Species Available (species + available)

Distribution by Scientific Domains


Selected Abstracts


Fatty acid composition of selected roes from some marine species

EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 9 2009
Miguel Ángel Rincón-Cervera
Abstract Fifteen roes from different marine fish species available in Spain were analyzed in order to determine their fatty acid (FA) composition, especially the eicosapentaenoic acid (20:5n -3, EPA) and docosahexaenoic acid (22:6n -3, DHA) contents. Roes from Atlantic bonito (Sarda sarda), European squid (Loligo vulgaris), cuttlefish (Sepia spp.), lumpfish (Cyclopterus lumpus), European hake (Merluccius merluccius), Atlantic salmon (Salmo salar) and gonads of male Atlantic mackerel (Scomber scombrus) reached EPA + DHA amounts higher than 30% of the total FA, and among them, roes from lumpfish, European hake and salmon provide different FA type ratios that could make them adequate as dietary sources of EPA and DHA. [source]


Effects of experimental canopy gaps on mangrove recruitment: lack of habitat partitioning may explain stand dominance

JOURNAL OF ECOLOGY, Issue 2 2004
Peter J. Clarke
Summary 1Few species of Indo-pacific mangroves co-occur at spatial scales of canopy gaps despite environmental heterogeneity and a flora that has varied physiological and morphological traits, but experiments on why such communities are species poor are uncommon. 2Lack of habitat partitioning, in concert with competitive exclusion, may explain low species richness at canopy gap scales. This study examined whether mangrove recruitment differs among species with respect to the effect of forest gap size, ground disturbance, position along an intertidal gradient and canopy membership. 3The canopy of a tropical mangrove forest in northern Australia was experimentally manipulated to create two gap sizes (50 m2 and 225 m2) in low and high intertidal forests with or without sediment disturbance. Propagules of six species, from three mangrove families, were sown into treatments and their predation, establishment, growth and survival measured for 5 years. 4All species established, and five survived, in canopy gaps in both high and low intertidal positions. Interspecific difference in establishment, growth and survival of seedlings in two intertidal positions were not closely matched to canopy membership and hence this does not explain zonation. 5No seedlings survived under the canopy and there was little evidence for shade-tolerant species. The interactions between canopy treatments and sediment disturbance that would have indicated gap partitioning were not detected. Seedling growth and survival was enhanced in large canopy gaps but there were no growth differences among species that matched canopy membership of plots. 6Most species appear to be able to recruit in canopy gaps if there is no dispersal limitation. Rather, the range of species available to fill gaps is limited because predation of propagules advantages species that are from the adjacent canopy. Lack of partitioning of resources within gaps by species may result in the exclusion of competitors that are not canopy members, further reducing coexistence. [source]


Diet selection in the green ringtail possum (Pseudochirops archeri): A specialist folivore in a diverse forest

AUSTRAL ECOLOGY, Issue 7 2006
KATHERINE M. W. JONES
Abstract This study investigated the feeding ecology of the green ringtail possum, Pseudochirops archeri (Pseudocheiridae) in a tropical rainforest with 94 plant species in the canopy. Over 50% of tree use was from only four tree species, Aleurites rockinghamensis, Ficus fraseri, Arytera divaricata and Ficus copiosa. These species were used significantly more frequently than would be expected if tree species were selected randomly in proportion to their relative abundance in the forest. Conversely, 88 other tree species present were used less frequently than expected. Possums also favoured particular individual trees within some of the preferred tree species. In 91% of feeding observations, possums consumed mature leaves only. The availability of young leaves, flowers and fruit varied throughout the year, with a peak in availability of these resources during the early wet season. By primarily selecting mature leaves, green ringtail possums reduce their dependence on seasonally variable resources. We suggest that green ringtail possums should be considered as specialist folivores, focusing on only a few of the tree species available, possibly due to advantages associated with limiting the number of plant secondary metabolites in their diet. Furthermore, they favour certain individual trees within species, perhaps due to intraspecific variation in plant secondary metabolites or nutrient content, behaviour that has been well established in eucalypt folivores. We conclude that green ringtail possums are highly specialized in their feeding ecology, limiting their diet to a small number of continuously available food items. [source]


The Beta-Binomial Model for Host Specificity among Organisms in Trophic Interactions

BIOMETRICS, Issue 3 2000
Ola H. Diserud
Summary. In this paper, we present a new stochastic model where the host specificity among organisms in trophic interactions in a community, say parasite-host interactions, is estimated by a beta-binomial model. The expected proportion of the host species in a community that a given parasite species is utilizing is modeled as a realization from an inhomogeneous Poisson process, where the rate of this process is assumed to be proportional to a beta probability distribution. The observed number of host species utilized by the parasites is then binomially distributed with the number of trials equaling the number of different host species in the sample. When the degree of polyphagy is estimated by the parameters of the beta-binomial model, quantities like community host specificity and the expected total number of parasite species that will utilize the host species in the community can be predicted as functions of the number of host species available. The predictions can then be applied in analysis of, e.g., symbiotic interactions among organisms, local species richness, and community structure. [source]


Camouflaged Carborarods Derived from B -Permethyl-1,12-diethynyl- para - and B -Octamethyl-1,7-diethylnyl- meta -carborane Modules

CHEMISTRY - A EUROPEAN JOURNAL, Issue 24 2005
Axel Herzog Dr.
Abstract Rigid camouflaged carborarods constructed from the corresponding C,C,-diethynyl derivatives of B -decamethyl-1,12-dicarbadodecaborane(12) (6) and B -octamethyl-1,7-dicarbadodecaborane(12) (48) have been synthesized by largely conventional organic transformations. These carborarods are the longest discrete rod species available by this method in which B-methylated p -carborane and m- carborane cages are linked through their carbon vertices by using butadiynylene moieties. They exhibit enhanced solubility in common organic solvents relative to all other presently known carborane-based rigid-rod molecules. The oxidative coupling of bis(ethynyl) derivatives of 6 generates oligomers containing, on average, 16 carborane modules. The structural characterization of the corresponding dimeric species revealed that the carborarods possess a sinusoidal chain distortion in the solid state. The stereoelectronic properties of these and related model carborarods were evaluated by using molecular dimensions as a monitor for the comparison of computational and experimental methods. In addition, the effect of exhaustive B-methylation of 12- and 10-vertex para -carborane cages in a series of model C,C,-diethynyl derivatives was similarly investigated by computational and structural studies. As expected, a correlation of intercage CC bond lengths with cage size was observed and was attributed to hybridization effects. B-Permethylation had no significant structural effect with either 10- or 12-vertex cage derivatives. Relative to unsubstituted compounds, thermal and chemical stabilities of B-permethylated derivatives were increased through the operation of a steric "bumper-car" process, and solubilities in organic solvents were enhanced. The formation of linear, sterically encumbered platina,carborarods using ethynyl derivatives of 6 as precursors is described. [source]