Variations in species richness among biological groups has often been considered an important macroevolutionary problem. Recently the explanations for these differences have been sought using new, more efficient methodologies and phylogenetic analyses. Variation in clade diversification rates (speciation minus extinction rate) could explain disparity in clade size. Therefore, identifying correlations between traits and this variation is necessary to hypothesise potential drivers of speciation responsible for affecting clade species richness. In this work, these problems have been investigated using Myrtaceae as a case study, with particularly attention focused on the BKMMST clade sensu Biffin et af. (2010). The clade contains two large genera (>500 species; sensu Frodin, 2004) mostly fleshy fruited (Eugenia and Syzygium), whilst the other genera in the clade are relatively species poor and predominantly dry fruited. It has been suggested that fleshy fruits could be the key innovation responsible for the hyper diversification of these large BKMMST genera but the hypothesis was never tested. In this study, an improved molecular dataset of Myrtcaeae was used to investigate macroevolutionary questions at a high taxonomical level. Previously unsampled new taxa were sequenced for a total of 143 taxa and four gene regions, the nuclear ITS and plastid matK, ndhF and rpL16 regions. The results confirmed the existence ofthe BKMMST clade and improved resolution and support among the BKMMST tribes. However, in the hypothesised phylogenetic tree, many of the deep nodes still remain poorly supported. A temporal approach was applied to understand the evolutionary patterns, and for the first time, a diversification rate shift was placed within the BKMMST clade, confirming the presence of fast radiation event associated with the clade. In, addition, a selection of abiotic (biogeography patterns) and biotic traits (flower colour, fruit type and habitat) were tested in order to explain the origin of the shift identified and/or the origin of the larger clades within the BKMMST.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:592664 |
| Date | January 2013 |
| Creators | Bernardini, Benedetta |
| Publisher | University of Reading |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.0025 seconds