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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Integrated conservation of the rare and endangered terrestrial orchid Caladenia huegelii H.G. Reichb /

Swarts, Nigel. January 2007 (has links)
Thesis (Ph.D.)--University of Western Australia, 2008.
12

The convention on international trade in endangered species of wild fauna and flora political or conservation success? /

Trexler, Mark Charles. January 1990 (has links)
Thesis (Ph. D.)--University of California, Berkeley, 1990. / Includes bibliographical references (leaves 156-169).
13

Levels and patterns of genetic diversity in the rare and endangered Cumberland Stitchwort, Minuartia cumberlandensis (Caryophyllaceae)

Winder, Charles Thomas. January 2004 (has links) (PDF)
Thesis (M.S.)--University of Tennessee, Knoxville, 2004. / Title from title page screen (viewed Feb. 2, 2005). Thesis advisor: Randall L. Small. Document formatted into pages (viii, 73 p. : ill. (some col.), maps). Vita. Includes bibliographical references (p. 39-44).
14

Systematic and reproductive studies of Mimulus (Scrophulariaceae) in the Pacific Northwest : implications for conservation biology

Meinke, Robert James 08 May 1992 (has links)
The Mimulus washingtonensis complex is a group of morphologically similar species centered in the Pacific Northwest. All are rare, and most are under consideration for listing as endangered. Morphometric and pollination data were used in developing a revised taxonomy for the group. Five species and two varieties are recognized. Mimulus pulsiferae Gray is the most widespread, occurring from southern Washington to northern California. Mimulus hymenophyllus Meinke and M. jungermannioides Suksd. are cliff species endemic to river drainages in northern Oregon. Mimulus washingtonensis Gand. occurs in east-central Oregon and western Idaho, represented by the var. washingtonensis and var. ampliatus (Grant) Meinke comb. et stat. nov., respectively. Mimulus patulus Pennell is resurrected from synonymy and differentiated from M. washingtonensis on the basis of morphology, distribution, and pollination biology. This autogamous species includes var. patulus, occurring in the Snake River drainage, and var. montanus Meinke var. nov., primarily from the northern Rocky Mountains. Mimulus evanescens Meinke sp. nov. is described from an extant population in Lassen County, California, and historic collections from widely scattered stations in Oregon and Idaho. The new species is morphologically intermediate between M. breviflorus Piper and M. latidens (Gray) Greene. Calyx and leaf morphology also suggest an affinity to M. grayi Grant, M. inconspicuus Gray, and M. acutidens Greene, of cismontane California. Mimulus evanescens should be considered critically endangered, because of its limited numbers and habitat degradation. Mimulus washingtonensis is pollinated by small native bees, primarily two species of Dialictus (Halictidae). These bees were specific to Mimulus flowers but did not distinguish between flowers of M. washingtonensis and M. guttatus DC., a related species that increases with habitat disturbance. Experiments showed that mixed pollen loads diminish seed set in M. washingtonensis, since the thigmotropic stigma of that species closes permanently after any amount of conspecific pollen is applied. Although M. washingtonensis has a low pollen/ovule ratio (29.9), it is considered facultatively xenogamous based on floral morphology, stigma sensitivity, and autogamous seed set levels. Populations occurred in small, edaphically restricted patches, and they exhibited seed set reductions related to outcrossing distance. Substrate disturbance may limit reproduction in M. washingtonensis by changing population structure, threatening pollinators, and increasing competition for pollination by promoting growth and flowering of M. guttatus. / Graduation date: 1992
15

The Role of Native Plant and Seed Collectors and Growers in Protecting Floral Diversity

Morris, David N. 25 August 2010 (has links)
The planting of native species is a common strategy for the conservation of biodiversity; it not only allows for the restoration of degraded habitat both within conservation reserves and the matrix lands between reserves, it supplements the populations of the floral species which are planted. These supplemental populations may play an important role in providing demographic security for rare species. However, the conservation of rare species depends on more than simply maintaining adequate numbers of the species: the diversity within the species must also be conserved. Although maintaining genetic diversity is increasingly a concern for formal species recovery efforts, there has been very little research done about the diversity within plantings by non-state actors. This research was undertaken to address this knowledge gap by studying the provenances of planted rare species and the activities of those who collect and grow these plants. This research was undertaken in the Carolinian zone of southern Ontario, a region with a large number of rare plant species and a large human population. Part of this study utilized semi-structured interviews with commercial seed collectors, commercial native plant growers, and non-commercial, hobbyist growers. A variety of factors limited the diversity with the seeds collected by commercial collectors. Due to difficulty in accessing information about the natural occurrences of rare species, collectors typically collected from the same, limited number of source plants. Trespassing on private property or protected lands was common to access these seed sources, although their preference for easily accessible, reliably fecund source plants on flat, mowed sites also meant that horticultural specimens were also desired. Many of these biases were passed on to commercial growers when the seed was sold by the commercial collectors. Commercial growers shared many collection practices with commercial collectors, creating similar restrictions on the diversity within their collections. However, further limitations in diversity were also created by the growers’ establishment of small populations of seed plants and by the trading of seeds and plants between growers. One boutique grower was a dominant source of seeds and plants in these trades. The limitations in the diversity within these rare species were passed onto those who purchased and planted them. This study also focused on enthusiastic native plant hobbyists and found that they not only purchased plants but collected and grew their own plants. They also traded with other hobbyists. Much of the information about where to collect seed or plants, as well as much of the seed or plants traded between hobbyists, originated with a key individual. Thus, this champion hobbyist plays a significant role in the character of planted examples of rare plant species and the genetics of the champion’s plants are heavily represented with other planted occurrences. The practices of commercial seed collectors, growers and native plant hobbyists create biases which limit the diversity within plantings of rare species. Although these plantings provide demographic security for these species, they do not represent the diversity within their remnant “wild” populations. Thus, important questions must be raised about the conservation value of these plantings. Since many of the practices of seed collectors and growers are also used when growing more common species, the diversity within plantings of these species should also be suspect. Although the lack of diversity within common species may not threaten the regional survival of the species in the short term, it may impact the ultimate success of restoration projects.
16

Reproductive biology and floral variation in the endangered Braya longii and threatened B. fernaldii (Brassicaceae) : implications for conservation management of rare plants /

Parsons, Kimberley A., January 2002 (has links)
Thesis (M.Sc.)--Memorial University of Newfoundland, 2002. / Restricted until October 2003. Includes bibliographical references.
17

The Role of Native Plant and Seed Collectors and Growers in Protecting Floral Diversity

Morris, David N. 25 August 2010 (has links)
The planting of native species is a common strategy for the conservation of biodiversity; it not only allows for the restoration of degraded habitat both within conservation reserves and the matrix lands between reserves, it supplements the populations of the floral species which are planted. These supplemental populations may play an important role in providing demographic security for rare species. However, the conservation of rare species depends on more than simply maintaining adequate numbers of the species: the diversity within the species must also be conserved. Although maintaining genetic diversity is increasingly a concern for formal species recovery efforts, there has been very little research done about the diversity within plantings by non-state actors. This research was undertaken to address this knowledge gap by studying the provenances of planted rare species and the activities of those who collect and grow these plants. This research was undertaken in the Carolinian zone of southern Ontario, a region with a large number of rare plant species and a large human population. Part of this study utilized semi-structured interviews with commercial seed collectors, commercial native plant growers, and non-commercial, hobbyist growers. A variety of factors limited the diversity with the seeds collected by commercial collectors. Due to difficulty in accessing information about the natural occurrences of rare species, collectors typically collected from the same, limited number of source plants. Trespassing on private property or protected lands was common to access these seed sources, although their preference for easily accessible, reliably fecund source plants on flat, mowed sites also meant that horticultural specimens were also desired. Many of these biases were passed on to commercial growers when the seed was sold by the commercial collectors. Commercial growers shared many collection practices with commercial collectors, creating similar restrictions on the diversity within their collections. However, further limitations in diversity were also created by the growers’ establishment of small populations of seed plants and by the trading of seeds and plants between growers. One boutique grower was a dominant source of seeds and plants in these trades. The limitations in the diversity within these rare species were passed onto those who purchased and planted them. This study also focused on enthusiastic native plant hobbyists and found that they not only purchased plants but collected and grew their own plants. They also traded with other hobbyists. Much of the information about where to collect seed or plants, as well as much of the seed or plants traded between hobbyists, originated with a key individual. Thus, this champion hobbyist plays a significant role in the character of planted examples of rare plant species and the genetics of the champion’s plants are heavily represented with other planted occurrences. The practices of commercial seed collectors, growers and native plant hobbyists create biases which limit the diversity within plantings of rare species. Although these plantings provide demographic security for these species, they do not represent the diversity within their remnant “wild” populations. Thus, important questions must be raised about the conservation value of these plantings. Since many of the practices of seed collectors and growers are also used when growing more common species, the diversity within plantings of these species should also be suspect. Although the lack of diversity within common species may not threaten the regional survival of the species in the short term, it may impact the ultimate success of restoration projects.
18

Demographic and ecological indicators of rarity in a suite of obligate-seeding Persoonia (Proteaceae) shrubs

McKenna, David J. January 2007 (has links)
Thesis (Ph.D.)--University of Wollongong, 2007. / Typescript. Includes bibliographical references: p. 128-139.
19

An analysis of the adaptive cluster sampling design with rare plant point distributions /

Tout, Jeremy. January 1900 (has links)
Thesis (M.A.)--Humboldt State University, 2009. / Includes bibliographical references (leaves 29-31). Also available via Humboldt Digital Scholar.
20

Genetic and ecological aspects of conserving the federally threatened Missouri bladderpod /

Keene, Jeremy, January 1900 (has links)
Thesis (M.S.)--Missouri State University, 2009. / "May 2009." Includes bibliographical references (leaves 12, 28-29, 39). Also available online.

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