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61.
62.
MARK WESTOBY KRISTINE FRENCH LESLEY HUGHES BARBARA RICE LOUISE RODGERSON 《Austral ecology》1991,16(4):445-455
Myrmecochores are plant species that bear seeds with food-bodies adapting them for dispersal by ants. Within Australia and South Africa, myrmecochores account for a large percentage of the flora in sclerophyll vegetation on very infertile soils. On fertile soils, there are few myrmecochores and more species with fleshy fruits adapted for dispersal by vertebrates. This effect of very infertile soils may also account for the high incidence of myrmecochores in the floras of Australia and South Africa compared with other continents. The taxonomic distribution of myrmecochory shows it has evolved many times within the Australian flora. Evidence has been collected in relation to eight hypotheses that might account for the prevalence of myrmecochory on very infertile soils: (1) Myrmecochore seeds do not appear to be relocated to nutrient-enriched microsites. Seed-removing ant species relocate their nest entrances frequently; active ant nests are not nutrient-enriched; and seedlings emerging after fire are not located in nutrient-enriched soil. (2) Traffic of seed-removing ants is not greater on infertile than on fertile soils. (3) Burial to avoid predation by small mammals is not a significant factor for seeds in Australian vegetation. (4) Experiments in which diaspore traits are manipulated support the idea that a larger food body increases the likelihood that a diaspore will be taken by a seed-disperser ant species that will not eat the embryo, rather than by a seed-predator ant. However, evidence so far does not support the hypothesis that, on very infertile soils, seed-disperser ants are consistently more available than seed-predator ants. (5) Removal rates of fruits adapted for dispersal by vertebrates were, on average, two and a half times greater in vegetation on fertile soils. Birds were the main removers. Our current opinion is that the fruit-removing bird assemblage is more likely to be a consequence of the high incidence of species with vertebrate-adapted fruits, rather than the reverse. (6) Fleshy fruits are more expensive in potassium than food bodies for ants, but not in nitrogen or phosphorus. This might be a reason why fleshy fruits are uneconomic on very infertile soils. (7) Species with smaller embryo-plus-endosperm weight are relatively more likely to be adapted for dispersal by ants rather than vertebrates. However, differences in the frequency distribution of embryo-plus-endosperm weights between infertile and fertile soils are moderate in the Sydney area. An indirect association between soil fertility and dispersal mode via embryo-plus-endosperm weight cannot account for much of the difference in dispersal spectrum. (8) Species growing to less than 2 m tall are relatively more likely to be adapted for dispersal by ants rather than vertebrates, and also account for more of the flora on infertile than on fertile soils. This indirect correlation is capable of accounting for as much as 80% of the higher incidence of myrmecochory on infertile soils. 相似文献
63.
ALEXANDER J. SULZER PHYLLIS L. STROBEL E. LOUISE SPRINGER IVAN L. ROTH CAREY S. CALLAWAY 《The Journal of eukaryotic microbiology》1974,21(5):710-714
SYNOPSIS. Freeze-etch preparations of Toxoplasma gondii reveal details of structure and organelles in 3-dimensional relationships. The subpellicular microtubules and their relationship to the polar ring, the tripartite pellicle, the pellicle constituents, and the spatial relationship of the rhoptries to the conoid and conoid canal are clearly demarcated. 相似文献
64.
RONG WANG ASHLEY MATTHEWS JOANNE RATCLIFFE LOUISE J. BARWELL YAN‐QIONG PENG LIEN‐SIANG CHOU HUI YU HUI‐WEN YANG STEPHEN G. COMPTON 《Ecological Entomology》2014,39(4):492-500
1. Fig trees require host‐specific agaonid fig wasps for pollination, but their figs also support numerous non‐pollinating fig wasps (NPFW) that gall fig tissues or develop as parasitoids. 2. Ficus microcarpa L. is widely naturalised outside its native range and the most invasive fig tree species. Seed predators are widely used for the biological control of invasive plants, but no obligate seed predatory (as opposed to ovule or fig wall galling) NPFW have been recorded previously from any fig trees. 3. Philotrypesis NPFW are usually regarded as parasitoids or ‘inquilines’ (parasitoids that also eat plant material) of pollinator fig wasps, but the present study provides evidence that Philotrypesis taiwanensis, a NPFW associated with F. microcarpa, is an obligate seed predator: (i) adults emerge from seeds of typical appearance, with a surrounding elaiosome; (ii) it shows no preference for figs occupied by fig wasp species, other than the pollinator; (iii) it only develops in figs that contain pollinated ovules, avoiding figs occupied by an agaonid that fails to pollinate; (iv) larvae are distributed in layers where seeds are concentrated and (v) it has a negative impact on seed but not pollinator offspring numbers. 4. Philotrypesis is a large genus, and further species are likely to be seed predators. 相似文献
65.
66.
LOUISE LAMPHERE 《American anthropologist》2004,106(1):202-204
Navajo Trading: The End of an Era. Willow Roberts Powers. Albuquerque: University of New Mexico Press, 2001. 282 pp. 相似文献
67.
LOUISE LAMPHERE 《American anthropologist》2004,106(1):126-139
Initially given as the Presidential Address at the 100th Meeting of the AAA, this article examines the contributions women and minority anthropologists who have struggled to gain a place at the center of the discipline. Despite 25 years of scholarship on women and minorities, anthropology needs to go further in terms of paying attention to their pioneering efforts and the breadth of their scholarship. The article explores four currently important areas of creativity: (1) the transformation of field research through problem-oriented participant observation and "native anthropology," as exemplified by George Hunt, the young Margaret Mead, Delmos Jones; (2) the evolution of more dialogical forms of ethnographic writing, as pursued by Elsie Clews Parsons, Gladys Reichard, Ella Deloria, and Zora Neale Hurston; (3) sources of critique, as embodied in the work of Ruth Benedict and Michelle Rosaldo; (4) forms of activism, engaged in by Anita McGee, Benedict, Mead, and Alfonzo Ortiz. 相似文献
68.
ROXINA SOLER SONJA V. SCHAPER T. MARTIJN BEZEMER ANNE M. CORTESERO THOMAS S. HOFFMEISTER WIM H. VAN DER PUTTEN LOUISE E. M. VET JEFFREY A. HARVEY 《Ecological Entomology》2009,34(3):339-345
Abstract 1. Several studies have shown that above‐ and belowground insects can interact by influencing each others growth, development, and survival when they feed on the same host‐plant. In natural systems, however, insects can make choices on which plants to oviposit and feed. A field experiment was carried out to determine if root‐feeding insects can influence feeding and oviposition preferences and decisions of naturally colonising foliar‐feeding insects. 2. Using the wild cruciferous plant Brassica nigra and larvae of the cabbage root fly Delia radicum as the belowground root‐feeding insect, naturally colonising populations of foliar‐feeding insects were monitored over the course of a summer season. 3. Groups of root‐infested and root‐uninfested B. nigra plants were placed in a meadow during June, July, and August of 2006 for periods of 3 days. The root‐infested and the root‐uninfested plants were either dispersed evenly or placed in clusters. Once daily, all leaves of each plant were carefully inspected and insects were removed and collected for identification. 4. The flea beetles Phyllotreta spp. and the aphid Brevicoryne brassicae were significantly more abundant on root‐uninfested (control) than on root‐infested plants. However, for B. brassicae this was only apparent when the plants were placed in clusters. Host‐plant selection by the generalist aphid M. persicae and oviposition preference by the specialist butterfly P. rapae, however, were not significantly influenced by root herbivory. 5. The results of this study show that the presence of root‐feeding insects can affect feeding and oviposition preferences of foliar‐feeding insects, even under natural conditions where many other interactions occur simultaneously. The results suggest that root‐feeding insects play a role in the structuring of aboveground communities of insects, but these effects depend on the insect species as well as on the spatial distribution of the root‐feeding insects. 相似文献
69.
LOUISE S. SPINDLER 《American anthropologist》1975,77(2):375-376
Book reviewed in this article:
Ethnology: Differentiation and Co-operation in an Israeli Veteran Moshav. ELAINE BALDWIN.
Ethnology: Family and Community in the Kibbutz. YONINA TALMON. 相似文献
Ethnology: Differentiation and Co-operation in an Israeli Veteran Moshav. ELAINE BALDWIN.
Ethnology: Family and Community in the Kibbutz. YONINA TALMON. 相似文献
70.
MARY LOUISE CHIAPPINO BARBARA A. NICHOLS G. RICHARD O'CONNOR 《The Journal of eukaryotic microbiology》1984,31(2):288-292
Scanning electron microscopy confirmed our previous finding that toxoplasmas actively invade mouse peritoneal cells that are inhibited from phagocytosis. The parasites entered cells with the conoid end first and sometimes showed a counter-clockwise torsion of the body during invasion. Counter-clockwise torsion was also noted in free toxoplasmas. Host-cell responses to active invasion varied with experimental conditions and with the type of host cell. Under adverse culture conditions for phagocytosis, normal macrophages formed rudimentary filopodia or lamellipodia around the tips of in vading toxoplasmas; macrophages subjected to hyperthermia before similar incubation with toxoplasmas showed little or no response to invasion. Normal and heat-treated lymphocytes showed little surface reaction to invasion, but occa ionally a flocculent collar was seen around the tip of an invading toxoplasma. Scanning electron microscopy provides clues to possil'e mechanisms of toxoplasma locomotion and host-cell invasion. 相似文献