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991.
Serological surveys were performed on Ethiopian camels with a history of abortion to investigate the presence of antibodies against viruses that infect animals classified in the order Artiodactyla. In 2013, 120 serum samples were collected from camels in various parts of Ethiopia. Several viruses related to abortion in ruminants were prevalent. In particular, antibodies against bluetongue virus, were detected at a high rate (76.7% of samples). Additionally, antibodies against Akabane virus and Japanese encephalitis virus were also detected in samples from more than 40% of the camels; however, their antibody titers were relatively low.  相似文献   
992.
Abstract. To determine the generality of avian diversity patterns, we investigated patterns of elevational zonation shown by birds and mammals along the eastern slope of the Andes Mountains in southeastern Peru. The strong environmental gradient sampled, entirely within Peru's Manu National Park and Biosphere Reserve, supports highly diverse faunas. Elevational distributions of 901 bird species, 129 bat species, and twenty-eight species of native mice exhibit contrasting patterns in species richness, species composition, and species turnover. Birds and bats showed smooth declines of species richness with elevation, whereas the richness of mouse assemblages was unrelated to elevation. For all three groups, the greatest differences were between lowland and highland faunas, although cutoff points for this contrast varied among groups (≈ 500 m for birds, 750 m for bats, and 1000 m for mice). Differences in composition also separated bird and bat faunas on either side of c. 1400 m (the boundary between montance forest and cloud forest); for mice, this faunal transition may take place nearer to 2000 m. Bird and bat faunas lacked the more discrete zonations suggested for mouse assemblages, as indicated by elevational range profiles and nested subset analyses. Distinct highland assemblages are apparent in two-dimensional histograms of range limits of birds and mice, but not for bats. Highland bat species occupy broader elevational ranges than lowland bat species, but for both birds and mice, species at intermediate elevations had the broadest amplitudes. Finally, clumping of range maxima and minima along the gradient identified zones of pronounced species turnover in each group, but these were generally not strongly associated with the locations of ecotones. Differences in zonation of these groups appear to reflect their different biological attributes and phylogenetic histories. Such differences obviously complicate discussions of ‘general’ diversity patterns, and limit the usefulness of birds to forecast or predict diversity patterns in other more poorly known groups—other groups may show elevated diversity and endemism in areas where avian diversity patterns appear unremarkable. The pronounced contrasts between bats and mice, and the generally intermediate character of avian patterns, suggest that future analyses might profitably partition birds into finer, more homogeneous groups of historically and/or ecologically similar species. Group differences in zonation may ultimately prove explicable with information on both species-abundance patterns and resource distributions.  相似文献   
993.
We describe the distribution and estimate densities of Grauer's gorillas (Gorilla gorilla graueri) and eastern chimpanzees (Pan troglodytes schweinfurthi) in a 12,770-km 2 area of lowland forest between the Lowa, Luka, Lugulu, and Oku rivers in eastern Democratic Republic of Congo, the site of the largest continuous population of Grauer's gorillas. The survey included a total of 480 km of transects completed within seven sampling zones in the Kahuzi-Biega National Park lowland sector and adjacent Kasese region and approximately 1100 km of footpath and forest reconnaissance. We estimate total populations of 7670 (4180–10,830) weaned gorillas within the Kahuzi-Biega lowland sector and 3350 (1420–5950) individuals in the Kasese survey areas. Within the same area, we estimate a population of 2600 (1620–4500) chimpanzees. Ape nest site densities are significantly higher within the Kahuzi-Biega lowland sector than in the more remote Kasese survey area in spite of a significantly higher encounter rate of human sign within the lowland sector of the park. Comparison of our data with information obtained by Emlen and Schaller during the first rangewide survey of Grauer's gorillas in 1959 suggests that gorilla populations have remained stable in protected areas but declined in adjacent forest. These findings underscore the key role played by national parks in protecting biological resources in spite of the recent political and economic turmoil in the region. We also show that forest reconnaissance is a reliable and cost-effective method to assess gorilla densities in remote forested areas.  相似文献   
994.
This study presents a detailed seasonal comparison of the abundance and distribution of cetaceans within 100-150 nmi (185-278 km) of the California coast during 1991 and 1992. The results of a shipboard line-transect survey conducted in July-November 1991 ("summer") were compared to those from aerial line-transect surveys conducted in March-April 1991 and February-April 1992 ("winter"). Using a confidence-interval-based bootstrap procedure, abundance estimates for six of the eleven species included in the comparison exhibited significant (α= 0.05) differences between the winter and summer surveys. Pacific white-sided dolphins ( Lagenorhynchus obliquidens ), Risso's dolphins ( Grampus griseus ), common dolphins ( Delphinus spp.), and northern right whale dolphins ( Lissodelphis borealis ) were significantly more abundant in winter. The abundance of blue whales ( Balaenoptera musculuss ) and gray whales ( Eschrichtius robustus ) reflected well-documented migratory patterns. Fin whales ( B. physalus ) were significantly more abundant during summer. No significant differences in seasonal abundance were identified for Dall's porpoises ( Phocoenoides dalli ), bottlenose dolphins ( Tursiops truncatus ), killer whales ( Orcinus orca ), sperm whales ( Physeter macrocephalus ), or humpback whales ( Megaptera novaeangliae ). Significant north/south shifts in distribution were found for Dall's porpoises, common dolphins, and Pacific white-sided dolphins, and significant inshore/offshore differences were identified for northern right whale dolphins and humpback whales.  相似文献   
995.
996.
Abstract. Progress in the European Vegetation Survey is described. 25 countries are now represented in a network committed to common data standards in phytosociological survey, the development of compatible software for data analysis and mapping, the encouragement of national programmes and the development of an overview of European plant communities. Advances in each of these areas of activity is summarised and plans for the future are outlined, most notably the production of a book ‘The Vegetation of Europe’.  相似文献   
997.
The stomatal types (i.e. the arrangement of epidermal cells in the vicinity of a stomatal pore in superficial view) have been examined in more than 150 taxa ofCactaceae, mostly using documented material. Preparations have been made by mazerating pieces of tissue with modified Jeffrey's Solution and staining with chlore-zinc-jodine.—The examined members of the subfamilyCactoideae showed parallelocytic stomata with only minor deviations in a number of cases. Members of the subfamiliesPereskioideae andOpuntioideae show parallelocytic stomata on the leaves, but the stomatas of the stem represent a different type, which apparently is not yet described. It is termed opuntioid here. In most cases the stomata are superficial but a few taxa show markedly sunken or hidden stomata.—In taxa of the subfamiliesPereskioideae andOpuntioideae the stomata are generally oriented parallel to the stem axis with only minor deviations. The stomata of taxa of the subfamilyCactoideae do in general not show a particular orientation with the notable exception of a number of epiphytic genera from the tribeHylocereeae.—The results of these investigations in general coincide well with the generic classification of theCactaceae byHunt (1967). A few cases where stomatal characters suggest a differing classification merit further investigations.—Additionally, the possibilities to distinguish between paracytic and parallelocytic stomata are discussed and an amended definition for the latter is given.  相似文献   
998.
Herpetological zoo research published in three journals between 1977 and 1981 was surveyed. Fifty-three of 1,084 published papers involved zoos. Research for 30 papers was conducted in zoos. Just under three fourths of zoo papers involved behavioral research. Sixteen zoos were involved in research in this survey.  相似文献   
999.
A survey for cyanogenesis in ferns and gymnosperms   总被引:1,自引:0,他引:1  
298 species of ferns and 48 species of gymnosperms were tested for cyanogenic activity. 5% of the fern species examined gave positive results, but these showed no correlation with taxonomic groupings. None of the gymnosperms surveyed gave a positive result. The limitations of a survey of this type for detecting cyanogenesis in plants is discussed.  相似文献   
1000.
Isolation between species, or taxa sharing a common lineage, depends primarily on the relative strengths of various reproductive barriers. Previous studies on reproductive isolation between orchids emphasized mechanical and ethological barriers in flowers of species showing food and/or sexual mimicry. In this study, we investigated and quantified a series of prepollination and postpollination barriers between pink and white forms of Spiranthes sinensis sl, a nectar‐secreting complex. We generated ML trees based on trnS‐G and matK to explore phylogenetic relationships in this species complex. Spiranthes sinensis sl segregated from some other congeners, but the white form constituted a distinct clade in relation to the pink form. The white form secreted 2‐Phenylethanol as it is a single‐scent compound and was pollinated almost exclusively by native, large‐bodied Apis cerana and Bombus species (Apidae). Apis cerana showed a high floral constancy to this form. The scentless, pink form was pollinated primarily by smaller bees in the genera Ceratina (Apidae), and members of the family Halictidae, with infrequent visits by A. cerana and Bombus species. Fruit set and the production of large embryos following interform pollination treatments were significantly lower compared to intraform pollination results for the white form. Our results suggested that pollinator isolation, based on color and scent cues, may result in greater floral constancy in white populations when both forms are sympatric as two different, guilds of pollinators forage selectively preventing or reducing prospective gene flow. Postpollination barriers appear weaker than prepollination barriers but they also play a role in interform isolation, especially in the white form. Our findings suggest that floral color forms in S. sinensis do not represent an unbalanced polymorphism. Interpretations of the evolutionary status of these forms are discussed.  相似文献   
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