The workshop is being jointly organized by Renee M. Borges (Indian Institute of Science, Bangalore) and Almut Kelber (Vision Group, Lund University, Sweden).

Background, concept and objectives:  The biology of nocturnal plants and animals has been an extremely neglected field, worldwide. This has largely been due to the following reasons: 1) most natural scientists are day-active and prefer to study day-active organisms, 2) there are very few nocturnal model systems that can be brought into the laboratory, e.g. the night-blooming Nicotiana in plants, and the night-active hawkmoth Manduca sexta among insects, 3) nocturnal observation of plants and animals often require specialized equipment and technologies, e.g. night-vision optics, that may have earlier been unavailable to many scientists,  4) nocturnal observations in the wild, especially in the tropics, and also in most parts of the world, are fraught with logistical impediments. Despite these difficulties, the world in dim light or that in darkness has been studied by pioneering groups of scientists who have made many astonishing discoveries about the specific adaptations of plants and organisms to the nocturnal realm. The principal aim of this workshop is therefore to share this excitement with young researchers, and to inspire them to take on research projects in this virtually unexplored area.

The focus of this workshop is the patterns and processes involved in nocturnal pollination.  This is an ideal cross-cutting discipline, because it deals with the interactions between plants and animals in the night.  Thus it necessitates cross-talk between botanists, plant physiologists, plant reproductive biologists, animal sensory biologists and physiologists, plant and animal ecologists and evolutionary biologists, as well as natural product chemists, and biomechanics experts.  The group of resource persons that has been assembled for this workshop has the necessary expertise in these areas, and thus can provide the required multi-disciplinary focus.

Evolution of nocturnality:  Most groups of nocturnal plants and terrestrial animals have evolved from diurnal ancestors including organisms that quintessentially associated with nocturnality such as bats, moths, geckos and owls (Rydell and Speakman 1995, Autumn et al. 1999). Yet, the lack of scientific work on this aspect is reflected in the fact that a Google Scholar search on the keywords: evolution and nocturnality, yield only 879 pages, more than 90% of which were completely irrelevant.  A recent book reviewing plant-pollinator interactions (Waser and Ollerton 2006) did not have a separate section on nocturnal pollination, and the word nocturnal pollination did not even feature in the index. Thus the body of work on nocturnal plants and animals is actually very small.  Precisely because most terrestrial organisms have evolved from diurnal ancestors, the particular adaptations of organisms to nocturnality are often constrained by this diurnal ancestry.  Since light (and perhaps temperature) is the most starkly different variable between the environments of day-active versus night-active organisms, it is not surprising that most investigations of nocturnality in animals have focused on the visual senses.  In some cases, as found in the nocturnal kiwi bird, adoption of a nocturnal lifestyle may require a tradeoff, and in this case, vision has been traded for olfaction (Martin et al. 2008), while in others spectacular adaptations for nocturnal vision have been evolved (Warrant and Nilsson 2006). In groups of organisms wherein there are both diurnal and nocturnal taxa, it is possible that it is largely the visual senses that are affected, since olfactory senses need not necessarily be compromised by nocturnal conditions, unless temperature is an important factor.  However, very few comparisons of nocturnal and diurnal taxa exist, and even within nocturnal taxa, it is only recently that studies are beginning to compare the relative deployment of different sensory modalities in night-active organisms (Soutar and Fullard 2004, Raguso and Willis 2005).  The adoption of the nocturnal niche is generally considered to be a selective response to competition from day-active organisms occupying the same spatial environments (Park 1940, Rydell and Speakman 1995); however, these explanations have been largely restricted to bats, and are used to explain the ancient transition to nocturnality that might have occurred in the Eocene, when bats were competing with birds (Rydell and Speakman 1995).  In bees on the other hand, such transitions to nocturnality are less widespread and have occurred only eight times (Wcislo et al. 2004).

Nocturnal pollination:  Pollination of nocturnally blooming plants requires the services of pollen vectors or pollinators.  Therefore, whether plants are day-blooming or night-blooming may depend largely on competition between plants for pollinators (Bronstein et al. 2006). While the visual sensory modality is reliable in the day-time, vision is not reliable under dim light (Warrant 1999, 2004, 2006); hence other sensory modalities may become important for night-active pollinators such as acoustics or olfaction. These night-active pollinators are usually insects, particularly beetles and moths, while vertebrates such as bats and rodents are also important (Johnson et al. 2001, Fleming and Muchhala 2008).  It is important however to note that owing to the lack of comprehensive studies on nocturnal pollination, it is not possible to estimate the relative contribution of different types of insects, for example, to nocturnal pollination.  Also, it is still not yet possible to evaluate why certain taxa of plants are largely night-blooming (Fleming et al. 2001) while other have a mixture of day- and night-blooming species (Jürgens 2006).  This is because although reviews on pollination systems exist they have been largely biased towards day-active systems (Corlett 2004), with one recent exception (Fleming and Muchhala 2008).  This is because of the state of the current research in this area.  Furthermore, this lack of research has lead to misconceptions about the capabilities of different taxa to be nocturnal pollinators.  Bees, for example, were thought to be mostly day-active with a few crepuscular species (Smith et al. 2007), or those that could only be active under moonlight conditions.  However, recent studies by the research groups of the workshop organizers (Borges and Kelber) have shown that bees can be active under extremely low light conditions (Somanathan and Borges 2001, Kelber et al. 2006).  This has lead to the discovery of the only known truly nocturnal bee Xylocopa tranquebarica in a seasonal cloud forest in India (Somanathan et al. 2008).  This bee can fly and navigate under starlight conditions, and so far is the only known bee to be able to do so.  Furthermore, this bee has also recently been found to exhibit colour vision under moonlight, twilight, and even starlight conditions and is, once again, the only insect with an aposition eye (i.e. one adapted to diurnality) to exhibit colour vision under such dim light conditions (Somanathan et al., under review). It is worth remembering that humans lose colour vision at light levels of less than half a moon.

The morphological adaptations of flowers to nocturnal pollinators have also been investigated to some extent (Singaravelan and Marimuthu 2004, Jürgens 2006, Muchhala 2007), but such studies are few and far between.  While visits by generalists rather than specialist pollinators appear to be the norm for many diurnal pollination systems (Waser et al. 1996), many recent studies are contradicting this view (Johnson and Steiner 2001). Yet, whether specialization is the norm for nocturnal systems rather than for diurnal systems, owing to the special nature of the nocturnal niche and perhaps the smaller pool of available nocturnal taxa, is completely unknown. There is considerable evidence that bat-pollination plays an important role in Neotropical forests where many plants are known to be bat-pollinated, or have flowers that are characteristic of a bat-pollination syndrome (Hopkins et al. 2000, Fleming and Muchhala 2008). However, such flowers are rare in the Palaeotropics.  Furthermore the floral scents of bat-pollinated flowers may vary between the Neotropics and the Palaeotropics (von Helversen et al. 2000, Pettersson et al. 2004) indicating phylogenetic inertia and the evolutionary history of the plants in these different geographical areas or selection pressures from the differing sensitivities of their bat pollinators.  Thus knowledge of nocturnal pollination systems is scant, and many discoveries are only waiting to be made.

Important discoveries in the nocturnal realm:

The nocturnal realm has afforded many exciting discoveries in recent years.  Some examples of this are the following:

1. Beetles have been discovered to be able to navigate using the polarization patterns of moonlight (Dacke et al. 2003).
2. Bats have been found to use the specially evolved acoustic guides provided by flowers to locate their targets (von Helversen and von Helversen 1999).
3. Bees (Somanathan et al. 2008), hawkmoths (Kelber et al. 2002, 2003) and geckos (Kelber and Roth 2006) have been found to have colour vision at night.  In the case of bees, this ability has been observed under moonlight, twilight and starlight.
4. Bees that have nocturnal vision using day-adapted eyes, use post-receptor mechanisms, such as spatial pooling of signals and temporal summation to magnify dim-light signals (Greiner et al. 2005).
5. Nocturnal bees have been found to have polarization vision (Greiner et al. 2007).
6. Nocturnal insects such as hawkmoths use mechanosensors in their antennae to effect flight control and thus achieve flight stability at night (Sane et al. 2007).
7. Nectar-feeding bats can retain up to 40 food locations in their working memory, indicating adaptations to foraging in complex and competitive nocturnal environments (Winter and Stich 2005).
8. Nocturnal moth-inspired tracking of odour plumes have been used in developing robotics applications for tracking volatile gradients (Edwards et al. 2005).
9. The ocelli of nocturnal bees and wasps may have very special adaptations (Warrant et al. 2006) 
   

These examples are indicative of the many fascinating opportunities for research that the nocturnal realm can provide.  It is this excitement that we would like to convey to the participants through this workshop. Participants will be exposed to perform exciting research with both limited technical tools as well as with high-tech tools.

Literature cited:

Autumn K, Jindrich D, DeNardo D, Mueller R. 1999. Locomotor performance at low temperature and the evolution of nocturnality in geckos. Evolution 53: 580-599.
Bronstein JL, Alarcon R, Geber M. 2006. Tansley Review: Evolution of insect/plant mutualisms. New Phytologist 172:412-428.
Dacke M, Nilsson D-E, Scholtz CH, Byrne M, Warrant EJ  2003. Insect orientation to polarized moonlight. Nature 424:33
Corlett RT. 2004. Flower visitors and pollinators in the Oriental (Indomalayan) region. Biological Reviews 79:497-532 
Edwards S, Rutkowski AJ, Quinn RD, Willis MA. 2005 Moth-inspired plume tracking strategies in three-dimensions.  Robotics and Automation 18-22: 1669-1674.
Fleming TH, Muchhala N. 2008. Nectar-feeding bird and bat niches in two worlds: pantropical comparisons of vertebrate pollination systems.  Journal of Biogeography 35:764-780.
Fleming TH, Sahley CT, Holland JN, Nason JD, Hamrick JL.  2001. Sonoran Desert columnar cacti and the evolution of generalized pollination systems. Ecological Monographs 71: 511-530
Greiner B, Ribi WA and Warrant EJ (2005) A neural network to improve dim-light vision? Dendritic fields of first-order interneurons in the nocturnal bee Megalopta genalis. Cell Tissue Research 322:313-320
Greiner B, Cronin TW, Ribi WA, Wcislo WT, Warrant EJ . 2007.  Anatomical and physiological evidence for polarisation vision in the nocturnal bee Megalopta genalis. Journal of Comparative Physiology 193:591-600
Hopkins MJG, Hopkins HCF, Sothers CA (2000) Nocturnal pollination of Parkia velutina by Megalopta bees in Amazonia and its possible significance in the evolution of chiropterophily.  Journal of Tropical Ecology 16:733-746
Johnson SD, Steiner KE.  2000. Generalization versus specialization in plant pollination systems. Trends in Ecology & Evolution 15: 140-143
Johnson SD, Pauw A, Midgley J. 2001. Rodent pollination in the African lily Massonia depressa (Hyacinthaceae). American Journal of Botany 88:1768–1773.
Jürgens A.  2006. Comparative floral morphometrics in day-flowering, night-flowering and self-pollinated Caryophylloideae (Agrostemma, Dianthus, Saponaria, Silene, and Vaccaria). Plant Systematics and Evolution 257: 233–250
Kelber A, Roth LSV.  2006.  Nocturnal colour vision — not as rare as we might think.  Journal of Experimental Biology 209:781-788
Kelber A, Warrant EJ, Pfaff M, Wallén R, Theobald JC, Wcislo W, Raguso R. 2006. Light intensity limits the foraging activity in nocturnal and crepuscular bees. Behavioral Ecology 17:63-72
Kelber A, Balkenius A, Warrant EJ. 2002.  Scotopic colour vision in nocturnal hawkmoths.  Nature 419:922-925
Kelber A, Balkenius A, Warrant EJ. 2003.  Colour vision in diurnal and nocturnal hawkmoths.  Integrative and Comparative Biology 43:571-579.
Martin GR, Wilson K-J, Wild JM, Parsons S, Kubke MF, Corfield J.  2008. Kiwi forego vision in the guidance of their nocturnal activities. PloS One 2(2): e198. doi:10.1371/journal.pone.0000198
Muchhala N. 2007. Adaptive trade-off in floral morphology mediates specialization for flowers pollinated by bats and hummingbirds. American Naturalist 169:494-504
Park O (1940) Nocturnalism: the development of a problem. Ecol Monogr 10:486-536
Pettersson S, Ervik F, Knudsen JT 2004. Floral scent of bat-pollinated species, West Africa vs. the New World. Biological Journal of the Linnean Society 82: 161-168.
Raguso RA, Willis MA.  2005. Synergy between visual and olfactory cues in nectar feeding by wild hawkmoths, Manduca sexta.  Animal Behaviour 69:407-418
Rydell J, Speakman JR 1995. Evolution of nocturnality in bats: Potential competitors and predators during their early history. Biological Journal of the Linnean Society 54: 183-191.
Sane SP, Dieudonné A, Willis, MA, Daniel TL.  2007.  Antennal mechanosensors mediate flight control in moths.  Science 315:863-866
Singaravelan N, Marimuthu M. 2004. Nectar feeding and pollen carrying from Ceiba pentandra by pteropodid bats. Journal of Mammalogy 85:1–7
Smith, AR; Wcislo, WT; O'Donnell, S 2007. Survival and productivity benefits to social nesting in the sweat bee Megalopta genalis (Hymenoptera : Halictidae). Behav Ecol 61:1111-1120
Somanathan H, Borges RM (2001) Nocturnal pollination by the carpenter bee Xylocopa tenuiscapa (Apidae) and the effect of floral display on fruit set of Heterophragma quadriloculare (Bignoniaceae) in India. Biotropica 33:78-89
Somanathan H, Borges RM, Chakravarthy VS (2004) Does floral display matter? Fruit set in the carpenter bee-pollinated Heterophragma quadriloculare and the beetle-pollinated Lasiosiphon eriocephalus. Biotropica 36:139-147
Somanathan H, Borges, R. M., Warrant E. J., and Kelber, A. 2008. Visual ecology of Indian carpenter bees I: Light intensities and flight activity.  Journal of Comparative Physiology A 194:97–107
Somanathan H., Borges, R. M., Warrant, E. J., Kelber, A.  2008. Nocturnal bees learn landmark colours in starlight. Current Biology 18:R996-997
Soutard AR, Fullard JH.  2004.  Nocturnal anti-predator adaptations in eared and earless Nearctic Lepidoptera. Behavioral Ecology 15:1016–1022
von Helversen D, von Helversen O. 1999. Acoustic guide in bat-pollinated flower. Nature 398:759-760
von Helversen O. Winkler L, Bestmann HJ. 2000. Sulfur containing “perfumes” attract flower-visiting bats. Journal of Comparative Physiology A 186:143-153.
Warrant EJ. 1999.  Seeing better at night: life style, eye design and the optimum strategy of spatial and temporal summation. Vision Research 39:1611-1630.
Warrant EJ. 2004. Vision in the dimmest habitats on earth.  Journal of Comparative physiology A 190:765-879.
Warrant EJ, Kelber A, Wallén R, Wcislo WT. 2006. Ocellar optics in nocturnal and diurnal bees and wasps.  Arthropod Structure & Development 35:293-305
Warrant EJ, Nilsson D-E. 2006.  Invertebrate Vision.  Cambridge University Press, Cambridge.
Warrant EJ. 2006.  Invertebrate vision in dim light.  In Invertebrate Vision (eds. EJ Warrant and D-E Nilsson), 83-126, Cambridge University Press, Cambridge
Waser NM, Chittka L, Price MV, Williams NM, Ollerton J. 1996. Generalization in pollination systems, and why it matters. Ecology 77: 1043-1060
Waser NM, Ollerton J.  2006.  Plant-pollinator interactions. From specialization to generalization.  University of Chicago Press, Chicago.
Wcislo W T, Arneson L, Roesch K, Gonzalez V, Smith A, and Fernández-Marín H (2004) The evolution of nocturnal behavior in sweat bees, Megalopta genalis and M. ecuadoria (Hymenoptera: Halictidae): an escape from competitors and enemies? Biol J Linn Soc 83:377-387
Winter Y, Stich KP. 2005.  Foraging in a complex naturalistic environment: capacity of spatial working memory in flower bats. Journal of Experimental Biology 208: 539-548


Proposed Program:

The workshop is scheduled over 5 days (March 23-27, 2009)

The workshop will have a mixture of theory (evolution; historical, biogeographical and phylogenetic patterns; mechanisms i.e., processes) and practicals (demonstration of some techniques: headspace sampling of volatiles, SPME, GC-MS, spectral reflectance curves, light measurements, behavioural observation methods).

The confirmed resource persons and their tentative lecture topics are (in alphabetical order):

Resource person and Address	Lecture Topic
Renee M Borges Indian Institute of Science, Bangalore, India	Evolution of nocturnal pollination; parasites of diurnal pollination systems that wait until dark; overlap between floral scents and fruit scents
Judith Bronstein University of Arizona Tucson, USA	Mutualism and exploitation in pollination systems: anything special about nocturnal systems?
Richard Corlett University of Hong Kong	Cross-continental comparisons of pollination systems
Almut Kelber Lund University, Sweden	Colour vision and sensory interactions in nocturnal insects
Jette Knudsen Lund University, Sweden	Floral volatiles: patterns and processes
G Marimuthu Madurai Kamaraj University, Madurai, India	Bat-pollinated plants in South India
Sanjay Sane National Centre for Biological Sciences, Bangalore, India	Mechanosensory flight control in nocturnal insects
Hema Somanathan Lund University, Sweden, and Indian Institute of Science, Bangalore	Pollination ecology of nocturnal bees
Eric Warrant Lund University, Sweden	Eyes and limits of vision in nocturnal animals
Mark Willis Case Western Reserve University, Cleveland, USA	Insect olfaction, insect flight and nocturnal pollination
York Winter Bielefeld University, Germany	Bat vision and cognition

Each day will be divided into three sessions:
Session 1: 9 am to 1 pm:  Two or three lectures and discussions
Session 2: 2 pm to 5 pm:  Practical demonstrations and discussions
Session 3: 6 pm to 7.30 pm:  Mini-talks by student participants on their own research; discussion on potential research problems

Practical demonstrations will include the following:

1. Fundamentals of Pollination Biology: measurements of nectar quality and quantity, pollen and stigma receptivity, pollen viability, hand-pollination experiments
2. Flower colour and chromatic contrast:  Spectral reflectance measurements, construction of colour triangles and colour hexagons, calculation of photo catch, measurement of chromatic and achromatic contrast
3. Light environment measurements: Radiometry and construction of ambient light decay curves at dusk and dawn
4. Floral volatile measurements:  Demonstration of dynamic headspace volatile sampling techniques for quantitative analysis of volatiles; discussion of different volatile sampling methods; demonstration of solid phase micro-extraction (SPME) technique for qualitative analysis of volatiles
5. Floral volatile analysis:  Demonstration of gas chromatograph coupled mass spectrometry (GC-MS) analysis to determine identity and quantity of volatiles
6. Electroantennogram measurements: Demonstration of sensitivity of insect antennae to floral volatiles by electroantennogram readouts
7. Nocturnal behaviour observation techniques:  Discussion and demonstration of night-vision viewing devices and infra-red photography
   

Sponsors of the workshop:  Swedish International Development Agency (SIDA), Department of Science and Technology (DST), Indo-US Science and Technology Forum (IUSSTF), Council of Scientific and Industrial Research (CSIR), Indian Institute of Science (IISc).