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The Galactic TeV
is currently an unidentified source. In an attempt to unveil its origin, we present here the most detailed study of interstellar gas using data from the Mopra Southern Galactic Plane CO Survey, 7- and 12-mm wavelength Mopra surveys and Southern Galactic Plane Survey of HI. Several components of atomic and molecular gas are found to overlap
at various velocities along the line of sight. The CS(1-0) emission clumps confirm the presence of dense gas. Both correlation and anti-correlation between the gas and TeV
-ray emission have been identified in various gas tracers, enabling several origin scenarios for the TeV
-ray emission from
. For a hadronic scenario,
and the progenitor supernova remnant (SNR) of
require cosmic ray (CR) enhancement factors of
times the solar neighbour CR flux value to produce the TeV
-ray emission. Assuming an isotropic diffusion model, CRs from both these SNRs require a slow diffusion coefficient, as found for other TeV SNRs associated with adjacent ISM gas. The morphology of gas located at 3.8 kpc (the dispersion measure distance to
) tends to anti-correlate with features of the TeV emission from
, making the leptonic scenario possible. Both pure hadronic and pure leptonic scenarios thus remain plausible.
There are two fundamentally distinct conservation strategies, in situ and ex situ that are distinguished based on whether the target taxa are conserved where they are found or are sampled and moved to a secondary location to be conserved. Within the two strategies there are a range of in situ and ex situ techniques, each of which aims to maximize the range of plant genetic diversity maintained. There are advantages and disadvantages associated with each strategy and technique. The two strategies for conservation, in situ and ex situ, complement each other and the mixture of strategies and techniques employed to conserve a target taxon will vary from taxon to taxon depending on its characteristics and the resources available to conserve that taxon.
This chapter provides a historical perspective on the development of community-based conservation and how approaches are grounded in changes that not only occurred in conservation practice but also in agriculture and rural development. This is achieved by looking at some of the pivotal changes in thinking and ideas that have taken place relatively recently in conservation practice and in agriculture and rural development. How these changes have been reinforced by the rapid rise of social movements lobbying for greater farmer and local community control over resources and food sovereignty is also reviewed in the context of its impact on conservation thinking. The chapter also highlights some key principles and guidance when considering collaboration and partnership with smallholder farmers, indigenous and community groups and provides an overview of approaches, tools and methods that are considered useful for facilitating community-based conservation and sustainable use of plant genetic resources.
The conservation of plant species where they naturally occur involves the planning, design, establishment, management and monitoring of viable populations of the target taxa to be conserved. It will involve the writing of a management plan as a guide to management implementation primarily based on knowledge of the target taxon’s ecology and its relationship to the biotic and abiotic environment. Regular monitoring of key populations within the reserve will ascertain whether the management plan is effective in conserving genetic diversity. Often, however, the conservationist will have to make a compromise between the objectives of the reserve and the desires of other users. The material conserved within the reserve should be made readily available to the various user groups.
Knowledge regarding gene bank accessions characters facilitates the identification of the most promising for future use. Sampling of accessions from a cultigen available at a gene bank may be based on diversity and variability analysis relying on characterization or evaluation data, DNA markers, or both. Core subsets may aid selection by guiding users to genetic differences. Evaluation results must be shared promptly and widely worldwide, so germplasm users can request them for further utilization in plant breeding or research on plant genetic resources. This chapter relates therefore to gathering accurate and precise evaluation of diverse accessions in well-designed trials. Such knowledge is essential for identifying the most relevant accessions for further use. This information needs to be shared widely and quickly with users to achieve a maximum impact because any germplasm user should be aware of the potential of gene bank accessions in order to fully exploit such plant genetic resources. This chapter also illustrates the need for an objective assessment of gene bank accessions, deals with sampling of core subsets for evaluation of gene bank accessions, explains the principles of experimental design for trials of gene bank accessions and provides basic knowledge regarding trial data analysis.
Conservation planning involves selecting target taxa, establishing the geographic and taxonomic breadth of the conservation actions and producing some form of strategy or action plan for implementation. The selection of which taxon or taxa to conserve should be based on a series of measurable criteria such as the threat of genetic erosion / extinction, value of the taxon to humankind or the ecosystem, or the potential ease of use of the taxon or taxa. Once the target taxon is chosen, its geographic distribution, habitat preferences, phenology, and taxonomy are established to identify gaps in existing conservation actions to formulate an effective conservation strategy. Gap analysis is used to analyse the literature, passport data on gene bank accessions, label information on herbarium specimens for each taxon, as well as consulting taxonomic experts, and databases and concludes with strategic action to enhance conservation. Increasingly these strategic actions are tested in terms of their mitigation of climate change for the target taxon / taxa and formulated into a national strategy and action plan that gives background to their selection and clearly establishes the required conservation actions needed. The success of these actions is then measured against biodiversity indicators, so progress can be reviewed.
Data management is key to conservation and this includes: the types of data, how data are recorded, data standardization and conservation data management. The main sources of data are passport (provenance) and ecogeographic data, characterization and evaluation data, and management or curatorial data, each of these data are collated and managed by conservationists. Although associated with these data management types, three fundamentally important pieces of data are pivotal. The accession number (or unique identifier), the scientific name of the taxon being conserved and the date of the conservation intervention (e.g. seed collection or population monitoring date). Often today data management is assisted by using a conservation data management system (e.g. GRIN Global) to improve efficiency and help enforce data standardization. Further data management is assisted by use of data collection templates or accession / population descriptors. Much of these data are then made available to the user community via web-based platforms such as EURISCO or GBIF. The importance of access to and ownership of the various kinds of data is emphasized as fundamental to good data management practice.
Conserving plant genetic diversity for further use by crossbreeding through various methods for crop improvement is an important goal. Indeed, plant germplasm remains the most important genetic resource for sustaining crossbreeding. Advances in cell and molecular biology enable us to further exploit inter-genera and interfamily variation along with capitalizing on intra-specific and inter-specific variation. Hence, this chapter describes the theory underpinning population genetics and how to use this knowledge for providing a sound and effective strategy and ensuing plan of work for collecting, conserving and using plant genetic diversity. The reader of this chapter will get enough knowledge to identify a suitable crossbreeding method to develop a new cultivar or to improve a breeding line or population and assess the feasibility of using recent advances in agro-biotechnology for transferring new traits into available cultivars or breed new cultivars. This acquired knowledge will allow understanding the basic principles of plant breeding and thereafter use them for crossing and selecting segregating offspring with desired characters.
An understanding of taxonomy is fundamental to effective conservation planning and implementation. Associated knowledge is used in the selection of species for conservation, understanding inter-taxon relationships and field identification. At its heart is the elucidation of relationships between taxa (families, genera, species or subspecific taxa) and the production of classifications that reflect their evolutionary relationships. The relationships are summarized in the classification, based commonly on analysis of molecular and / or morphological characters, and the included taxa are placed in a taxonomic hierarchy with decreasing relatedness or similarity between the ranks as you go up the hierarchy. Once the classification is established a series of other products can be derived for the included taxa such as descriptions, synonyms, distribution maps, identification aids and accepted nomenclature.
On-farm conservation involves the maintenance of traditional varieties by farmers in agroecosystems. The important role of small farmers living and cultivating in complex, diverse and risk-prone marginal and heterogeneous environments in maintaining crop diversity on-farm is described. The on-farm conservation of plant genetic resources is complex because there are many factors that will influence a farmer’s decision on the management of their crops and fields, which in turn affect the quantity and quality of the inherent genetic diversity. The multiple private and public values and benefits of on-farm conservation are highlighted, as well as the options and interventions that can help strengthen the role of small farmers and farming communities in on-farm conservation. A major focus for the conservationist or development practitioner will be to encourage the farmer to continue cultivation of traditional varieties and this may be achieved by niche marketing, seed shows, participatory traditional variety improvement or even financial incentives. Key steps that need to be considered when implementing an on-farm conservation project are outlined and a brief review of the impact of on-farm conservation projects and the implications for scaling up actions is provided.