420 research outputs found
Dynamic Multi-species Animal Habitat Modeling with Forest Succession Models
This research determines and demonstrates the ability to simulate dynamic multispecies animal habitat suitability with forest succession models. A literature review of dynamic animal habitat models is presented. The structure of an existing forest simulation model (MASS10) was modified from a basal area-based model to a volume-based model (DYNAM10). The forest model was calibrated using data from permanent-plot growth and vegetation samples collected by USDA Forest Service Forest Survey procedures. The theoretical growth parameters used to simulate stand development were validated. Predictions of DBH and height growth, as well as stand-level behavior, were verified. A subroutine, VEGDYN, was added to DYNAMlO to simulate 34 structural vegetation parameters required by animal Habitat Suitability Index (HSI) models. Predictions of the structural parameters were verified. Ten animal-species HSI models were linked to DYNAMlO via the program HSI.FOR, and predicted dynamic HSI values were verified by hand-calculation. Typical patterns of dynamic HSI predictions are presented and discussed
Plant–herbivore–parasitoid interactions in an experimental freshwater tritrophic system: higher trophic levels modify competitive interactions between invasive macrophytes
Natural enemies are known to modify competitive hierarchies among terrestrial plants. Here we examine whether the same applies to freshwater systems. Lagarosiphon major (Hydrocharitaceae) is a submerged aquatic macrophyte, indigenous to South Africa. Outside its native range, it outcompetes with indigenous submerged species and degrades aquatic habitats. Hydrellia lagarosiphon (Diptera: Ephydridae) is the most abundant and ubiquitous herbivore associated with L. major in South Africa and is a potential biological control agent elsewhere. Chaenusa anervata (Hymenoptera: Braconidae: Alysiinae) is its main parasitoid. We generated an experimental system involving one, two or three trophic levels to monitor variation in the competitive ability of L. major relative to that of Myriophyllum spicatum (Haloragaceae), a second submerged macrophyte that can also be invasive. Using inverse linear models to monitor competition, we found that herbivory by H. lagarosiphon greatly reduced the competitive ability of L. major. Addition of the wasp at typical field densities halved the impact of herbivory and re-established the competitive advantage of L. major. Our results demonstrate how multitrophic interactions modify relative competitive abilities among aquatic plants, emphasize the significance of higher tropic levels in these systems and illustrate how parasitoids can reduce the effectiveness of insects released as biocontrol agents
Why old maids stay sweet
The usual function of floral nectaries in plants is to attract and reward pollinators, while extra-floral (foliar) nectaries function in the defence of the plant, attracting ants and other insects that can act as bodyguards (Beattie 1985). In a few plants these functions have been reversed, with floral nectar used to attract bodyguards (Dominguez et al. 1989) or foliar nectar used to attract pollinators, Poinsettias, Euphorbia pulcherimma L. are a well-known example (Thorp and Sugden 1990)
Morphology and geochemistry of glauconite from the Te Kuiti Group, South Auckland region, New Zealand
The late Eocene - Oligocene Te Kuiti Group comprises calcareous mudstone, calcareous sandstone and skeletal or sandy limestone formed in marginal marine to fully marine shelf settings. Glauconite is ubiquitous in all sedimentary units in low concentration (5-10%), but at unconformities or near formation boundaries can attain concentrations > 75%.
Binocular microscope studies show· the following morphological form abundances: ovoidal(40-55%) > fragmentary(20-40%) > lobate(5-15%) > casts (0-5%) with trace quantities of tabular, capsule, and vermicular grains. The abundance of ovoidal and fragmentary glauconite suggests the glauconite is dominantly allogenic. Only the highly fragile cast and lobate grains are considered reliable indicators of authigenic glauconite.
Because distinction of morphological types using the binocular microscope is subjective, an alternative classification based on measured variables using image analysis was attempted. Seven measurements (area, formfactor, convexicity, length, fractal, aspect, and fibre) were made for each grain image. Seven glauconite morphological types were investigated: capsule, cauliflower, fragmentary, lobate, ovoidal, tabular, and vermicular. Measurement data were analysed using canonical variate analysis. The calculated discriminating vectors were then used to distinguish the seven morpological forms. Using two canonical variates 81.5% of the variability within the database was accounted for.
X-ray diffraction studies shows a predominance of poorly crystalline glauconite. Many difficulties were encountered when applying previous literature techniques for calculating the expandable content of glauconite. An alternative technique based on the relationship between %K₂0 and % expandables is favoured for the calculation of % expandables. A relationship between host sediment lithology and glauconite expandable content was found; siltstone = 20-32%. expandables in the glauconite, sandstone = 8-15% expandables in the glauconite.
Major element data were obtained with the electron microprobe for 327 individual glauconite grain centres of 70 samples from 45 sites and 7 formations in the Te Kuiti. Group. The. chemical data were analysed using canonical variate analysis and the seven formations were clearly distinguished. Because only a small glauconite sample size is required (4-5 grains) the technique has potential for determining the stratigraphic correlation of drill core samples and small hand specimens of Te Kuiti Group material containing glauconite.
The range composition of Te Kuiti Group glauconite calculated from EMP major element data using the "Clayform" program is:
(Si ₃.₄₀₋₃.₆₈ Al ₀.₃₂₋₀.₆₀) (Al ₀.₀₈₋₀.₄₁ Fe ₁.₀₀³⁺₋₁.₃₆ Fe ₀.₁₉²⁺₋₀.₂₆ Mg ₀.₄₀₋₀.₆₀) (Ca ₀.₀₂₋₀.₁₆ Na ₀.₀₀₋₀.₀₄ K₀.₄₉₋₀.₆₇) O₁₀(OH₂)
The Te Kuiti Group passes stratigraphically upward from terrigenous and mixed terrigenous-skeletal carbonate deposits to very pure limestones. Early post-depositional diagenetic processes probably released Mg from the carbonate lattice of accumulating skeletal grains. Some of the released Mg was incorporated into the glauconite lattice as evidenced by the increase in Mg content of glauconite stratigraphically upward, parallel with the increased carbonate content of the rocks.
Major and trace element data were obtained using X-ray fluorescence for 29 bulk glauconite concentrates from 21 sites and 5 formations. Notably there were anomalous Mg, Pb and Ni concentrations in glauconite from the Otorohanga - Waitomo -Te Kuiti area. This suggests the area existed as a small semi-enclosed embayment, with a significantly higher terrigenous input compared with adjacent depocentres.
A strong correlation between the La/Ce ratio of glauconite and paleontological and oxygen isotope-derived sea-water temperatures suggests glauconite La/Ce ratio may be a useful paleotemperature indicator. The data collected in this study show no single previously suggested process adequately decribes the development of glauconite. Rather, glauconite should be considered polygenetic
An association between epichrysomallines and eurytomids (Hymenoptera: Chalcidoidea) in southern African fig wasp communities
Figs, the fruits of Ficus species (Moraceae), support diverse communities/assemblages of fig wasps belonging mainly to the families Agaonidae and Eurytomidae (Boucek et al. 1981; Compton and Hawkins, in press). Southern African fig wasp communities are composed mainly of species associated with the ovules of the plants, either as ovule-gallers or their parasitoids, although some species also gall fig primordia or the walls of the figs (Compton and van Noort 1992). The trophic relationships of only a few fig wasp species have been determined (Compton and van Noort 1992), but these suggest that the various subfamilies of fig wasps are generally consistent in that they contain either gallers or parasitoids. Amongst the gall-forming species are the Epichrysomallinae and Agaoninae (Agaonidae)(Boucek 1988). Eurytomids provide an exception to this general uniformity of larval feeding methods. For example, Sycophila Walker is a major genus of fig wasp eurytomids which includes species that are either gall-formers or parasitoids (Claridge 1959; Boucek 1988)
Fig Pollinating Wasp Transfers Nematodes into Figs of Ficus racemosa in Sumatra, Indonesia
The fruits (figs) of fig trees (Ficus spp, known as ‘bak ara’ in Aceh), are the source of food for many species of faunas in the forest, including birds, monkeys, orangutans, etc. Pollination within the figs totally depends on female fig wasps that belong to family Agaonidae. Fig trees and their pollinating wasps rely on each other to survive. Female fig wasps are known to transport nematodes into receptive figs when the wasps enter the figs to lay eggs. An investigation on the nematodes carried by female pollinating wasps Ceratosolen fusciceps Mayr into figs of Ficus racemosa was conducted in Sumatra, Indonesia. The figs on the trees were regularly sampled to determine the presence of nematodes and infer their ecology. The Baermann funnel method was employed to extract the nematodes from the figs. Eight species of nematodes were recorded from the figs, two of which are still unidentified. The species found were (1) Teratodiplogaster fignewmani, (2) Teratodiplogaster sp., (3) Parasitodiplogaster sp., (4) Schistonchus sp1., (5) Schistonchus sp2., (6) Mononchoides sp., (7) and (8) two undescribed Diplogastridae species (‘umbrella-like’ species 1 and species 2). This is the most diverse fig nematode community recorded. The highest nematode populations were routinely found in D-phase figs, when the new generations of wasps were about to emerge. Details of the ecology of each nematode species are likely to differ, but as a group they did not seem to significantly affect seed and wasp development in F. racemosa fig
Comorbidity and Quality of Life in Adults with Hair Pulling Disorder
Hair pulling disorder (HPD; trichotillomania) is thought to be associated with significant psychiatric comorbidity and functional impairment. However, few methodologically rigorous studies of HPD have been conducted, rendering such conclusions tenuous. The following study examined comorbidity and psychosocial functioning in a well-characterized sample of adults with HPD (N=85) who met DSM-IV criteria, had at least moderate hair pulling severity, and participated in a clinical trial. Results revealed that 38.8% of individuals with HPD had another current psychiatric diagnosis and 78.8% had another lifetime (present and/or past) psychiatric diagnosis. Specifically, HPD showed substantial overlap with depressive, anxiety, addictive, and other body-focused repetitive behavior disorders. The relationships between certain comorbidity patterns, hair pulling severity, current mood and anxiety symptoms, and quality of life were also examined. Results showed that current depressive symptoms were the only predictor of quality of life deficits. Implications of these findings for the conceptualization and treatment of HPD are discussed
Factor Analysis of the Milwaukee Inventory for Subtypes of Trichotillomania-Adult Version
The Milwaukee Inventory for Subtypes of Trichotillomania-Adult Version (MIST-A; Flessner et al., 2008) measures the degree to which hair pulling in Trichotillomania (TTM) can be described as “automatic” (i.e., done without awareness and unrelated to affective states) and/or “focused” (i.e., done with awareness and to regulate affective states). Despite preliminary evidence in support of the psychometric properties of the MIST-A, emerging research suggests the original factor structure may not optimally capture TTM phenomenology. Using data from a treatment-seeking TTM sample, the current study examined the factor structure of the MIST-A via exploratory factor analysis. The resulting two factor solution suggested the MIST-A consists of a 5-item “awareness of pulling” factor that measures the degree to which pulling is done with awareness and an 8-item “internal-regulated pulling” factor that measures the degree to which pulling is done to regulate internal stimuli (e.g., emotions, cognitions, and urges). Correlational analyses provided preliminary evidence for the validity of these derived factors. Findings from this study challenge the notions of “automatic” and “focused” pulling styles and suggest that researchers should continue to explore TTM subtypes
- …