| Abstract Detail
Systematics Section / ASPT McDade, Lucinda A. [1], Kiel, Carrie A. [1], Daniel, Thomas F. [2]. Molecular phylogenies reveal multiple origins for distinctive pollen types in Acanthaceae. Acanthaceae are certainly among the most eurypalynous (i.e., exhibiting significant diversity of pollen types) of flowering plant families. Further, although some lineages within the family are fairly conservative in terms of pollen morphology (e.g., the Tetramerium lineage [Justicieae], New World Aphelandra [Acantheae]), others comprise remarkable diversity of pollen types (e.g.. Old World Crossandra [Acantheae], New World justicioids [Justicieae], Strobilanthes s.l. [Ruellieae]). This leads to the prediction that, compared to other morphological characters, pollen morphology in Acanthaceae may be prone to homoplasious or apparently homoplasious evolution. We use phylogenetic hypotheses built from DNA sequence data to explore two cases of remarkable parallel evolution of very similar pollen types in Acanthaceae. First, "Toblerone" pollen (i.e., pollen that is rectangular in equatorial view and triangular in polar view) has evolved at least twice and perhaps three or more times in Old World Crossandra, Crossandrella and Streptosiphon (Acantheae). Second, core Isoglossinae (Justicieae) share "Gürtelpollen" (i.e., girdled pollen that is usually lenticular in shape) which has been interpreted as a synapormorphy for the group. However, remarkably similar pollen occurs in taxa belonging to the distantly related Old World Whitfieldia lineage (Barlerieae). This has led to the classification of some groups (e.g., Malagasy Forcipella) in the former taxon whereas DNA data (and further morphological study) indicate that they are part of the Whitfieldia lineage. We compare pollen in these two groups, asking whether the inference from phylogenetic analysis that they are not homologous is supported by other evidence.
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1 - Academy of Natural Sciences, Department of Botany, 1900 Benjamin Franklin Parkway, Philadelphia, Pennsylvania, 19103, USA
2 - California Academy of Sciences, Department of Botany, 875 Howard Street, San Francisco, California, 94103-3009, USA
Keywords:
Acanthaceae
palynology
Phylogeny
homoplasy.
Presentation Type: Oral Paper
Session: 48-11
Location: Salon G - Austin Grand Ballroom/Hilton
Date: Wednesday, August 17th, 2005
Time: 3:45 PM
Abstract ID:220 |
