Browsing by Subject "Paleobotany"

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    Dated Plant Phylogenies Resolve Neogene Climate and Landscape Evolution in the Cape Floristic Region
    (Public Library of Science, 2015) Hoffmann, Vera; Verboom, G. Anthony; Cotterill, Fenton P. D.
    In the context of molecularly-dated phylogenies, inferences informed by ancestral habitat reconstruction can yield valuable insights into the origins of biomes, palaeoenvironments and landforms. In this paper, we use dated phylogenies of 12 plant clades from the Cape Floristic Region (CFR) in southern Africa to test hypotheses of Neogene climatic and geomorphic evolution. Our combined dataset for the CFR strengthens and refines previous palaeoenvironmental reconstructions based on a sparse, mostly offshore fossil record. Our reconstructions show remarkable consistency across all 12 clades with regard to both the types of environments identified as ancestral, and the timing of shifts to alternative conditions. They reveal that Early Miocene land surfaces of the CFR were wetter than at present and were dominated by quartzitic substrata. These conditions continue to characterize the higher-elevation settings of the Cape Fold Belt, where they have fostered the persistence of ancient fynbos lineages. The Middle Miocene (13-17 Ma) saw the development of perennial to weakly-seasonal arid conditions, with the strongly seasonal rainfall regime of the west coast arising ~6.5-8 Ma. Although the Late Miocene may have seen some exposure of the underlying shale substrata, the present-day substrate diversity of the CFR lowlands was shaped by Pliocene-Pleistocene events. Particularly important was renewed erosion, following the post-African II uplift episode, and the reworking of sediments on the coastal platform as a consequence of marine transgressions and tectonic uplift. These changes facilitated adaptive radiations in some, but not all, lineages studied.
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    Palynology of the Cape's top ten richest families and its taxonomic implications
    (2011) Ingram, Steven
    Principal pollen characters, of the Cape floristic Regions ten richest families, which are phylogenetically useful at higher taxonomic levels (including aperture type, exine structure, pollen-unit, polarity, symmetry, shape), and their evolutionary trends are examined. Monocotyledons differ from eu-dicotyledons (and eu-dicots from basal-dicots) in their aperture number and form, and exine structure and are discussed in relation to their pollination syndrome aswell as their evolutionary trends. We also discuss the possibilities of creating a taxonomic key at species level, if not only for use at the vegetation-type scale for paleobotanists aswell as honey farmers.