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  • 1
    Electronic Resource
    Electronic Resource
    Selection of cyanogenesis in the leaves and petals of Lotus corniculatus L. at high latitudes (1983)
    Springer
    Oecologia 60 (1983), S. 353-358 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A survey of Lotus corniculatus populations in the Jostedal valley of S. W. Norway has revealed that plants with cyanogenic leaves are rare in the south of the valley, but predominate in the harsh conditions which are found further north. A similar cline occurs for cyanogenesis in the petals and scoring of plants for both leaf and petal cyanogenesis has confirmed that there is a relationship between the expression of cyanogenesis in these two parts of the plant. The colour of the keel petals, a third polymorphic character, also has a clinal distribution in the Jostedalen, but its expression is not associated with cyanogenesis. Factors which might be responsible for the cline in cyanogenesis have been investigated, and we conclude that variation in edaphic conditions droughting, temperature and invertebrate herbivory are unlikely to be important. Norway lemmings (Lemmus lemmus) were present at a very high density in one of the areas where L. corniculatus is mainly cyanogenic and differential feeding by this mammal may constitute a strong selective pressure. Further field studies are required to test this hypothesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00376851
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  • 2
    Electronic Resource
    Electronic Resource
    The contribution of rabbits (Oryctolagus cuniculus L.) to soil fertility in semi-arid Spain (2000)
    Springer
    Biology and fertility of soils 31 (2000), S. 379-384 
    Details
    ISSN: 1432-0789
    Keywords: Key words Bioassay ; Fertile islands ; Latrine ; Mediterranean ecosystem ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Degradation of land in vulnerable areas can be significantly reduced by the maintenance or establishment of plant cover and diversity. Animals can facilitate plant diversity by grazing, by dispersing seeds or by contributing, through excreta, to the heterogeneous distribution of nutrients in soil. We investigated the latter property by examining the effects of rabbit (Oryctolagus cuniculus L.) dung deposition on soil properties in three adjacent plant communities at a semi-arid site in south-east Spain. Rabbit faecal pellets had concentrations of total N and P comparable to dung of stock animals, with K and Mg somewhat lower, although decomposition rates at this site are evidently very low. There was no significant difference in pH, but conductivity and concentrations of organic C, N (as NH4 + and NO3 –), K, P and Mg in soils from rabbit latrines were significantly greater relative to controls in each community. Barley plants grown as a bioassay of soil fertility had significantly greater total biomass, and lower root : shoot ratios in latrine compared to control soils. There were differences among communities in conductivity and concentrations of N, P and organic C under latrines which were reflected in the bioassay. Although latrines only comprised approximately 0.1% of the ground surface area in each community, they make significant localised contributions to soil fertility and may therefore be important in establishing and maintaining plant cover.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003749900183
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Gamergate reproduction in the antStreblognathus aethiopicus Smith (Hymenoptera: Formicidae: Ponerinae) (1990)
    Springer
    Insectes sociaux 37 (1990), S. 189-199 
    Details
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Wir untersuchten Aspekte der Morphologie und des Verhaltens der Fortpflanzungsbiologie beiStreblognathus aethiopicus (Unterfamilie Ponerinae). Die Untersuchung der Ovarien und Spermatheken zeigte, daß jede Kolonie über eine einzige Gamergate verfügte. Dieses Individuum konnte morphologisch nicht von seinen Nestgenossen unterschieden werden. Auch im Verhalten kann sie nur durch das Eierlegen erkann werden. Wurde die Gamergate im Experiment aus der Kolonie entfernt, vergrößerten sich bei einigen der Arbeiterinnen die Ovariolen. Demzufolge kann die Gamergate die Fortpflanzungsaktivität der Nestgenossen unterdrücken.
    Notes: Summary We examined morphological and behavioral features of the reproductive biology of the ponerine ant,Streblognathus aethiopicus. Investigation of the ant's ovaries and spermathecae showed that each colony had a single reproductive (= gamergate). Morphologically this individual could not be distinguished from her nestmates, while the only clear-cut behavioural difference between the gamergate and workers was that the former laid eggs. Experimental removal of the gamergate from colonies resulted in the enlargement of the ovaries in some of the workers. This appears to show that the reproductive is able to suppress reproductive activity of her nestmates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02224047
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  • 4
    Electronic Resource
    Electronic Resource
    Foraging, food selection and worker size in the seed harvesting ant Messor bouvieri (2000)
    Springer
    Oecologia 125 (2000), S. 35-44 
    Details
    ISSN: 1432-1939
    Keywords: Key words Allometry ; Granivory ; Optimal foraging ; Seed predation ; Size matching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Interactions among granivores and seeds depend on the foraging behaviour and morphology of the granivores and on the attributes and availability of seeds. We investigated seed selection by the seed harvesting ant Messor bouvieri in three adjacent plant communities in Spain by relating the harvested seeds to those in the seed rain. Preference was positively correlated with seed size and abundance which accounted for 43% and 20% of the variance respectively. Contrary to predictions of central place foraging theory, the size of seeds harvested did not increase with distance from the nest. Inclusion of a less-preferred item in the diet was more strongly related to the abundance of more-preferred items (60% of the variance) than the abundance of the less-preferred item (14% of the variance). Worker size accounted for 20–30% of the variance in the size of harvested seeds, although small workers did not appear to be constrained by load size for the range of seeds available. The body size of ants was significantly larger in the community with the greatest proportion of large seeds, although this was not due to their ability to carry larger loads or due to the greater force required to crush these seeds. The strong preference of M. bouvieri for large seeds may have important consequences for the plant communities in which they forage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00008889
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  • 5
    Electronic Resource
    Electronic Resource
    Determinants of species richness in southern African fig wasp assemblages (1992)
    Springer
    Oecologia 91 (1992), S. 68-74 
    Details
    ISSN: 1432-1939
    Keywords: Agaonidae ; Cospeciation ; Figs ; Ficus ; Galls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We investigated the species richness of 24 fig wasp (Hymenoptera) assemblages associated with southern African fig trees (Ficus species, Moraceae). Assemblage sizes ranged between 3 and 30 species on different host tree species, with parasitoids slightly outnumbering gall-forming phytophages. Ten potential taxonomic, geographic and ecological determinants of assemblage richness were examined. Galler richness differed significantly between taxonomic sub-groups of Ficus and was significantly correlated with several ecological characteristics of the host trees, but there was no species-area effect. Parasitoid richness was strongly correlated with galler richness. We conclude that both ecological and historical factors have combined to determine the numbers of species that form fig wasp assemblages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317243
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  • 6
    Electronic Resource
    Electronic Resource
    Rhodanese in insects (1985)
    Springer
    Journal of chemical ecology 11 (1985), S. 45-50 
    Details
    ISSN: 1573-1561
    Keywords: Cyanide ; rhodanese ; cyanogenesis ; detoxification ; Lotus corniculatus ; Vicia sativa ; Zygaena ; Insecta ; chalk grassland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Forty-four species of insects were assayed for the presence of rhodanese, an enzyme generally considered to be responsible for the detoxification of cyanide. Rhodanese was found to be widely distributed in both adults and larvae and was not restricted to those species which encounter exogenous cyanide through feeding on cyanogenic plants. These results indicate that cyanide detoxification is unlikely to be the primary role for rhodanese in insects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00987603
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    Paper (German National Licenses)
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