A comparison of the efficiencies of the shotgun and the bow in neotropical forest hunting

Whenever introduced into Amazonia and its neighboring regions, the shotgun has quickly replaced the bow and arrow and other aboriginal weapons of the hunt. The quick and widespread adoption of the shotgun is plainly a matter of its superiority over most aboriginal weapons. This paper compares the hunting efficiencies of the shotgun and the bow by means of a controlled field experiment among the Ye'kwana and Yanomamö Indians of the Upper Orinoco River of southern Venezuela. It also examines the impact of the shotgun on local animal populations and the economic changes brought about by the need to cash-crop in order to purchase Western hunting technology.Funds for the research and writing of this paper were made possible by an NIMH predoctoral fellowship to Napoleon A. Chagnon, Grant No. NIMH 5 R01 MH 26008-SSR.     

Tree communities and soil properties influence fungal community assembly in neotropical forests

The influence exerted by tree communities, topography, and soil chemistry on the assembly of macrofungal communities remains poorly understood, especially in highly diverse tropical forests. Here, we used a large dataset that combines inventories of macrofungal Basidiomycetes fruiting bodies, tree species composition, and measurements for 16 soil physicochemical parameters, collected in 34 plots located in four sites of lowland rain forests in French Guiana. Plots were established on three different topographical conditions: hilltop, slope, and seasonally flooded soils. We found hyperdiverse Basidiomycetes communities, mainly comprising members of Agaricales and Polyporales. Phosphorus, clay contents, and base saturation in soils strongly varied across plots and shaped the richness and composition of tree communities. The latter composition explained 23% of the variation in the composition of macrofungal communities, probably through high heterogeneity of the litter chemistry and selective effects of biotic interactions. The high local heterogeneity of habitats influenced the distribution of both macrofungi and trees, as a result of diversed local soil hydromorphic conditions associated with contrasting soil chemistry. This first regional study across habitats of French Guiana forests revealed new niches for macrofungi, such as ectomycorrhizal ones, and illustrates how macrofungi inventories are still paramount to can be to understand the processes at work in the tropics. Abstract in Spanish is available with online material.     

Three-dimensional dispersion of drosophilid flies in a cool temperate forest of northern Japan

Three-dimensional dispersion of drosophilid flies was studied within a secondary broad-leaved forest in relation to forest structure. The survey area included the forest margin and old canopy gaps and varied in the foliage height profile from place to place. Using multivariate analyses on the data of drosophilid dispersion, five microhabitats which were different from one another for drosophilids were recognized: (i) canopy layer; (ii) middle layer; (iii) floor layer of forest interior; (iv) upper layer of forest margin; and (v) herbaceous layer of forest margin and gap. The height of living space of canopy species was remarkably lowered at the forest margin. The forest edge was richer in both numbers of individuals and species than the forest interior from the overlap of the grassland and the forest canopy subcommunities and the addition of invaders from other habitats. However, no ‘edge’ species, which were mostly restricted to or spend most of their time in ecotones, were found. It is hypothesized that the above-ground forest structure consists fundamentally of three zones: (i) the canopy; (ii) the floor; and (iii) the edge. A significant positive correlation was found between the foliage height diversity and the degree of vertical habitat segregation among drosophilid species. The patchiness of vegetation structure influential to the three-dimensional dispersion in a forest drosophilid community was estimated to be on the scale of 110–450 m². This scale of subjective habitat patchiness or ‘ecological neighbourhood’ corresponds well with the most prevalent size of canopy gaps occurring in various forests.     

Nematode parasitism in a Danish drosophilid community: further evaluation of the disproportionate parasitism hypothesis

The nematodes Parasitylenchus diplogenus and Howardula aoronymphium (Allantonematidae) are parasites of drosophilids (Diptera). Nematodes were found in 3/14 drosophilid species sampled in Danish woodlands: Drosophila phalerata Meigen (3.5% parasitism) was parasitized by H. aoronymphium and D. obscura Fallén (0.5%) and D. subobscura Collin (2.1%) by P. diplogenus. Parasitism was generally rare, and few drosophilid species parasitized, compared to elsewhere in Europe. Parasitism was positively correlated with relative host abundance both within Denmark and across communities, suggesting that species diversity is promoted by a disproportionately high parasitism of more common host species. The prevalence of H. aoronymphium, but not P. diplogenus, parasitism is positively related to temperature across communities.     

Degradation of acetochlor by four microbial communities

Four microbial communities capable of degrading acetochlor, designated A, D, E, and J, were obtained from acetochlor-contaminated soil and sludge. Acetochlor at an initial concentration of 55mg/L was completely degraded by the four mixed cultures after 4 days. At 80 mg/L acetochlor, more than 99% degradation was observed with D, 84% with A and E, and 88% with J after 9 days. There are primary eight strains of bacteria in community A, three in community D, E, and J, respectively. No single isolate was able to degrade acetochlor efficiently. The acetochlor biodegradation products were identified by gas chromatography-mass spectrometry. The probable degradative pathways of acetochlor involved dechlorination, hydroxylation, deethoxymethylation, cyclization, carboxylation, and decarboxylation. Propachlor, alachlor, and metolachlor, which are also the main components of the chloroacetanilide herbicide, could be degraded by the four mixed cultures to some degree. Given the high degradation rates observed here, the four mixed cultures obtained may be useful in the degradation processes of acetochlor.     

DNA fingerprinting in three species of neotropical primates

DNA fingerprinting allows the simultaneous detection of a large number of hypervariable loci consisting of highly polymorphic tandem repeat units that are extensively dispersed in the genome. With the 33.6 human minisatellite probe, hypervariable fragments were detected, for the first time, in the genome of three different species of wild-caught neotropical primates: Aotus infulatus, Aotus azarae, and Cebus apella. As in the human, these species were highly polymorphic, showing distinctive, individual-specific patterns. Estimates of relatedness within each group were calculated from interspecific comparisons based on the number of shared fragments between individuals. This work shows that the 33.6 human minisatellite probe can be very useful for increasing our understanding of population dynamics and behavior of these species in their natural habitat. © 1996 Wiley-Liss, Inc.     

An eight year phenological study of a local drosophilid community in Central Chile

In the outskirts of Santiago, Chile (La Florida), collections of drosophilids were performed every month from 1984 to 1991. Some of the species are cosmopolitan, like D. melanogaster and D. simulans, or subcosmopolitan, like D. subobscura. A few others are endemics, like D. pavani and some Scaptomyza. The population sizes of all the species show annual and monthly periodic fluctuations, detected by autocorrelations analyses, excepting D. melanogaster, that exhibits very weak monthly correlations. This seems to indicate that D. melanogaster is weakly coupled to periodic phenomena that are acting on the rest of the drosophilid fauna. Furthermore, biogeographic categories, like cosmopolitan, or subcosmopolitan, or endemic species, are of very little importance when applied to single localities, since species cluster irrespective of them being endemic or cosmopolitan.     

Arterial vascularization of the mandible and maxilla of neotropical primates

The objective of the present investigation was to conduct a comparative macroscopic study of the arterial vascularization of the mandible and maxilla of neotropical primates of the genera Cebus, Alouatta, Callithrix, and Leontopithecus. After vinyl was injected into the arterial system of the head of each specimen, the pieces were macerated and corroded. The level of the bifurcation of the common carotid artery into the internal and external carotids varied between the first and third cervical vertebrae. The external carotid artery accounts for most of the vascularization of the facial structures. The actual vessels responsible for the supply of this region are the sublingual, facial, angular, lingual, submandibular, submental, inferior and superior labial, maxillary, inferior alveolar, infraorbital, superior posterior alveolar, palatine major, and sphenopalatine arteries. We conclude that although the arterial vascular pattern was similar in all the genera studied, and resembles the human pattern, there are notable variations in the vasculature of the mandible and maxilla among these four neotropical genera.     

Generalizability of neotropical bird abundance and richness models

Predicting the consequences of land-cover change on tropical biotas is a pressing task. However, testing the applicability of models developed with data from one region to another region has rarely been done. Bird faunas were sampled along 3.0-km routes in southern Costa Rica (Coto Brus) to develop statistical models to describe the abundance and richness of groups as a function of land-cover characteristics. The relative value of the land-cover models was assessed by comparing them with null models. The generalizability of the models was tested with data from north-western Costa Rica (Monteverde) to determine whether the models were applicable to another area that has undergone significant land-cover change in the last 60 years. The richness and abundance of understory, open-country and edge non-insectivore groups showed clear relationships with land-cover variables, and the land-cover models had lower prediction errors than the null models for Coto Brus. With one exception, useful models for canopy birds, edge insectivores and hummingbirds could not be developed. The land-cover models of abundance of canopy insectivores, understory insectivores and non-insectivores, and edge non-insectivores were generalizable to Monteverde whereas the land-cover models of abundance of open-country birds and species richness for any of the groups were not better than null models for Monteverde. The results indicate that land-cover models that describe the abundance or richness of various bird groups provide useful predictions in the area where the data were collected and that models of abundance of some canopy, understory and edge birds may perform well in areas that are similar in elevation, life zones and land use to the area from which data were collected. Land-cover models of the abundance of other groups, and of the richness of the majority of groups, may be less generalizable to other areas, or it may be difficult to develop models at all.     

Development of microsatellite markers for the neotropical tree species Dipteryx alata (Fabaceae)

? Premise of the study: Microsatellite markers were developed for the population genetic analyses of the neotropical tree Dipteryx alata (Fabaceae). ? Methods and Results: Microsatellites were developed from a genomic shotgun library. Polymorphism at each microsatellite loci was analyzed based on 94 individuals from three populations. Eight loci amplified successfully and presented one to 10 alleles, and expected heterozygosities ranged from 0.097 to 0.862. Four loci also amplified in Pterodon emarginatus and presented similar polymorphism. ? Conclusion: The eight microsatellite primer pairs are potentially suitable for population genetic studies and successfully amplified in another Fabaceae species.     

Relationships between plant communities and late snow melting on Mount Prado (Northern Apennines,Italy)

Relationships between the spatial and temporal distribution of long-lasting snow-cover and the spatial distribution of plant communities above timberline were studied on Mount Prado (2054 m), a representative sample area of the summit vegetation of the Northern Apennines (Italy). The spatial analysis was carried out by creating a geographic information system. Vegetation map and two snow-cover maps were both georeferenced to a scale 1 : 2000. The vegetation map is formed by 28 plant communities (including 7 combinations of communities, or vegetation mosaics) distributed into 277 map polygons. The maps were compared by an overlay procedure. The results show that the six plant communities (including three mosaics) which have a June snow-cover higher than 60% are diversified by a snow-melting gradient from early June to mid-July. The slowest snow melt corresponds to a snow-bed community (Salicetum herbaceae) and to a mesophytic grassland (Trifolium thalii-Festuca puccinellii community, Luzula alpino-pilosa variant).     

A model of biocomplexity and its application to the analysis of some terrestrial and marsh eukaryotic microbial communities with an emphasis on amoeboid protists

Biocomplexity theory has become increasingly important in understanding ecosystem dynamics as we realize that the interactions among subunits in a multi-component system often produce elaborate states that are not easily explained in terms of the individual parts of the system. A Euclidean geometric model of biocomplexity is presented and illustrated using protistan communities. The model is based on three quantitative biotic dimensions (indices) for small subsamples (0.01 g) taken from each sample core of substratum: (1) richness of morphospecies expressed as mean count per 0.01 g, (2) spatial diversity of protists expressed as then umber of unique morphospecies (i.e. those occurring in only one of the 0.01-g subsamples and not in any of the other subsamples), and (3) patchiness (non-uniform aggregation) of the distribution of protists across the 0.01-g subsamples. These three indices are mapped into a three-dimensional Euclidean space model, and the position of each point and its geometric distance from the origin are used as a general index of biocomplexity. The usefulness of the model is illustrated by applying it to a range of terrestrial and marsh communities. Within the set of 15 samples examined in this study, the marsh rhizosphere samples are among the most complex.     

Yeast communities of the cactusPilosocereus arrabidae as resources for larval and adult stages ofDrosophila serido

The feeding behavior ofDrosophila serido on the yeast communities of necrotic stem tissue ofPilosocereus arrabidae were studied in a sand dune ecosystem of Rio de Janeiro, Brazil. The prevalence of cactophilic yeasts includingPichia barkeri, Candida sonorensis andGeotrichum sp. in the crops and external surfaces ofD. serido reflected its association with the cactus habitat. The effective number of yeasts vectored on the surface of flies was higher than that in the crops. Also overlap between the yeasts from stems and from crops was partial suggesting selective feeding by the flies in the substrates visited. The females had a higher effective number of yeast species and a lower similarity than males with the yeast community ofP. arrabidae. This was probably related to the search for oviposition sites by females. The presence ofPichia thermotolerans-like andPichia amethionina varpachycereana in the flies, but not inP. arrabidae stems, indicated thatD. serido was not limited to this cactus species. The larvae and adults lived in different patches with the adults feeding in patches with higher yeast species richness. The larvae had a narrower feeding niche and higher overlap withP. arrabidae, and preferredP. barkeri andPichia cactophila as food. Adult flies fed on patches with the most frequent yeasts except forP. cactophila. Pichia caribaea was found in higher frequency in the adult crops than in the stems. Our data suggested that there was food selection and diet partitioning between adult and larval stages ofD. serido.     

湖南省4种森林群落土壤氮的矿化作用

2007年7月,用树脂芯原位测定土壤无机氮含量的方法,对湖南杉木、马尾松、樟树和枫香4种森林群落的土壤氮矿化进行了研究.研究结果表明,经过28d培养,4种森林群落土壤中NH+4-N含量分别下降了31.4%～50.5%,NO-3-N含量增加了8.2～17.3倍,氮矿化主要表现为硝化作用;氮矿化速率由大到小依次为樟树(0.05mg·kg-1·d-1)>马尾松(0.04 mg·kg-1·d-1)>枫香(-0.12 mg·kg-1·d-1)>杉木(-0.15 mg·kg-1·d-1).在4个森林群落的土壤中,NH+4-N是无机氮的主要存在形式,表现为在杉木群落中占78.42%、在马尾松中占79.17%、在樟树中占71.14%和枫香中占79.22%,而且NH+4-N的变化可以解释氮矿化量变化的96.1%～98.8%.土壤氮矿化速率与0～15 cm土壤的C/N、pH值呈显著性正相关,但与凋落物量和0～30 cm 土壤中细根生物量相关性不显著.     

间作密植和单行茶园节肢动物群落组成差异

1998年1－12月每月下旬,对皖南敬亭山茶场栗－茶间作,梨－茶间作,3行密植和单行条植茶园节肢动物群落的调查表明：植食性昆虫种数分别占各类型茶园总物种数51．9％,53．6％,54．4％和56．6％,个体数依次占各类茶园总个体数92．0％,93．5％,93．6％和95．0％,捕食性昆虫和捕食螨种数则分别占11．3％,10．0％,9．8％,10．9％,个体数占2．0％,1．1％,2．0％和1．5％,寄生性昆虫种数占9．2％,9．1％,9．3％,和9．3％,个体数占1．8％,1．1％,1．8％和1．3％。蜘蛛种数占24．7％,20．1％,22．4％和19．4％,个体数占3．5％,3．4％,2．1％和1．8％,4类茶园中的优势类群都是鳞翅目,同翅目,翅目,双翅目和蜘蛛目,月平均丰富度（S）和多样性指数H大小,栗－茶间作（S＝74,H＝1．33）,梨－茶间作（S＝49,H’＝1．24）,3行密植（S＝31,H’＝1．03）和单行条植茶园（S＝23,H’＝0．89）,主成分分析揭示了群落稳定性的大小：栗－茶间作＞梨－茶间作＞3行密植＞单行条植茶园。