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PubMed1991

Sandfly distribution and abundance in a tropical rain forest.

1. The distribution patterns of sandflies (Diptera: Psychodidae) upon tree buttresses were studied in tropical rain forest at Finca la Selva in the Caribbean lowlands of Costa Rica. 2. Four species of sandfly, Lutzomyia shannoni Dyar, L. trapidoi F. & H., L. ylephiletor F. & H. and L. vespertilionis F. & H. comprising 97% of those caught, used tree buttresses as diurnal resting sites. Their distribution on the buttresses was aggregated. 3. During the dry season tree species had no significant effect upon the distribution of the sandflies. However, during the wet season the distributions of two of the species, L. trapidoi and L. ylephiletor, were significantly affected by the species of tree; it is suggested that some species of tree may provide greater protection from rainfall than others. 4. L. vespertilionis was restricted to a single buttress on each positive tree. Distribution of this species is evidently determined by the distribution of its host animal, the bat (Emballonuridae). Female flies feed upon the bat's blood and male flies may be attracted to the bat as it provides a source of female sandflies. It is suggested, therefore, that tree buttresses serve as sandfly swarming sites. 5. Within a large buttress the sandflies are not randomly distributed but are aggregated in particular areas. Within these aggregations, the sandflies are vertically zoned upon the buttress with a shift in species composition with height. Two hypothesis were suggested to account for this distribution pattern: a response to an environmental gradient or an interaction between the four species of fly.

Animals↗

PubMed2002

Attending to the big picture: mood and global versus local processing of visual information.

Two experiments employed image-based tasks to test the hypothesis that happier moods promote a greater focus on the forest and sadder moods a greater focus on the trees. The hypothesis was based on the idea that in task situations, affective cues may be experienced as task-relevant information, which then influences global versus local attention. Using a serial-reproduction paradigm, Experiment 1 showed that individuals in sad moods were less likely than those in happier moods to use an accessible global concept to guide attempts to reproduce a drawing from memory. Experiment 2 investigated the same hypothesis by assessing the use of global and local attributes to classify geometricfigures. As predicted, individuals in sad moods were less likely than those in happier moods to classify figures on the basis of globalfeatures.

Affect↗

PubMed2001

Networking senescence-regulating pathways by using Arabidopsis enhancer trap lines.

The last phase of leaf development, generally referred to as leaf senescence, is an integral part of plant development that involves massive programmed cell death. Due to a sharp decline of photosynthetic capacity in a leaf, senescence limits crop yield and forest plant biomass production. However, the biochemical components and regulatory mechanisms underlying leaf senescence are poorly characterized. Although several approaches such as differential cDNA screening, differential display, and cDNA subtraction have been employed to isolate senescence-associated genes (SAGs), only a limited number of SAGs have been identified, and information regarding the regulation of these genes is fragmentary. Here we report on the utilization of enhancer trap approach toward the identification and analysis of SAGs. We have developed a sensitive large-scale screening method and have screened 1,300 Arabidopsis enhancer trap lines and have identified 147 lines in which the reporter gene GUS (beta-glucuronidase) is expressed in senescing leaves but not in non-senescing ones. We have systematically analyzed the regulation of beta-glucuronidase expression in 125 lines (genetically, each contains single T-DNA insertion) by six senescence-promoting factors, namely abscisic acid, ethylene, jasmonic acid, brassinosteroid, darkness, and dehydration. This analysis not only reveals the complexity of the regulatory circuitry but also allows us to postulate the existence of a network of senescence-promoting pathways. We have also cloned three SAGs from randomly selected enhancer trap lines, demonstrating that reporter expression pattern reflects the expression pattern of the endogenous gene.

Arabidopsis↗

PubMed2006

You focus on the forest when you're in charge of the trees: power priming and abstract information processing.

Elevated power increases the psychological distance one feels from others, and this distance, according to construal level theory, should lead to more abstract information processing. Thus, high power should be associated with more abstract thinking-focusing on primary aspects of stimuli and detecting patterns and structure to extract the gist, as well as categorizing stimuli at a higher level-relative to low power. In 6 experiments involving both conceptual and perceptual tasks, priming high power led to more abstract processing than did priming low power, even when this led to worse performance. Experiment 7 revealed that in line with past neuropsychological research on abstract thinking, priming high power also led to greater relative right-hemispheric activation.

Adult↗

PubMed2006

Phylogeography of human lymphatic filarial parasite, Wuchereria bancrofti in India.

Wuchereria bancrofti, a nematode parasite causing human lymphatic filariasis is widely distributed in India. The phylogeography of this parasite was studied by constructing RAPD profiles of parasite populations collected from 71 microfilaria carriers residing in different geoclimatic regions of India. The analysis showed that the phylogeography of W. bancrofti populations is complex, with a high genetic divergence and gene flow among populations. The total genetic diversity (H(T)) and genetic differentiation (G(ST)) estimated for all the parasite populations were 0.0926 and 0.5859, respectively. The gene flow (Nm) between different regions indicated that two strains of W. bancrofti were prevalent in the country, one in the eastern side and the other on the western side of the Western Ghats. A highly significant genetic differentiation (F(ST) [theta] = 0.7978) was estimated between these two strains (chi 2 = 308.2789; P < 0.001). The gene flow between these strains was very low (0.2338). These two strains appear to have drifted genetically because of their geographic isolation by this thickly forested mountain range. The strain in the eastern side was found to be monophyletic in origin and is undergoing genetic divergence as the major parasite population in the country, spanning from eastern peninsular region to the northern plains. The variable geoclimatic factors and the antifilarial chemotherapeutical pressure on the parasite, which is in place for the past half a century, might have contributed for the high genetic heterogeneity its strains/populations in the country. The route of entry of the parasite into Indian sub-continent possibly appeared to be from an ancient origin from the countries of the Southeast Asian archipelago, through the eastern coastal line of the southern peninsula.

Animals↗

PubMed2006

Deposition in boreal forests in relation to type, size, number and placement of collectors.

Open precipitation and throughfall was collected at a Norway spruce stand in Finland using funnel-type collectors and at a black spruce stand in Canada using trough-type collectors. The presence or absence of a rim on the funnel, funnel diameter (9, 14 and 20 cm) and length of sampling period (1, 2 and 4 weeks) on monthly values were evaluated at the Norway spruce stand, and the number of collectors required for defined levels of accuracy and precision of throughfall loads to be reached and the influence of the spatial arrangement of collectors on solute concentrations was studied at both stands. The presence of a rim had no significant effect on open precipitation and throughfall amounts, but did on throughfall DOC, Ca(2+), Mg(2+), K(+), Na(+) and Cl(-) ion loads. Deposition loads increased with decreasing funnel diameter; for open precipitation, this was due to increased catch efficiency while for throughfall the increase was attributed to canopy interaction and leaching of litter trapped in the collectors. Calculated monthly H(+) loads decreased and those for all other constituents increased with collection period length. Using 15 collectors at the Norway spruce stand would allow throughfall loads to be determined to within 20% of the true mean weekly value with a confidence level of 95% for most solute, but not for NH(4) (+)-N, NO(3) (-)-N, Mg(2+) and SO(4) (2-)-S. Using 15 trough collectors, the same confidence level at the more heterogeneous black spruce stand would only be achieved for H(+), Cl(-), DOC and SO(4) (2-)-S loads. In both stands, using either random or systematic placements of throughfall collectors gave similar results.

Ecosystem↗

PubMed2004

The forest, the trees, and the chameleon: context dependence and mimicry.

Three studies examined the relation between context dependence in information processing and behavioral mimicry. In Experiment 1, a field-dependent cognitive style was related to a greater tendency to mimic a target's behavior. In Experiment 2 context dependence was experimentally manipulated, and results showed more mimicry in the session where a context-dependent processing style was induced compared with the session where a context-independent processing style was induced. Experiment 3 provided evidence for bidirectionality in the relation between context dependence and mimicry. Specifically, participants whose posture and behavior had been unobtrusively mimicked by an experimenter subsequently processed information in a more context-dependent manner than did nonmimicked participants. Taken together, these results illustrate the interplay between basic cognitive and behavioral processes.

Adult↗

PubMed2001

Dose-dependent response and preliminary observations on attraction range of Ips typographus to pheromones at low release rates.

Responses of the European spruce bark beetle, 1. typographus (Coleoptera: Scolytidae), to low release-rate pheromones were investigated in two experiments in a spruce forest at Wellin, southern Belgium. Dose-response of the beetle was first examined in a trapping experiment in August 1999. The major pheromone components of L. typographus, (S)-cis-verbenol (cV) and 2-methyl-3-buten-2-ol (MB) were released from window traps. Five treatments were replicated five times: (1) blank trap, (2) 0.03 and 1.2, (3) 0.11 and 4.5, (4) 0.34 and 15.2 mg/day of cV and MB, respectively, and (5) Pheroprax. Trap catches increased linearly as a function of increasing release rates of cV and MB. A second study aimed at making preliminary observations on the attraction range of the pheromones as compared to Pheroprax. A release-recapture experiment was carried out in May 2000: four trap-trees located 50 m away from a central release platform were equipped with window traps baited with increasing release rates, tested in separate releases: 0.03 and 1.2; 0.11 and 4.5; 0.34 and 15.2 mg/day of cV and MB, respectively, and Pheroprax. Recaptures increased with the release rate. Trap catches were different at lower release rates, but not between the release rate of 15.2 mg/day of MB and Pheroprax. Variations in captures in relation to wind parameters showed persistently random flight at the lower release rates. Significant upwind flight was observed for Pheroprax only. These results imply that trap interference existed for Pheroprax and suggest that its attraction range may be greater than 50 m.

Animals↗

PubMed2004

Correlations between adult mimicry and larval host plants in ithomiine butterflies.

The apparent paradox of multiple coexisting wing pattern mimicry 'rings' in tropical butterflies has been explained as a result of microhabitat partitioning in adults. However, very few studies have tested this hypothesis. In neotropical forests, ithomiine butterflies dominate and display the richest diversity of mimicry rings. We show that co-mimetic species occupy the same larval host-plant species significantly more often than expected in two out of five communities that we surveyed; in one of these, the effect remains significant after phylogenetic correction. This relationship is most probably a result of a third correlated variable, such as microhabitat. Host-plant microhabitat may constrain adult movement, or host-plant choice may depend on butterfly microhabitat preferences and mimicry associations. This link between mimicry and host plant could help explain some host-plant and mimicry shifts, which have been important in the radiation of this speciose tropical group.

Adaptation, Biological↗

PubMed1991

[Nutrition survey in the Republic of the Congo: results from a national survey conducted in 1987].

The objective was to evaluate the nutritional status of preschool children in the rural areas in order to establish a baseline for the measurement of the impact of a Government Nutrition Education Project (NUTED) in forthcoming years. The household cross-sectional survey was carried out on a representative sample of the rural population. The sample was stratified in order to portray the nutritional status of the children in the northern regions (more thinly populated) and in the southern regions: one stratum for small towns (between 2000 and 30,000 inhabitants) and 4 strata for rural localities. The sampling method used was by clusters of 30 children, distributed randomly in 20 zones per stratum. The nutritional indices of 2429 children were calculated and analysed according to WHO recommendations. The prevalence of the different types of malnutrition was 27.5% (95% confidence interval (CI), 24.2-30.8) for stunting (height-for-age retardation) and 5.5% (CI = 4.2-6.8) for wasting (weight-for-height retardation). Both types coexisted among 1.9% of the children; 23% of children were underweight for their age (CI = 21.6-26.2), and 15.8% (CI = 14.7-16.9) aged greater than 12 months had a mid-arm circumference below 135 mm. No sex difference was observed in the results. Stunting seems to appear in the second trimester of life (3-5 months), and wasting appeared between 9 and 23 months (highest rate between 12 and 17 months: 14.0% (CI = 9.3-18.8], which presents a real public health problem. The stratification did not show any significant differences in nutritional status among the children living in rural zones and those living in the small towns. However, the prevalence of malnutrition in the rural zones was 2 or 3 times higher than that observed in 1986 in Brazzaville. The division of the country into five main ecological zones allows some useful comparisons, e.g., the prevalence of stunting ranges from 15.5% (CI = 12.8-18.2) in the northern inundated forest zone to 38.8% (CI = 32.9-44.7) in the southern forests of Mayombe and Chaillu. The diet also varied, the frequency of animal protein consumption on the preceding day ranging from 76.3% to 59.1% in the different zones. The Republic of the Congo differs from other African countries in having relatively lower rates of stunting but an astonishingly high prevalence of wasting.(ABSTRACT TRUNCATED AT 400 WORDS)

Child Nutrition Disorders↗

PubMed2006

[Differentiation of closely related oyster fungi Pleurotus pulmonarius and P. ostreatus by mating and molecular markers].

Classical matings and RAPD-PCR analysis were used to differentiate two closely related basidial fungi, Pleurotus pulmonarius and P. ostreatus, which are widespread in Russian forest biocenoses with moderate climate. Monokaryon-monokaryon (mon-mon) and dikaryon--monokaryon (di-mon) matings demonstrated complete reproductive isolation of the two species, which have partly overlapping morphological traits. The prevalence of a particular species in nature was shown to depend to a great extent on the natural conditions, namely, the day and night temperature ranges. The clustering of natural Pleurotus strains displayed two trends: one was associated with natural reproductive isolation of the two species (D = 0.61) and the other, with the geographical factor (D = 0.39). A relatively recent origin is suggested for the divergence of the two species and the reproductive barrier between them. Adaptation to natural conditions was considered to be the main factor causing the divergence of natural Pleurotus populations and, eventually, allopatric speciation.

DNA, Fungal↗

PubMed2006

The phylogenetic pattern of speciation and wing pattern change in neotropical Ithomia butterflies (Lepidoptera: nymphalidae).

Species level phylogenetic hypotheses can be used to explore patterns of divergence and speciation. In the tropics, speciation is commonly attributed to either vicariance, perhaps within climate-induced forest refugia, or ecological speciation caused by niche adaptation. Mimetic butterflies have been used to identify forest refugia as well as in studies of ecological speciation, so they are ideal for discriminating between these two models. The genus Ithomia contains 24 species of warningly colored mimetic butterflies found in South and Central America, and here we use a phylogenetic hypothesis based on seven genes for 23 species to investigate speciation in this group. The history of wing color pattern evolution in the genus was reconstructed using both parsimony and likelihood. The ancestral pattern for the group was almost certainly a transparent butterfly, and there is strong evidence for convergent evolution due to mimicry. A punctuationist model of pattern evolution was a significantly better fit to the data than a gradualist model, demonstrating that pattern changes above the species level were associated with cladogenesis and supporting a model of ecological speciation driven by mimicry adaptation. However, there was only one case of sister species unambiguously differing in pattern, suggesting that some recent speciation events have occurred without pattern shifts. The pattern of geographic overlap between clades over time shows that closely related species are mostly sympatric or, in one case, parapatric. This is consistent with modes of speciation with ongoing gene flow, although rapid range changes following allopatric speciation could give a similar pattern. Patterns of lineage accumulation through time differed significantly from that expected at random, and show that most of the extant species were present by the beginning of the Pleistocene at the latest. Hence Pleistocene refugia are unlikely to have played a major role in Ithomia diversification.

Animals↗

PubMed2005

Inter-simple sequence repeat (ISSR) variation in forest coffee trees (Coffea arabica L.) populations from Ethiopia.

Genetic variation of forest coffee trees (Coffea arabica L.) from four regions of Ethiopia was investigated using inter-simple sequence repeat (ISSR) markers. A total of 160 individuals representing 16 populations were sampled. Eleven ISSR primers amplified a total of 123 fragments of which 31 fragments (25%) were polymorphic. Estimate of total gene diversity (HT), and the coefficient of genetic differentiation (GsT) were 0.37 and 0.81, respectively. This indicates that most of the variability is between populations than within populations. The partitioning of genetic variation into within and between populations based on Shannon's information index also revealed more differentiation between populations (0.80) than within populations (0.20). In the phenogram most of the coffee tree samples were clustered on the basis of their regions of origin but failed to cluster according to their respective populations, which could be attributed to the presence of substantial gene flow between adjacent populations in each region assisted by man in the process of transplantation or by wild animals such as monkeys, which eat the berries and defecate the seeds elsewhere. On the other hand, the inter-regional clustering of some coffee tree samples from Bale and Jimma regions could be due to the transport of coffee seeds across regions and their subsequent planting. Although ISSR markers detected lower polymorphic loci than previously reported results with random amplified polymorphic DNA (RAPD) markers on the same materials, it can be used as an alternative method for molecular characterization of C. arabica populations. The results may provide information to select sites for in situ conservation.

Base Sequence↗

PubMed2001

Missing the forest for the trees? Deficient memory for linguistic gist in obsessive-compulsive disorder.

BACKGROUND: Patients with obsessive-compulsive disorder (OCD) exhibit recall deficits on word learning tasks, mediated by their failure to detect semantic connections among the words. METHODS: In the present experiment, using methods devised by Bransford & Franks (1971), we tested whether this encoding problem impairs their extraction of gist from complex linguistic material. RESULTS: Consistent with our hypothesis, OCD patients extracted less gist from related sentences than did healthy participants. The groups did not differ in recognition memory for individual sentences or in criterion for affirming previously encountered sentences as 'old', as evinced by signal detection indices of memory sensitivity (d') and response bias (beta), or in recognition memory confidence. CONCLUSIONS: These data provide further evidence that OCD patients exhibit less reliance on organizational strategies than do healthy control participants. These data are consistent with neuropsychological research suggestive of prefrontal executive problems in OCD.

Adult↗

PubMed2004

A randomised trial of an online lecture with and without audio.

OBJECTIVE: To determine the impact of adding audio-feed to an online lecture on screening given to medical students who were participating in an outpatient clerkship. DESIGN: Prospective, randomised, controlled study. SETTING: Vanderbilt University School of Medicine, Nashville and Wake Forest Medical School, Winston-Salem. PARTICIPANTS: A total of 59 Years 3 and 4 medical students. MAIN OUTCOME MEASURES: Students' use of time, satisfaction with the lecture experience, and knowledge. Educational intervention The online lecture was developed at Vanderbilt University. At Vanderbilt, 16 Year 4 medical students were randomised to the lecture on screening with audio and 17 Year 4 medical students were randomised to the same lecture without audio. At Wake Forest, 13 Year 3 medical students were randomised to the lecture on screening with audio and 13 Year 3 students were randomised to the same lecture without audio. RESULTS: The audio lecture required 20 more minutes to complete than the non-audio lecture. Students in the audio group were more satisfied with their experience than students in the non-audio group. Students in the audio-feed group achieved a trend for higher post-intervention knowledge scores, with the difference attributed to the students at Vanderbilt. CONCLUSION: Audio narration is an important aspect of an online lecture. The distribution of online lectures to students at different sites and different training levels requires further study.

Analysis of Variance↗

PubMed1998

Acoustically dimorphic advertisement calls separate morphologically and genetically homogenous populations of the grey mouse lemur (Microcebus murinus).

Sexual advertisement calls of male mouse lemurs from two neighbouring demes in a dry deciduous forest of western Madagascar were recorded during the breeding season. Demes were located about 1.5 km apart with no geographic barrier between them. They were characterised morphometrically and genotyped by RAPD fingerprinting. According to univariate and multivariate statistical analysis, demes differed neither in body measurements, nor in the banding patterns produced by RAPD fingerprinting. The acoustic pattern of the advertisement call, however, showed significant differences: Six variables of the frequency and time domain differed between the demes. Discriminant function analysis revealed that one variable, total call duration, was sufficient to classify more than 89% of the calls correctly to the corresponding deme. We postulate that these differences are comparable to dialects in birds, because demes were morphologically and genetically indistinguishable and no barrier prevented genetic exchange between them. Possible explanations for the emergence of dialects in a prosimian species are outlined.

Acoustics↗

PubMed2001

Habitat association in two genetic groups of the insect-pathogenic fungus metarhizium anisopliae: uncovering cryptic species?

Strains of insect-pathogenic fungi with high virulence toward certain pest insects have great potential for commercial biological control applications. Identifying such strains has been a central theme in using fungi for biological control. This theme is supported by a persistent paradigm in insect pathology which suggests that the host insect is the predominant influence on the population genetics of insect-pathogenic fungi. In this study, a population genetics analysis of the insect-pathogenic fungus Metarhizium anisopliae from forested and agricultural habitats in Ontario, Canada, showed a nonrandom association of alleles between two distinct, reproductively isolated groups (index of multilocus association = 1.2). Analyses of the mitochondrial DNA showed no differences between the groups. The two groups were associated with different habitat types, and associations with insect hosts were not found. The group from forested areas showed an ability for cold-active growth (i.e., 8 degrees C), while the group from the agricultural area showed an ability for growth at high temperatures (i.e., 37 degrees C) and resilience to UV exposure. These results represent a significant paradigm shift; habitat selection, not host insect selection, drives the population structure of these insect-pathogenic deuteromycetous fungi. With each group we observed recombining population structures as well as clonally reproducing lineages. We discuss whether these groups may represent cryptic species. Worldwide, M. anisopliae may be an assembly of cryptic species, each adapted to certain environmental conditions. The association of fungal genotypes with habitat but not with host insects has implications on the criteria for utility of this, and perhaps other, fungal biocontrol agents.

Agriculture↗

PubMed1995

Laboratory and field evaluations of a repellent soap containing diethyl toluamide (DEET) and permethrin against phlebotomine sand flies (Diptera: Psychodidae) in Valle del Cauca, Colombia.

The repellency and insecticidal efficacy of Nopikex, a soap formulation containing 20% diethyl toluamide and 0.5% permethrin, was evaluated against a laboratory colony of phlebotomine sand flies (Lutzomyia longipalpis). The repellency of Nopikex soap was also compared with that of a placebo soap against another species (Lu. youngi) in a forest near Tulua, Valle del Cauca, Colombia. In laboratory trials of the soap, no reduction in repellency was seen 4 hr after application, but within 8 hr, repellency decreased significantly to 67.0% of the initial value (P < 0.05) based on calculations of the coefficient of protection (CP). Under field conditions, the soap gave up to 100% protection immediately after application, but within 4 hours its CP value had decreased to a median value of only 44.3%. The placebo soap was also found to be somewhat repellent when compared with no treatment, giving a median CP value of 67.7 immediately after application. No significant mortality was seen in sand flies within 24 hr of exposure to the soap in the laboratory, even in those that had fed on protected volunteers.

Animals↗