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21.
Donna Robbins Colin A. Chapman Richard W. Wrangham 《Primates; journal of primatology》1991,32(3):301-305
Gibbons and spider monkeys have similar diets, body size, and locomotor patterns. They are therefore expected to be subject
to similar socioecological rules. However their grouping patterns differ. Gibbons live in small stable groups, whereas spider
monkey form unstable sub-groups that vary from small to large during different seasons. If similar principles apply to the
two species, food abundance should vary more for spider monkeys than for gibbons; food density should be similar for the two
species when spider monkey sub-groups are the same size as gibbon groups; and the highest level of food abundance should be
higher for spider monkeys than for gibbons. These predictions are upheld for a comparison of particular populations ofHylobates muelleri andAteles geoffroyi. 相似文献
22.
Jörg U. Ganzhorn Jean Prospère Abraham Marlène Razanahoera-Rakotomalala 《Primates; journal of primatology》1985,26(4):452-463
Two groups ofAvahi laniger were studied in the Forêt de Analamozoatra near Perinet in the eastern rainforest of Madagascar from August to October 1984.
Overlap between the home ranges of neighbouring groups ofA. laniger was minimal. Group size ranged from one to four individuals with a median group size of two. In four out of ten groups a
baby was born between August and September.A. laniger were most active after dusk and before dawn. They had an extended resting period around midnight. Their diet consisted mostly
of leaves from at least 17 different plant species. They also ate flowers. Fruit eating was recorded twice. Leaves eaten had
high contents of protein and sugar but did not contain alkaloids. The concentration of condensed tannins did not differ between
food items and non-food items. There was no indication of competition with other prosimians that might explain their nocturnality. 相似文献
23.
The present studies were undertaken to further assess the role of plasma beta-endorphin (beta-EP) in the hyperphagia induced by the glucose antimetabolite, 2-deoxy-D-glucose (2-DG). Plasma concentrations of immunoreactive beta-EP (ir-beta-EP) were measured at the end of the first hour of feeding in all animals treated with 400 mg/kg 2-DG. Previous studies had shown a consistent, positive association between 2-DG hyperphagia and plasma ir-beta-EP concentrations, but the present data revealed dissociations between hyperphagia and plasma ir-beta-EP. Dexamethasone administration blocked the 2-DG-induced rise in plasma ir-beta-EP, but had no effect on the 2-DG hyperphagia measured at 1 hour. Forced drinking of a 2% NaCl solution decreased 2-DG hyperphagia, but not the 2-DG induced rise in plasma ir-beta-EP. Thus, elevations in plasma ir-beta-EP are not necessary for the full expression of 2-DG-induced hyperphagia in dexamethasone-treated rats. Furthermore, decreased feeding responses to 2-DG could coexist with increased levels of plasma ir-beta-EP in NaCl-treated normal rats. Elevations in plasma ir-beta-EP do not appear to be the critical opiate link in 2-DG induced hyperphagia. 相似文献
24.
D A Hill 《Bioelectromagnetics》1985,6(1):33-40
Further studies of human whole-body radiofrequency (RF) absorption rates were carried out using a TEM-cell exposure system. Experiments were done at one frequency near the grounded resonance frequency (approximately 40 MHz), and at several below-resonance frequencies. Absorption rates are small for the K and H orientations of the body, even when grounded. For the body trunk in an E orientation, the absorption rate of a sitting person is about half of the rate for the same person standing with arms at the sides; the latter in turn is about half the rate for the same subject standing with arms over the head. Two-body interactions cause no increase in absorption rates for grounded people. They do, however, increase the absorption rates for subjects in an E orientation in free space; the largest interaction occurs when one subject is lambda/2 behind the other (as seen by the incident wave). When these results are applied to practical occupational exposure situations, the whole-body specific absorption rate does not exceed the ANSI limit of 0.4 W/kg for exposures permitted by the ANSI standard (C95.1-1982) at frequencies from 7 to 40 MHz. 相似文献
25.
Douglas M. Carlson William L. Pflieger Linden Trial Pamela S. Haverland 《Environmental Biology of Fishes》1985,14(1):51-59
Synopsis
Scaphirhynchus albus and S. platorynchus were studied in Missouri during 1978–1979 to assess their distribution and abundance, to obtain information on their life
histories, and to identify existing or potential threats to their survival. S. platorynchus was collected in substantial numbers (4355 specimens) at all 12 sampling stations in the Missouri and Mississippi rivers,
while only 11 S. albus were captured from 6 stations. Twelve specimens identified in the field as hybrids between the two species were captured
from 4 stations. Morphometric and meristic comparisons of presumed hybrids with the parent species, using cluster and principal
components analyses, demonstrated intermediacy of most specimens identified in the field as hybrids. Aquatic insects comprised
most of the diet of S. platorynchus and S. albus, but S. albus and the hybrids had consumed considerable quantities of fish. S. albus grew more rapidly than S. platorynchus, while the growth of hybrids was intermediate. Hybridization appears to be a recent phenomenon, resulting from man-caused
changes in the big-river environment. Hybridization may be a threat to survival of S. albus in the study streams. 相似文献
26.
Akira Inokuchi Yasunobu Tomida Chizuko Yanaihara Ryogo Yui Yutaka Oomura Hiroshi Kimura Takanobu Hase Tomoaki Matsumoto Noboru Yanaihara 《Cell and tissue research》1986,246(1):71-75
Summary Immunohistochemically, nerve fibers and terminals reacting with anti-N-terminal-specific but not with anti-C-terminal-specific glucagon antiserum were observed in the following rat hypothalamic regions: paraventricular nucleus, supraoptic nucleus, anterior hypothalamus, arcuate nucleus, ventromedial hypothalamic nucleus and median eminence. Few fibers and terminals were demonstrated in the lateral hypothalamic area and dorsomedial hypothalamic nucleus. Radioimmunoassay data indicated that the concentration of gut glucagon-like immunoreactivity was higher in the ventromedial nucleus than in the lateral hypothalamic area. In food-deprived conditions, this concentration increased in both these parts. This was also verified in immunostained preparations in which a marked enhancement of gut glucagon-like immunoreactivity-containing fibers and terminals was observed in many hypothalamic regions. Several immunoreactive cell bodies were found in the ventromedial and arcuate nuclei of starved rats. Both biochemical and morphological data suggest that glucagon-related peptides may act as neurotransmitters or neuromodulators in the hypothalamus and may be involved in the central regulatory mechanism related to feeding behavior and energy metabolism. 相似文献
27.
A. J. P. Raat 《Aquatic Ecology》1989,23(1):67-72
In ten 0.1 ha drainable ponds O+ cyprinids were stocked to assess their impact on the aquatic community. Bream and roach were stocked in early June, 1986, and carp in early July, 1986. The ponds were drained mid November, 1986. The relationship between the fish community and its food resource was estimated in terms of production and consumption with use of the data on growth and mortality of the fish. The average gross production of the fish species in the ten ponds (48.4 kg during the experiment) was dominated by the carp (58.5%). A minimum estimate of the food consumption of the O+ cyprinids is 760 kJ.m–2. The average production of bream and roach was much lower than that of carp due to a higher mortality and a more specialized feeding pattern. The gross productions of carp, bream and roach in the ten ponds were not significantly related, although stomach analysis showed diet overlap between the carp and the bream. 相似文献
28.
Synopsis This paper describes a study performed in the Gulf of Aqaba on food selectivity and hunting behaviour of three species of sympatric fish from the genusCephalopholis. These fishes occur in the shallow-water coral habitats of the Red Sea and feed on fishes and invertebrates. Of these,C. argus andC. miniata prefer selected fish species (95 and 86% of their diet respectively), whereasC. hemistiktos consumes more invertebrates (36%) and is less selective with respect to fish species. All three species employ various techniques to catch their prey and in situations where their elected food is absent they readily switch to substitute prey species. 相似文献
29.
Mitsuhiko Sano 《Environmental Biology of Fishes》1989,25(1-3):195-203
Synopsis Stomach content data from 32 species of Japanese butterflyfishes of the family Chaetodontidae were used to classify them into
feeding groups and to determine their important food resources. Four major feeding groups were distinguished: (1) obligative
coral feeders which prey exclusively or mostly on Scleractinian corals, (2) facultative coral feeders that take both corals
and other benthic organisms, (3) noncoralline invertebrate feeders which consume benthic invertebrates other than corals,
and (4) zooplankton feeders. Ten species representing 31% of the butterflyfishes belong to the first category. The second
and third categories include 13 (41%) and 8 (25%) species, respectively. The fourth category is represented by only one species
which picks individual zooplankters, especially calanoid copepods, in midwater above the reefs. Facultative coral feeders
consumed varying quantities of scleractinians (from 2 to 74% of food volume), along with a variety of benthic organisms including
algae, alcyonarians, sea anemones, sedentary polychaetes, sponges, hydroids, etc. Noncoralline invertebrate feeders, on the
other hand, tend to have low diversified diets, predominated by one prey item such as sea anemones, zoanthideans, polychaetes,
or colonial ascidians. These dietary data suggest that scleractinian corals are the most important food resource for the Japanese
butterflyfishes, and next important are sea anemones, sedentary polychaetes, alcyonarians, and algae. 相似文献
30.
Growth versus molting time of caterpillars as a function of temperature,nutrient concentration and the phenolic rutin 总被引:1,自引:0,他引:1
Nancy E. Stamp 《Oecologia》1990,82(1):107-113
Summary A factorial experiment tested the effects of varying nutrient concentration (normal versus diluted), presence or absence of the phenolic allelochemical rutin and daytime temperature (20, 25 and 30° C) on growth, molting and food utilization efficiencies of tobacco hornworms (Manduca sexta). Two of the utilization efficiencies (approximate digestibility and efficiency of conversion of ingested food) were unaffected by temperature; the third one, efficiency of conversion of digested food, was affected by temperature but there was no consistent effect. Lower temperatures significantly increased the proportion of the stadium spent molting, with larvae at a daytime temperature of 20° C spending 9% more of the stadium in molting than larvae at 30° C. Growth time was not influenced by nutrient concentration. When temperature was low and rutin absent, molt time and the proportion of the stadium spent molting were affected by nutrient concentration. Addition of the phenolic rutin did not have an appreciable effect on growth time or digestive processes. However, it increased molting time by 7 to 14% and thus increased the duration of the stadium and reduced relative growth rate. These results indicate that the effect of food quality on growth rate is a function of the thermal conditions of insect herbivores. At cooler temperatures, a disproportionate increase in time spent molting, rather than altered food utilization efficiencies, contributed to lower growth rates. The consequences for larval growth of fluctuating temperatures due to diurnal cycles and the presence of predators forcing larvae into thermally suboptimal microhabitats are discussed. 相似文献