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M.M.M. Okumura  S. Eggers 《HOMO》2005,55(3):263-281
Sambaquis are huge shellmounds built along almost the entire Brazilian coast between 8000 and 600 years ago. In the present article, 14 osteological markers from 89 individuals excavated at the Sambaqui Jabuticabeira II (2890±55/2186±60 BP) are analyzed in order to reconstruct the population′s health status and way of life. The present palaeopathological findings (such as lower frequency of degenerative joint diseases in legs, as compared to arms, and the rarity of traumas) together with archaeological findings support the idea of nearby resource abundance and infrequent interpersonal competition. The presence of auditory exostoses mainly in males corroborates previous findings indicating the importance of marine resources. The low caries frequency and the high degrees of dental wear point to a diet poor in cariogenic food, and rich in abrasives such as sand, shell fragments and phytoliths. This suggests a broader diet, based on marine protein as well as plants, than previously thought. The etiology of cribra orbitalia could be explained by gastrointestinal parasites or other sources of physiological stress. These parasites, in turn, could have led to higher frequencies of infectious diseases, either by the debilitation of the immune system or by the direct contact with infectious agents. Despite the periods of illness various individuals experienced, the daily life among the builders of the Sambaqui Jabuticabeira II seems to have been relatively easy due to the abundance and predictability of resources and the paucity of violent traumas.  相似文献   
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Although Brook Trout are distributed across most of eastern North America, population numbers have declined in many regions due to habitat loss, climate change, and competition with non‐native species. In New York State, Brook Trout habitat has been substantially reduced, with many areas showing complete extirpation of Brook Trout populations, predominantly in the western portion of the state. Small, fragmented populations are at risk of genetic diversity loss, inbreeding depression, and reduced fitness, leading to a greater potential for local extirpation. Genetic monitoring is a practical tool that can facilitate further conservation‐decision making regarding small populations. In this study, we used 12 microsatellite loci to examine 3,436 sampled Brook Trout, representing 75 sites from the Allegheny, Erie/Niagara, Genesee, Oswego, Lake Ontario, and Susquehanna drainage basins throughout western New York State. Three Brook Trout hatchery strains were also genetically characterized to evaluate the degree of hatchery introgression between wild populations and hatchery strains stocked in the region. Overall, estimates of genetic diversity varied widely: Allelic richness ranged from 2.23 to 7.485, and expected heterozygosity ranged from 0.402 to 0.766. As observed for Brook Trout in other regions, we found a high degree of genetic differentiation among populations, with all comparisons except one showing significant FST values. Hatchery introgression was found to be minimal, with estimates ranging from 1.96% to 3.10% of wild individuals exhibiting membership proportions to a hatchery strain cluster exceeding 10% (q ≥ 0.10). Results from this investigation can be used to prioritize management efforts for Brook Trout in western New York State and act as a baseline to monitor future population trends.  相似文献   
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ABSTRACT

Predation is potentially an in?uential source of early post-settlement mortality of benthic marine invertebrates, but previous studies demonstrate con?icting results. We investigated the effect of large predators on developing subtidal invertebrate communities in cobble-?lled collectors in the southwest Bay of Fundy, Canada. Two predation treatments (exclusion of predators ≥ 7 mm body width or full access for predators < 50 mm) were used to test the effect of large predators, and a partial-cage control tested for caging artefacts. Despite a reduction in the abundance and biomass of large predators, multivariate analyses indicated no effect of predator exclusion on the composition of the prey and micropredator communities. Results indicated that the largest differences were between the predator-access treatment and the other two treatments, which was potentially in?uenced by the caging material. There were signi?cant but weak positive correlations between the micropredator and the other two communities. Previous studies indicate that at low predation intensity, as seemed to be the case here, other factors may play a stronger role in controlling recruit abundance. Predation control probably varies spatially and temporally, and the in?uence of large predators was not likely the driving force for early post-settlement mortality in the invertebrate communities measured in this study.  相似文献   
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By means of functional, morphological, and biophysical methods the in vitro interaction of Echo virus, type 9, strain A. Barty with human polymorphonuclear leucocytes (PMNs) was investigated and analyzed by statistical methods. Control cells and virus-treated PMNs (15 min, 37 degrees C; PMN: virus (pfu)-ratio ranging from 1:1 to 1:50) were exposed to a chemotactic gradient (N-formylmethionyl-leucylphenylalanine = f-Met-Leu-Phe, 10(-8) M/mm) in a Zigmond chamber. Whereas the track velocity of the moving PMNs was not affected by the virus, the degree of orientation of virus-treated PMNs declined in a way dependent on the viral dose and on the time of PMN:virus interaction, resulting in a shift from chemotactic to chemokinetic response. This virus-induced order-disorder transition of chemotactic response can be described by a logarithmic law in analogy to the Weber-Fechner law. Parallel to the functional disturbances, virus-induced changes of cell shape, which could be confirmed by additional light and electron microscopy techniques, were also detected using statistical analysis of cytological data (median cell size, anisotropy of cell shape) by means of two-dimensional histograms. To investigate f-Met-Leu-Phe- or/and Echo 9 virus-induced PMN-cell membrane changes, the monomer-excimer technique with pyrenedecanoic acid as fluorescent probe was applied, which gives information about structural changes of the cell membrane. Addition of the chemotactic peptide (10(-8) M) to control PMNs resulted in a higher rate of excimer formation obviously due to the formation of new functional (receptor) units (= activated cell membrane). Echo 9 virus exhibited an opposite effect. Quantitative analysis of these results revealed that the f-Met-Leu-Phe-induced cell membrane changes were extinguished by the addition of 2 pfu Echo 9 virus. So far, we have additional indicators of a virus-induced order-disorder transition of chemotactic response of human PMNs on a molecular biological level.  相似文献   
526.
The distribution of the deposit-feeding, orbiniid polychaete, Scoloplos fragilis (Verrill, 1873), was examined in relation to differences in elevation along-shore and down-shore from August 1976 to April 1977. The sand flat at Cape Henlopen, Lewes, Delaware U.S.A., is characterized by swash bars extending perpendicular to the shore, which undergo annual vertical and lateral fluctuations and have marked differences in elevations. Six stations were monitored on a single swash bar. Three sites were sampled monthly at an area on the swash bar near the beach berm (high-tide zone) and at an area near the water's edge (low-tide zone). The sites were the swash bar ridge, its depositional slope and the adjacent trough.Distribution patterns of S. fragilis were not associated with elevational gradients or a particular tidal level. Highest numbers were found on the slopes, lowest numbers on the high-tide ridge, and second lowest numbers in the low-tide trough. On the high-tide ridge, the sediments were too unstable for habitation by S. fragilis. In the low-tide trough, predation and other biological interactions apparently keep numbers of S. fragilis low. Wave and wind activity may have concentrated S. fragilis at slope stations, where sediment deposition occurs.Mean body size of S. fragilis varied spatially and temporally. Within each tidal level, mean sizes increased significantly from ridge to trough. Body sizes were significantly larger in the high-tide zone than in the low-tide zone and varied significantly with time. Reproductive maturity appears to occur after two years and at least three age-classes are present.  相似文献   
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Restoration has the potential to increase habitat heterogeneity through the creation of unique habitat patches that, in turn, increase regional species richness or gamma diversity. While biological diversity and habitat heterogeneity are important factors to consider under a shifting climate, restoration actions and outcomes rarely examine these components. In this study, we examined the effects of riparian beaver dam analog (BDA) restoration on aquatic invertebrate diversity and habitat heterogeneity. Although the effects of BDAs on hydrology, geomorphology, and salmonid habitat have been explored, we are unaware of any studies assessing their effects on aquatic invertebrate diversity and the food web that supports them. We sampled aquatic invertebrates, basal carbon resources, dissolved nutrients, turbidity, and water temperature in pre- and post-BDA pond, side channel, and mainstem habitat over a three-year period. The BDAs functioned similarly to natural beaver dams and created slow-water environments that accumulated fine particulate organic material and increased pelagic phytoplankton production. Nonmetric multidimensional scaling, permutation multivariate analysis of variance, and Mantel's tests demonstrated that these changes led to the formation of a unique invertebrate community populated by lentic macroinvertebrates and zooplankton, which increased beta-diversity and gamma diversity. Further, BDAs in our study maintained high densities of invertebrates and buffered water temperatures in comparison to adjacent lotic habitats. These results support our hypothesis that BDAs can enhance invertebrate beta and gamma diversity through the creation and colonization of unique pond habitat and improve habitat and resource heterogeneity for native fishes under variable climate conditions.  相似文献   
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