"The energy intake rate during feeding influences foraging efficiency (Wolf et al., 1972; Heinrich, 1975; Whitham, 1977; May, 1988) and reproductive fitness (Hainsworth et al., 1991). Rapid feeding should therefore be favoured by natural selection (Emlen, 1966; Schoener, 1971; Pyke et al., 1977). "
[Show abstract][Hide abstract] ABSTRACT: Extremely long proboscides are rare among butterflies outside of the Hesperiidae, yet representatives of several genera of skipper butterflies possess proboscides longer than 50 mm. Although extremely elongated mouthparts can be regarded as advantageous adaptations to gain access to nectar in deep-tubed flowers, the scarcity of long-proboscid butterflies is a phenomenon that has not been adequately accounted for. So far, the scarceness was explained by functional costs arising from increased flower handling times caused by decelerated nectar intake rates. However, insects can compensate for the negative influence of a long proboscis through changes in the morphological configuration of the feeding apparatus. Here, we measured nectar intake rates in 34 species representing 21 Hesperiidae genera from a Costa Rican lowland rainforest area to explore the impact of proboscis length, cross-sectional area of the food canal and body size on intake rate. Long-proboscid skippers did not suffer from reduced intake rates due to their large body size and enlarged food canals. In addition, video analyses of the flower-visiting behavior revealed that suction times increased with proboscis length, suggesting that long-proboscid skippers drink a larger amount of nectar from deep-tubed flowers. Despite these advantages, we showed that functional costs of exaggerated mouthparts exist in terms of longer manipulation times per flower. Finally, we discuss the significance of scaling relationships on the foraging efficiency of butterflies and why some skipper taxa, in particular, have evolved extremely long proboscides. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
"Second, in addition to only testing for effects of one microorganism, we only examined the foraging response of one guild of pollinators, bumble bees. Delphinium is frequently utilized as a nectar resource by hummingbirds, hawkmoths, and other floral visitors , whose energetic demands differ in comparison to bumble bees . And third, though yeast frequency of occurrence and density varied spatio-temporally, the mean densities observed at each site were all dense enough to potentially elicit foraging responses by pollinators , , . "
[Show abstract][Hide abstract] ABSTRACT: Microorganisms frequently colonize the nectar of angiosperm species. Though capable of altering a suite of traits important for pollinator attraction, few studies exist that test the degree to which they mediate pollinator foraging behavior. The objective of our study was to fill this gap by assessing the abundance and diversity of yeasts associated with the perennial larkspur Delphinium barbeyi (Ranunculaceae) and testing whether their presence affected components of pollinator foraging behavior. Yeasts frequently colonized D. barbeyi nectar, populating 54-77% of flowers examined depending on site. Though common, the yeast community was species-poor, represented by a single species, Metschnikowia reukaufii. Female-phase flowers of D. barbeyi were more likely to have higher densities of yeasts in comparison to male-phase flowers. Pollinators were likely vectors of yeasts, as virgin (unvisited) flowers rarely contained yeasts compared to flowers open to pollinator visitation, which were frequently colonized. Finally, pollinators responded positively to the presence of yeasts. Bombus foragers both visited and probed more flowers inoculated with yeasts in comparison to uninoculated controls. Taken together, our results suggest that variation in the occurrence and density of nectar-inhabiting yeasts have the potential to alter components of pollinator foraging behavior linked to pollen transfer and plant fitness.
PLoS ONE 10/2014; 9(10):e108214. DOI:10.1371/journal.pone.0108214 · 3.23 Impact Factor
"Observations of the wattlebirds feeding showed that they exhibited a strong fidelity to Anigozanthos humilis flowers in August, feeding from the ground, and to Anigozanthos manglesii in September, feeding perched on the elongate stems. Highly significant departures from random expectations were observed during both study periods and conform to minimal energy expenditure expectations for foraging nectarivores, i.e. the Anigozanthos species providing the greatest calorific reward for the least effort at a given time was preferentially utilised (Heinrich, 1975). The assortative pollination by red wattlebirds constituted a 97% effective barrier to hybridisation between the two species and the authors speculate that honeyeaters may have acted as '… "
[Show abstract][Hide abstract] 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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