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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 393 (1998), S. 529-529 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Floral nectar is rich in chemicals and induces pollination. Although it may be tainted by algae or mould, it usually lacks colouring agents. However, a few plant species in Mauritius break this rule and produce red nectar. We attempted to find a function for this coloration, but its role ...
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 107 (1996), S. 95-101 
    ISSN: 1432-1939
    Keywords: Hepatica nobilis ; Mutualism ; Myrmecochory ; Myrmica ruginodis ; Seed dispersal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several studies relate removal of diaspores from different ant-dispersed plant species to the size of their claiosomes. This study is the first one to relate intraspecific variation in claiosome size to removal of diaspores by ants. This approach circumvents the problem posed by interspecific variation in chemistry and morphology of elaiosomes. We used the systemHepatica nobilis Mill. (Ranunculaceae) andMyrmica ruginodis Nyl. The elaiosome was the attractive part of the diaspore and its attractiveness decreased quickly after release from the fruit. In experimental runs where ants collected diaspores, the elaiosome size of accepted diaspores was larger than of those rejected and the largest diaspores were collected first. Since size of diaspore, elaiosome and achene were correlated, the diaspores that were removed first had both the largest elaiosome and achene. However, our experiments suggested that elaiosome size was more important to removal than achene size or the elaiosome:achene size ratio. If ant dispersal improves plant fitness, elaiosome size and hence diaspore size would be expected to increase over time. However, such directional selection mediated by the ants is probably counterbalanced by the plant. Seed predators and a negative trade-off between number and size of seeds would, among other factors, select for smaller diaspore size,i.e. counteract the effect of the ants' preference for larger elaiosomes.
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  • 3
    ISSN: 1432-1939
    Keywords: Cross-population flights ; Ecological neighbourhood ; Flower foraging ; Syrphidae ; Zygaena trifolii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The population are of flowering shoots of the perennial herb, Saxifraga hirculus, reaches a max. of 134 m2 and an overall density of flowers/m2 of 11.4. The flower is mainly visited by a syrphid sp., Eurimyia lineata, and to a lesser extent by another syrphid Neoscia tenur, a moth, Zygaena trifolii, and a fungus gnat, Asindulum nigrum. The distribution of the interfloral flight distance is leptokurtic. The mean flight distance of the visitors is 101 cm. 10% of the flights are much longer (2–8 m: cross-flower patch, and about 20 m: cross-population flights). If they are not included, the mean of flights (〈1.7 m) becomes 28 cm. These flights become shorter with increasing flower density. The visitors do not have a nearest-neighbour foraging pattern. They visit on average the 8th nearest neighbour. The distribution of flight directions is uniform. Seed dispersal distances have a leptokurtic distribution and a mean dispersal distance of 13 cm. The ecological neighbourhood area is 66.4 m2 and 64.9 m2 assuming normality and allowing for leptokurtosis. Z. trifolii with its large proportion of long flights increases the size of the neighbourhood area considerably. The mean flight distance (〈1.7 m) is correlated with neighbourhood area. The evolutionary impact of moths and butterflies to plant population structure is stressed.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 131 (1979), S. 121-128 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Green lacewings in stationary flight respond by stopping some or all of their flight muscles for a variable period of time in response to ultrasonic stimulation (Figs. 1, 3 and 4 A). 2. The direct depressors show a greater tendency for stopping than the indirect depressors. The elevators show the lowest tendency for stopping (Figs. 1 and 2). 3. The activity recorded from flight muscles during stationary flight agrees closely with maneuvers actually observed in free flying green lacewings in response to hunting bats and ultrasound (Fig. 6 and Miller and Olesen, 1979). 4. The stopping of flight muscles is probably produced by an uncoupling of their motor neurons from a continuously active flight pattern generator. The uncoupling is variable; causing variation in the number of muscles that stop and the time that elapses for stopping. Consequently, behavioral responses include a measure of unpredictability (Miller and Olesen, 1979) that probably provides the green lacewing certain advantages when encountering bats.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 81 (1972), S. 53-55 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pressure waves responsible for the labial extension and jet propulsion in dragonfly nymphs are produced by the contraction of several muscles on both sides of the abdominal diaphragm. The duration and intensity of muscular activity differ in the two acts (Fig. 1).
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 131 (1979), S. 113-120 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Free flying green lacewings (Chrysopa carnea) fold their wings and nose dive in response to cries of hunting bats. This is an early warning response that tends to take the insect out of the bat's acoustic field (Fig. 1). 2. However, should a bat detect and attempt to catch a falling green lacewing, the insect can switch to a last chance maneuver. This maneuver consists of a momentary extension of the wings, or wing flip, released by the bat's high cry repetition rate during the buzz, which is always associated with an attempted catch (Fig. 2). The last chance response can also be released by using artificial bat cries (Fig. 3). 3. The green lacewing's behavioral repertoire is not limited to early warning and last chance responses. The insects can change their pattern of flight or fall with the wings extended. The release of avoidance behavior depends upon the intensity and repetition rate of the ultrasonic stimulus (Fig. 4). 4. The responses of a single insect can vary for the same stimulus repeated successively. Avoidance behavior and variability are discussed in relation to selective advantage and to the interpretation of physiological results.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Plant systematics and evolution 212 (1998), S. 143-157 
    ISSN: 1615-6110
    Keywords: Lauraceae ; Laurus azorica ; Halictinae ; Tachinidae ; Tachina canariensis ; Canary Islands ; dioecy ; male-biased sex ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pollination ofLaurus azorica (Lauraceae), a dioecious Macaronesian tree, was studied. Male and female trees had the same size distribution. The population had 2.5 times as many male trees as females. In addition, males produced more flowers, and their inflorescences lasted longer. Individual flower lifetime and length of flowering season were the same in both sexes. Between the years of observation, one tree changed sex. Pollinators wereHalictinae bees and the flyTachina canariensis. The bees collected pollen and nectar and the fly collected nectar from both sexes. Both species visited other plants as well. The evolution of breeding systems inLauraceae is discussed.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Plant systematics and evolution 212 (1998), S. 159-176 
    ISSN: 1615-6110
    Keywords: Lamiaceae ; Cedronella canariensis ; Apidae ; Bombus canariensis ; Lepidoptera ; Macroglossa stellatarum ; Canary Islands ; cross-pollination ; gynodioecy ; gynomonoecy male sterility ; mixed mating system ; nectar-robbing ; self-pollination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract On the Canary Islands, we studied reproductive ecology of the perennial laurel forest herbCedronella canariensis (Lamiaceae). Flowers contained small quantities of concentrated nectar. Flower visitors were mainly bumblebees (Bombus terrestris subsp.canariensis) and lepidopterans (especiallyMacroglossa stellatarum). Their abundance, pollen load, and behaviour are reported.Cedronella canariensis was facultatively autogamous. The P:O ratio was higher than expected for a plant with a breeding system of this nature. Seed set was not pollen-limited. Selfed and outcrossed seeds differed in weight. Small, lightly coloured flowers with dysfunctional stamens appeared towards the end of the season. This male-sterility might be induced by drought.
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  • 9
    Publication Date: 2003-04-01
    Print ISSN: 0169-5347
    Electronic ISSN: 1872-8383
    Topics: Biology
    Published by Cell Press
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  • 10
    Publication Date: 2006-05-01
    Print ISSN: 0022-5193
    Electronic ISSN: 1095-8541
    Topics: Biology
    Published by Elsevier
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