Phylogenetic patterns of extinction risk in the Eastern Arc Ecosystems, an African biodiversity hotspot
- Authors: Yessoufou, Kowiyou , Daru, Barnabas H. , Davies, T. Jonathan
- Date: 2012
- Subjects: African biodiversity , Biodiversity , Ecosystems , Climate change , Phylogenetics , Eatern Arc Mountains
- Type: Article
- Identifier: uj:5853 , ISSN 1932-6203 , http://hdl.handle.net/10210/7950
- Description: There is an urgent need to reduce drastically the rate at which biodiversity is declining worldwide. Phylogenetic methods are increasingly being recognised as providing a useful framework for predicting future losses, and guiding efforts for preemptive conservation actions. In this study, we used a reconstructed phylogenetic tree of angiosperm species of the Eastern Arc Mountains – an important African biodiversity hotspot – and described the distribution of extinction risk across taxonomic ranks and phylogeny. We provide evidence for both taxonomic and phylogenetic selectivity in extinction risk. However, we found that selectivity varies with IUCN extinction risk category. Vulnerable species are more closely related than expected by chance, whereas endangered and critically endangered species are not significantly clustered on the phylogeny. We suggest that the general observation for taxonomic and phylogenetic selectivity (i.e. phylogenetic signal, the tendency of closely related species to share similar traits) in extinction risks is therefore largely driven by vulnerable species, and not necessarily the most highly threatened. We also used information on altitudinal distribution and climate to generate a predictive model of at-risk species richness, and found that greater threatened species richness is found at higher altitude, allowing for more informed conservation decision making. Our results indicate that evolutionary history can help predict plant susceptibility to extinction threats in the hyper-diverse but woefully-understudied Eastern Arc Mountains, and illustrate the contribution of phylogenetic approaches in conserving African floristic biodiversity where detailed ecological and evolutionary data are often lacking.
- Full Text:
The effect of genetically modified maize on biodiversity in South Africa
- Authors: Haasbroek, Leonard F.
- Date: 2009-02-05T07:08:53Z
- Subjects: Corn genetic engineering , Crops genetic engineering , Genetically modified foods , Agricultural biotechnology , Biodiversity
- Type: Mini-Dissertation
- Identifier: uj:14878 , http://hdl.handle.net/10210/1998
- Description: M.Sc. , South Africa is a maize producing country. Similar to many other African countries, maize is one of the primary staples. Genetically modified (GM) maize was introduced in 1997 to the South African agricultural sector by multinational seed companies. At present thirteen yellow and six white GM maize hybrids are grown in all the major local cultivation areas. About 10% of all local maize hectares are under GM cultivars, which is about half of the global average for GM maize producing countries. Biotechnology has been the focus of much controversy. This is hardly surprising, since it is a technology that exerts a change on the environment and therefore causes a shift in biodiversity. This study focuses on the effect that GM maize has on biodiversity and the factors that contribute to this change in the maize industry. The effects of biotechnology can be felt in the political, economical and environmental arenas of society. The United States of America and the European Union are locked in a trade war over the safety of bio-engineered crops. Certain African countries are very reluctant to import GM maize due to these prevailing uncertainties. At a global level, the Cartagena Protocol on Biosafety seeks to address these concerns. On a national level, South Africa has enacted the Genetically Modified Organisms Act (Act No. 15 of 1997) to provide a mechanism to implement South Africa’s obligations to the Cartagena Protocol. The farming community has been struggling to cope with the new biotechnology, which places a heavy burden of responsibility on them. The struggle to protect non- GM and organic crops against contamination from cross-pollination seems neverending. The labelling of GM products in order to have liability and traceability in the event of mishaps has been requested around the world. All of these factors contribute to the rapid change that is observed in biodiversity. It is apparent that a large pool of new genetic material is available now and the impetus is there to take advantage of this. It remains to be seen if biotechnology will be the answer to the looming question of world hunger. At the very best, it is an immediate solution toward safe-guarding crops against certain pests and diseases.
- Full Text:
From aloes to zebras (and five new species using vital differences not perceivable by humans)
- Authors: Van der Bank, Herman
- Date: 2008-11-03T07:17:46Z
- Subjects: Genetic biological diversity , Biodiversity , Plants - Genetic data , Animals - Genetic data , Pollimyrus marianne , Pollimyrus castelnau
- Type: Inaugural
- Identifier: uj:14901 , http://hdl.handle.net/10210/1451
- Description: Inaugural lecture--Dept. of Zoology, University Johannesburg, 21 July 2005 , South Africa is a signatory of the convention on biological diversity, in which three levels (genetic, species and ecological) are addressed. My field of research is mainly on the first level mentioned. Genetic data is useful since inferences about the past (e.g. time of divergence and population history), present (diversity, population size, reproductive mixing, hybridisation, inbreeding) and future (selection, conservation, management) can be made. In addition, the technique I use can be applied to plants and animals. Results of studies that range from aloes to zebras are discussed and also how five new species were discovered. This is how Rachel Ashton (section editor, BBC Wildlife Magazine, Broadcasting House, U.K.) described one of our new electric fish: Species are traditionally defined by something we can perceive - be it size, shape, colour or song. But for Pollimyrus marianne, a snout fish from the Okavango-Upper Zambezi River System, the vital difference is something humans can't perceive at all - the discharge pattern from its electric organ. P. marianne of the Zambezi River is virtually indistinguishable from another species, P. castelnaui of the Okavango River, both in looks and in habitat preference. But Herman van der Bank found significant genetic differences and Bernd Kramer discovered that the electric signals are very different, especially those used for mate choice. Comparisons of mitochondrial DNA also confirmed the new Zambezi species. Only individuals from one smaller river (the Kwando), which is running between and mostly in parallel to the two main rivers, have a specific, third electric pattern. Except for occasional very high flooding, this river has been isolated from the Zambezi for at least 60 years, too small a time for definable mitochondrial DNA differences to accumulate by random mutation. But in spite of the sporadic floodings P. marianne was capable of conserving its distinct species-specific signal to identify it in its new electric fish community. The species mentioned above was named after professor Kramer’s late mother (Marianne) and another new species was named after my late father-in-law (Pierre Wessels). These names (and people) are now fixed in history and will be remembered for eternity.
- Full Text: