http://precedings.nature.com/users/5108c78b82c88e603191b1d6709c5518/ Documents posted by Lars Chittka Nature Publishing Group en Nature Precedings http://precedings.nature.com/images/header_logo.gif http://precedings.nature.com http://precedings.nature.com/documents/1977/version/1 The Canary Islands are home to a guild of endemic, threatened bird pollinated plants. Previous work has suggested that these plants evolved floral traits as adaptations to pollination by flower specialist sunbirds, but subsequently they appear to be have co-opted passerine birds as sub-optimal pollinators. To test this idea we carried out a quantitative study of the pollination biology of three of the bird pollinated plants, Canarina canariensis (Campanulaceae), Isoplexis canariensis (Veronicaceae) and Lotus berthelotii (Fabaceae), on the island of Tenerife. Using colour vision models, we predicted the detectability of flowers to bird and bee pollinators. We measured pollinator visitation rates, nectar standing crops, as well as seed set and pollen removal and deposition. These data showed that the plants are effectively pollinated by non-flower specialist passerine birds that only occasionally visit flowers. The large nectar standing crops and extended flower longevities (>10days) of Canarina and Isoplexis suggests that they have evolved bird pollination system that effectively exploits these low frequency non-specialist pollen vectors and is in no way suboptimal. Seed set in two of the three species was high, and was significantly reduced or zero in flowers where pollinator access was restricted. In L. berthelotii, however, no fruit set was observed, probably because the plants were self incompatible horticultural clones of a single genet. We also show that, while all three species are easily detectable for birds, the orange Canarina and the red Lotus (but less so the yellow-orange Isoplexis) should be difficult to detect for insect pollinators without specialised red receptors, such as bumblebees. Contrary to expectations if we accept that the flowers are primarily adapted to sunbird pollination, the chiffchaff (Phylloscopus canariensis) was an effective pollinator of these species. http://precedings.nature.com/documents/1977/version/1 Mon, 16 Jun 2008 18:22:33 UTC Bird pollination of Canary Island endemic plants hdl:10101/npre.2008.1977.1 2008-12-04 Lars Chittka Nature Precedings 2008-06-16T18:22:33Z Manuscript Ecology Plant Biology http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/1766/version/1 In recent years, colour vision abilities have been rather generously awarded to vari-ous invertebrates and even bacteria. This uncertainty of when to diagnose colour vi-sion stems in part from confusing what colour vision can do with what it is. What col-our vision can do is discriminate wavelength independent of intensity. However, if we take this as a definition of what colour vision is, then we might indeed be obliged to conclude that some plants and bacteria have colour vision. Moreover, there is a simi-lar confusion of what are necessary and what are sufficient mechanisms and behav-ioural abilities for colour vision. To humans, seeing in colour means seeing an image in which objects/lights have chromatic attributes – in contrast to the sensation that we have when viewing monochrome movies, or our experience in dim light when only rod vision is possible. The necessary basic equipment for this is to have at least two types of photoreceptors that differ in spectral sensitivity, and at least one type of spectrally opponent cell to compare the signals from the photoreceptors. Clearly, however, a necessary additional prerequisite for colour vision is to have vision, which entails the identification of shapes, sizes and locations of objects in the world. Thus if an animal has colour vision, it should see an image in which distinct objects/lights have colour attributes. This distinguishes colour vision from what has historically been called wavelength-specific behaviour: a type of behaviour triggered by fixed configurations of spectral receptor signals; however, we discuss difficulties in diagnosing wavelength specific behaviour as an indicator of the absence of colour vision. http://precedings.nature.com/documents/1766/version/1 Mon, 07 Apr 2008 19:05:03 UTC Towards a cognitive definition of colour vision hdl:10101/npre.2008.1766.1 2008-07-04 Lars Chittka Nature Precedings 2008-04-07T19:05:03Z Manuscript Ecology Neuroscience http://creativecommons.org/licenses/by/3.0/ http://dx.doi.org/10.1038/npre.2008.1846.1 Floral reflectance measurements are of great value to researchers who need consider the real colour of flowers, for example in the context of how the flowers appear to their pollinators. We have thus developed the Floral Reflectance Database (FReD) to assist these researchers, gathering together floral reflectance data in a publicly available, searchable online database. The first version of the database is now available online at http://www.reflectance.co.uk. We anticipate that this resource will be of interest to researchers working on flower colour and animal vision. http://dx.doi.org/10.1038/npre.2008.1846.1 Wed, 30 Apr 2008 18:07:30 UTC FReD: The floral reflectance spectra database doi:10.1038/npre.2008.1846.1 2008-04-30 Sarah E. J. Arnold Nature Precedings 2008-04-30T18:07:30Z Manuscript Ecology Bioinformatics http://creativecommons.org/licenses/by/3.0/ http://dx.doi.org/10.1038/npre.2008.1719.1 Circadian rhythms enable organisms to anticipate and to prepare for predictable changes in their environment. Most previous studies on circadian rhythms focused on solitary animals. However, in social insects, the colony as a superorganism has a foraging rhythm aligned to the patterns of resource availability. Within this colony rhythm, the activity patterns of individuals are embedded. In temperate regions bumblebee foragers show strong circadian rhythms that adjust their foraging activity to the changing light conditions in the course of the day. But what about circadian foraging patterns under continuous daylight? One would assume that the colony as a whole extends its foraging activity over the whole 24 hours of a day under such light conditions to maximise colony growth. To answer this question four colonies of Bombus terrestris terrestris have been set up in north-western Finland (Kilpisjärvi Biological Station, 270km north of the Arctic Circle) between 20/06/07 and 18/07/07. During that time period the sun is always above the horizon in that area. Each worker of each colony was fitted with a small RFID tag, allowing to continuously monitor the foraging activity of each individual worker for the whole duration of the experiment. Against the hypothesis the foragers still showed strong circadian rhythms and ceased their activity from about 0000h until about 0600h each day. http://dx.doi.org/10.1038/npre.2008.1719.1 Tue, 25 Mar 2008 17:35:21 UTC Bumblebees under the midnight sun – Monitoring circadian rhythms of bumblebees under continuous daylight, using radio frequency identification (RFID) doi:10.1038/npre.2008.1719.1 2008-03-25 Ralph J. Stelzer Nature Precedings 2008-03-25T17:35:21Z Poster Ecology http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/1298/version/1 Despite the widespread assumption that the learning abilities of animals are adapted to the particular environments in which they operate, the quantitative effects of learning performance on fitness remain virtually unknown. Here we evaluate the learning performance of bumblebees (Bombus terrestris) from multiple colonies in an ecologically relevant associative learning task under laboratory conditions, before testing the foraging performance of the same colonies under the field conditions. We demonstrate that variation in learning speed among bumblebee colonies is directly correlated with foraging performance, a robust fitness measure, under natural conditions. Colonies vary in learning speed by a factor of nearly 5, with the slowest learning colonies collecting 40% less nectar than the fastest learning colonies. Such a steep fitness function suggests strong selection for higher learning speed in bumblebees. Demonstrating the adaptive value of differences in learning performance under the real conditions in which animals function represents a major step towards understanding how cognitive abilities of animals are tuned to their environment. http://precedings.nature.com/documents/1298/version/1 Tue, 06 Nov 2007 21:03:13 UTC Bumblebees gain fitness through learning hdl:10101/npre.2007.1298.1 2007-11-06 Nigel E. Raine Nature Precedings 2007-11-06T21:03:13Z Manuscript Ecology http://creativecommons.org/licenses/by/2.5/ http://precedings.nature.com/documents/1258/version/1 Many palatable insects, for example hoverflies, deter predators by mimicking well-defended insects such as wasps. However, for human observers, these flies often seem to be little better than caricatures of wasps – their visual appearance and behaviour are easily distinguishable. This imperfect mimicry baffles evolutionary biologists, because one might expect natural selection to do a more thorough job. Here we discuss two types of cognitive processes that might explain why mimics distinguishable mimics might enjoy increased protection from predation. Speed accuracy tradeoffs in predator decision making might give imperfect mimics sufficient time to escape, and predators under time constraint might avoid time-consuming discriminations between well-defended models and inaccurate edible mimics, and instead adopt a “safety first” policy of avoiding insects with similar appearance. Categorization of prey types by predators could mean that wholly dissimilar mimics may be protected, provided they share some common property with noxious prey. http://precedings.nature.com/documents/1258/version/1 Fri, 26 Oct 2007 14:39:34 UTC Cognitive dimensions of predator responses to imperfect mimicry? hdl:10101/npre.2007.1258.1 2007-10-26 Lars Chittka Nature Precedings 2007-10-26T14:39:34Z Manuscript Ecology Neuroscience http://creativecommons.org/licenses/by/2.5/