanz : Bibliothek der Universität Konstanz, 2017. http://d-nb.info/1138566349/34.
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Fox, Call Christina Elizabeth. "Population Structure, Genetic Diversity, Geographic Distribution, and Morphology of Two Boechera (Brassicaceae) Parental Species (Boechera thompsonii and Boechera formosa) and of Their Resultant Hybrid Boechera duchesnensis." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/6233.
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Background: Over the relatively short period of its evolutionary history, Boechera (Brassicaceae) has undergone rapid radiation that has produced 70+ morphologically distinct, sexual diploids. However, reproductive isolation has moved more slowly than morphological divergence in this group and the diploids appear to hybridize frequently where they coexist. Boechera duchesnensis appears to be the result of hybridization between its putative parents Boechera thompsonii and Boechera formosa. Objectives: The objectives of this study are to (i) analyze and document genetic diversity patterns in the population structure, - including allelic and heterozygosity frequencies - of B. thompsonii and B. formosa in concert with their geographic distribution to determine clustering relationships within these populations, (ii) confirm and expand the morphological characteristics of B. thompsonii and B. formosa, as initially proposed in the literature, including pollen and trichome structure using Scanning Electron Microscopy (SEM) to confirm ploidy level and to determine whether both putative parent species share morphological characteristics with their apomictic diploid offspring, and (iii) use genetic and morphologic evidence to show that B. thompsoii and B. formosa are, in fact, the parents of B. duchesnensis by comparing the genetic diversity patterns, population structure, and morphological characteristics of B. duchesnensis, to those of its proposed putative parents (B. thompsonii and B. formosa) and to confirm that B. duchesnensis shares characteristics of Boechera. Methods: Microsatellite data from 14 loci previously identified in Boechera were used to reexamine the current classifications and taxonomic foundations of three Boechera spp. GenAlEx 6.501 (Peakall and Smouse, 2006, 2012) was used to analyze genetic population structures of two divergent sexual diploids in the genus Boechera: B. thompsonii and B. formosa and to later compare those with the population structure of B. duchesnensis. Geographicaldata were plotted using ArcGIS 10.1 (Esri, 2012) to map heterozygosity distribution. Cluster analysis was run with STRUCTURE 2.3.3 (Pritchard et al., 2000; Falush et al., 2003, 2007) and distribution of allelic diversity and heterozygosity was subsequently compared within each taxon and correlated with geographic distribution characteristics. Resultant data were then compared with B. duchesnensis data to document genetic diversity patterns, population structure, and morphological characteristics. Key Results: Analysis of genetic diversity patterns, allelic distribution of the populations, and heterozygosity of B. thompsonii and B. formosa across their geographic range identified four genetically distinct clusters within B. thompsonii, and one genetically distinct cluster in B. formosa. Allelic frequencies in all four discrete population clusters of B. thompsonii and in one discrete population cluster of B. formosa were close to values found in species on the decline. Reproductive isolation, genetic variability, and allelic frequencies were determined, specimen elevations reported, and morphological characteristics reported in the literature were confirmed and expanded. A codominant genetic analysis performed for 14 different loci for B. duchesnensis against those of its parents showed that B. duchesnensis inherits alleles from both putative parents and confirms B. thompsonii and B. formosa as the parents of B. duchesnensis. Observed levels of heterozygosity of B. thompsonii and B. formosa were lower than expected levels and lower than those of other outcrossing diploids. The mean overall observed heterozygosities for each cluster were determined and documented by geographic location. A substantially higher level of observed heterozygosity in B. duchesnensis (Ho = 0.908) consistent with genetic fixation of a heterozygote and apomixis, supports hybridization as a speciation mechanism and apomixis as a mode of reproduction accounting for genotypic and phenotypic diversity. Morphological characteristics, especially those of pollen and trichomes were confirmed, expanded, and documented with SEM imagery. Discussion: This study provides an analysis of the genetic diversity patterns inherent in the population structure, allelic frequencies, allelic variation among individuals of the rare sexual diploids B. thompsonii, B. formosa, and the apomictic diploid B. duchesnensis in correlation with their geographic distribution. There is an implication of a reproductive barrier, within populations of the same species, that contributes to genetic isolation between clusters. I analyze the tendency of reduced heterozygosity to lead to genetic fixation, reproductive isolation, and how the heightened heterozygosity supports the classification of B. duchesnensis as an apomict. Assessing potential populations that might exist based on similar characteristics could possibly provide inferences about where future research might find similar examples of this hybridization. Reproductive isolation is hypothesized to limit gene flow between identified clusters of B. thompsonii and B. formosa exacerbating low observed heterozygosity levels and low allelic frequency levels. Population studies and cluster analysis have implications for offering future conservation strategies for both taxa.
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Barreto, Bruno de Souza. "Biogeografia da conservação de morcegos no cerrado brasileiro." Universidade Federal de Goiás, 2008. http://repositorio.bc.ufg.br/tede/handle/tede/3178.
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Fundação de Apoio à Pesquisa - FUNAPE
The units of conservation are main strategy adopted by the rulers to guarantee that the negative effects of the socioeconomic development reach less the biodiversity. recent researches have been trying to outline the problem through reserve selection that seek larger representativeness of the goals of conservation (in general some estimador of the biodiversity as the species) in terms of a smaller number of areas as possible. in the last 50 years the cerrado is going by transformations in their natural landscapes due to the progress of the modern agriculture and of the livestock. due to that, the objective of that work was to define priority areas network for conservation of bats in terms of five conservation sceneries differents. the generated nets were restricted by socioeconomic cost, presence of cave and a cost that considers the previous two cost. the results revealed main features of analyses of complementarity: multiple solutions, flexibility of the nets, and influence of the rarity of the species for the definition of groups starting from the pattern of rarity. the costs were important for definition of nets that avoided as much conflicts of conservation as prioritized the species in areas of cave.
As unidades de conservação são principal estratégia adotada pelos governantes para garantir que os efeitos negativos do desenvolvimento socioeconômico atinjam menos a biodiversidade. recentes pesquisas têm tentado contornar o problema através de seleção de reservas que visam maior representatividade das metas de conservação (em geral algum estimador da biodiversidade como as espécies) em termos de um menor número de áreas quanto possível. nos últimos 50 anos o cerrado vem passando por transformações em suas paisagens naturais em decorrência do avanço da agricultura moderna e da pecuária. os morcegos são também ameaçados e em decorrência disso, o objetivo desse trabalho foi definir redes de reservas regionais prioritárias para conservação de morcegos em termos de cinco cenários de conservação diferentes. as redes geradas foram restringidas por custo socioeconomico, custo presença de caverna e custo que podera os dois anteriores. os resultados reelaram as principais caracteísticas de análises de complementaridade: multiplas soluçoes, flexibilidade das redes, influência da raridade das espécies pela definição de grupos a partir do padrão de raridade. os custos foram importantes para definição de redes que evitaram tanto conflitos de conservação quanto priorizaram as espécies em regioes de caverna.
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Sgarbi, Luciano Fabris. "Determinantes da raridade das espécies e seus efeitos sobre a estrutura de comunidades biológicas." Universidade Federal de Goiás, 2018. http://repositorio.bc.ufg.br/tede/handle/tede/8612.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
A recurrent pattern seen in nature is that species vary in abundance among sites, being common in a few sites and rare at the majority of sites. This intraspecific distribution of abundance, in turn, generates an excess of rare species in biological communities. This excess may cause problems in data analyses as datasets include many zeros. In this thesis I studied the causes of species rarity and how the excess of rare species influence the detection of patterns at the community level. In the first chapter I observed that species classified as rare were common in other habitat types, in other sites elsewhere, and in other years. However, among these three factors, the rarity was explained mainly by the habitat type. In the second chapter I observed that species tend to become rarer as they distance themselves (above, below or in both directions) from their optimal elevation. This pattern was quite robust and independent of taxonomic group or geographic region. In the third chapter, I observed that remotion of rare species in general did not have effects on the recovery of community structure patterns. In addition, the effect of that remotion of rare species was similar to that observed for the common species exclusion or random species exclusion.
Um padrão repetidamente observado na natureza é que as espécies variam em abundância entre os locais, sendo que em poucos locais a espécie é abundante, enquanto que na maioria a espécie é rara. Esta distribuição intraespecífica de abundância, por sua vez, gera um padrão recorrente que é o excesso de espécies raras nas comunidades biológicas. Este excesso de espécies raras pode complicar análises ao nível de comunidade visto que produzem conjuntos de dados com muitos zeros. Nesta tese busquei entender quais são as causas para a raridade das espécies e como excesso de espécies raras influência a detecção de padrões ao nível de comunidades. No primeiro capítulo observei que espécies classificadas como raras, foram comuns em outros habitats, em outros locais e em outros anos. No entanto, entre estes três fatores, a raridade foi melhor explicada pelo tipo de habitat em que ela foi amostrada. No segundo capítulo observei que as espécies tendem a se tornar mais raras conforme elas se distanciam (acima, abaixo ou em ambas as direções) de sua elevação ótima. Este padrão foi bastante robusto pois foi independente do grupo taxonômico ou da região geográfica. No terceiro capítulo, observei que a remoção das espécies raras têm pouco efeito na recuperação dos padrões de estrutura das comunidades. Além disso, o efeito da remoção de espécies raras foi similar ao observado quando exclui as espécies comuns, ou exclui as espécies de forma aleatória.
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Bender, Gomes Mariana. "La structuration des communautés de poissons de récif à différentes échelles : de la taxonomie aux fonctions." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20073/document.
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Comprendre les mécanismes d'assemblages des communautés est l'une des principales questions en écologie et biogéographie. Elle est également essentielle pour prédire les conséquences des changements globaux sur la distribution future de la biodiversité. Les communautés écologiques sont la résultante de facteurs interagissant à plusieurs échelles spatiales et temporelles. En outre, ces processus peuvent affecter différemment les composantes taxonomique, fonctionnelle et phylogénétique de la biodiversité. Nous étudions ici les processus écologiques qui structurent les communautés de poissons de récif, l'un des assemblages de vertébrés les plus diversifié sur Terre. Les facettes taxonomique et fonctionnelle de ces assemblages ont été étudiées au travers de plusieurs échelles spatiales. Nos objectifs sont (i) d'identifier les facteurs structurant les assemblages de poissons de récif à différentes échelles (du régional au local), (ii) d'évaluer dans quelles mesures les processus structurant les groupes taxonomiques et fonctionnels sont consistants entre eux et (iii) de comprendre la distribution de la rareté fonctionnelle dans les assemblages de poissons de récif. Deux bases de données ont été utilisées : (1) une base de données sur les caractéristiques fonctionnelles et les distributions globales de plus de 6000 espèces de poissons dans six régions biogéographiques ; (2) un ensemble de données comprenant les occurrences de 1 474 espèces de poissons sur 9 681 échantillons obtenus le long de transects (comptages visuels en scaphandre autonome) de 40m² à travers 252 sites dans plusieurs régions biogéographiques. Dans l'océan Atlantique, la structure taxonomique et fonctionnelle des communautés de poissons a une signature biogéographique, avec une différence marquée entre les espèces des récifs biogènes riches (dans les Caraïbes et composée des petites espèces) et les régions périphériques dominées par des espèces plus grandes. L'environnement joue également un rôle important dans la structuration des assemblages dans d'autres domaines biogéographiques. Alors que la composition taxonomique des communautés est principalement liée à l'isolement des récifs, la structure fonctionnelle est influencée par la disponibilité de l'habitat à l'échelle locale. Encore une fois, il y a une plus grande contribution des petites espèces dans les sites les plus riches alors que les grandes espèces dominent en périphérie, suite à la plus forte capacité de colonisation des grandes espèces. Les assemblages présentent des structures fonctionnels emboîtées. Plus précisément les sites pauvres en diversité fonctionnelle, ici mesurée en nombre d'entités fonctionnelles différentes, sont des sous-ensembles des sites riches. Cette structure résulte de l'interaction entre les capacités de dispersion/colonisation des espèces et/ou des besoins en ressources, ainsi que des gradients d'isolement et de surface. Malgré la présence de groupes fonctionnels essentiels et de redondance dans les assemblages de poissons, la majorité des espèces dans les communautés sont rares. De plus, les espèces rares occupent une large proportion de la gamme de traits fonctionnels et effectuent souvent des fonctions uniques. Selon les scénarios simulant la perte d'espèces rares (de 8 à plus de 200 espèces rares / moyenne : 78,2 ± 62), il y aurait une perte élevée - 80 % dans un seul site - de la diversité fonctionnelle. Nos résultats révèlent que les processus au sein d'un domaine biogéographique sont responsables d'une structuration taxonomique et fonctionnelle. De plus, le rôle essentiel de la capacité de colonisation de l'espèce met en évidence l'importance de la connectivité pour le maintien de la structure fonctionnelle des communautés de poissons de récif. Enfin, la contribution des espèces rares à la diversité fonctionnelle montre que ces taxons doivent être protégés afin de maintenir l'ensemble des fonctions et services des écosystèmesUnderstanding the mechanisms of community assembly is one of the main questions in ecology and biogeography, and is essential for predicting the implications of future biodiversity loss. It is known that an array of processes operating at different spatial and temporal scales interact to produce ecological communities. These processes may affect differently the multiple components of communities: the taxonomic, functional and phylogenetic components. Here we investigate the patterns and processes structuring one of the most diverse vertebrate assemblages on Earth: reef fishes. Reef fish assemblages were assessed across multiple spatial scales, under a taxonomic and functional perspective. Our main objectives included: (i) the identification of determinants of structure in reef fish assemblages across scales (regional to local); (ii) assessing to which extent the processes behind assemblage structures are consistent for taxonomic and functional groups; (iii) understanding the patterns of functional rarity in reef fish assemblages at a global scale. Two databases were utilized: (1) an extensive database on the functional traits and the global distributions of over 6,000 reef fish species across six marine biogeographic regions; (2) a dataset comprising the occurrences of 1,474 fish species over 9,681 underwater visual transects of 40m2 across 252 sites, also throughout the major biogeographic regions. Within the Atlantic Ocean, the taxonomic and functional structure of reef fish assemblages exhibit a biogeographic fingerprint, with a marked discrimination between species rich biogenic reefs – primarily in the Caribbean, where communities were dominated by small invertebrate feeders – and poorer peripheral regions dominated by larger species with more diverse diets. At the regional scale, both historical events and environmental characteristics (coral reefs vs. periphery) have played a role in structuring both components of assemblages. The role of environment features also holds for the structure of assemblages in other biogeographic realms (i.e. Indo-Pacific and Tropical Eastern Pacific). While the taxonomic composition of assemblages is mainly related to reef isolation, the functional structure is influenced by local habitat availability. Again, there is a greater contribution of small-bodied species in the most species-rich locations; and large-bodied species prevailing in peripheral assemblages, a pattern related to species' colonization capacity. Reef fish assemblages across most regions depicted significantly functional nested structures, attributed to functional redundancy – different species constitute a number of key functional entities. The nested structure results from the interaction between species' dispersal/colonization capabilities and/or resource requirements, with isolation and area gradients. Despite the existence of key functional groups and redundancy, the majority of species are rare (low abundance or occupancy). Also, rare species fulfil much of the range of functional traits within reef fish communities and often perform unique roles. Under scenarios of rare species loss (from 8 to over 200 rare species/ mean: 78.2±62) there would be high functional diversity erosion in the majority of reef fish communities, this level reaching up to 80% of functional diversity in one location. However the extent to which these functional groups actually contribute to ecosystem functioning is unknown. Our results reveal that within-realm processes, such as evolutionary histories, have shaped the taxonomic and functional structure of assemblages in each realm. Moreover, the key role of species' colonization capacity highlights the importance of connectivity to the maintenance of the functional structure across reef fish communities. Finally, the contribution of rare species to functional diversity indicates that protecting these taxa is essential to maintain ecosystem functioning and services in reef fish communities
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Craig, Tracy-Ann. "Kidney stone rarity in South Africa's black population : investigation of the biochemical and physico-chemical properties of Tamm Horsfall Mucoprotein as a possible contributory factor." Doctoral thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/7443.
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Includes bibliographical references.Tamm Horsfall mucoprotein (THP) is a powerful inhibitor of calcium oxalate crystallisation. Since urolithiasis in South African blacks is extremely rare, this study was undertaken to compare the relative inhibitory and biochemical properties of this protein in South African black and white healthy and stone—forn1ing male subjects. THP was isolated by salt precipitation, purified by column chromatography and verified by electrophoresis on SDS-polyacrylamide gels. MALDI-TOF mass spectroscopy was used to determine the molecular weights of the protein from each group and their respective amino acids were analysed. All four THP groups were subjected to tryptic finger printing digestion and matched those of the database. The secondary structures of the four THP proteins were also determined using circular dichroism. The carbohydrate moeities of the four THP groups were analysed for and O-linked oligosaccharides. THP from each of the four groups were subjected to a series of crystallisation experiments using a crossover design in which the protein was added to the urine from which it had been originally isolated, as well as to the urines from the other three groups. This process generated a 4x4 protein-urine grid for investigation of the inhibitory properties of THP in different urine environments. Calcium oxalate crystallization was induced by administration of aqueous sodium oxalate and was monitored Using a Coulter Counter. In another series of experiments 14C-oxalate was used to initiate crystallization. Monitoring in these experiments was achieved by scintillation counter techniques. Calcium oxalate crystal aggregation was investigated in the presence and absence of THP using zeta potential measurements and crystal sedimentation experiments.
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Haydu, Kristie. "Mapping Plant Biodiversity Hotspots at the County Scale: A New Tool for Establishing Resource Conservation Strategies." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/749.
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Myers first identified the world’s 25 biodiversity hotspots and pioneered innovative ideas about the usefulness of biodiversity models for establishing long-term resource conservation strategies at global scales. Since Myers, most of the subsequent studies using hotspot science for biodiversity modeling have used large spatial scales like countries, provinces or states, and other biogeoraphic regions. The California Floristic Province continues to be one of the recognized global biodiversity hotspots. Our study site, San Luis Obispo County is within this hotspot and we created a map of plant biodiversity hotspots at the county scale using GIS technology. We wanted to determine the effectiveness and applicability of biodiversity hotspot mapping at this scale with anticipation that the map will serve as a new tool for establishing long-term resource conservation strategies in the County. Our plant biodiversity hotspot map is based on distribution data collected from herbarium specimens of San Luis Obispo County’s rare flora. These data were extracted from the Hoover Herbarium at Cal Poly and manually digitized into GIS. We built a model with GIS to identify, locate, and quantify the resultant hotspots from the data. The overall approach was successful at identifying and quantifying the attributes and geographic extents of plant biodiversity hotspots at the county scale. Our results are highly applicable for establishing local and regional plant conservation priorities at lower resolutions, which is frequently where land acquisition and reserve establishment occurs. We conclude that biodiversity hotspot modeling with GIS is an effective tool that can be applied to many other finer-scale biological inventories for conservation purposes.
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BULINSKI, KATHERINE VICTORIA. "Relationship of sample-level properties to biodiversity at multiple scales: analyses of Upper Ordovician and Cenozoic ecological and latitudinal gradients." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1212001254.
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Iannuzzi, Victoria N. "School Shootings in the United States from 1997 to 2012: A Content Analysis of Media Coverage." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6866.
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This study is a content analysis of news articles of school shooting incidents that occurred within the United States between 1997 and 2012. This paper was designed to (a) address the current profile of school shooting offenders and offenses, (b) assess a proposed typology of school shootings, (c) consider common case processing characteristics for offenders of school shootings incidents, and (d) address the potential for offender and offense characteristics to affect the amount of media coverage an incident receives. The database of “Major School Shootings in the United States Since 1997” by the Brady Campaign to Prevent Gun Violence was used to compile a sample of 101 incidents in which a single offender committed a school shooting. To the extent possible, media accounts were used to corroborate details of each school shooting incident. Data pertaining to the offender characteristics, case processing characteristics, offense characteristics, characteristics regarding a typology, and media coverage characteristics were examined. The current profile and typology were, for the most part, upheld. Six variables proved to be significantly related to the total amount of media coverage an incident received: mental health history, school-related mass murder type, offender/victim type, total victims injured or killed, region of the U.S., and year of incident occurrence. Of these variables, three remained significant in a regression analysis: the school-related mass murder type, region of the U.S., and year of incident occurrence were predictive of the amount of media coverage an incident received. Implications and limitations of this study are discussed, and directions for future research are suggested.
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Williams, Aleida Helen. "An ecophysiological comparison of rare ironstone endemics and their common congeners." University of Western Australia. School of Plant Biology, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0241.
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[Truncated abstract] In south-western Australia a rare plant community occurs on shallow soils overlaying massive ironstone rock. These 'ironstone communities' are open shrublands, which are subject to extremes in drought and solar radiation and support many rare and endemic species. The restricted distribution of many of these species may be related to their high degree of specialisation to this harsh habitat and their inability to respond plastically to different environmental conditions. Indeed, earlier work has shown that ironstone Hakea species (Proteaceae) have a specialist root-system morphology investing mainly in deep roots, thereby increasing their chance of accessing cracks in the rock surface and obtaining water before the onset of summer drought. In this thesis I further examine aspects of specialisation and its possible consequences for species rarity using two ironstone Hakea species and comparing them with two of their widely distributed congeners. In the first experiment (Chapter 2) I explore inherent drought tolerance, independent of root-system morphology, as a further specialisation to the ironstone environment. All species were grown in sand in pots in a glasshouse for 7 months and then droughted for 5 weeks. There was no evidence that the ironstone species had a greater inherent drought tolerance than their common congeners. During drought all species maintained leaf water content of mature leaves by reducing stomatal conductance and osmotically adjusting, though ironstone species tended to OA (osmotic adjustment) more than common species. ... This suboptimal investment of resources may result in a lower competitive ability in shadier environments, and thus could partially explain their restricted distribution. In Chapter 4, I investigated the plasticity of root traits in response to levels of phosphorus supply. South-western Australian soils are phosphorus impoverished and phosphorus is well known to elicit plastic responses in root allocation and architecture. Ironstone species showed less plasticity in total root length, producing similar root length across P treatments, while common species showed an increase in root length with increasing [P]. Other root characteristics were similarly plastic in response to P treatment between species. However, when supplied with increasing [P], ironstone species invested an increasing proportion of roots in the bottom of pots while common species invested more in the top. This differential response in root allocation in response to P may reflect a fundamental trade-off between nutrient and water acquisition, with the ironstone species mainly foraging for water and investing in deeper roots, while the common species invest more in superficial roots to obtain nutrients. In conclusion, the rarity and restricted distribution of the ironstone Hakea species may be related to their specialist root-system morphology as well as a lowered phenotypic plasticity of functional traits. A reduction in plasticity may reduce their competitive ability outside their ironstone habitats, and thus contribute to the restricted distribution of these species. This may also be the case for other rock-outcrop endemics and more generally, for other rare plant species restricted to particular habitats where a lowered phenotypic plasticity in traits relevant to their particular habitat may contribute to their restricted distribution.
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Nakamura, Nodoka. "Dissecting the Japanese hotspot : refining evaluation of biodiversity in forests at different scales in the Japanese landscape." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:c625c75e-b983-48ab-b8c8-fbe0cea0d53e.
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Japan is one of the world’s 34 biodiversity hotspots, according to Conservation International (CI). The methods used by various organisations to define priorities differ, however, and all have weaknesses when trying to identify hotspots at finer resolutions. The goal of this thesis is to investigate how biodiversity hotspots in Japan could be revealed and mapped in order to encapsulate conservation elements of biodiversity in practical ways and at various scales. Bioquality is a term that emphasises the concentration within a community of elements of biodiversity with high conservation value. It evaluates the global rarity and taxonomic distinctiveness of plant species or infra-specific taxa using four Star categories. At a plant community level, the Genetic Heat Index (GHI), which is a standardised global range size rarity score, is calculated using weighted Star statuses of species in the community. Bioquality hotspots are assessed here for the first time for the flora and vegetation in Japan – and for temperate Asia – by categorising the Japanese flora into Stars and by applying GHI to survey data and literature-based sources. Keys to Stars are developed for the Japanese flora, with adjustments for variability in species geographic range size information and for taxonomic relatedness. A Flora of Japan (FOJ) database was compiled as a BRAHMS database, containing 8,262 accepted names (30,656 taxon names in total, including synonyms) in 258 families – the first full database of Japanese vascular plants. A total of 7,145 taxa are assigned Stars; from the rarest to the widespread class, there are 884 Black, 756 Gold, 833 Blue, and 4,672 Green Star taxa, confirming that Japan as a whole contains a high proportion of globally rare taxa (23% taxa in Black or Gold). A protocol for calibrating the weight of Stars based on species geographic range is developed based on fine-resolution distribution maps within Japan and coarse–resolution Taxonomic Database Working Group (TDWG) code information. The protocol optimises calculation for temperate regions. The first ever bioquality hotspot maps of Japan are produced using two independent data sources on species distribution at national level: 1) 50 botanical prefectures using 4,830 species from the FOJ database; 2) 1,418 Horikawa ‘geoquadrats’ (0.1° latitude by 0.15° longitude grid) maps covering 829 species. The Ryukyu Islands and Ogasawara Islands are identified as bioquality hotspots, and high mountain ranges in mainland Japan are predicted to contain areas potentially high in GHI; the spatial patterns of GHI are generally concordant between maps of different resolutions. These findings highlight that bioquality assessment can be applied meaningfully at various spatial resolutions. Using field sampling data and existing literature, three study sites are further investigated on a local level: 1) the satochi-satoyama landscape, the current national priority area for biodiversity conservation; 2) various vegetation types of Okinawa-jima Island, the Ryukyu Islands; and 3) the Utaki sacred groves within the predicted hotspot of the Ryukyu Islands. The Ryukyu Islands are confirmed to contain bioquality hotspots within many individual sites, while there was generally low GHI across the satochi-satoyama landscape. The field study outcomes, together with a gap analysis of the existing coverage of protected areas, highlight three important points that are directly relevant to national biodiversity conservation planning: 1) the Ryukyu Islands urgently need newly designated protected areas; 2) the satochi-satoyama landscape conservation should redirect its focus on cultural benefits to the public; 3) the existing protected areas, particularly on mountain areas, need re-evaluation in terms of upgrading their status in light of the bioquality assessment.
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Palazy, Lucille. "La chasse aux trophées : menace ou alliée pour les espèces rares." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10020/document.
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La chasse aux trophées, type de chasse récréative dont l'objectif premier est de prélever un trophée d'intérêt, est un sujet très controversé. Cette activité est potentiellement génératrice d'un effet Allee anthropogénique (EAA). Ce processus démographique stipule que la valorisation de la rareté d'une espèce peut stimuler son exploitation et mener à son extinction. L'objectif de ce travail a été de tester le risque d'EAA dans la chasse aux trophées. Nous avons mis en évidence que les espèces rares ont une forte valeur économique dans la chasse aux trophées, quelque soit la taille du trophée, ce qui témoigne d'une demande forte pour ces espèces. Nous avons également montré que le nombre d'importations/exportations de trophées et le nombre de trophées de chasse enregistrés par le Safari Club International s'accroît pour les espèces les plus rares lorsque l'indice de rareté de l'espèce augmente. La chasse aux trophées sur les espèces rares a été proposée comme outil pour financer leur conservation. Cependant, nos résultats valident le risque d'EAA pour ces espèces. De plus, les chasseurs ne semblent pas motivés en priorité par la participation à la conservation de la vie sauvage et le peu de données disponibles sur les populations, la chasse illégale, la corruption et le manque de contrôle rendent possible l'exploitation non durable de ces ressources à forte valeur économique. Néanmoins, la vie sauvage doit apporter des bénéfices économiques pour motiver sa préservation. Ainsi, la chasse aux trophées des espèces rares peut être utilisée pour financer leur conservation mais certaines mesures sont à prendre au préalable pour prévenir leur surexploitationTrophy hunting, which is a form of recreational hunting with the main objective of collecting a trophy of interest, is a controversial subject. This activity could potentially generate an anthropogenic Allee effect (AAE). This demographic process states that the valuation of rarity could drive rare species exploitation and even lead to their extinction. Our project aims at testing the potential for an AEE in trophy hunting. We demonstrate that rare species have a high financial value, regardless of the trophy size, indicating that there is a high demand for those species. We also show that the number of trophies traded internationally and the number of recorded trophies by the Safari Club International (one of the largest clubs for international trophy hunters in the USA) rises as the degree of rarity (as measured by a rarity index) increases. Trophy hunting of rare species has been proposed as a tool to fund their conservation. However, our results indicate that there is a risk of an AAE for rare species. Furthermore, the combined effects of trophy hunting, illegal hunting, corruption as well as the lack of population knowledge and of management controls have potential to result in the unsustainable exploitation of rare species of high financial value. Nonetheless, trophy hunting has potential to generate strong financial incentives that are necessary for wildlife preservation. Such incentives are only likely to be effective if strict measures are required and enforced to prevent overexploitation of rare trophy species
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Kondratyeva, Anna. "Measuring inter-specific diversity. Benefits of species originality indices in community ecology and conservation biology." Thesis, Paris, Muséum national d'histoire naturelle, 2019. http://www.theses.fr/2019MNHN0012.
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L'humanité dépend fortement de la biodiversité et des services qu'elle nous fournit. Pour prévenir la perte de biodiversité et établir des relations durables avec la nature, l'humanité doit gérer et protéger des ressources naturelles. Le problème de "what to protect" n'est pas nouveau, mais il est devenu aujourd'hui plus important que jamais et pourrait être résolu par une utilisation appropriée des mesures de la biodiversité. De nombreuses mesures de biodiversité ont été élaborées au cours des quatre dernières décennies avec l'abondance des espèces comme l'une des unités centrales. Cependant, les études en écologie et évolution nécessitent une description précise des caractéristiques des espèces pour quantifier au mieux la diversité interspécifique, car en effet les espèces ne sont pas équivalentes. Les premières mesures tenant compte des différences biologiques entre les espèces étaient fondées sur les relations phylogénétiques et les valeurs de traits des espèces. Cependant, beaucoup d'entre elles mesurent la diversité d'un ensemble d'espèces et n'indiquent pas la contribution de chaque espèce à la diversité de l'ensemble. Comme une solution à ce problème, d'autres types de mesures sont apparus au début des années 90's, comparant les espèces en fonction de ce qu'elles ont en commun, mais elles ont été mises de côté, classées à tort comme mesures de la diversité. Néanmoins, ces mesures donnent une valeur à chaque espèce et non à l'ensemble des espèces. Dans cette thèse, nous appelons ces mesures des indices d'originalité des espèces. Une espèce est originale si elle possède des valeurs de traits inhabituels par rapport à toutes les autres espèces dans une communauté ou si elle est phylogénétiquement éloignée des autres. Ainsi, les espèces les plus originales sont celles qui contribuent le plus à la diversité de cette communauté. Dans cette thèse, nous avons cherché à démontrer des avantages des mesures d'originalité, en particulier en biologie de la conservation et en écologie des communautés. Tout d'abord, nous examinons la relation entre les concepts de l'originalité, de la diversité et de la rareté des espèces et nous comparons leurs mesures associées. Poursuivant des liens théoriques entre les mesures d'originalité et de diversité, nous proposons une application pratique d'indices d’originalité en deux étapes (et à deux échelles) à un jeu de données réel des espèces végétales. Enfin, nous discutons des principaux points forts et faibles liés aux données sur les espèces, à l'échelle spatiale des études et au choix des mesures d'originalité, impliqués dans l'analyse d'originalité. Un outil prometteur, les mesures d'originalité pourraient être utilisés avec d'autres entités que des espèces, tels que les gènes ou les habitats, et donc élargir notre compréhension et la conservation de la biodiversitéHumanity strongly depends on biodiversity and services it provides. To prevent the biodiversity loss and to establish sustainable relations with nature humanity has to efficently manage and protect natural resources. The problem of “what to protect” is not new but became more important than ever and could be resolved by an appropriate use of biodiversity measures. Many indices of biodiversity have been developed in the last four decades, with species being one of the central units. However, evolutionary and ecological studies need a precise description of species’ characteristics to best quantify inter-species diversity, as species are not equivalent and exchangeable. First measures taking into account species biological differences were based on species phylogenetic relations and trait values. However, many of them measure a diversity of a set of species, and does not indicate the respective contribution of each species to the diversity of the set. To find a remedy to this issue, other type of measures appeared in early 90’s, comparing species through the shared amount of characteristics, but were put aside, erroneously classified as diversity measures too. In this thesis we refer to these measures as species originality indices. A species is original if it possesses unusual trait values compared to all others in a community or if it is distantly related with other species in a community. Thus, the most original species have the greatest contribution to the diversity of that community. In this thesis we sought to demonstrate the benefits of originality metrics, particularly in conservation biology and community ecology. First we review the relation of species originality with concepts of species’ diversity and rarity and we compare their related measures. Following theoretical links between originality and diversity measures we propose a practical application of a two-step (and two-scale) originality framework to a real plant species data. Finally, we discuss main pitfalls and advantages related to species data, spatial scale of a study and the choice of an originality measure. Future studies could use originality measures with other entities than species, such as genes or habitats, and therefore broad the extent of biodiversity assessment and conservation
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Vanderplank, Sula E. "The Vascular Flora of Greater San Quintín, Baja California, Mexico." Scholarship @ Claremont, 2010. http://scholarship.claremont.edu/cgu_etd/2.
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The plants of San Quintín (Baja California, Mexico) were documented through intensive fieldwork and the collection of herbarium specimens to create a checklist of species. This region is home to a diverse flora with high levels of local endemism and many rare plants. The flora documented in this study was compared to historical records from the region and shows the impact of agriculture and urbanization on the plants, including several extirpated species. A study of the perennial vegetation using a 1 km grid provides species distribution data for 140 native species, which were assessed to highlight areas of significant species richness for native, rare, and endemic taxa. Several non-native plants were also mapped to provide baseline data. Areas of conservation priority for the flora of Greater San Quintín are discussed in light of these combined findings.
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Ferreira, Tiago de Souza. "Raridade de espécies arbóreas em fragmentos florestais no Planalto Sul Catarinense." Universidade do Estado de Santa Catarina, 2013. http://tede.udesc.br/handle/handle/1919.
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Previous issue date: 2013-10-04This study was conducted in different fragments in Planalto Sul Catarinense distributed in along an altitudinal gradient. The objective of the first chapter was to identify local rarity patterns and its proportions, basing on characteristics of habitat range and population size. For this, a vegetational matrix of tree species abundance, from 11 sampling units distributed in different forest fragments in Planalto Sul Catarinense region, was elaborated. In each of sampling plots all living tree individuals with diameter at breast height (dbh) greater than or equal to 5cm were counted and identified. The local rarity patterns were defined through a grid of descriptors used to classify the species in four categories: NE = non-specific species; R1 = scarce euryecious species; R2 = non-scarce stenoecious species; R3 = scarce stenoecious species. From all 144 analyzed tree species, 92 (63.89%) were classified as non-specific (NE). The rarity form R1 demonstrated 5 (3.47%) species, the rarity form R2 showed 33 (22.92%) species and the form R3 had 14 (9.72%) species. The most important conditioning of rarity was habitat preference, i.e., stenoecious species, represented in rarities forms R2 and R3. The species classified in rarity form R3 are those that require the most concentrated efforts in conservation measures. In the second chapter the present study aimed to analyze how the distribution and the richness of rare tree species occurs along an altitudinal gradient, in Araucaria Forests fragments. For this, tree species (diameter at breast height ≥ 5 cm) were sampled in 10 forest fragments located on different altitudinal floors in Planalto Sul Catarinense region, totaling 10ha of sampling area. The species with only one or two individuals in at least one fragment were classified as rare. The species distribution was verified by a dendrogram constructed through the Jaccard floristic distance index and the UPGMA clustering algorithm. The total species richness per forest fragment and the number of rare species was compared among montane and upper-montane sub-formation by the Mann-Whitney (U) test. The relationship between the altitude and the values of total richness and number of rare species in each fragment were determined by simple linear regressions. The results indicated the formation of two groups of rare species, in function of the altitude floor. Despite the total richness of communities decreases with increasing altitude, the number of rare tree species did not change significantly. We conclude that in the Planalto Sul Catarinense region, the fragments of Araucaria Forest have different set of rare species according to altitude and that the reduction of the richness of communities with increasing altitudinal floor is not accompanied by a reduction in the number of rare species
Este trabalho foi realizado na região fito-ecológica do Planalto Sul Catarinense em fragmentos localizados em diferentes cotas altitudinais. O primeiro capítulo teve como objetivo identificar os padrões de raridade local e suas proporções, com base nas características de amplitude de habitat e tamanho populacional. Para isso, foi elaborada uma matriz vegetacional de abundância de espécies arbóreas a partir de 11 unidades amostrais distribuídas em diferentes fragmentos florestais na região do Planalto Sul Catarinense. Em cada unidade amostral foram contados e identificados todos os indivíduos arbóreos que apresentaram diâmetro na altura do peito (DAP) igual ou superior a 5 cm. Para definir os padrões de raridade local foi utilizada uma grade de descritores que classificou as espécies em quatro categorias: NE= espécies não-específicas; R1= espécies escassas eurióicas; R2= espécies não-escassas estenóicas; R3= espécies escassas estenóicas. Das 144 espécies arbóreas analisadas, 92 (63,89%) foram não-específicas (NE). A forma de raridade R1 apresentou cinco (3,47%) espécies, a forma R2 apresentou 33 (22,92%) espécies e a forma R3 apresentou 14 (9,72%) espécies. O condicionante mais importante da raridade foi a preferência por habitat, ou seja, espécies estenóicas, representadas nas formas de raridade R2 e R3. As espécies classificadas na forma de raridade R3 são as que mais necessitam concentração de esforços em medidas de conservação. O segundo capítulo buscou verificar como a distribuição e a riqueza de espécies raras ocorrem em fragmentos de Floresta Ombrófila Mista, ao longo de um gradiente altitudinal. Foram amostradas espécies arbóreas (diâmetro na altura do peito ≥ 5cm) em 10 fragmentos florestais localizados em diferentes pisos altitudinais do Planalto Sul Catarinense, numa área total de 10ha. As espécies que apresentaram número de indivíduos igual ou inferior a dois em pelo menos um fragmento foram classificadas como raras. A distribuição das espécies foi verificada por meio de um dendrograma construído a partir do índice de distância florística de Jaccard e o algoritmo de agrupamento UPGMA. A riqueza total de espécies por fragmento florestal e o número de espécies raras foi comparada entre as subformações Montana e Alto-Montana por meio do teste de Mann-Whitney (U). As relações entre a altitude e os valores de riqueza total e número de espécies raras em cada fragmento foram determinadas por meio de regressões lineares simples. Os resultados indicaram a formação de dois grandes grupos de espécies raras, em função do piso altitudinal. Apesar da riqueza total das comunidades diminuir com o aumento da altitude, o número de espécies raras não apresentou alterações significativas. Conclui-se que na região do Planalto Sul Catarinense, os fragmentos de Floresta Ombrófila Mista apresentam diferentes conjunto de espécies arbóreas raras de acordo com altitude e que a redução da riqueza das comunidades com o aumento do piso altitudinal não é acompanhado pela redução do número de espécies raras
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Lin, Wuying. "Comparative Reproductive Biology of a Rare Endemic Orchid and its Sympatric Congeners in Southwestern China." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/570.
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Comparative studies on endangered species and their more common congeners can shed light on the mechanism of species rarity, and enable conservationists to formulate effective management strategies. I compared the breeding and pollination systems of the endangered Geodorum eulophioides and its two more common sympatric congeners in subtropical China. Geodorum eulophioides and G. recurvum were self-compatible, both depending on Ceratina cognata for fruit production, while G. densiflorum can autonomously self. Although the floral visitation frequency of G. eulophioides was the highest among the three, its natural fruit set was similar to that of G. recurvum, but both lower than that of G. densiflorum. These results partially explain the difference in species abundance. Coupled with severe habitat loss and degradation, the extremely low pollinator visitation and natural fruit set of G. eulophioides calls for rapid establishment of ex-situ collection, in conjunction with improving in-situ habitat. Natural hybridization tendencies were also studied among species.
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Hong, Ellen. "Understanding the Antecedents of Perceived Authenticity to Predict Cultural Tourists’ Behavioral Intention: The Case of Cambodia’s Angkor Wat." Ohio University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1620270040944891.
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Deppa, Ntsapokazi. "Rarity of kidney stones in South Africa's black population : studies of urinary macromolecules, crystal matrix extract containing osteopontin, and bone turnover markers in urine and serum from black and white subjects as a key to understanding this paradox." Doctoral thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/19147.
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The work described in this thesis was undertaken to investigate physicochemical, biochemical and physiological factors contributing towards the rarity of kidney stone disease in the South African black population. Healthy, age-matched male subjects from the black and white population groups were recruited for this purpose. In several of the studies, subjects followed a standardized diet and were required to provide 24 hour urine collections. These were analyzed for sodium, potassium, calcium, oxalate, uric acid, citrate, chloride, magnesium, phosphate, sulphate and creatinine using standard laboratory techniques. Urine composition values were used as input data for the calculation of relative supersaturation (RS) values for calcium oxalate (CaOx), calcium phosphate (CaP, or brushite) and uric acid (U A) using the computer programme EQUIL and for the calculation of the Tiselius Risk Index (TRI). CaOx crystallization experiments were performed. These included CaOx metastable limit (MSL) and BONN Risk Index (BRI) determinations, particle formation kinetics, 14 C-oxalate cry stal deposition kinetics and CaOx crystal aggregation and nucleation inhibition. Crystallizati on experiments were also supplemented with scanning electron microscopy (SEM) and zeta potential measurements. Urine compositions, crystallization data and physicochemical risk indices were analyzed statisitically using ANOV A. Several different investigations were undertaken. These included crystallization experiments involving urinary macromolecules from both race groups, crystal matrix extract isolation (with osteopon tin as its major component) from both race groups and its testing for inhibitory capacity in ultrafiltered urine from both race groups. Similar crystallization experiments were conducted with commercially available osteopontin. In addition, a comprehensive trial was conducted in which the ingestion of three sodium salts (sodium chloride, sodium bicarbonate and sodium citrate) was investigated for their effects on urinary risk factors of CaOx stone formation and for their effects on bone turnover markers in urine and in serum. For the biochemical isolation of crystal matrix extract, COD-CME was precipitated in urine from both black and white subjects. The proteins included in COD-CME were detected using sodium dodecyl sulfate polyacryalamide gel electrophoresis (SDS-PAGE). Western Blotting was used for semi-quantitative analysis of OPN v For the trial involving different sodium salts, four experimental protocols were investigated. The four protocols included low NaCl (3 g/day), high NaCl (12 g/day), sodium bicarbonate (6 g/day) and sodium citrate in the form of Citro-Soda (16 g/day). A Latin Square Design was followed for the random assignment of participants to sequences of protocols. The studies on macromolecules showed that those in the urine of black subjects were more potent inhibitors of CaOx crystal deposition and aggregation than those in the urine of white subjects. Isolation and characterization of the crystal matrix extract in COD crystals confirmed that osteopontin is the main intracrystalline protein in the extract. The crystallization experiments performed on the crystal matrix extract isolated from the urine of both race groups demonstrated that the extract isolated from the urine of black subjects was a superior inhibitor of CaOx deposition, growth and aggregation. Crystallization studies performed on commercially available osteopontin in urine from black and white subjects showed that this protein is a more effective inhibitor of CaOx crystal deposition, growth and nucleation in the urine from the former group compared to that from the latter. The studies on supplemental sodium salts demonstrated that the two race groups respond differently to lithogenic and anti-lithogenic dietary challenges. High NaCl protocol resulted in a favourable and counter-intuitive significant decrease in free unbound calcium in samples from black subjects whereas no such change was observed in white subjects. Supplemental sodium bicarbonate and sodium citrate induced favourable decreases in urinary total calcium, urinary ionized calcium, BRI, RS of CaOx, RS of uric acid and RS of brushite, and a favourable increase in urinary citrate and pH in both groups. Interestingly and more importantly, these factors were more prominent in samples from black subjects than those from white subjects. Bone turnover measurements showed that urinary deoxypyridinoline (DPD) levels were lower while serum osteocalcin (OC) levels were higher in blacks than in whites at baseline, but these differences were not statistically significant. Smaller increases in urinary DPD levels after high aCl and sodium bicarbonate and corresponding bigger increases in serum osteocalcin (OC) levels after these protocols (and sodium citrate) in black subjects than in white subjects indicate less bone resorption and higher bone formation, respectively, in the former group. Vl The results presented in this thesis have provided convincing evidence that in the context of CaOx kidney stone formation, several physicochemical, biochemical and physiological factors are different in black and white South African subjects and that these factors are more effective in the former group with respect to providing protective mechanisms against CaOx kidney stone formation
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Teshima, Fernanda Ayumi. "Ecologia das assembleias de peixes do Parque Estadual de Jurupará (PEJU,SP)." Universidade Federal de São Carlos, 2013. https://repositorio.ufscar.br/handle/ufscar/1527.
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Previous issue date: 2013-09-13Financiadora de Estudos e Projetos
The general aim of this thesis is to understand the fish assemblages of headwater and small streams of Jurupará State Park, a protected area located in São Paulo State. Located among other four protected areas, the park functions as a connector and contributes to the conservation of the Atlantic Forest and Upper Juquiá River basin, located in the Ribeira de Iguape River basin. Ten stream reaches (3rd to 5th order) were sampled between June and December 2010. Ichthyofauna was collected with electrofishing equipment, while environmental variables were visually quantified during onsite surveys and with cartographic maps of the region. Local environmental variables consisted of coarse substrate, diversity of water velocity, proportion of mesohabitats (i.e., riffles, pools and runs), banks stability and shading. Regional environmental variables consisted of vegetation cover, catchment area, altitude and stream reach position according to sub-basin. Fish assemblages structure analyses according to environmental variables were divided into two chapters, presented as scientific papers. The first chapter analyzed two issues, (i) fish assemblages α and β components and (ii) patterns in species composition according to environmental variables. In order to approach the first issue, we used multiplicative partitioning of true diversities to calculate α and β components and compare them with expected values in a null model. The second issue was approached by reducing the number of environmental variables with PCA and using the most significant gradients as predictor variables in a db-RDA, followed by a species composition variation partitioning according to each significant variable. The α and β components observed were different from expected by chance and the variation in species composition was strongly related to environmental variables operating at different scales. The proportion of coarse substrate and bank stability contributed with 6% of species composition variation, while sub-basin contributed with 10%. Possibly, the low percentage of variation explained by the model can be justified by the scale of the environmental variables. If the structuring of fish assemblages follows the null metacommunity model predictions, then variables related to stream topology and species intrinsic characteristics are more likely to better explain the spatial organization of the fauna. In Chapter II, we used data of occurrence frequency, average abundance and biomass to identify rare and common species of the fish assemblages. Withal, we used linear multiple regression models to analyze the abundance of Isbrueckerichthys epakmos according to local environmental variables. The importance of this species relies on its classification as endemic in Ribeira de Iguape River basin and threatened, according to IUCN criterion. Five species were very abundant and widely distributed in the sampled reaches, including I. epakmos, whose distribution was strongly related to coarse substrate and proportion of riffles and runs. Eight rare species were identified, two of them being also endemic of Ribeira de Iguape River basin, Astyanax ribeirae e Neoplecostomus ribeirensis. The elevated taxonomic and functional diversity observed indicates that the studied streams still hold physical integrity to support the biota and, probably, local ecological processes, despite the presence of impoundments that support four small dams installed inside the park.
O objetivo geral desta dissertação é entender as assembleias de peixes dos riachos de cabeceiras e pequeno porte do Parque Estadual do Jurupará, uma unidade de conservação de proteção integral do estado de São Paulo. Localizado entre outras quatro áreas protegidas, o parque possui função conectora e contribui para a conservação da Mata Atlântica do estado, além de contribuir para a proteção da bacia do Alto Rio Juquiá, inserida na bacia hidrográfica do Rio Ribeira de Iguape. Dez trechos de riachos (3ª a 5ª ordem) foram amostrados entre junho e dezembro de 2010. A ictiofauna foi coletada com equipamento de pesca elétrica, enquanto variáveis ambientais foram mensuradas em campo e com bases cartográficas da região. As variáveis ambientais consideradas de atuação local foram substrato grosso, diversidade de velocidades, proporção de mesohábitats (i.e, corredeiras, poções e rápidos), estabilidade das margens e sombreamento. As variáveis ambientais de atuação regional foram vegetação no entorno, área à montante do trecho amostrado, altitude e posição do riacho de acordo com a sub-bacia hidrográfica. As análises da estrutura das assembleias ícticas em função das variáveis ambientais foram divididas em dois capítulos, apresentados na forma de artigos científicos. O primeiro capítulo tratou de duas questões, (i) as diversidades α e β das assembleias de peixes dos riachos e (ii) padrões na composição de espécies em função das variáveis ambientais. Para analisar a primeira questão, aplicamos a relação multiplicativa proposta por Whittaker, utilizando a diversidade equivalente de Shannon, para calcular os componentes α e β e comparamos os valores obtidos com o esperado em um modelo nulo. Para a segunda questão, reduzimos o número de variáveis ambientais com uma PCA e os eixos mais significativos foram utilizados como variáveis preditoras em uma db-RDA, seguida do particionamento da variação da composição de espécies de acordo com cada variável significativa. As diversidades α e β dos riachos foram diferentes do esperado ao acaso e a variação na composição de espécies esteve relacionada a variáveis ambientais que atuam em diferentes escalas. A proporção de substrato grosso no canal e a estabilidade das margens contribuíram com 6% na variação da composição de espécies, enquanto que a posição do riacho de acordo com a subbacia contribuiu com 10%. Possivelmente, a baixa porcentagem de variação explicada pelo modelo pode ser justificada pela escala das variáveis selecionadas. Se a estruturação das assembleias de peixes seguir as previsões do modelo nulo da teoria de metacomunidades, é provável que variáveis relacionadas à topologia da bacia hidrográfica e às características intrínsecas das espécies sejam mais eficientes em explicar a organização espacial da fauna. No segundo capítulo, utilizamos dados de frequência de ocorrência, abundância média de indivíduos e representatividade em massa para identificar as espécies raras e mais comuns das assembleias. Paralelamente, utilizamos modeloslineares de regressão múltipla para analisar a abundância de Isbrueckerichthys epakmos em função de variáveis ambientais locais. O interesse nessa espécie justifica-se por sua classificação como endêmica da bacia do Rio Ribeira de Iguape e ameaçada de extinção, segundo os critérios da IUCN. Cinco espécies foram muito abundantes e amplamente distribuídas nos riachos estudados, entre elas I. epakmos, cuja distribuição esteve fortemente relacionada à proporção de substrato grosso e poções e corredeiras. Oito espécies raras foram identificadas, sendo duas endêmicas da bacia do Rio Ribeira de Iguape, Astyanax ribeirae e Neoplecostomus ribeirensis. A elevada diversidade taxonômica e funcional observada indica que os riachos amostrados ainda apresentam integridade física capaz de sustentar a biota e, provavelmente, os processos ecológicos locais, apesar da presença dos represamentos no interior do parque que abastecem quatro pequenas centrais hidrelétricas.
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Marcilhac, Vincent. "Le luxe alimentaire français. Histoire et géographie d’une singularité." Thesis, Paris 4, 2011. http://www.theses.fr/2011PA040203.
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La prééminence française en matière de luxe alimentaire est souvent présentée comme une évidence. Pourtant il a existé et il existe d’autres cultures du luxe alimentaire dans le monde. Alors, pourquoi et comment la culture française du luxe alimentaire s’est-elle différenciée des autres en s’affirmant et en étant reconnue comme singulière ? Derrière l’apparente évidence, Il importe de démontrer et d’expliquer l’hypothèse d’une singularité française en matière de luxe alimentaire. Celle-ci est aujourd’hui remise en cause, en raison même de l’extension de son marché liée à l’industrialisation de sa production, à la diversification de ses circuits de distribution et à l’internationalisation de sa consommation, ainsi qu’à la montée d’une nouvelle concurrence et à l’évolution de la société. Alors, est-il toujours pertinent de parler de « luxe alimentaire français » ? Au-delà du marketing, cette question soulève le problème du maintien d’une créativité, d’une culture de consommation et d’un savoir-faire spécifiquement français. La valorisation patrimoniale et touristique des lieux de production contribue aujourd’hui à la reconnaissance de l’originalité, de la rareté et de l’excellence des produits alimentaires de luxe. Elle est aussi un outil de développement territorialThe prominence of France in the food luxury sector is often presented as a given. But other food luxury cultures have existed and still exist. So why and how has the French culture of food luxury differentiated itself from others by affirming itself and being recognized as a singularity? Behind the seeming evidence, it is important to demonstrate and explain the hypothesis of a French singularity in the matter of food luxury. Today, this singularity is called into question because of its own market extension linked to the industrialization of its production, to the diversification of its distribution channels, to the international reach of its consumption, as well as to the rise of a new competition and the evolution of society. So is it still relevant today to talk about "French food luxury"? Beyond marketing, this raises the challenge of maintaining a creativity, a culture of consumption and a know-how quintessentially French. Today, the patrimonial and touristic valuation of the production sites contributes to the recognition of originality, rarity and excellence of luxury food products. This valuation is also a mean for territorial development
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Matlock, Peter. "The Rarita-Schwinger field and the AdS/CFT correspondence." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0026/MQ51412.pdf.
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Cundy, Mark A. "The Rarita-Schwinger equation in algebraically special space-times." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365285.
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Pais, Hirigoyen Pablo. "Unconventional Supersymmetry, Massless Rarita-Schwinger Theory and Strained Graphene." Doctoral thesis, Universite Libre de Bruxelles, 2017. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/258427.
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In this Thesis, we propose to analyze three different aspects of Fundamental Physics.The first part is devoted to the detailed study of what is called "unconventional supersymmetry" in three and four dimensions for Abelian and non-Abelian internal groups. We show the dynamical content of the odd-dimensional theory, counting at the same time the local degrees of freedom for some particular sectors of the phase space. In the non-Abelian three-dimensional case, some black hole solutions are presented, including their Killing spinors. In four dimensions, the supersymmetry is broken explicitly and a standard Dirac Lagrangian coupled with the electromagnetic field and the background geometry is obtained.In the second part, the dynamical content for the free and gauge coupled massless Rarita-Schwinger theory is presented. We are able to do that through the Dirac's Hamiltonian formalism and the Faddeev-Jackiw method, showing at the same time the symmetries of the theory. It is shown that in the gauge extended theory, which includes extra fermionic fields to restore the fermionic symmetries of the free case, the anticommutator of the Rarita-Schwinger field in the canonical quantization is not positive definite in general.As the graphene has been proposed as an on ``table-top laboratory" for some Quantum Gravity scenarios, in the third part of this Thesis we clarify some subtle features of strained graphene in order to manage properly this material. We show particularly that the pseudo-magnetic field induced by the in-plane strain tensor field cannot emerge from a Quantum Field Theory in curved spacetime approach (bottom-up approach) but from the detailed analysis of the tight-binding Hamiltonian of pi electrons in graphene (top-down approach) instead.Dans cette Thèse, nous nous proposons d'analyser trois aspects différents de la Physique Fondamentale.La première partie est consacrée à l'éude détaillée de ce qu'on appelle "supersymétrie non conventionnelle" à trois et quatre dimensions pour des groupes internes abéliens et non abéliens. Nous montrons le contenu dynamique de la théorie de la dimension impaire, comptant en même temps les degrés de liberté locaux pour certains secteurs particuliers de l'espace des phases. Dans le cas tridimensionnel non-abélien, certaines solutions de trous noirs sont présentées, y compris leurs spinors de Killing. En quatre dimensions, la supersymétrie est brisée explicitement et un Lagrangien de Dirac standard couplé à l'électromagnétisme et à la géométrie d'arriére-plan est obtenu.Dans la deuxième partie, le contenu dynamique de la théorie de Rarita-Schwinger libre et couplée à un champ de jauge sans masse est présenté. Nous sommes en mesure de le faire par le formalisme Hamiltonien de Dirac et la méthode dite de Faddeev-Jackiw, en montrant en même temps les symétries de la théorie. Il est démontré que dans la théorie étendue de jauge, qui comprend des champs fermioniques supplémentaires pour restaurer les symétries fermioniques du cas libre, l'anticommutator du champ Rarita-Schwinger dans la quantification canonique n'est pas définiti positif en général.Comme le graphène a été proposé comme un "laboratoire de table" pour certains scénarios de gravité quantique, dans la troisième partie de cette Thèse, nous clarifions certaines caractéristiques subtiles du graphène sous tension afin de gérer correctement ce matériel. Nous montrons en particulier que le champ pseudo-magnétique induit par le champ tensoriel de déformation dans le plan ne peut pas émerger d'une théorie de champ quantique dans un espace courbe (approche bottom-up), mais bien à partir de l'analyse détaillée de l'Hamiltonien tight-binding des pi électrons dans le graphène (approche top-down).
En esta Tesis se propone analizar tres aspectos diferentes de la Física Fundamental.La primera parte está dedicada al estudio detallado de lo que ha pasado a llamarse "supersimetría no convencional" en tres y cuatro dimensiones para grupos internos abelianos y no abelianos. Se muestra el contenido dinámico en dimensiones impares de la teoría, contando al mismo tiempo los grados de libertad locales para ciertos sectores del espacio de fases. En el caso tridimensional no abeliano, se presentan algunas soluciones de agujeros negros, incluyendo sus espinores de Killing. En cuatro dimensiones, la supersimetría está rota explícitamente y se obtiene un lagrangiano estándar de Dirac acoplado con el campo electromagnético y la geometría de fondo.En la segunda parte, se presenta el contenido dinámico de la teoría de Rarita-Schwinger libre y con acoplamiento gauge. Esto se puede hacer a través del formalismo hamiltoniano de Dirac y el método de Faddeev-Jackiw, mostrando al mismo tiempo las simetrías de la teoría. Se observa que en la teoría gauge extendida, la cual incluye campos fermiónicos extra para restaurar la simetría fermiónica del caso libre, el anticonmutador del campo de Rarita-Schwinger no es definido positivo en la cuantización canónica.Ya que el grafeno se ha propuesto como una "mesa de laboratorio" para algunos escenarios de gravedad cuántica, en la tercera parte de esta Tesis se clarifican algunas características sutiles del grafeno extendido con el objetivo de manejar debidamente el material. Se muestra particularmente que el campo seudo-magnético inducido por el campo de tensión planar no puede emerger de una teoría cuántica de campos en espacios curvos (abordaje top-down), sino de un análisis detallado del hamiltoniano tight-binding de los electrones pi en el grafeno (abordaje bottom-up).
Doctorat en Sciences
info:eu-repo/semantics/nonPublished