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Energetics of Pollination

Annals of the Missouri Botanical Garden (Impact Factor: 2). 11/2003; 6:139-170. DOI: 10.1146/annurev.es.06.110175.001035
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    ABSTRACT: AUSTRALIAN PLANTS DIFFER FROM THOSE in the northern hemisphere in the extent to which they are pollinated by birds and mammals (Levin & Kerster, 1974; Armstrong, 1979; Proctor et al., 1996; Menz et al., 2011). The primary pollination vectors in Europe are insects and wind (chapter 7A) and the importance of vertebrates as pollinators of many Australian flowers was slow to be appreciated (Ford et al., 1979). These differing modalities can have far-reaching genetic consequences for plants, and it has often been assumed that mating opportunities are largely restricted to nearest neighbours, because of the forces extrinsic to plants that limit pollen dispersal (Smouse & Sork, 2004). This is the case where wind and insects are the pollination vectors, and a skewed distribution is typical in northern-hemisphere plants with many grains dispersed close to the pollen source and a long tail of fewer, far-dispersed grains (Webb, 1998; Sork et al., 1999). A recent molecular analysis of paternity in a natural population of the Australian plant species, Banksia hookeriana (Proteaceae), however, has demonstrated a significant departure from these assumed patterns of pollen dispersal (He et al., 2004; Krauss et al., 2009), comparing the vertebrate-pollinated Banksia hookeriana with a bee-pollinated species, Persoonia mollis (Krauss, 2000) (Fig. 1). These data from Banksia hookeriana signal hitherto unexpected genetic consequences of pollination by vertebrate vectors and the need for a landscape approach to gene flow in plants (Sork et al., 1999). In the study, 96% of two-seeded fruits were multiply sired, indicating extensive pollen carry-over with promiscuity facilitated by highly-mobile nectar-feeding birds (White-cheeked honeyeater) moving effectively in a random manner (Krauss et al., 2009). In another study of fragmented populations in kwongan of the shrub Calothamnus quadrifidus, pollen was regularly dispersed by honeyeaters between fragments as much as 5 km apart (Byrne et al., 2007). The highly-diverse Southwest Australian Floristic Region (SWAFR) is an internationally-recognised biodiversity hotspot under multiple threats (chapter 8) (Myers et al., 2000; Phillips et al., 2010) and one where vertebrate pollinators are of great significance. Fifteen per cent of some 7380 plant species are considered to be either bird or mammal pollinated, a striking 40% of which are threatened endemics (Hopper & Gioia, 2004). This contrasts with other vertebrate-pollinated regions of South Africa and Central America where only 4% of the flora is bird pollinated (Bawa, 1990). Bird pollination is a prominent feature of the ancient Gondwanan families Proteaceae and Myrtaceae, and 110 species of birds have been recorded visiting the flowers of 1000 species of plants in more than 64 genera and 16 families (Ford et al., 1979; Keighery, 1982; Brown et al., 1997). The 'otherness' of the Australian environment and its plants and animals has long attracted and intrigued biologists, but it is only now that the underlying reasons for this are beginning to be understood (Stafford Smith & Morton, 1990). The immense age of the continent, particularly its western Yilgarn craton with some of the oldest rocks on the planet (Myers, 1995), and the weathering that has depleted
    Plant Life on the Sandplains in southwest Australia, a Global Biodiversity hotspot., Edited by Lambers, H, 09/2014: chapter 7D: pages 207-213; UWA Publishing.
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    ABSTRACT: The pollination ecology of Rauvolfia micrantha Hook. F., a critically endangered medicinal plant, was studied in the mountains of southern Western Ghats. The species has scanty distribution in the wild due to habitat degradation, fragmentation of population and narrow environmental niche. A comprehensive phenological investigation revealed that the plant flowers between March and October and the peak time of blooming period resides in May. Anthesis occurred from 0500 to 0830 hr with peak during 0700 hr. Anthers dehisced between 0600 and 1030 hr on the day of anthesis. Although the stigma becomes receptive one day before the opening of flowers, maximum receptivity (~70%) was recorded on the day of anthesis. Nearly 82% pollen grains were viable on the day of anthesis. The plants were self-incompatible and reproduced by means of cross-pollination, which enhanced the rate of fruit-set up to 80%; this strongly indicates the role of pollinators. The major insect pollinators included Apis florea (honeybee), Oecophylla smargadina (red ant), Trigona iridipennis (pollen bee) and butterflies such as Pachliopta aristolochaea, Pachliopta hector, Delias eucharis and Euploea core. The presented data will be of immense use for any rational strategy to conserve, multiply and genetically improve the species.
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