Tesi: "Biological diversity"

1

Miroshnichenko, Y. V. "Protection of biological diversity". Thesis, Видавництво СумДУ, 2012. http://essuir.sumdu.edu.ua/handle/123456789/26038.

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Life comes in an almost unending variety of shapes and sizes, and we all depend on this biodiversity for our food, health and security. This incredible natural wealth is a priceless resource. Loss of just one species could have untold effects on the world as we know it. So, the importance of safeguarding biodiversity is paramount. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/26038

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2

Barraclough, Timothy Giles. "Biological correlates of species diversity". Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320144.

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3

Lundgren, Andreas. "Relation between herbivore abundance, herbivore diversity and vegetation diversity". Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-150095.

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4

Polfus, Jean. "An interdisciplinary approach to describing biological diversity". Ecology and Society; Journal of Biogeography, 2016. http://hdl.handle.net/1993/31986.

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The concept of biodiversity – the phenotypic and genotypic variation among organisms – is central to conservation biology. There is growing recognition that biodiversity does not exist in isolation, but rather is intrinsically and evolutionarily linked to cultural diversity and indigenous knowledge systems. In Canada, caribou (Rangifer tarandus) occupy a central place in the livelihoods and identities of indigenous people and display substantial variation across their distribution. However, quantifying caribou intraspecific variation has proven challenging. Interdisciplinary approaches are necessary to produce effective species characterizations and conservation strategies that acknowledge the interdependent relationships between people and nature in complex social-ecological systems. In this dissertation I use multiple disciplinary traditions to develop comprehensive and united representations of caribou variation through an exploration of population genetics, phylogenetics, traditional knowledge, language, and visual approaches in the Sahtú region of the Northwest Territories, Canada. First, I examine caribou variation through analysis of population genetics and the relationships Dene and Métis people establish with animals within bioculturally diverse systems. Next, I focus on how the Pleistocene glacial-interglacial cycles have shaped the current patterns of caribou phylogeographic lineage diversification. Finally, I explore how art can be used to facilitate cross-cultural collaboration and externalize the unique heterogeneity of biocultural diversity. The results demonstrate a broad scale understanding of the distribution, spatial organization, and the degree of differentiation of caribou populations in the region. I found evidence for caribou population differentiation that corresponds to the caribou types recognized by Dene people: tǫdzı “boreal woodland caribou,” ɂekwę́ “barren-ground caribou,” and shúhta ɂepę́ “mountain caribou.” Phylogenetic results reveal that in their northern margin the boreal ecotype of woodland caribou evolved independently from the northern Beringian lineage in contrast with southern boreal caribou which belong to the sub-Laurentide refugia lineage. In addition, I demonstrate how art can be used improve communication, participation, and knowledge production among interdisciplinary research collaborations and across language and knowledge systems. A collaborative process of research that facilitates łeghágots'enetę “learning together” has the potential to produce sustainable conservation solutions, develop efficient and effective wildlife management policies, and ensure caribou remain an important part of the landscape.
February 2017

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5

Schaefer, Sandra M. "An Assessment of Methods for Testing the Reliability of Wildlife Occurrence Models Used in Gap Analysis". Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/SchaeferSM2002.pdf.

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6

Al-Kaff, Nadia Saleh Ahmed. "Biological and molecular diversity of cauliflower mosaic virus". Thesis, University of East Anglia, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240834.

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7

Marline, Lovanomenjanahary. "Diversity and biogeography of Madagascan bryophytes with an analysis of taxic and functional diversity along an elevational gradient in Marojejy National Park". Doctoral thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29263.

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A central goal of ecology is to understand the influence of biodiversity on ecosystem functioning and the processes that determine the composition and diversity of biological assemblages. In this thesis, I investigate the regional and global context of the bryophytes of Madagascar, an ecologically important but poorly studied group, and the factors affecting epiphytic bryophyte diversity, distribution and assemblage of communities along an elevational gradient in Marojejy National Park, north-eastern Madagascar. Firstly, based on literature reviews and available herbarium data, I examined the bryophytes of Madagascar through a historical, floristic and phytogeographic synthesis. Secondly, the ecological survey of bryophytes from a range of diversity and functional perspectives provided insight on: (1) the pattern of species richness and range-size distribution of epiphytic bryophytes and the factors affecting the distribution patterns. (2) The variations in species composition between sites. I documented how the two components of beta-diversity (turnover and nestedness) are influenced by elevational variation. (3) The relationship between bryophyte species functional diversity and community assembly based on a morphological trait-based approach. I tested how bryophyte species functionally interact with their abiotic and biotic environments and how habitat filtering and niche differentiation influence bryophyte assemblages along an elevational gradient. The bryoflora of Madagascar, with its 1188 species and infraspecific taxa is relatively rich and highly diversified. Along the Marojejy elevational gradient, 254 epiphytic bryophytes species including 157 liverworts and 97 mosses were reported. Species richness distribution has a hump-shaped pattern along the elevational gradient, with a richness peaking at mid-elevation, 1250 m. My results suggest that middomain-effect was the most effective in predicting species richness, but environmental variables such as mean temperature, relative humidity, vapour deficit pressure and canopy height also play important roles in shaping richness pattern. Throughout the gradient, species dissimilarity due to replacement (species turnover) contribute the most to variation in species composition between sites. Both habitat filtering and niche differentiation were found to be involved in structuring species abundances within the studied communities. This combination of biogeographic, taxic, and community ecology approaches, is the first detailed study on the bryoflora of Madagascar and contributes to the direct application of bryological data to conservation planning for Madagascar’s unique ecosystems.

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8

Lindholm, Petra. "Cytotoxic Compounds of Plant Origin – Biological and Chemical Diversity". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5728.

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9

Kotsakis, Andreas. "The biological diversity complex : a history of environmental government". Thesis, London School of Economics and Political Science (University of London), 2011. http://etheses.lse.ac.uk/216/.

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The thesis understands biodiversity as a complex consisting of a form of environmentalism, a mode of governance for the global South, and a set of policy prescriptions all mobilized by the guiding idea of ‘genetic gold,’ the belief that biodiversity possesses significant latent economic value. The thesis primarily analyses the historical origins of biodiversity and the formation of a rationality of governing centred on genetic gold, deploying tools and methods from the work of Michel Foucault. It further applies these insights into the examination of two specific regulatory mechanisms developed within this project of environmental governance: the mechanism for securing access to genetic resources and the fair and equitable sharing of benefits arising from their utilisation, and local and indigenous community participation in biodiversity conservation and utilisation. The aim of this research is a dual critique. First, the unpacking of the complexity of the biodiversity concept and its integrative rendering of biodiversity loss as a governance problem constitutes a critique of environmental law’s enthusiastic acceptance and subsequent regulation of biodiversity as genetic gold. Secondly, the conception of a broader governance complex pervaded by non-legal forms of knowledge, expertise and practices challenges an international environmental law that continues to regard itself as the instrumental centre of environmental concern and discourse.

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10

Schuman, Irina. "The Molecular Diversity and Biogeography of Tardigrades". Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-143134.

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Tardigrades can handle extreme conditions such as heat, cold and drought, thanks to a process called cryptobiosis which can be found in a limited amount of taxa on Earth. More knowledge about such animals may help us to understand the potential and limitations of life both on Earth and possibly in space. Such knowledge may also help develop novel, useful applications for the society, such as better storage of sensitive medicine. However, our knowledge about tardigrades is limited. We know little about their distribution and diversity, especially in Sweden, and above all in northern Sweden. The aim of this study was threefold; i) to explore the biogeography of the tardigrades based on molecular data; ii) to screen for tardigrades in Umeå by examining moss samples from different locations; and iii) to explore some of the associates of tardigrades in moss (such as bacteria and micro- and meiofauna). The biogeography was explored by collecting all published ribosomal gene sequences (the small subunit 18S rRNA) from the Silva gene database. These sequences were used for plotting the locations from which these gene sequences had been retrieved on a world map and the correlation between gene sequence, country and biotope was examined. The tardigrade groups most sequenced are Macrobiotus, Ramazottius and Echiniscus, and the milieu most studied seems to be different types of soil. Other investigated isolation sources are drinking water, cryconite and church walls. However, much remains to be further explored. For example, the world map showed that the only molecular data on Swedish tardigrades have been retrieved from Öland. In the lab, tardigrades were found in some of the moss samples, together with other micro- and meiofauna. Three groups of bacteria (Betaproteobacteria, Gammaproteobacteria and Firmicutes) could be identified in one of the investigated mosses. These results suggest that tardigrades live in a diverse environment with different types of organisms both on the microbial as well as on the micro-meio-fauna level.

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11

Zhang, Li. "Diversity and conservation of Hong Kong bryophytes". Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk:8888/cgi-bin/hkuto%5Ftoc%5Fpdf?B23316731.

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12

Kelly, Andrew Harley Heron. "The role of local government in the conservation of biodiversity". Faculty of Law, 2004. http://ro.uow.edu.au/theses/386.

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This thesis comprises a critical review of the role of Local Government in the conservation of biological diversity (or ‘biodiversity’). Whilst the vast majority of the text relates to NSW, much of the broader commentary may extend to other Australian jurisdictions. The nub of the thesis is that despite the rhetoric in key documents – including the National Strategy for the Conservation of Australia’s Biological Diversity, the NSW Biodiversity Strategy, the National Local Government Biodiversity Strategy and various plans and policies made at the municipal level – the outlook is grim without fundamental policy, legal and fiscal change. The topic is huge but crucial to any person concerned about the mammoth decline of biodiversity in Australia. Whilst being intrinsically transdisciplinary in nature, the thesis attempts to contribute to the ‘new production of knowledge’.¹ It raises issues, problems, ideas and recommendations. The work is based on: • A literary search until 2001. The long gap between this date and thesis submission is due to a severe illness suffered by the author, which arose in late Dec 2001.² • Empirical research into: o nine 1998/1999 ‘state of environment’ reports prepared for by councils located roughly in or around the ‘NSW South-western Slopes’ bioregion that is recognised for the extremely limited extent of remnant native vegetation; o conservation related clauses in all gazetted ‘comprehensive’ Local Environmental Plans - i.e. those applying to entire Local Government areas - prepared by councils between 1995 and 2000 inclusively and which remain in force; • Personal discussion with various officials and onlookers directly involved in, or concerned about, biodiversity conservation at the municipal level. Brief summaries of each chapter are provided herein. The introduction initiates discussion on (i) the meaning of ‘biodiversity’, including its shift from a scientific concept to a populist expression, (ii) the position of councils in Australian government and (iii) the significance of biodiversity conservation at the local sphere. It also introduces two related concepts that are met throughout the thesis, which arguably erode council conservation capability: Local Government’s ‘historical and cultural baggage’ and the ‘ratepayer ideology’. The following three chapters provide the ‘historical and institutional’ context. Chapter Two focuses on changing societal perspectives towards the biophysical environment, together with resultant statutory and environmental trends that have paralleled the advancement of Local Government. Chapter Three traces the history of NSW Local Government, demonstrating its entrenchment in the political landscape. It examines major changes, especially functional expansion and managerial reform. Chapter Four scrutinises a particular aspect of municipal experience, namely top-down and bottom-up cooperation between neighbouring councils. This chapter adds consideration of state appointed regional bodies that may arguably sideline Local Government. The regional context is fundamental to environmental management due to the inappropriateness of many council boundaries. The next three chapters concentrate on legislative and financial detail. Chapter Five reviews the Local Government Act 1993 (NSW), which provides wide service powers, limited regulatory opportunity and special requirements for council-owned land. Chapter Six explores the land-use planning system under the Environmental Planning and Assessment Act 1979 (NSW), especially the ongoing influence of its urban background. It raises the perennial influence of ‘developmentalism’ in the determination of applications for development, which directly benefits property interests. Recent statutory change, especially in relation to ‘threatened species’ law, may do little more than support informed habitat destruction. A closely related matter is funding, as discussed throughout Chapter Seven. The issue goes beyond insufficiency. It is argued that Local Government’s primary financial source - i.e. rating, a property tax - works against biodiversity conservation. Not only is there no policy rationale to support rating in the conservation context but the system can provide a ‘perverse incentive’ to rural landholders to clear their lands. This problem is exacerbated by the type of valuation and differential rates. The system demands major overhaul, including consideration of increased conditional Commonwealth funding. The following two chapters relate to attitudes towards the biophysical environment that are popular amongst the general community. Chapter Eight considers the provision of vegetated, passive recreational open space whilst Chapter Nine deals with securing and enhancing local amenity. These approaches, however, can be directly inconsistent with biodiversity conservation. Parochial ‘green’ desires of local constituents can lead to environmental damage. Notwithstanding this, Chapter Ten provides some impressive examples of Local Government supporting biodiversity conservation. But these are isolated and rely on committed individuals. Whilst the pervasive prospect throughout this thesis is one of gloom, the concluding chapter builds on previous discussion by presenting ideas and recommendations to improve the role of Local Government in conserving biodiversity. It emphasises the need for regional approaches, improved funding mechanisms and fresh visions. Councils with bigger areas, supported by community structures to maintain ‘grass roots’ public participation, together with massive change to Local Government funding, may provide a desirable path for municipal reform and retention of Australia’s precious biodiversity. The law discussed throughout this work stands at 1 Jan 2003. Major changes since then are noted in the Postscript.¹ See ch 1 at 2.² On 31 Dec 2001, after hospitalisation for 9 days, the author was diagnosed as suffering from a malignant brain tumour, known as astrocytoma. It was removed in 2002, followed by heavy radiotherapy and chemotherapy, and a long period of torpor during which I lived the life a cat, sleeping for over twelve hours per day. I returned to this thesis in July 2002, then spending about 30 minutes per day which expanded over time, and recommenced part-time academic work in 2003. I am now convinced that I have left the cancer behind, being one of the fortunate 20% of astrocytoma sufferers to survive, supported by a medical team of professional excellence.

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13

Crook, Carolyn. "Biodiversity prospecting agreements evaluating their economic and conservation benefits in Costa Rica and Peru /". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58978.pdf.

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14

Ragnarsson, Henrik. "Biological Diversity of Fish and Bacteria in Space and Time". Doctoral thesis, Uppsala University, Department of Ecology and Evolution, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8494.

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Biological diversity is controlled by an array of factors and processes all active at different spatial and temporal scales. Regional factors control what species are available to occur locally, whereas the local factors determine what species are actually capable of colonizing the locality.

I have investigated how these local and regional factors affect species richness and diversity, mainly of fish in Swedish lakes and in order to assess the impact of dispersal mode one study on bacteria was also performed. In addition, potential first steps towards speciation were investigated in perch (Perca fluviatilis) from two different habitats.

Fish species richness and diversity were found to be regulated by history, dispersal limitation and the local environment. In addition, striking similarities were found in the control of community composition for fish and bacteria. Both were regulated by nearly equal parts regional and local factors. The study of morphological and genetical variation in perch (Perca fluviatilis) revealed genetic differentiation at small spatial scales, suggesting that genetic differences can evolve between groups at strikingly small spatial scales, which might have implications for speciation in a long time perspective.

Based on these findings I conclude that space and time matter. Space has the potential to isolate sites. And both dispersal and local extinctions, it seems, might take a long time, as effects of the last ice-age can still be seen on the contemporary fish community richness and composition.

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15

Gyllin, Mats. "Biological diversity in urban environments : positions, values and estimation methods /". Alnarp : Swedish University of Agricultural Sciences, 2004. http://diss-epsilon.slu.se/archive/00000566/.

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Thesis (doctoral)--Swedish University of Agricultural Sciences, 2004.
Appendix consists of reprints of five manuscripts, four of which are co-authored with others. Includes bibliographical references. Also partially available online in PDF format; online version lacks appendix.

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16

Moran, Dominic. "Investing in biological diversity : economic valuation and priorities for development". Thesis, University College London (University of London), 1997. http://discovery.ucl.ac.uk/1317651/.

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By all informed scientific accounts the world's biological diversity is currently in a critical condition. Biodiversity is vital for the continued existence of the global biosphere and, by extension, human wellbeing and development. It is inconceivable that a discipline predicated on the issues of scarcity and choice has nothing to contribute in terms of an understanding of either the causes and consequences of biodiversity loss, or in proposing solutions to the crisis. This thesis examines some of the economic parameters of the issue. Alongside the acknowledged root problems of market and institutional failure lies the question of economic valuation. Valuation of biodiversity puts conservation on a more level playing field with the economic forces which threaten its demise. Provided economic values can be appropriated (i.e. converted to flows of real economic resources) it becomes worthwhile for countries to invest in valuable biological assets. But the practice of economic valuation and the quantification of biodiversity are in their infancy and the complexity of the latter hinders the precise application of the former. Much of this thesis focuses on the use and development of the contingent valuation method (CV) as a flexible approach to valuing biodiversity. The method has a useful role to play in resource allocation, and, for valuing biological resources. Faced by the irreducible complexity of life which is the essence of biodiversity, CV does have its limitations. It is possible to conclude that existing valuation methods are a vital part of a "holding operation" alongside other surrogate approaches to setting priorities for global conservation. Nevertheless, the development of an interface between economic (preference-based) values, and biological values, which together can comprehensively inform conservation decisions remains the objective for the future.

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17

Scott, Alistair Norman John. "Biological and genetic diversity of highly-passaged chicken anaemia virus". Thesis, Queen's University Belfast, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314144.

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18

Horsnell, Philip Richard. "Molecular approaches to understanding biological diversity in rhino- and enteroviruses". Thesis, University of Essex, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235801.

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19

Munyenyembe, Mutiyenkhu Paul. "Biological diversity of species in the leguminosae genus Dolichos L". Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332062.

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20

Roberts, Ronel. "Genetic and Biological diversity of 'candadatus liberibacters' from South Africa". Thesis, University of Pretoria, 2019. http://hdl.handle.net/2263/77879.

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Citrus greening disease (CG) in South Africa is associated with the phloem-limited bacterium, ‘Candidatus Liberibacter africanus’ (Laf). This disease has been known to cause yellowing leaf symptoms as well as the formation of unprofitable fruit for nearly a century in this country. In addition to Laf, Liberibacters have been described from indigenous trees belonging to the Rutaceae family in this country. The first of these to be described was ‘Ca. L. africanus subsp. capensis’ and was followed by the description of ‘Ca. L. africanus subsp. clausenae’ (LafCl), ‘Ca. L. africanus subsp. vepridis’ (LafV) and ‘Ca. L. africanus subsp. zanthoxyli’ (LafZ). It has been speculated that either one of these Laf-subspecies may have given rise to Laf senso stricto associated with commercial citrus in South Africa. This dissertation aimed to expand on the indigenous rutaceous host species evaluated for the presence of Laf either as alternative hosts, or harbouring close relatives of Laf. From Oricia, Teclea and Agathosma spp sampled, a novel Liberibacter was only described from a Teclea gerrardii collected in Southern KwaZulu-Natal. This Liberibacter was named ‘Ca. L. africanus subsp. tecleae (LafT)’. It was further assessed whether any of these Laf-subspecies infect commercial citrus species in South Africa. Previous epidemiological studies on CG in South Africa found that Laf was the sole agent associated with this disease, with the current study supporting these findings. Finally, the genetic diversity of Laf was assessed across four provinces from different citrus types using microsatellite markers. This analysis indicated that the genetic diversity of Laf in South Africa is comparatively high, and that the genetic populations observed were mainly influenced by geographic distribution rather than citrus type. This study gave support to the hypothesis that Laf originated on the African continent from an indigenous species present in the country. The study further supports that Laf is well adapted to its commercial citrus host as genetically distinct populations are formed based on geographical populations.
Thesis (PhD)--University of Pretoria, 2019.
Microbiology and Plant Pathology
PhD
Unrestricted

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Mawdsley, Nicholas Anthony. "Community structure of the Coleoptera assemblage in Bornean tropical forest". Thesis, Imperial College London, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361655.

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Byron, Helen Jane. "Treatment of biodiversity issues in environmental impact assessments of road schemes". Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249434.

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23

Gwynne-Evans, David. "The dispersal paradox : can lowland granivorous mice also disperse the seeds they devour?" Bachelor's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/24830.

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The relationship between two rodent species and the Cape Reed (Willdenowia incurvata) were examined. Many studies have focussed on the role of rodents as predators of plant seeds. However, it seems that certain rodents may actually perform a crucial role in the dispersal of plants. Experiments to uncover the dispersal mechanism were carried out. Also examined is the role of the appendages present on the Restio seeds, possibly as energy-rich rewards for dispersal for the rodents. It was found that the Restio may be dependent on seed-dispersing rodents, although this mutualism is not so important in fragmented habitats.

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Musker, Seth. "Dispersal, gene flow, niche divergence and local adaptation in the hyper-diverse ruschioid Aizoaceae: testing alternative modes of speciation in the Knersvlakte quartz field flora of the Succulent Karoo, South Africa". Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/27384.

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What are the roles of alternative modes of speciation in the generation of biological diversity? This question is fundamental to the debate surrounding the origins of extraordinarily diverse regions and clades. Diversification in the Cape flora of South Africa has been intensively studied owing to its remarkable diversity, for which significant roles for both ecological and non-ecological speciation have been invoked as drivers. However, much of this research has focused on the mesic fynbos vegetation, with far less attention paid to its neighboring biodiversity hotspot, the arid Succulent Karoo (SK), which has hosted the spectacular radiation of the ecologically dominant ruschioid Aizoaceae, a succulent group which exhibits extreme morphological diversity and convergence. This thesis focused on ruschioid Aizoaceae in the Knersvlakte, a small region of the SK which holds a diverse and endemic-rich flora specially adapted to the ecologically unusual quartz fields - whose patchy distribution in the landscape suggests that diversification may have been facilitated by divergence of populations isolated on these 'environmental islands' in a similar fashion to serpentine systems such as those in California - and continues from previous work on the Knersvlakte-endemic ruschioid genus Argyroderma which supported an adaptive radiation in allopatry hypothesis. A population genomic approach was used to investigate the scale of seed dispersal (which is thought to be very limited due to the group's highly specialized ballistic dispersal mechanism) as well as correlates of population divergence in two ruschioid quartz-field specialists with very different growth forms (the shrubby Ruschia burtoniae versus the dwarf Conophytum calculus) and which co-occurred at four sites distributed throughout the Knersvlakte. This, in combination with ecological and experimental transplant data to test the adaptive underpinning of edaphically-driven community structure, ecological isolation and niche divergence in these and other quartz field species, made it possible to tease apart the roles of local adaptation and limited dispersal in driving gene flow and speciation in the system. Quartz fields were found to be a highly insular habitat with strong internal edaphic community structure, suggesting that they represent an environmental island system. In addition, intrinsic dispersal ability was very poor in the specialist shrub, which showed complete genetic isolation between the four populations separated by just 17-42 km. This species showed strong local adaptation between the populations as well as some evidence that this inhibited gene flow, though it is more likely that dispersal limitation allowed for fundamental niche divergence. In contrast, the dwarf showed surprisingly good dispersal ability and consequent weak genetic structure, which accounted for the lack of edaphic local adaptation between the populations. The study showed that, contrary to expectation, not all ruschioid Aizoaceae are poor dispersers, and also suggested that the likelihood of ecological speciation in response to edaphic heterogeneity is contingent on dispersal ability. Strongly limited dispersal may thus have contributed to the group's diversification either through non-adaptive radiation or edaphically driven adaptive radiation, but other factors are more likely to have driven diversification in sections of ruschioid Aizoaceae that possess mechanisms of long-distance dispersal. Future work might focus on inferring the scale of dispersal (e.g. based on morphological traits) and whether it predicts diversification rates. Finally, the lack of morphological variation in R. burtoniae belies its strong ecological and genetic divergence; in light of this, systematists are encouraged to investigate cryptic speciation in the group.

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Cheung, chi-ming. "Improving environmental sustainability in Hong Kong : the role of biodiversity /". Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B2524789x.

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Loomis, Eli Stuart. "SEX AND DIVERSITY IN THE INVASIVE PLANT HIERACIUM AURANTIACUM". The University of Montana, 2007. http://etd.lib.umt.edu/theses/available/etd-05302007-121438/.

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Sexual reproduction is generally thought to provide long-term fitness advantages over asexual reproduction in the form of increased genetic diversity. Some work, however, suggests that asexual reproduction can also be advantageous. One situation when asexual reproduction provides an advantage is when colonizing a new range (Bakers law), as in plant invasions. This study investigated the population structure of the invasive plant Hieracium aurantiacum. H. aurantiacum is an apomict producing much of its seed asexually and has become a common invasive in North America and New Zealand. The genetic diversity of H. aurantiacum was assessed over its invasive ranges in the Eastern and Western North America, as well as one location from its native range in the Czech Republic. Using AFLP analysis (with 45 loci), I generated genetic profiles of 225 H. aurantiacum and 60 individuals from 6 other Hieracium species (some native to and some introduced to North America) for comparison. Virtually no genetic variability was found in H. aurantiacum (clonal diversity was 0.035). Other Hieracium species, however, showed a range of diversity, showing clonal diversities from 0.154 to 1.0. One H. aurantiacum genotype dominated the sampled range (G1, in 51 of 53 sampled locations) and was identical to the sample from the Czech Republic. Two other genotypes were found in restricted ranges (G2 and G3). One was a population recently derived from nursery stock, and the other may represent another introduction or a mutated clonal line each differed from each other and G1 at only two loci. It is quite possible that virtually all H. aurantiacum worldwide are clones. Despite this plants lack of genetic variation, it is able to grow over a wide invaded range, which may be due to phenotypic plasticity in fitness-related traits. Many theories about invasion success involve genetic diversity in invading populations to provide the necessary flexibility to flourish in a variety of habitats in an invaded range. In asexual invaders tending towards low genetic diversity, however, phenotypic plasticity of fitness-related traits is a more likely possibility.

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Nunkoo, Muhammad Azher Irfan. "Studies on the diversity and distribution of marine ichthyoparasites in Southern Africa". Doctoral thesis, Faculty of Science, 2019. http://hdl.handle.net/11427/30941.

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Abstract (sommario):

Parasites are a vital component of ecosystems. However, their contribution to the functioning and structuring of ecosystems has historically been overlooked worldwide. In South Africa, marine ichthyoparasitology has a long history but research has largely been confined to taxonomic studies and the literature pertaining to marine ichthyoparasites is highly fragmented. This situation makes it difficult to gauge advances in marine parasitology, identify knowledge gaps and hampers our understanding of their ecological roles in the marine environments of Southern Africa as well as their use as tools in fisheries science. This thesis aims to explore the diversity of metazoan marine ichthyoparasites reported from Southern African waters and to examine their inter- and intraspecific distribution in marine fishes. A review of two centuries of parasitological literature, 1818 to 2017, revealed that 378 marine ichthyoparasites have been recorded off South Africa and included taxa from six phyla: Acanthocephala (12), Annelida (6), Arthropoda (210), Cnidaria (11), Nematoda (6) and Platyhelminthes (133). The parasites formed 723 unique host-parasite pairs with 269 host taxa spread across the classes Actinopterygii (186), Elasmobranchii (80), Holocephalii (2) and Myxini (1). Host species with the most diverse parasite assemblages were species of commercial significance, namely Thyrsites atun (20) followed by Merluccius capensis (17). The dominance of arthropods and platyhelminthes, which together accounted for 90.7% of the parasites found, reflects the interest and expertise of local and foreign researchers who have worked in South Africa. The parasite assemblage of selected commercially significant fish species was used to assess the degree of interspecific similarity in parasite community structure and identify the drivers of ichthyoparasite community assembly in the Southern Benguela. The examination of 554 specimens comprising six fish species (Brama brama, Chelon richardsonii, Merluccius capensis, Merluccius paradoxus, Sardinops sagax and Thyrsites atun) caught off the South African west coast revealed that they hosted 41 metazoan parasite taxa. These included 10 new host records and five new geographic records. Thyrsites atun and C. richardsonii had the most speciose component communities being infected by 17 and 14 taxa respectively. Multivariate analyses revealed that host habitat and identity in conjunction with the host specificity of ectoparasites influenced the community structure of ectoparasitic assemblages. Larval endoparasite community structure, on the other hand, differed between inshore and offshore habitats. Within the offshore habitat, further variation in endoparasite communities were driven by the host species‘ position in the food web, its trophic ecology and its vulnerability to potential final hosts of larval parasite taxa. A survey of the metazoan parasites of snoek (Thyrsites atun) caught in the Southern Benguela (n = 262) and the Northern Benguela (n = 87) revealed 18 taxa comprising 12 new geographic records for the Northern Benguela. A generalised additive mixed model (GAMM) indicated that infracommunity richness of snoek was determined by host size. Multivariate analyses revealed an ontogenetic shift, driven by an increase in the prevalence and infection intensity of trophically transmitted taxa (Anisakis sp., Corynosoma australe, Hepatoxylon trichiuri, Molicola uncinatus), in infracommunity structure as well as in the long-lived larval parasite assemblage. A ‗Random Forest‘ analysis selected Anisakis sp. and M. uncinatus as potential biological tags for assessing the population structure of snoek in the Benguela ecosystem. GAMMs with binomial and Tweedie error distributions were used to respectively assess the prevalence and abundance of both selected taxa in relation to host traits, seasonality and region of origin. The analyses demonstrated that anisakids were more prevalent and abundant in snoek caught in the Southern Benguela while M. uncinatus were more prevalent in snoek from the Northern Benguela. The spatial differences in infection levels of both parasite taxa suggest the presence of two snoek populations in the Benguela ecosystem. The information collected, collated and presented in this thesis has enabled an assessment of the present state of marine ichthyoparasitology off Southern Africa. Although the work uncovered a diverse ichthyoparasite fauna, it also revealed a bias towards particular parasitic taxa. The study highlighted a need for wide-ranging parasite surveys not restricted to certain host or parasite taxa in order to improve our knowledge of marine ichthyoparasite diversity in South Africa. The thesis also provided the first assessment of the drivers of parasite community assembly in the Southern Benguela and demonstrated that host ecology and the characteristics of the parasites played an important role in determining their distribution and interspecific distribution. Geographic differences in snoek parasite distribution patterns which reflect ecological variations across ecosystems have also proved useful to inform fishery management.

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28

Garcia, Carlos Eduardo. "Isolamento e identificação de actinobacterias em solos de terra preta antropogenica (TPA) da Amazonia Central por ARDRA e sequenciamento do gene 16S rRNA". [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256616.

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Abstract (sommario):

Orientadores: Fumio Yokota, Tasi Siu Mui
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-05T16:40:59Z (GMT). No. of bitstreams: 1 Garcia_CarlosEduardo_D.pdf: 3424911 bytes, checksum: 6338d2ede1846761521ec0cfb4c5e1ec (MD5) Previous issue date: 2006
Doutorado
Doutor em Ciência de Alimentos

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29

Chu, Wing-hing. "Conservation of terrestrial biodiversity in Hong Kong /". Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19737439.

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30

Gilbert, Janice M. "Examining the link between macrophyte diversity, bacterial diversity, and denitrification function in wetlands". Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1086098505.

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Abstract (sommario):

Thesis (Ph. D.)--Ohio State University, 2004.
Document formatted into pages; contains xiii, 234 p. Includes bibliographical references. Abstract available online via OhioLINK's ETD Center; full text release delayed at author's request until 2005 June 1.

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31

Cortobius, Fredriksson Moa. "ProBenefit : Implementing the Convention on Biological Diversity in the Ecuadorian Amazon". Thesis, Södertörn University College, School of Life Sciences, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-2771.

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Abstract (sommario):

Legislation on benefit sharing dates back to 1992 and the commandment of the UNConvention on Biological Diversity, hence implementation still has few cases to fall back on(CBD, 1992). The case study of the project ProBenefit presented by the thesis highlights howlack of deliberation can undermine a democratic process. The objective of the thesis is thatProBenefit’s attempt to implement the standards of the CBD on access and benefit sharingwill highlight not only problems met by this specific project, but difficulties that generallymeet democratic processes in contexts of high inequality. To define if the project ProBenefitsucceeded in carrying out a deliberative process the project will be analyzed by the criteria:access to information, representation, legitimacy and involvement.The population in the project area of ProBenefit had a long history of social marginalization,which made it hard for foreign projects to gain legitimacy. The lack of independentorganizations and the late establishment of the project, which resulted in time shortage, madeit impossible to prevent the distrust of the local population. The failure of the projectcoordinators to ensure active participation of all stakeholders resulted in a late and lowinvolvement of the local participants. The absence of independent organization also madedemocratic legitimacy of the process questionable. Even if ProBenefit had a vision ofdemocratic deliberation the project was unable to break down the prevailing unequal powerdistribution which resulted in an unsustainable process and failure. The conclusion of thethesis is that the attainment of deliberation foremost depends on how a project deals with theexisting distribution of power and how it succeeds in involving all stakeholders.

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32

Syahailatua, Augy BEES UNSW. "Biological oceanography of larval fish diversity and growth off eastern Australia". Awarded by:University of New South Wales. BEES, 2005. http://handle.unsw.edu.au/1959.4/22791.

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Abstract (sommario):

Fish larvae in Australian waters have been studied progressively in the last 2-3 decades including the distribution and abundance of taxa, growth and age, their prey and predators. However, the effect of nutrient limitation on ichthyoplankton is unstudied, particularly in the oligotrophic Australian waters. My study was aimed to examine the effect of natural or anthropogenic nutrients on the abundance, distribution, growth and condition of fish larvae along-shore of the NSW coast (latitude 30-34S), where the East Australian Current departs the NSW coast and generates local upwelling of cool nutrient-rich water. This study shows no significant difference in the total abundance or diversity of either larval fishes amongst the 112 taxa (111 families and 1 order), among regions within or upstream of the upwelling. However in both months, there were distinctive ichthyoplankton assemblages at the family level. The Carangidae, Labridae, Lutjanidae, Microcanthidae, Myctophidae and Scombridae were more abundant in the EAC or oceanic water masses, while the Callionymidae, Clupeidae, Platycephalidae, Sillaginidae and Terapontidae were mostly found in the surface or deep upwelled/uplifted water masses. This pattern is observed in other ichthyoplankton studies and may be a general and useful method to determine mixing of water masses. Larvae of silver trevally (Pseudocaranx dentex) and yellowtail scad (Trachurus novaezelandiae) were generally larger and less abundant in the topographically induced upwelling region, than north of the region in pre-upwelled conditions of the East Australian Current. Both species were mostly at the preflexion stage (less than 4.3 mm in body length and less than 10 days old) in the pre-upwelled conditions, particularly during November, and proportionally more larger and older larvae in the upwelled waters (mostly post-flexion, greater than 4.3 mm in body length and greater than 10 days old). Ages from sagittal otoliths ranged from 2-25 increments (~days) and exhibited linear growth for both species and months over the size range (3-15 mm standard length). The otolith radius-length relationship and the growth rates were similar between species and months, despite the 3-4C difference between months. Overall growth rates of the younger larvae were uniform throughout the entire sampling area (0.5-0.6 mm.d-1), while older larvae grew significantly faster in the upwelled water (0.41 mm.d-1) compared to the non-upwelled conditions (0.34 mm.d-1). Both species tended to be depleted in 13C in the upwelling region (from ???18.5 to ???19.0), consistent with expected ratios from deeper water, whereas the 15N composition tended to increase in Pseudocaranx, but decrease in Trachurus indicating different diets and possibly trophic level. The early life history of both species indicates spawning in pre-upwelled waters, but larval transport into upwelled waters is necessary for faster growth in the post-flexion stage. The assemblage of larval fishes did differ between the upwelled region and a region south of Sydney???s deepwater outfalls, but the difference was ascribed to a latitudinal effect and the EAC. Both larval carangids were enriched in 15N, possibly due to the enriched dissolved organic matter of primary treated sewage. In summary, this study found that the larval fish community can provide a biological means to trace water masses, and estimate their degree of mixing. Remarkably there was no significant effect of upwelling or sewage addition to the abundance or diversity of larval fish, in the nutrient poor waters of the East Australian Current. Larval carangids and pilchards were abundant in late spring off northern NSW, and their early life histories were inferred. Both larval carangid species seem to be spawned in the EAC waters, but as post-flexion larvae grew faster in the upwelled zone. Pre-flexion (less than 10 day old) larval carangids of both genera indicated spawning in the EAC, and the rarer post-flexion (greater than 10 days old) carangids grew faster in the upwelled waters. Here, both genera had stable isotope signatures characteristic of upwelled waters for carbon, but had different nitrogen signatures, indicative of different diets and trophic level status. Larval pilchards actually grew more slowly in the upwelling region, as observed in coastal waters off Japan, and their nursery grounds may be further offshore in the Tasman Front, analogous to their early life history in the Kuroshio Extension.

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33

Marshall, Lynn P. "Conservation of biological diversity in Canada, pristine wilderness or mythical camelot?" Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq24880.pdf.

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34

Stockwell, Gareth Rhys. "Structural diversity of biological ligands and their binding sites in proteins". Thesis, University College London (University of London), 2005. http://discovery.ucl.ac.uk/1432660/.

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Abstract (sommario):

The phenomenon of molecular recognition, which underpins almost all biological processes, is dynamic, complex and subtle. Establishing an interaction between a pair of molecules involves mutual structural rearrangements guided by a highly convoluted energy landscape, the accurate mapping of which continues to elude us. The analysis of interactions between proteins and small molecules has been a focus of intense interest for many years, offering as it does the promise of increased insight into many areas of biology, and the potential for greatly improved drug design methodologies. Computational methods for predicting which types of ligand a given protein may bind, and what conformation two molecules will adopt once paired, are particularly sought after. The work presented in this thesis aims to quantify the amount of structural variability observed in the ways in which proteins interact with ligands. This diversity is considered from two perspectives: to what extent ligands bind to different proteins in distinct conformations, and the degree to which binding sites specific for the same ligand have different atomic structures. The first study could be of value to approaches which aim to predict the bound pose of a ligand, since by cataloguing the range of conformations previously observed, it may be possible to better judge the biological likelihood of a newly predicted molecular arrangement. The findings show that several common biological ligands exhibit considerable conformational diversity when bound to proteins. Although binding in predominantly extended conformations, the analysis presented here highlights several cases in which the biological requirements of a given protein force its ligand to adopt a highly compact form. Comparing the conformational diversity observed within several protein families, the hypothesis that homologous proteins tend to bind ligands in a similar arrangement is generally upheld, but several families are identified in which this is demonstrably not the case. Consideration of diversity in the binding site itself, on the other hand, may be useful in guiding methods which search for binding sites in uncharacterised protein structures: identifying those regions of known sites which are less variable could help to focus the search only on the most important features. Analysis of the diversity of a non-redundant dataset of adenine binding sites shows that a small number of key interactions are conserved, with the majority of the fragment environment being highly variable. Just as ligand conformation varies between protein families, so the degree of binding site diversity is observed to be significantly higher in some families than others. Taken together, the results of this work suggest that the repertoire of strategies produced by nature for the purposes of molecular recognition are extremely extensive. Moreover, the importance of a given ligand conformation or pattern of interaction appears to vary greatly depending on the function of the particular group of proteins studied. As such, it is proposed that diversity analysis may form a significant part of future large-scale studies of ligand-protein interactions.

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35

Ahmad, Amirrudin Bin. "Biological diversity of freshwater fishes in small streams in peninsular Malaysia". Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/3144.

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Abstract (sommario):

Peninsular Malaysia has a diverse flora and fauna, much of which is yet to be documented. The freshwater fishes are one important group that have received little attention. Accordingly, the overarching goal of my study is to investigate the pattern of species richness and analyse the community composition and assemblage structure of fishes in the small streams in Peninsular Malaysia. Small stream habitats appeared to be particularly important repositories of fish biodiversity in this region thus obtaining a reliable census of species occurring in such habitats is critical for conservation and management of biodiversity. Although samplings were far from completed, these habitats support a great variety of species with more than 100 species were recorded from fifty streams sampled in this study. A few are extremely rare with restricted distribution and can thus be considered important in biodiversity conservation of the Peninsular Malaysian ichthyofauna. Human-influenced modification of lowland, headwater stream habitats in Peninsular Malaysia is common and often exemplified by the creation of pools in stretches of rapids and riffles. However, it was not possible to separate pristine and disturbed sites which contained almost identical for species diversity. These findings suggest that local habitat modification does not necessarily cause a decrease in freshwater fish diversity, with only minor negative consequences for other community variables recorded in this study, and therefore raise interesting issues regarding conservation. That said it remains premature to conclude that small stream fishes are insensitive to disturbance and thus their potential utility as bioindicators of disturbance-influenced community changes remain to be confirmed. The maintenance practises being applied to small streams modified for recreational usage were not imposing detectable negative consequences, at least across the sites sampled in this study. The rich diversity of tropical stream environments is the result of both within-habitat (alpha) diversity and between-habitat (beta) diversity. The results showed that there was substantial beta diversity particularly amongst sites that are geographically separated from one another. On the contrary, the lowest beta diversity values were portrayed by contiguous sites. Many fishes exhibited discontinuous patterns of distribution and were considered to be rare while only a handful were widely distributed and abundant. Ordination based on the relative resemblance of fish communities to one another support the existence of two distinct ichthyogeographic divisions in Peninsular Malaysia. It was possible to assign the species recorded to all seven of Rabinowitz's categories of rarity, with at least 10 restricted to a single stream and locally scarce, although not all of these could be described as hyper-endemic. It is recommended that a sizeable augmentation of the existing protected areas is needed to safeguard Malaysia's exceptionally diverse stream-dwelling fauna of which fishes are simply the most well-known inhabitants. Conservation managers should therefore place particular emphasis on small streams since localities in close proximity to one another can exhibit surprisingly high beta diversity, meaning that partial or small-scale habitat protection may prove insufficient.

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36

Verschuyl, Jacob Pieter. "Biodiversity potential in the Pacific and Inland Northwest the relative importance of forest structure and available energy in driving species diversity /". Diss., Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/verschuyl/VerschuylJ0507.pdf.

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37

Wuichet, John Weir. "Ecosystem management for biodiversity : a comparative and theoretical analysis of federal polices". Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/31042.

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38

Brown, Maryfrances McGrath. "A description of floral diversity in the southern Appalachians with forest management considerations for conservation /". This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-03172010-020143/.

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39

Peterson, Ann. "Integrated landscape buffer planning model /". St. Lucia, Qld, 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16351.pdf.

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40

Gunnin, R. Davis, Blaine W. Schubert, Joshua X. Samuels e Keila E. Bredehoeft. "A new genus of desmognathan salamander (Plethodontidae) from the early Pliocene Gray Fossil Site of Northeast Tennessee". Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/asrf/2019/schedule/65.

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Abstract (sommario):

Many organisms are known to reach high levels of endemism and biodiversity in the temperate forests of Southern Appalachia, especially in the dense forests and rugged terrain of the Blue Ridge physiographic province. Many plants and fungi reach their highest levels of biodiversity in these mountains, as does one group of vertebrates: the lungless salamanders, Plethodontidae. This family of salamanders hosts the most species of any other group of salamanders on earth and has adapted to a wide range of habitats. Only two of the approximately twenty-seven known genera are not found in North or South America, and while we know much about the modern-day biology of this family, few fossils older than ~15,000 years have been recovered, complicating our understanding of the historical distribution of this group and the timing of key evolutionary events within the family. Recently discovered salamander fossils from the Gray Fossil Site provide the foundation of this project. We describe these exceptionally large plethodontid remains to a new genus that belongs to the group containing dusky salamanders, or desmognathans. The morphology of the fossil material resembles Phaeognathus hubrichti, an extant burrowing species from southern Alabama with a suite of primitive characteristics. Comparison of the fossil material to modern desmognathans using geometric statistical methods has revealed that the extinct form was likely similar in lifestyle to P. hubrichti, but considerably larger. It was unparalleled in the southern Appalachians in terms of size and ecology, and reveals a more complex evolutionary history for desmognathan salamanders.

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41

Öster, Mathias. "Biological diversity values in semi-natural grasslands : indicators, landscape context and restoration". Doctoral thesis, Stockholm University, Department of Botany, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-1352.

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Abstract (sommario):

Semi-natural grasslands, which are a declining and fragmented habitat in Europe, contain a high biodiversity, and are therefore of interest to conservation. This thesis examines how plant diversity is influenced by the landscape context, and how plant and fungal diversity can be targeted by practical conservation using indicator species and congruence between species groups. Reproduction and recruitment of the dioecious herb Antennaria dioica was also investigated, providing a case study on how fragmentation and habitat degradation may affect grassland plants.

Grassland size and heterogeneity were of greater importance for plant diversity in semi-natural grassland, than present or historical connectivity to other grasslands, or landscape characteristics. Larger grasslands were more heterogeneous than smaller grasslands, being the likely reason for the species-area relationship.

A detailed study on A. dioica discovered that sexual reproduction and recruitment may be hampered due to skewed sex-ratios. Sex-ratios were more skewed in small populations, suggesting that dioecious plants are likely to be particularly sensitive to reduced grassland size and fragmentation.

A study on indicators of plant species richness, used in a recent survey of remaining semi-natural grasslands in Sweden, revealed several problems. A high percentage of all indicator species were missed by the survey, removing an otherwise significant correlation between indicator species and plant species richness. Also, a null model showed that the chosen indicator species did not perform significantly better than species chosen at random from the available species pool, questioning the selection of the indicators in the survey. Diversity patterns of the threatened fungal genus Hygrocybe were not congruent with plant species richness or composition. Plants are thus a poor surrogate group for Hygrocybe fungi, and probably also for other grassland fungi. Implications from this thesis are that conservation of semi-natural grasslands should target several species groups, and that an appropriate scale for plant conservation may be local rather than regional.

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42

Öster, Mathias. "Biological diversity values in semi-natural grasslands : indicators, landscape context and restoration /". Stockholm : Department of Botany, Stockholm university, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-1352.

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43

Larrimer, Audrey K. "Biological diversity associated with bigtooth aspen patches in a mixed oak forest". Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1088178638.

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44

Figueira, Fernandes Elizalde Sara Raquel. "Bee diversity in Angola and community change along an altitudinal gradient at Serra da Chela (Bruco)". Master's thesis, Faculty of Science, 2020. http://hdl.handle.net/11427/32262.

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Abstract (sommario):

Insects, including wild bees (Hymenoptera: Anthophila) are exceptional model organisms to assess the effect of climate variation on species richness along altitudinal gradients. Climate variables and weather conditions are of extreme importance for insects particularly since their capacity of body temperature regulation is determined by the ambient temperature. Additionally, bee diversity has proven to be strongly related to the availability of host plants, determinant factors for their presence or absence and both of which are limited at higher altitudes. Therefore, the study of wild bee diversity at various altitudes in the tropics could provide information on possible responses of bee species and communities to climate variations, important to estimate effects of climate change on an important ecosystem service such as pollination. Bees being ecologically important insects with close links to plants, high richness and abundance are well-suited as terrestrial habitat bioindicators. The group is sensitive to environmental disturbances relies upon local plant communities and comprises an assemblage of species with varying social structure, nesting guilds and other life history traits. Additionally, bees are likely more susceptible to negative effects of small effective population size. The life history traits determine the individual and community response to environmental changes. Records from the literature revealed a collector and seasonal bias, with greater effort applied around big cities or specific collecting locations and mainly in the wet season. A preliminary checklist of bees of Angola was created and comprises 209 bee species from 47 genera and five families, but a major proportion of the country's area remains to be surveyed. A national inventory of Angolan bees is proposed, making use of standardized methods and sampling either one quarter degree cell or half degree cells, ideally in both dry and rainy seasons. Wild bee communities were sampled along an altitudinal gradient (760-1651 m.a.s.l) in the biodiversity rich and critically endangered Angolan escarpment. Pan traps, malaise traps and sweep netting were used at twelve sampling points, with an average of 70 m difference in altitude between points. Sweep netting proved to be the most efficient technique. Overall, 845 individuals were collected, representing 51 identified species, 34 genera and five bee families. Contrary to the trends observed in other studies in the tropics, a consistent increase in bee diversity (carried out at genera level) with increasing altitude, from the lower altitude (H'=2,14) to the higher altitude of the gradient (H'=2,26) was found. In addition, community structure differed along the gradient, with distinctive communities in low elevation sites being dominated by Braunsapis, Ceratina, Hypotrigona and Anthidiellum, and high elevation sites the distinctive communities were dominated by Amegilla, Macrogalea, Patellapis and Xylocopa. This result might be consistent with findings from studies of other taxa that attribute to the Angolan escarpment an importance as a centre of endemism and speciation. The results from this study are possibly explained by a combination of factors where the exceptional geomorphology and landscape shape the (direct) influence of environmental variables such as temperature and precipitation on the vegetation communities along the gradient therefore (indirectly) affecting bee community assemblages, particularly for the more specialized bee genera and species. Limited research has been done on the variation of bee body size along altitudinal gradients, but the few studies that have been carried out indicate that future changes (warming) in climatic conditions will most probably alter bees body size (by reduction), consequently affecting their thermoregulatory capacity and, at a larger scale, the overall patterns of community assembly. Along the tropical altitudinal gradient of this study, bee body size was found to increase with altitude by 58% (mean length at lower altitude = 5.06mm against mean = 7.99mm at higher altitude elevation sites) at the community level but also at the intra-specific level, with Macrogalea candida increasing 4% in size between the lower altitude and summit of the transect (mean length at lower altitude = 8.76mm against mean = 9.12mm at higher altitude elevation sites), suggesting that the fairly small temperature gradient along the transect was sufficient to select for body size – either directly, but more likely through multiple avenues, including indirect effects such as changes in rainfall, plant community composition and plant phenology. This result constitutes, to my best knowledge, the first demonstration of Bergmann's rule applicability at different levels of biotic organization of bee communities in the tropical region. Effective conservation planning is highly dependent on robust, spatially explicit biodiversity data. The generation of comprehensive insect profiles through long term monitoring studies at the national level can identify areas with high species turnover and endemism – patterns that could be missed if only vertebrate data were considered. In under-developed countries like Angola, where a poorly documented but highly rich biodiversity is severely threatened by unregulated land use, and research is hampered by financial constraints and lack of human resources, the combined use of indicator taxa for both terrestrial (bees) and freshwater (Odonata) environments might be a reasonable surrogate for total biodiversity status assessments. The results from this study highlight the need for long term monitoring to efficiently assess bee diversity, especially in critically endangered landscapes where anthropogenic pressures are high.

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45

Petersen, Leif Michael. "Granivores as ecosystem regulators of woody plant increasers in semi-arid Savannas of the Lowveld, South Africa". Thesis, University of the Western Cape, 2006. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_8725_1210750329.

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Abstract (sommario):

In recent years, a global trend of increasing woody vegetation densities in semi-arid savanna habitats has been recorded, commonly described in South Africa as 'bush encroachment'. The shrubs and trees that do this (Increasers) have wrought significant economic and ecological impacts upon carrying capacities of large areas of savannas. This occurs, as suitable grazing areas are incrementally engulfed in shrubs and trees establishing new equilibria, from open savannas (essentially grasslands with scattered trees) into closed woodlands (treelands with scattered grasses). This thesis demonstrated a link between grass biomass, small mammal abundance and diversity, and their potential increaser seed/seedling predatory activities in the semi-arid Lowveld Savannas of South Africa.

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46

Petersen, Hana. "Patterns of plant species richness and diversity across two habitat types in the Upper Karoo, South Africa". Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29209.

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The Nama-Karoo biome is relatively understudied in terms of its baseline biodiversity. Apart from its rich agricultural land-use history, the region is also under pressure from the development of the Square Kilometre Array, an increased demand for cleaner energy from shale gas fracking and/or other renewable energy installations, and the overarching impacts of global climate change. A reliable baseline inventory of biodiversity for the region is essential if these impacts are to be monitored and managed effectively. The main aim of this study was to relate fine-scale patterns of plant diversity and community structure to broader-scale vegetation mapping in the Karoo regions. It also investigated the role of several environmental and climatic variables as drivers of species richness, relative cover, and growth form diversity in two habitat types (i.e. plains and rocky dolerite hillslopes), and along a longitudinal environmental gradient. A pairwise floristic survey approach was implemented, using modified Whittaker plots in each habitat type at 30 sites within the shale gas exploration area in the Upper Karoo bioregion. Data were collected on species richness, relative cover, and growth form diversity of the observed vegetation. Soil samples were collected from each Whittaker plot, and climate data were obtained by point sampling from raster layers using GIS. The results showed that mean species richness was significantly higher (p < 0.01) in slope habitats than in plains habitats across the environmental gradient. Trees and woody shrubs had significantly higher species richness (p < 0.001) and relative cover (p < 0.01) in slope habitats. Low woody shrubs comprised the greatest percentage of growth form diversity in both habitat types in terms of species richness and relative cover, and were the dominant growth form across the longitudinal gradient. At the arid western extent, leaf-succulent shrubs had slightly higher relative cover (~ 25%) in slope habitats compared to other growth forms, apart from low woody shrubs. In the central regions, perennial grasses were more abundant (25 – 60%) in slope habitats, while annual grasses were more abundant (25%) in plains habitats. At the more mesic eastern end of the longitudinal gradient, perennial grasses were dominant (> 50%) in plains habitats. Cluster analysis, based on species presence data in each habitat type, showed relatively strong correspondence between plant associations in slope habitats and their respective vegetation types as currently defined. These plant associations were spatially aggregated according to their position along the environmental gradient. Little to no correspondence was found between plant associations in plains habitats and their respective vegetation types. These plant associations were interspersed with each other when plotted spatially, and occurred in a repeating pattern in plains habitats across the study area. Multiple regression models indicated that a combination of climatic and environmental variables, and soil properties significantly predicted overall species richness and relative cover of the five dominant growth forms. Habitat type commonly emerged as a significant predictor for overall species richness and relative cover. Overall dissimilarity, and dissimilarity in the relative cover of five plant functional types between plains and slope habitats, were also predicted by a combination of climatic and environmental variables, and soil properties. These predictors varied greatly between the different response variables, suggesting that different plant functional types are influenced by different drivers, depending on the habitat in which they occur. Habitat heterogeneity, coupled with local and regional variation in prevailing climate and soils, has consistently emerged as an important driver of plant species richness and relative cover in global drylands research. Measuring richness and diversity within habitats requires a high sampling resolution in both plot size and number. This study has shown that sampling at the 0.1 ha scale (or larger) captures a representative sample of richness and diversity within a given habitat type in the Nama-Karoo biome, where low woody shrubs (< 60 cm tall) are the dominant growth form. In the current vegetation map of South Africa, the vegetation types for the Upper Karoo bioregion are coarse, and hence give the impression of homogeneity in what is in reality a relatively heterogenous landscape. Fine-scale baseline biodiversity data such as are presented in this study may improve the resolution of the existing vegetation map, as well as inform better conservation and management practices in economically important and biologically diverse rangelands in the Nama-Karoo biome, prior to future developments in the region.

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Tesi sul tema "Biological diversity"

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