PHYLOGENETIC RELATIONSHIPS IN THE FAMILY AMARYLLIDACEAE

• Main Author: Strydom, Adéle
• Other Authors: Prof JJ Spies
• Format: Others
• Language: en-uk
• Published: University of the Free State 2006
• Subjects: Plant Sciences
• Online Access: http://etd.uovs.ac.za//theses/available/etd-09122006-103922/restricted/

The subject of this study is the family Amaryllidaceae with emphasis on 14 genera which represent six of the 15 tribes in this family. The genera are Amaryllis L., Ammocharis Herb., Boophone Herb., Brunsvigia Heist., Clivia Lindl., Crinum L., Crossyne Salisb., Cyrtanthus Aiton, Gethyllis L., Haemanthus, Hippeastrum, Narcissus L., Scadoxus Raf. and Strumaria Jacq. ex Willd. The Amaryllidaceae is a cosmopolitan, predominantly pantropical, family of petaloid, perennial or biennial monocots. The Amaryllidaceae form one of the climax groups in the Asparagales. They are probably more closely related to Alliaceae and Hyacinthaceae. The Amaryllidaceae is a large group consisting of about 860 species in 59 genera. Its centre of diversity is in Africa (19 genera) and South America (28 genera). Some genera also occur in the Mediterranean (8 genera) and temperate regions of Asia. Only one genus, Crinum L., is represented in both the Old and New Worlds because of seeds well adapted for dispersal over water. For this study a chloroplast gene and DNA region: matK and trnL-F, respectively, and a nuclear DNA region: ITS, were used in the phylogenetic reconstruction. All three give DNA sequences that are useful for comparing species and closely related genera. Despite a lack of consensus on generic limits and tribal delimitation within the Amaryllidaceae, cladistic analysis has only rarely been applied to problems in the family. Homoplasy for many conspicuous characters within some ge nera impedes the application of phylogenetic studies for the entire family. The combined trnL-F and matK matrix gave better results than the separate trnL-F analysis. The results of both the matK data and the combined matrix were well supported by bootstrap and jackknife. The sister status of the Eurasian/American/Mediterranean clades were better resolved in the separate matK analysis than the combined matrix. The indigenous tribes Amaryllideae, Haemantheae, Cyrtantheae and Gethyllideae were resolved and well supported in the separate matK and combined analysis. The results between the two combined matrices were very similar but the different tribes were better resolved in the combined matrix of all three DNA regions. In this study, the combined matrices indicated stronger bootstrap and jackknife support compared to the separate data sets of trnL-F, matK and ITS. Reported chromosome numbers of genera in the Amaryllidaceae indicates that variation between somatic chromosome numbers in each tribe is not high, except where hybridization may occur. Most of these somatic chromosome numbers agree with the given basic chromosome numbers that may occur in each tribe. As more becomes known of the southern African species in the family Amaryllidaceae, the lack of knowledge regarding chromosome morphology and behaviour becomes more apparent. In this study, the results of a cytogenetic study on several Cyrtanthus species are included. Chromosomes in this genus are large, as in the rest of the Amaryllidaceae. Variations in their karyotypes have been described. A somatic chromosome number of 2n = 2x = 16 was observed in most of the Cyrtanthus species except for two specimens of C. mackenii var. mackenii. A somatic chromosome number of 2n = 4x = 32 was indicated by these specimens. A tetraploid Cyrtanthus species has not been previously reported. However, this study did not support previous studies that ideograms vary among the different Cyrtanthus species and may be used in the identification of certain species. The variation in the ideograms was minimal and not sufficient for identification purposes. The results of this study strongly support those from previous studies and can be used in the classification of Amaryllidaceae.