Changes in diet,prey size and feeding habit in Bagrus bayad,and possible interactions with B. docmac in a Nile canal

Synopsis Bagrids in Bahr Shebeen Nilotic canal depend mainly on fish, insects and shrimp as well as fish embryos for food and their stomachs included runoff materials (e.g. plant foliage, glass, black crystals, coloured gravel). B. bayad maximised its efficiency of catching prey catfish by face to face attack to avoid damage by the prey's pectoral and dorsal spines. In the size classes of 10 to 30 cm standard length, B. bayad and B. docmac show diet overlap and interact with each other especially with respect to tilapias as prey. After this length, B. docmac, aided by its relatively larger mouth, shifted to larger size of tilapias to coexist with B. bayad.     

Ecophysiology of Aufwuchs-eating cichlids in Lake Tanganyika: niche separation by trophic specialization

Synopsis The Aufwuchs-eating cichlids of Lake Tanganyika show clear trophic differences that are correlated to their morphology, physiology and foraging behaviour. The species are grouped into three categories of relative intestinal length according to their feeding habits. A correlation between the intestinal length and the diet could be demonstrated, ranging from around 2.5 for species ingesting more animal food, to 7.8 for detritivorous and microalgivorous species. The relative intestinal length of domesticTropheus moorii, raised in aquaria was significantly lower than that of wild individuals by a factor of 1.7, demonstrating a wide range of phenotypic adaptability. The activities of trypsin and amylase were at an equal level in four Aufwuchseating species, but the activity of laminarinase of a detritivorous-microalgivorous species (Petrochromis orthognathus) was 2.6 times higher than that of an algivorous species (Tropheus moorii). The laminarinase seems to be an excellent marker enzyme for detritivorous or microalgivorous feeding.     

Effects of experience on palatability hierarchies of novel plants in the polyphagous grasshopperSchistocerca americana

Summary We studied the influence of diet composition and breadth on the subsequent acceptability of three novel plants to sixth instarSchistocerca americana. Rearing diets of equal breadth differing in composition, and diets differing in breadth, significantly altered first meal length on some but not all of the test plants. These effects on palatability altered and at times reversed the palatability hierarchy of insects reared on different diets. The effects of rearing insects on broad diets were not produced by exposure to the plant odors alone, but apparently required contact with a diversity of plants while feeding. Switching diets for 24 h prior to testing did not alter preferences induced by rearing diets. The relationship of these patterns to induced preferences in other insects, and some possible mechanisms for generating induced preferences, are discussed.     

Elemental and isotopic analyses of mammalian fauna from Southern Africa and their implications for paleodietary research

Elemental analyses of mammalian bone (e.g., strontium-calcium ratios, or Sr/Ca) distinguish between herbivores and carnivores; however, the relationships among herbivores are unclear. To study this question, a modern faunal sample from the Nagupande Tsetse Control Area (Zambezi drainage, Northwestern Zimbabwe) was used. This collection has the advantage of well-established geographical controls in addition to a varied fauna, which includes both bovids and suids. The grazing/browsing dietary status of each species was ascertained by means of isotopic analysis of carbon. Clear differences were seen in the δ¹³C of grazing and browsing animals; a specialized grazer was found to have significantly lower Sr/Ca than less specialized grazers and browsers. In this study it was also possible to examine differences in Sr/Ca by sex; female warthogs were found to have significantly lower Sr/Ca than males. The variation in certain animal groups was found to be abnormal. Implications for reconstruction of prehistoric human diets using trace-element techniques are discussed.     

Alterations in the Fatty Acid Composition of Rat Brain Cells (Neurons, Astrocytes, and Oligodendrocytes) and of Subcellular Fractions (Myelin and Synaptosomes) Induced by a Diet Devoid of n-3 Fatty Acids

Abstract: Rats were fed through four generations with a semisynthetic diet containing 1.0% sunflower oil (6.7 mg/ g n-6 fatty acids, 0.04 mg/g n-3 fatty acids). Ten days before mating, half of the animals received a diet in which sunflower was replaced by soya oil (6.6 mg/g n-6 fatty acids, 0.8 mg/g n-3 fatty acids) and analyses were performed on their pups. Fatty acid analysis in isolated cellular and subcellular material from sunflower-fed animals showed that the total amount of unsaturated fatty acids was not reduced in any cellular or subcellular fraction (except in 60-day-old rat neurons). All material from animals fed with sunflower oil showed an important reduction in the docosahexaenoic acid content, compensated (except in 60-day-old rat neurons) by an increase in the n-6 fatty acids (mainly C22:5 n-6). When comparing 60-day-old animals fed with soya oil or sunflower oil, the n-3/n-6 fatty acid ratio was reduced 16-fold in oligodendrocytes, 12-fold in myelin, twofold in neurons, sixfold in synaptosomes, and threefold in astrocytes. No trienes were detected. Saturated and monounsaturated fatty acids were hardly affected. This study provides data on the fatty acid composition of isolated brain cells.     

Genetic diversity and environmental associations of wild barley,Hordeum spontaneum (Poaceae), in Iran

Genetic diversity and structure of populations of the wild progenitor of barleyHordeum spontaneum in Iran was studied by electrophoretically discernible allozymic variation in proteins encoded by 30 gene loci in 509 individuals representing 13 populations of wild barley. The results indicate that: a)Hordeum spontaneum in Iran is extremely rich genetically but, because of predominant self-pollination, the variation is carried primarily by different homozygotes in the population. Thus, genetic indices of polymorphismP-1% = 0.375, range = 0.267–0.500, and of genetic diversity,He = 0.134, range = 0.069–0.198, are very high. b) Genetic differentiation of populations includes clinal, regional and local patterns, sometimes displaying sharp geographic differentiation over short distances. The average relative differentiation among populations isGst = 0.28, range = 0.02–0.61. c) A substantial portion of the patterns of allozyme variation in the wild gene pool is significanctly correlated with the environment and is predictable ecologically, chiefly by combinations of temperature and humidity variables. d) The natural populations studied, on the average, are more variable than two composite crosses, and more variable than indigenous land races of cultivated barely,Hordeum vulgare, in Iran. — The spatial patterns and environmental correlates and predictors of genetic variation ofH. spontaneum in Iran indicate that genetic variation in wild barley populations is not only rich but also at least partly adaptive. Therefore, a much fuller exploitation of these genetic resources by breeding for disease resistance and economically important agronomic traits is warranted.     

The mandibular corpus of female primates: taxonomic, dietary, and allometric correlates of interspecific variations in size and shape

Measurements were taken on skulls of 253 adult female anthropoid primates from 32 species, in order to determine patterns and possible causes for variation among species in the cross-sectional size and shape of the mandibular corpus under M1. When all 32 species are considered as a group, there is a tendency for corpus shape to become more robust with increasing body size. However, this does not hold for colobines or cercopithecines evaluated separately. When diets are classified into the general categories of folivory or frugivory, neither size-adjusted measurements of mandibular corpus breadth and height, nor estimates of the second moments of inertia or the polar moment of inertia of the mandibular cross section, show any relationship to dietary variation among species. Species reported to include hard nuts in their diets have larger mandibular cross sections than other species, and the size of the corpus is significantly correlated with size of the dentition and molar enamel thickness. A biomechanical model taking into account frictional effects of tooth-to-tooth contact indicates that mandibular corpus robusticity may not be related to a large horizontal component of force during mastication.     

四川大型真菌资源调查研究

本文介绍了四川大型真菌资源348种,包括药用真菌163种、食用真菌123种、有毒真菌41种、菌根真菌101种等。全国新记录26种。其中冬虫夏草(cordyceps sinensis)、凉山虫草(c.liangshanensis)、松口蘑(Tricholoma matsutake)、银耳(Tremella fuciformis)、短裙竹荪(Dictyophora duplicata)猴头(Hericium erinaceus)、鸡(土从)(Termitomyces albuminosus)、木耳(Auricuiaria auricula)、灵芝(Ganoderma lucidum)等尤为著名。并对四川大型真菌中部分重要种类的分布、资源及用途进行了分析和评价。为合理开发利用及有关教学科研提供了资料。     

Feeding habits of Japanese butterfyfishes (Chaetodontidae)

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.     

Evolution of feeding niches in New World monkeys.

The adaptive radiation of modern New World monkeys unfolded as the major lineages diversified within different dietary-adaptive zones predicated upon a fundamentally frugivorous habit. The broad outlines of this pattern can be seen in the fossil record, beginning in the early Miocene. Cebids are obligate frugivorous predators. The smallest forms (Cebuella, Callithrix) are specialized exudativores, and the largest (cebines) are seasonally flexible omnivores, feeding particularly on insects (Saimiri) or "hard" foods, such as pith and palm nuts (Cebus), when resources are scarce. The smaller-bodied atelids (Callicebus, Aotus) may use insects or leaves opportunistically, but pitheciins (saki-uakaris) specialize on seeds as their major protein source. The larger atelines (Alouatta, Brachyteles) depend on leaves or on ripe fruit (Ateles). Locomotion, body size, and dietary adaptations are linked: claws and small body size opened the canopy-subcanopy niche to callitrichines; climbing and hanging, the fine-branch setting to the atelines; large size and strength, semiprehensile tails, and grasping thumbs, the extractive insectivory of Cebus; deliberate quadrupedalism, the energy-saving transport of folivorous Alouatta. Body size increases and decreases occurred often and in parallel within guilds and lineages. Conventional dietary categories, particularly frugivory, are inadequate for organizing the behavioral and anatomical evidence pertinent to evolutionary adaptation. Related models of morphological evolution based on feeding frequencies tend to obfuscate the selective importance of "critical functions," responses to the biomechanically challenging components of diet that may be determined by a numerically small, or seasonal, dietary fraction. For fossils, body size is an unreliable indicator of diet in the absence of detailed morphological information. More attention needs to be given to developing techniques for identifying and quantifying mechanically significant aspects of dental form, the physical properties of primate foods, their mode of access, and the cycles of availability and nutritional value.