PREFATORY NOTE

The Audiovisuals Editor has embarked on a new format in which every second or third issue will contain a comprehensive section of reviews under the direction of an expert in the field of consideration. It is our hope to provide, in addition to the general reviews, a resource for scholars and teachers.
In this issue David Horr of Brandeis University presents the first in the series: Primate Behavior films. Professor Horr is now completing a film on free-ranging behavior and ecology of orang-utans, shot during his nearly three years of field research on that species in eastern Borneo.
Donald Miller is currently developing a review section on Archeology, Nancie Gonzalez on Urban Anthropology and Scott Robinson on Problems in Politics and Development. We are also planning special issues on Physical Anthropology, Medical Anthropology, Hunters and Gatherers, Horticulturalists, Pastoralists and Peasants.
We hope that this compilation of film reviews on a single subject and similar review sections in the future will not only provide a resource for teaching, but will offer standards for specialists in anthropology making films in the field.     

Cladistic information in phylogenetic definitions and designated phylogenetic contexts for the use of taxon names

A phylogenetic definition of a taxon name associates that name with a clade through its reference to a particular ancestor and all of its descendants. Depending on one's perspective, phylogenetic definitions name either clades on the one true, but unknown, phylogeny, or components on cladograms (clades on hypotheses regarding the true phylogeny). Phylogenetic definitions do not contain enough information to identify components without a reference cladogram. As a result, (1) if clades are equated with components on cladograms, a phylogenetic definition may associate a taxon name with different clades on different cladograms, and (2) the inclusiveness, diagnostic synapomorphies, and distribution in time and space of the clade with a particular name can differ markedly depending on the phylogenetic hypothesis one chooses to adopt. This potentially unacceptable lability in the clade to which a name refers can be avoided by using a taxon name in conjunction with only phylogenetic hypotheses on which specific taxa are related in a particular fashion. This designated phylogenetic context can be described in an n-taxon statement that would be appended to the phylogenetic definition. Use of the taxon name would be considered inappropriate in conjunction with cladograms on which the relationships contradict those in the n-taxon statement. Whereas phylogenetic definitions stabilize the meaning of taxon names, designated phylogenetic contexts would stabilize the usage of those names.     

Metapopulations of moths on islands: a test of two contrasting models

1. We describe a generalized mainland-island metapopulation model which includes migration among the island populations. We test model predictions with quantitative data on more than 200 species of moths in two contrasting networks of small islands. The data include a direct measure of migration rate, based on trapping of moths on rocky skerries with no local populations of the vast majority of species.
2. We predicted that moths which are strong fliers but uncommon on the islands have a higher incidence on scattered islands than on islands in a group, because the latter 'compete' for immigrants from the mainland. In contrast, we predicted that weakly flying species with potentially large local populations on the islands occur more frequently on islands in a group due to enhanced colonization rate.
3. Both predicted patterns were observed. Island occupancy increased significantly with the number of individuals caught on the rocky skerries, which is our measure of migration rate from the mainland, supporting the basic assumption that the species occur on the islands in a balance between colonizations and extinctions.
4. These results demonstrate that the moth metapopulations on islands represent a mixture of Levins's and mainland-island metapopulations, and that the mixture is different for different species in the same landscape.     

Differential inhibition of branching enzyme in a morphological mutant and in wild type Neurospora. Influence of carbon source in the growth medium.

1. A morphological mutant of Neurospora crassa, smco 9, (R2508) that exhibits colonial morphology when grown on sucrose or on maltose, showed a partial reversal of this morphology toward that of the wild type when it was grown on potato starch or on isomaltose. 2. A common feature of both potato starch and isomaltose is the presence of alpha-1, 6 glucosidic linkages. This suggested that these morphological effects might be due to differences in alpha-1,4 glucan: alpha-1,4 glucan 6 glycosyltransferase, (EC 2.4.1.18) commonly known as "the branching enzyme". 3. The branching enzyme was purified from wild type, Neurospora crassa, and from the semicolonial mutant, R2508, both grown on sucrose or on potato starch. It has a molecular weight of 140,000 as estimated by gel filtration on a Bio Gel A 1.5 m column. This enzyme plus phosphorylase a in an unprimed reaction catalyzes the synthesis of a branched polysaccharide in vitro. 4. No branching enzyme activity was apparent in extracts of the mutant R2508, grown on potato starch until a thermolabile inhibitor was removed by fractionation on a DEAE column. 5. This inhibitor has a molecular weight greater than 100,000 as estimated on a P-100 polyacrylamide gel column. The specificity of the inhibitor is not absolute in that it inhibits glycogen synthetase in addition to the branching enzyme in Neurospora.     

Inter-joint coordination of posture on a seesaw device

Even though specific adjustments of the multi-joint control of posture have been observed when posture is challenged, multi-joint coordination on a seesaw device has never been accurately assessed. The current study was conducted in order to investigate the multi-joint coordination when subjects were standing on either a seesaw device or on a stable surface, with the eyes open or closed. Eighteen healthy active subjects were recruited. A principal component analysis and a Self-Organizing Maps analysis were performed on the joint angles in order to detect and characterize dominant coordination patterns. Intermuscular EMG coherence was analysed in order to assess the neurophysiological mechanisms associated with these coordination patterns. The results illustrated a multi-joint organization of posture on both stable ground and on the seesaw, with a higher variability among the individual postural responses observed when standing on the seesaw. These findings challenge the classical assumption of ankle mechanisms as dominating control on seesaw devices and confirm that inter-joint coordination in postural control is strongly modulated by stance conditions. When standing on the seesaw without vision, a decrease in intermuscular coherence was observed without any impact on the joint coordination patterns, likely due to an increase dependence on proprioceptive information.     

Emergence of donor control in patchy predator—prey systems

We study a general predator—prey system in a spatially heterogeneous environment. The predation process, which occurs on a behavioural time-scale, is much faster than the other processes (reproduction, natural mortality and migrations) occurring on the population dynamics time-scale. We show that, taking account of this difference in time-scales, and assuming that the prey have a refuge, the dynamics of the system on a slow time-scale become donor-controlled. Even though predators may control the prey density locally and on a behavioural fast time-scale, nevertheless, both globally and on a slow time-scale, the prey dynamics are independent of predator density: the presence of predators generates a constant prey mortality. In other words, in heterogeneous environments, the prey population dynamics depend in a switch-like manner on the presence or absence of predators, not on their actual density.     

Effect of an additional manual motor task on the maintenance of equilibrium in the frontal and sagittal planes in standing subjects

The postural oscillations of a standing subject during an additional manual motor task consisting in holding a movable ball in the center of a flat box were studied. The movements of the center of pressure (CP) in the frontal and sagittal planes were studied when subjects were standing on a stable rigid support and on a movable unstable support. The effect of the additional motor task on the movement of the CP depended on the stability of the support. When the additional task was performed, the sagittal movements of the CP increased in the case a movable support and did not increase when the support was stable. The additional task decreased the frontal movements of CP in the case of a stable support, and it did not change the frontal movements of CP when the support was unstable. Thus, the performance of an additional motor task led to a reduction of the efficiency of the postural control system in maintaining equilibrium on an unstable support. This decrease may be due to a greater cortical influence on the posture control system in subjects standing on a movable support in comparison with this influence in the case of a stable support.     

Accumulative Difference Image Protocol for Particle Tracking in Fluorescence Microscopy Tested in Mouse Lymphonodes

The basic research in cell biology and in medical sciences makes large use of imaging tools mainly based on confocal fluorescence and, more recently, on non-linear excitation microscopy. Substantially the aim is the recognition of selected targets in the image and their tracking in time. We have developed a particle tracking algorithm optimized for low signal/noise images with a minimum set of requirements on the target size and with no a priori knowledge of the type of motion. The image segmentation, based on a combination of size sensitive filters, does not rely on edge detection and is tailored for targets acquired at low resolution as in most of the in-vivo studies. The particle tracking is performed by building, from a stack of Accumulative Difference Images, a single 2D image in which the motion of the whole set of the particles is coded in time by a color level. This algorithm, tested here on solid-lipid nanoparticles diffusing within cells and on lymphocytes diffusing in lymphonodes, appears to be particularly useful for the cellular and the in-vivo microscopy image processing in which few a priori assumption on the type, the extent and the variability of particle motions, can be done.     

MICROBIAL COLONIZATION ON NATURAL AND ARTIFICIAL MACROPHYTES IN A PHOSPHORUS-LIMITED,HARDWATER LAKE1

Epiphyte communities in a phosphorus-limited hard-water lake were compared over a 14-week period from Potamogeton illinoensis and structurally similar artificial plants of different leaf ages. Artificial plants were serially incubated in the lake to simulate the age of natural leaves. The physiognomy of loosely attached epiphytes appeared similar on the two substrata. Algal cell number and biovolume were 15-fold and 17-fold higher, respectively, on artificial leaves early in the growing season, but total algal density gradually became similar on natural and artificial plants. In contrast, the taxonomic composition of loosely attached algae became increasingly distinct, and mean cell biovolume on natural leaves was twice that on artificial leaves. Adnate epiphytes on both substrata developed from sparse populations of bacteria on new leaves to a community of diatoms, blue-green algae and numerous bacteria on mature and senescent leaves. Adnate community succession on natural leaves in late senescence/death differed from that on artificial leaves colonized for comparable periods in having (1) a marked increase in filamentous blue-green algae, (2) a subsequent decrease in all algae, and (3) a final fungi-dominated stage. The trends in colonization indicate that macrophytes in this oligotrophic lake provided a distinct habitat from that of artificial substrata for epiphytes throughout the growing season.     

Plant cues influence searching behaviour and parasitism in the egg parasitoid Trichogramma nr. brassicae

Abstract. 1. The effect of experience of plant cues at emergence on searching behaviour and parasitism was investigated in two strains of Trichogramma nr. brassicae (Hymenoptera: Trichogrammatidae).
2. Wasps reared on Sitotroga cereallela were allowed to emerge on a tomato plant or in a vial, with or without food. For one of the strains, females emerging on tomato searched significantly longer on a tomato seedling than females emerging in a vial.
3. The experience effect lasted between 1 and 2 days. It involves associating plant stimuli with the remains of the host, because females emerging from their host on a tomato plant had an increased searching response to tomato, but females transferred to the plant immediately after emergence did not.
4. The effect of emergence environment on parasitism of the host Helicoverpa punctigera on tomato and lettuce seedlings was tested. Wasps were allowed to emerge on seedlings of tomato or lettuce, or in an empty vial. For one strain, females experienced with tomato at emergence parasitized significantly more hosts on tomato than did females emerging on lettuce or in a vial. Parasitism on lettuce was not influenced by the treatments.     

TV is Moving in

Visual arts teachers engage in complex work on a daily basis. This work is informed by practical knowledge that is rarely examined or drawn on in research or in the development of policy. Focusing on the work of secondary visual arts teachers, this article reports on a research program conducted in a regional area of New South Wales, Australia. The research engages in a collaborative process of educational connoisseurship and educational criticism to examine and discuss classroom practice. The process is underpinned by a belief in research as an act of discovery and is guided by a framework that provides a language and grammar of practice. Drawing on qualitative data, discussion focuses on how the collaborative process enables the mobilization and generation of new knowledge. The article concludes by considering the relationship between teaching practice, research, and policy development and by recommending support for collaborative research-based initiatives that foreground the knowledge of teachers.     

Central place foraging by an ant (Cataglyphis bicolor Fab.): a model of searching

A computer model of the searching activity of Cataglyphis bicolor (Fab.), based on quantitative data obtained in the field in Greece, was investigated. This ant searches for individual items of food (mainly dead arthropods) in the open on flat ground, on which its paths can be followed and mapped. The model was based on an analogy with molecular diffusion from a centre, suggested by the fact that the average distance of ants from the nest increased in proportion to the square root of time, up to a distance more than half the radius of a circle enclosing 90% of the search area. Actual behaviour was well described by a model in which individual ants went out for the first time to search in a direction determined at random. Subsequently they went out in a straight line in a direction and to a distance related to that of the previous find before commencing a semi-random search, on a path consisting of straight portions branching at random angles, with restriction on turns in a backward direction. Individual real ants search in restricted areas, commonly sectors centred on the nest. This behaviour was reproduced in the model as were quantitative aspects of the nest behaviour. Communication between individuals was not required in the model.     

Site selection in a polymorphic mangrove snail

Three species of littorinid snail live on mangroves of the genus Rhizophora on the north coast of Papua New Guinea. They have recently been placed in the genus Littoraria. The species are L. scabra and L. intermedia , which are monomorphic and cryptic and live on bark, and L. pallescens which is polymorphic and lives in foliage. Littoraria intermedia was found mostly on mangroves facing on to partially fresh water, while L. scabra occurred only at sites facing on to the sea; L. pallescens occurs at both types of site. When kept together in plastic containers, L. pallescens shows a greater propensity to climb than the other two species. The morphs of L. pallescens are principally yellow, orange or dark. Orange is present at a frequency of 0–9% and yellow at 10–50%. There is little evidence of geographical variation in frequency over 80 km of coast, although one central locality has a significantly higher frequency of yellow than sites to the north or south of it. Throughout the tropics where the species occurs, orange is the rarest and yellow usually the next rarest morph. Larger individuals are on average higher in the foliage than smaller ones, and there is a higher frequency of yellows among larger shells than smaller ones. As the air temperature increases, a progressively larger fraction of a sample was found to be on the under-surfaces of leaves rather than on the upper epidermis or on flower or leaf buds. When over 30% of a sample is situated on lower surfaces there is a significant excess of yellows and a deficiency of darks on the upper surfaces. This indicates that individuals selectively take up different positions depending on morph colour, resulting in a degree of optimal background matching. Such a choice of location may be of direct relevance to the maintenance of the polymorphism. A difference in morph frequency between the same sites examined in 1979 and 1984 is interpreted as being a result of site selectivity.     

The use of pH indicators to identify suitable environments for freezing samples in aqueous and mixed aqueous/nonaqueous solutions

The colours of frozen solutions containing pH indicators are shown to provide a test for changes in pH in the solvent environment which occur on freezing. Yeast alcohol dehydrogenase loses activity on freezing in phosphate buffer (a buffer in which pH indicator colour changes shows a marked decrease in pH on freezing) but when frozen in bis-tris, Hepes, or N-glycylglycine buffers (all of which show little change in the colour of universal pH indicator and hence of pH on freezing) is stable on freezing. The effects of freezing in different buffer systems on the rate of decomposition of NADPH, and on the rate hydrolysis of 4-nitrophenyl acetate, are rationalised in terms of the pH shifts in these buffers which were determined using universal pH indicator. It is proposed that a major reason for the instability of samples on freezing is the pH changes which occur when some systems are frozen. From the results a general scheme for selecting the best environment for safely freezing samples is proposed which is based on the use of pH indicators.     

Effects of insects on primary production in temperate herbaceous communities: a meta-analysis

Abstract.  1. The effects of insects on primary production in temperate herbaceous communities were investigated in a meta-analysis. The following hypotheses were tested: (1) the effect of insects on primary production depends on community type, (2) the effect of insects on primary production varies as a function of productivity, (3) insects have a greater effect on primary production in communities with low species diversity, and (4) insects have a larger effect on primary production during outbreaks.
2. Data were collected from 24 studies in which insecticides were used to suppress insects in self-sown or pastoral communities. Effect sizes were calculated from sprayed and control plot standing crop or yield, expressed as the log response ratio, ln (sprayed plot phytomass/control plot phytomass).
3. There was a significant increase in primary production as a result of insect suppression. Forb-dominated communities showed a more variable response than graminoid communities. During outbreaks, insects had a greater negative impact on primary production. Effect size was unaffected by productivity or plant species richness.
4. Although insects lower primary production in a diversity of temperate herbaceous communities, the basic measures by which such communities are often described have little effect on the proportional impact that insects have on primary production. While outbreaks are significant predictors of higher negative impact on primary production, causes of outbreaks are not always related to traits of the plant community.     

Loads on an internal spinal fixation device during sitting.

Sitting is often assumed to involve high loads on the spine as well as on implants for stabilising the spine. Loads on internal spinal fixation devices were therefore measured in ten patients sitting on several types of seats, including a stool, a stool with a padded wedge, a chair, a physiotherapy ball, a knee-stool, and a bench. The patients also successively sat relaxed and erect on a stool. In addition, six of them sat on a special chair allowing different inclinations of the backrest. Implant loads were also measured for standing up and sitting down. There were only minor differences in fixator loads for sitting on the different types of seats. Sitting erect caused an average of 11% higher implant loads than sitting relaxed. Implant loads decreased with increasing inclination of the upper body while sitting on a chair with an adjustable backrest. Implant loads were about 27% higher for standing up and sitting down than for sitting.     

Singing in the rain. Rainfall and moonlight affect daily activity patterns of rodents in a Neotropical forest

Rainfall is often indirectly related to the availability of resources, which in turn regulates the abundance of rodents over time. However, the direct influence of rainfall on daily activity is poorly understood, despite the fact that it likely has a great effect on small animals. Furthermore, the influence of the moon on the movement of rodents has been the subject of debate but limited to studies conducted in open areas. Based on a study using pitfall traps in a subtropical region of southern Brazil, this study aimed to investigate the effects of rainfall and the phases of the moon on the daily movements of five species of sigmodontine rodents in a Neotropical forest. Activity patterns were assessed over 130 days, and the daily rainfall and moon phase were verified. Rainfall exhibited a significant positive effect on all studied species. This reflects an increase in the movement of rodents on rainy days, which should be primarily associated with the immediate harmful effects of rain, such as a wet coat and the destruction of shelters. The five species responded differently to moon phase, with a lack of effect for three of them and a positive effect of a full moon on the activity patterns of the other two species. This increase in activity rhythm due to a full moon may indicate a benefit of clear nights for foraging, in contrast to the most common outcome, which associates the brightness of the moon with increased predation risk.     

Effect of intrauterine iodine infusion on luteal function and blood PGF2a concentration in cycling goats

Studies were conducted to determine the effect of iodine infusion on the luteal function of goats, as evident by blood progesterone concentration, and on plasma PGF2a levels. Ten cycling mixed breed goats were synchronized for estrus by PGF2a (5 mg) and given a single intrauterine iodine infusion on day 5 and on day 15 of the estrous cycle. Iodine infusion on day 5 (group II) resulted in shorter estrous length (8.2 days) and a 7-fold increase in plasma PGF2a concentration as compared to control animals (group I) given distilled water infusion. Similar infusion on day 15 (group III), on the other hand, failed to alter the estrous cycle length but induced a moderate increase in PGF2a concentration which lasted only for a brief period. The progesterone levels declined concomitantly as PGF2a levels rose after iodine infusion in group II animals but failed to decline until after 24 hours in group III animals. The studies indicate that the endometrium reacts to the chemical stimuli and releases PGF2a which, in turn, alters the luteal function.