Knowledge Resource Center for Ecological Environment in Arid Area
| Polyploid speciation in the Greater Cape Floristic Region : species limits within Ehrhara calycina | |
| Musker;Seth | |
| 出版年 | 2013 |
| 学位授予单位 | University of Cape Town, Faculty of Science, Department of Biological Sciences |
| 英文摘要 | Ehrharta calycina J. E. Sm. (Poaceae) is a widespread and often abundant species whose core distribution lies within the Greater Cape Floristic Region (GCFR). Importantly, it shows a high degree of morphological and ploidy level variation. Based on observations of distinct forms co-occurring at multiple sites, the hypothesis that E. calycina comprises more than one species was tested. Morphological analysis of herbarium specimens using a multivariate approach found strong evidence for the presence of two distinct phenetic clusters among specimens from sites of sympatry, and these were termed ???robust??? and ???slender??? forms. This translated to a broader sampling of specimens from across the GCFR (n = 516), of which over 91% could be attributed to one or other form with >90% confidence using linear discriminant analysis. Importantly, chromosome counts supported the hypothesis that these phenetic clusters represent distinct cytotypes, with slender forms being diploid (n = 12) and robust forms tetraploid (n = 24), thus providing the primary reproductive isolating mechanism between the forms. Furthermore, differences in climatic niche suggest that these forms represent ecologically independent entities. Finally, evidence that the forms differ in palatability has considerable practical implications given that E. calycina is regarded as having high pasture value. Together, our results provide multiple lines of evidence for the existence of at least two morphologically distinct, reproductively isolated species within E. calycina, and suggest that the role of polyploidy in generating floral diversity in the GCFR may be more important than previously thought. |
| 英文关键词 | Biological Sciences |
| 语种 | 英语 |
| URL | http://hdl.handle.net/11427/14016 |
| 来源机构 | University of Cape Town |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/247541 |
| 推荐引用方式 GB/T 7714 | Musker;Seth. Polyploid speciation in the Greater Cape Floristic Region : species limits within Ehrhara calycina[D]. University of Cape Town, Faculty of Science, Department of Biological Sciences,2013. |
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