In this study I documented the convergence of five congeneric bird-pollinated plants (Aloe pluridens, A. lineata var. muirii, A. speciosa, A. africana, and A. ferox) into three functional groups based on size, shape, and the arrangements of flowers on the inflorescence, but also nectar rewards, pollen deposition sites on the bird-pollinators, and the degree to which bees play a role in their pollination. Individuals of similar functional groups were divergent in their peak flowering times and limited their degree of flowering overlap further by spatial aggregation and niche separation, within the Thicket of the Gamtoos River Valley. The nectar properties were especially useful in structuring the bird pollinator community, which resulted in greater ethological isolation and hence, greater reproductive assurance in the mixed co-flowering plant communities. Choice array experiments revealed that it was the fine scale aggregation of flowering individuals that ensured that bird-pollinators feed selectively, since when equal choice was available, interspecific visitation increased significantly compared to natural scenarios. Bird behaviour and the ecological intermediateness of one to the species explained its prominence in hybrid combinations. The spatial occurrence of hybrid individuals can be traced back to the energetics of foraging and its influence on bird floral constancy. The pollination ecology of similar South African Aloe species were extrapolated from these and recent findings by various authors, but emphasises the need for a robust natural phylogeny of the Aloaceae in order to draw comprehensive conclusions on the evolutionary radiation of this highly charismatic group.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:nmmu/vital:10628 |
| Date | January 2007 |
| Creators | Botes, Christo |
| Publisher | Nelson Mandela Metropolitan University, Faculty of Science |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis, Masters, MSc |
| Format | vi, 55 leaves, [13] leaves, pdf |
| Rights | Nelson Mandela Metropolitan University |
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