Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 15 of 15 for “"Cycad"”.
-
Species-level phylogenetic reconstruction of the African cycad genus Encephalartos (Zamiaceae)
… phylogenetic relationships of the African cycad genus Encephalartos, which is one of the eleven genera of cycads. The genus is confined to Africa and comprises approximately 65 species, 38 of which are found naturally in South Africa. The phylogenetic studies on Encephalartos to date still …
-
Crime, culture and collecting: the illicit cycad market in South Africa
… crime market in South Africa, that of rare cycad plants. Cycads are widely exploited, moved and sold in the country by a network of increasingly criminalised operations. State action against these markets is not a priority and has had only few successes in limiting the trade of an …
-
The ecology and management of the Kaapsehoop cycad (Encephalartos laevifolius Stapf and Burtt Davy)
The Kaapsehoop Cycad (Encephalartos laevifolius Stapf and Burtt Davy) has the international, national, and provincial status of "endangered" by virtue of a number of factors which threaten it with extinction. It occurs in only three disjunct populations in southern Africa, of which two are very …
-
Effects of habitat degradation on the evolutionary dynamics of populations in a rainforest cycad (Gymnospermae)
… dynamics of populations of the rainforest cycad Zamia fairchildiana, specifically how habitat degradation affects gene dispersal, inbreeding, directional selection, and genotype-by-environment interactions, and the potential for genetic differentiation between populations. Colonies of Z. …
-
Adaptation to the host-plant, and the evolution of host specialization, in 'cycad weevils' (Coleoptera: Brentidae)
… These beetles occur only on species of the cycad genus Encephalartos and appear to retain an ancient association with cycads, a group of plants that were widespread in the Mesozoic era (ca. 200 MYA) before the rise of the angiosperms and which are now represented by 11 genera with relict …
-
Systematics and evolutionary biology of the Weevils associated with cycads in Australia
Cycads are subtropical and tropical palm-like gymnosperms, commonly known as "living fossils" as they arose in the late Paleozoic and were much more diverse and dominant during the Mesozoic. Modern cycads underwent a recent global diversification in Miocene (ca. 11-20 mya). Even though cycads were …
-
Systematics and evolutionary biology of the Weevils associated with cycads in Australia
Cycads are subtropical and tropical palm-like gymnosperms, commonly known as "living fossils" as they arose in the late Paleozoic and were much more diverse and dominant during the Mesozoic. Modern cycads underwent a recent global diversification in Miocene (ca. 11-20 mya). Even though cycads were …
-
Cycad forensics: tracing the origin of poached cycads using stable isotapes, trace element concentrations and radiocarbon dating techniques
In South Africa, the greatest threat to cycad populations is the illegal removal of wild plants for landscaping purposes and collector's gardens, resulting in declining populations that are already threatened with extinction. Radiocarbon dating in conjunction with stable isotopes and trace element …
-
The role of cone volatiles and thermogenesis in the pollination of Encephalartos cycads with particular reference to E.villosus
Pollination systems of cycads usually involve obligate mutualisms in which the cycad taxa depend on between one and three insect pollinators. Generally, the pollination periods of many cycad taxa are characterised by odour emissions in pollen shedding (male) and receptive (female) cones usually …
-
Poaching of encephalartos transvenosus, in the Limpopo Province, South Africa
… and in severe cases, local or global extinction. Cycad species in the Limpopo Province, South Africa, are poached for traditional medicine, ornamental and wildlife trade purposes. The study was conducted in nature reserves in the Limpopo Province which are: Mphaphuli Nature Reserve which is in the …
-
In vitro tissue culture: Towards conservation of threatened desiccation sensitive Encephalartos cycads seeds
Approximately 62% of the 355 cycad species in the world are classified as threatened with extinction. The African genus, Encephalartos, has a total of 65 species, approximately 70% of which are threatened. This status emphasizes the need to conserve these species; however, the recalcitrant nature …
-
Assessing species richness patterns and conservation threats (due to overharvesting and climate change) in South African Cycads, with emphasis on a population of Encephalartos tranvenosus Stapf and Burt Davy from the Soutpansberg Mountain, Limpopo Province
Cycads are regarded as the oldest living seed plants on earth and they have existed for about 300 million years. Ever since the awareness of the existence of this plant group, they have been facing high extinction risk. Currently they are referred to as the most threatened plant group in the world. …
-
Preparing plant collections for biological invasions: a study of the effects of emerald ash borer (Agrilus planipennis Fairmaire) through case study analysis
… (Phytophthora ramorum Werres et al.), and Asian cycad scale (Aulacaspis yasumatsui Takagi) that are affecting institutions in other regions of the United States. To aid in research initiatives, such as resistance breeding pertaining to the EAB invasion, this study also sought to investigate the …
-
Characterization of grapevine vein clearing virus expression strategy and development of caulimovirus infectious clones
… The longtailed mealybugs were collected from a cycad plant in Tucker greenhouse (University of Missouri), whereas a mixed population of longtailed and citrus mealybugs were collected from infested grapevines in the Ashland-Gravel greenhouses (University of Missouri). Both populations were able …
-
Life history traits of South African Encephalartos spp. (Zamiaceae) and their implications for understanding population structure, responses to threats and effective conservation action
… analysis of life history traits was applied to cycads, the oldest living seeds plants which are at risk of extinction due to vulnerability to illegal wild harvesting and habitat loss. The study focused on South African cycad species within the genus Encephalartos, as well as two species from …