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Among the more important [[moth]] pollinators are the [[hawk moth]]s ([[Sphingidae]]). Their behaviour is similar to [[hummingbird]]s: they hover in front of flowers with rapid wingbeats. Most are [[nocturnal]] or [[crepuscular]]. So moth-pollinated flowers tend to be white, night-opening, large and showy with tubular [[petal|corolla]]s and a strong, sweet scent produced in the evening, night or early morning. Much nectar is produced to fuel the high [[metabolic rate]]s needed to power their flight.
Other moths ([[Noctuid]]s, [[Geometrid]]s, [[Pyralid]]s, for example) fly slowly and settle on the flower. They do not require as much nectar as the fast-flying hawk moths, and the flowers tend to be small (though they may be aggregated in heads).<ref>{{cite journal |author1=Oliveira PE |author2=PE Gibbs |author3=AA Barbosa |last-author-amp=yes |year=2004 |title=Moth pollination of woody species in the Cerrados of Central Brazil: a case of so much owed to so few? |journal=Plant Systematics and Evolution |volume=245 |issue=1–2 |pages=41–54 |doi=10.1007/s00606-003-0120-0|s2cid=21936259 }}</ref>
[[File:Aasblume Aug 2005.jpg|thumb|right|150px|Sapromyophilous ''[[Stapelia]] [[Stapelia gigantea|gigantea]]'']]
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===Beetle pollination (cantharophily)===
[[Beetle]]-pollinated flowers are usually large, greenish or off-white in color and heavily scented. Scents may be spicy, fruity, or similar to decaying organic material. Most beetle-pollinated flowers are flattened or dish shaped, with pollen easily accessible, although they may include traps to keep the beetle longer. The plant's ovaries are usually well protected from the biting mouthparts of their pollinators.<ref name="Gullan2005">{{cite book |author1=P.J. Gullan |author2=P.S. Cranston |lastauthoramp=yes |year=2005 |title=The Insects: An Outline of Entomology |publisher=Blackwell Publishing Ltd |page=[https://archive.org/details/isbn_9781405111133/page/282 282] |isbn=978-1-4051-1113-3 |url-access=registration |url=https://archive.org/details/isbn_9781405111133/page/282 }}</ref> A number of cantharophilous plants are [[Thermogenic plant|thermogenic]], with flowers that can increase their temperature. This heat is thought to help further spread the scent, but the [[infrared]] light produced by this heat may also be visible to insects during the dark night, and act as a shining beacon to attract them.<ref>{{cite journal |
===Bird pollination (ornithophily)===
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There are major differences between [[bat]] pollination in the [[New World]] as opposed to the [[Old World]]. In the Old World pollinating bats are large fruit bats of the family [[Pteropodidae]] which do not have the ability to hover and must perch in the plant to lap the nectar; these bats furthermore do not have the ability to [[animal echolocation|echolocate]].<ref name=Fleming2009>{{cite journal|doi=10.1093/aob/mcp197 | pmid=19789175 | volume=104 | issue=6 | title=The evolution of bat pollination: a phylogenetic perspective | journal=Annals of Botany | pages=1017–1043| pmc=2766192 | year=2009 | last1=Fleming | first1=Theodore H. | last2=Geiselman | first2=Cullen | last3=Kress | first3=W. John }}</ref> Bat-pollinated flowers in this part of the world tend to be large and showy, white or light coloured, open at night and have strong musty odours. They are often large balls of stamens.
In the Americas pollinating bats are tiny creatures called [[glossophagine]]s which have both the ability to hover as well as echolocate, and have extremely long tongues. Plants in this part of the world are often pollinated by both bats and hummingbirds, and have long tubular flowers.<ref name=Fleming2009/> Flowers in this part of the world are typically borne away from the trunk or other obstructions, and offer nectar for extended periods of time. In one essay, von Helversen ''et al''. speculate that maybe some bell-shaped flowers have evolved to attract bats in the Americas, as the bell-shape might reflect the sonar pulses emitted by the bats in a recognisable pattern.<ref name="Von2003">{{cite journal |author1=von Helversen D |author2=MW Holderied |author3=O von Helversen |last-author-amp=yes |year=2003 |title=Echoes of bat-pollinated bell-shaped flowers: conspicuous for nectar-feeding bats? |journal=Journal of Experimental Biology |volume=206 |issue=6 |pages=1025–1034 |url=http://jeb.biologists.org/cgi/content/abstract/206/6/1025 |doi=10.1242/jeb.00203 |format=abstract page |pmid=12582145|doi-access=free }}</ref> A number of species of ''[[Marcgravia]]'' from Caribbean islands have evolved a special leaf just above the inflorescence to attract bats. The leaf petiole is twisted so the leaf sticks upwards, and the leaf is shaped like a concave disc or dish reflector. The leaf reflects echolocation signals from many directions, guiding the pollinating bats towards the flowers. The [[Epiphyte|epiphytic]] bean ''[[Mucuna holtonii]]'' employs a similar tactic, but in this species it is a specialised petal that acts as a sonar reflector.<ref>{{cite journal |
Bat-pollinated plants have bigger pollen than their relatives.<ref>{{cite journal |doi=10.1007/BF00984104 |author=Stroo, A. |year=2000 |title=Pollen morphological evolution in bat pollinated plants |journal=Plant Systematics and Evolution |volume=222 |issue=1–4 |pages=225–242|s2cid=42391364 }}</ref>
===Pollination by non-flying mammals (therophily)===
The characteristics of the pollination syndrome associated with pollination by mammals which are not bats are: a yeasty odour; cryptic, drab, axillary, geoflorous flowers or inflorescences often obscured from sight; large and sturdy flowers, or grouped together as multi-flowered inflorescences; either sessile flowers or inflorescences or subtended by a short and stout peduncle or pedicel; bowl-shaped flowers or inflorescences; copious, sucrose-rich nectar usually produced during the night; tough and wiry styles; an adequate distance between the stigma and nectar to fit the rostrum of the pollinating animal; and potentially a winter–spring flowering period.<ref name=Wiens1983>{{cite journal |
Many non-flying mammals are nocturnal and have an acute sense of smell, so the plants tend not to have bright showy colours, but instead excrete a strong odour. These plants also tend to produce large amounts of pollen because mammals are larger than some other pollinators, and lack the precision smaller pollinators can achieve.<ref name=Carthewa1997>Carthewa, S. M., R. L. Goldingay. "Non-flying mammals as pollinators." Trends in Ecology & Evolution. Vol. 12, Issue 3. (March 1997) pp. 104–108. DOI:10.1016/S0169-5347(96)10067-7</ref>
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===Advantages of specialization===
*Efficiency of pollination: the rewards given to pollinators (commonly nectar or pollen or both, but sometimes oil,<ref>{{cite journal |author=Buchmann, SL. |year=1987 |title=The ecology of oil flowers and their bees |journal=Annual Review of Ecology and Systematics |volume=18 |issue=1 |pages=343–70 |doi=10.1146/annurev.es.18.110187.002015}}</ref> scents, resins, or wax) may be costly to produce. Nectar can be cheap, but pollen is generally expensive as it is relatively high in nitrogen compounds. Plants have evolved to obtain the maximum pollen transfer for the minimum reward delivered. Different pollinators, because of their size, shape, or behaviour, have different efficiencies of transfer of pollen. And the floral traits affect efficiency of transfer: [[Aquilegia|columbine]] flowers were experimentally altered and presented to hawkmoths, and flower orientation, shape, and colour were found to affect visitation rates or pollen removal.<ref>{{cite journal |vauthors=Fulton M, Hodges SA|lastauthoramp=yes |year=1999 |title=Floral isolation between ''Aquilegia formosa'' and ''A. pubescens.'' |journal=Proceedings of the Royal Society B: Biological Sciences|volume= 266 |issue=1435 |pages=2247–2252 |doi=10.1098/rspb.1999.0915|pmc=1690454}}</ref><ref>{{cite journal |author1=Hodges SA |author2=JB Whittall |author3=M Fulton |author4=JY Yang |last-author-amp=yes |year=2002 |title=Genetics of floral traits influencing reproductive isolation between ''Aquilegia formosa'' and ''A. pubescens'' |journal=American Naturalist |volume=159 |issue=s3 |pages=S51–S60 |doi=10.1086/338372 |pmid=18707369}}</ref>
*[[Flower constancy|Pollinator constancy]]: to efficiently transfer pollen, it is best for the plant if the pollinator focuses on one species of plant, ignoring other species. Otherwise, pollen may be dropped uselessly on the stigmas of other species. Animals, of course, do not aim to pollinate, they aim to collect food as fast as they can. However, many pollinator species exhibit constancy, passing up available flowers to focus on one plant species. Why should animals specialize on a plant species, rather than move to the next flower of any species? Although pollinator constancy was recognized by [[Aristotle]], the benefits to animals are not yet fully understood.<ref>{{cite journal |author1=Gegear, RJ |author2=TM Laverty |lastauthoramp=yes |year=2005 |title=Flower constancy in bumblebees: a test of the trait variability hypothesis |journal=Animal Behaviour |volume=69 |issue=4 |pages=939–949 |doi=10.1016/j.anbehav.2004.06.029|s2cid=53159128 }}</ref> The most common hypothesis is that pollinators must learn to handle particular types of flowers, and they have limited capacity to learn different types. They can only efficiently gather rewards from one type of flower.
These honeybees selectively visit flowers from only one species for a period of time, as can be seen by the colour of the pollen in their baskets:
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===Criticisms of the syndromes===
Whilst it is clear that pollination syndromes can be observed in nature, there has been much debate amongst scientists as to how frequent they are and to what extent we can use the classical syndromes to classify plant-pollinator interactions.<ref>{{cite journal | author = Ollerton J | year = 1998 | title = Sunbird surprise for syndromes | url = | journal = Nature | volume = 394 | issue = 6695| pages = 726–727 | doi=10.1038/29409| s2cid = 204999526 }}</ref> Although some species of plants are visited only by one type of animal (i.e. they are functionally specialized), many plant species are visited by very different pollinators.<ref name="Waser1996" /><ref>{{cite encyclopedia |author=Herrera, CM |year=1996 |title=Floral traits and adaptation to insect pollinators: a devil's advocate approach |encyclopedia=Floral Biology |editor1=DG Lloyd |editor2=SCH Barrett |pages=65–87 |publisher=Chapman & Hall, New York}}</ref> For example, a flower may be pollinated by bees, butterflies, and birds. Strict specialization of plants relying on one species of pollinator is relatively rare, probably because it can result in variable reproductive success across years as pollinator populations vary significantly.<ref name="Waser1996" /> In such cases, plants should generalize on a wide range of pollinators, and such ecological generalization is frequently found in nature. A study in Tasmania found the syndromes did not usefully predict the pollinators.<ref>{{cite journal |author1=Hingston, AB |author2=PB Mcquillan |lastauthoramp=yes |year=2000 |title=Are pollination syndromes useful predictors of floral visitors in Tasmania? |journal=Australian Journal of Ecology |volume=25 |issue=6 |pages= 600–609 |doi=10.1046/j.1442-9993.2000.01059.x|url=https://eprints.utas.edu.au/8330/1/Are_pollination_syndromes_useful_predictors_of_floral_visitors_in_Tasmania_2000.pdf }}</ref>
This debate has led to a critical re-evaluation of the syndromes, which suggests that on average about one third of the flowering plants can be classified into the classical syndromes.<ref name="Ollerton" /> This reflects the fact that nature is much less predictable and straightforward than 19th-century biologists originally thought. Pollination syndromes can be thought of as extremes of a continuum of greater or lesser specialization or generalization onto particular functional groups of pollinators that exert similar selective pressures"<ref name="Fenster2004" /> and the frequency with which flowers conform to the expectations of the pollination syndromes is relatively rare. In addition, new types of plant-pollinator interaction, involving "unusual" pollinating animals are regularly being discovered, such as specialized pollination by spider hunting wasps ([[Pompilidae]]) and fruit chafers ([[Cetoniidae]]) in the eastern grasslands of South Africa.<ref name="Ollerton_a">{{cite journal |author1=Ollerton J. |author2=Johnson S. D. |author3=Cranmer L. |author4=Kellie S. | year = 2003 | title = The pollination ecology of an assemblage of grassland asclepiads in South Africa | journal = Annals of Botany | volume = 92 | issue = 6| pages = 807–834 | doi=10.1093/aob/mcg206 | pmid=14612378 | pmc=4243623}}</ref> These plants do not fit into the classical syndromes, though they may show evidence of convergent evolution in their own right.
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