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1.
Lynda D. Corkum 《Hydrobiologia》1992,239(2):101-114
This study was designed to test the biome dependency hypothesis, which predicts that similar assemblages of macroinvertebrates occur along rivers both within and among drainage basins if the basins occupy the same biome. Benthic macroinvertebrates were collected from three drainage basins within each of three biomes in Canada, the eastern deciduous forests (EDF) of southwestern Ontario, the grasslands of south-central Alberta, and the montane coniferous forests (MCF) of southeastern British Columbia. A total of 225 benthic samples (3 biomes × 3 rivers/biome × 5 sites/river × 5 samples/site) was collected in spring using a cylinder sampler.The significant interaction effect between biome and a site's location along a river indicated that spatial patterns of variation in total density and taxonomic composition were not spatially consistent among sites along rivers or among biomes. Total macroinvertebrate densities were equivalent between the EDF and grassland sites. However, total density was substantially lower at the MCF sites than at sites in the other two biomes. The greatest differences in taxonomic composition occurred among biomes, although significant differences also occurred for all other sources of variation examined. Macroinvertebrate composition was more strongly associated with local, site-specific factors (riparian vegetation and land use) than with longitudinal gradients. Distinct site-specific taxonomic assemblages were evident in EDF, but not in the other two biomes where land use was more homogeneous. 相似文献
2.
Remarkable genetic diversity detected at river buffalo prolactin receptor (PRLR) gene and association studies with milk fatty acid composition 下载免费PDF全文
G. Cosenza M. Iannaccone B. Auzino N. P. P. Macciotta A. Kovitvadhi I. Nicolae A. Pauciullo 《Animal genetics》2018,49(3):159-168
Prolactin is an anterior pituitary peptide hormone involved in many different endocrine activities and is essential for reproductive performance. This action is mediated by its receptor, the prolactin receptor, encoded by the PRLR gene. In this study, we sequenced and characterized the Mediterranean river buffalo PRLR gene (from exon 3 to 10), and we found remarkable genetic diversity. In particular, we found 24 intronic polymorphisms and 13 exonic SNPs, seven of which were non‐synonymous. Furthermore, the polymorphisms identified in the 3′‐UTR were investigated to establish their possible influence on microRNA binding sites. Considering all the amino acid changes and the observed allelic combinations, it is possible to deduce at least six different translations of the buffalo prolactin receptor and, consequently, the presence at the PRLR gene of at least six alleles. Furthermore, we identified a deletion of a CACTACC heptamer between nucleotides 1102 and 1103 of exon 10 (3′‐UTR), and we developed an allele‐specific PCR to identify the carriers of this genetic marker. Finally, the SNP g.11188A>G, detected in exon 10 and responsible for the amino acid replacement p.His328Arg, was genotyped in 308 Italian Mediterranean river buffaloes, and an association study with milk fat traits was carried out. The statistical analysis showed a tendency that approached significance for the AA genotype with higher contents of odd branched‐chain fatty acids. Thus, our results suggest that the PRLR gene is a good candidate for gene association studies with qualitative traits related to buffalo milk production. 相似文献
3.
本文用法瑞植物社会学学派的方法,并经主分量分析验证,对元谋干热河谷的植被进行了重点在群丛及其以下单位的系统分类研究。结果得到9个群丛以及各群丛之下的6个亚群丛、3个群丛变型和两个群丛相的一套系统单位。 相似文献
4.
The Importance of Hydrodynamics for Protected and Endangered Biodiversity of Lowland Rivers 总被引:3,自引:3,他引:0
R. J. W. de Nooij W. C. E. P. Verberk H. J. R. Lenders R. S. E. W. Leuven P. H. Nienhuis 《Hydrobiologia》2006,565(1):153-162
This paper examines the relationship between protected and endangered riverine species (target species) and hydrodynamics
in river-floodplain ecosystems, combining ecological and policy-legal aspects of biodiversity conservation in river management.
The importance of different hydrodynamic conditions along a lateral gradient was quantified for various taxonomic groups.
Our results show that (i) target species require ecotopes along the entire hydrodynamic gradient; (ii) different parts of
the hydrodynamic gradient are important to different species, belonging to different taxonomic groups; (iii) in particular
low-dynamic parts are important for many species and (iv) species differ in their specificity for hydrodynamic conditions.
Many species of higher plants, fish and butterflies have a narrow range for hydrodynamics and many species of birds and mammals
use ecotopes along the entire gradient. Even when focussing only on target species, the entire natural hydrodynamic gradient
is important. This means that the riverine species assemblage as a whole can benefit from measures focussing on target species
only. River reconstruction and management should aim at re-establishing the entire hydrodynamic gradient, increasing the spatial
heterogeneity of hydrodynamic conditions. 相似文献
5.
J. K. Bush 《Plant Ecology》2006,183(2):215-225
This study evaluated the relationships among soil moisture, soil salinity, and soil oxygen on the growth of Helianthus paradoxus (Asteraceae), a threatened inland salt marsh species of western North America. The study was conducted in large growth boxes
(1×2×0.3 m) tilted at an angle to achieve a saturated to dry water gradient similar to that found in the marsh. This experimental
design allowed the evaluation of major abiotic factors (soil moisture and soil salinity) which have been shown to be potentially
important for this species, while removing major biotic factors, such as competition from other community dominants. Maximum
aboveground biomass occurred in the middle rows of the boxes, where surface soil water was reduced and subsurface soil water
was intermediate in the gradient. Regression analyses indicated that H. paradoxus would grow best where surface soil water is approximately 5%, subsurface soil water ranges from 20 to 30%, and where surface
soil salinity is less than 0.5 g kg−1. Edaphic variables, particularly soil moisture and soil salinity, affect the growth of H. paradoxus. Data presented here suggest that the survival of this species depends on maintenance of the hydrologic regime. 相似文献
6.
7.
Aquatic environmental impact associated with stream-crossing by a pipeline was monitored at Archibald Creek, B.C. for two years. Water chemistry and benthic macroinvertebrates were used as monitoring tools. Results indicated that impacts arising from stream-crossing were short-term and non-residual.Funded by a contract from Canadian Arctic Gas Study Limited, calgary, to Aquatic Environments Limited, Calgary.Aquatic Environments Limited, Calgary.Aquatic Environments Limited, Calgary. 相似文献
8.
Tim Rixen Antje Baum Thomas Pohlmann Wolfgang Balzer Joko Samiaji Christine Jose 《Biogeochemistry》2008,90(2):129-140
The Siak is a black water river in central Sumatra, Indonesia, which owes its brown color to dissolved organic matter (DOM)
leached from surrounding, heavily disturbed peat soils. The dissolved organic carbon (DOC) concentrations measured during
five expeditions in the Siak between 2004 and 2006 are among the highest reported world wide. The DOM decomposition appeared
to be a main factor influencing the oxygen concentration in the Siak which showed values down to 12 μmol l−1. Results derived from a box-diffusion model indicated that in addition to the DOC concentration and the associated DOM decomposition
the water-depth also plays a crucial role in regulating the oxygen levels in the river because of its impact on the turbulence
in the aquatic boundary layer and the surface/volume ratio of water in the river. Model results imply furthermore that a reduced
water-depth could counteract an increased oxygen consumption caused by an enhanced DOM leaching during the transition from
dry to wet periods. This buffer mechanism seems to be close to its limits as indicated by sensitivity studies which showed
in line with measured data that an increase of the DOC concentrations by ~15% could already lead to anoxic conditions in the
Siak. This emphasizes the sensitivity of the Siak against further peat soil degradation, which is assumed to increase DOC
concentrations in the rivers. 相似文献
9.
Francesca Gherardi Sandro Bertolino Marco Bodon Sandra Casellato Simone Cianfanelli Marco Ferraguti Elisabetta Lori Graziella Mura Annamaria Nocita Nicoletta Riccardi Giampaolo Rossetti Emilia Rota Riccardo Scalera Sergio Zerunian Elena Tricarico 《Biological invasions》2008,10(4):435-454
The paper provides a list of the non-indigenous animal species occurring today in Italian inland waters. Xenodiversity was
found to amount to 112 species (64 invertebrates and 48 vertebrates), which contribute for about 2% to the inland-water fauna
in Italy. Northern and central regions are most affected, and Asia, North America, and the rest of Europe are the main donor
continents. The large majority of non-indigenous species entered Italy as a direct or indirect effect of human intervention.
A difference between invertebrates and vertebrates was found for their mode of arrival (unintentional for invertebrates and
intentional for vertebrates). Accidental transport, in association with both fish (for aquaculture or stock enhancement) and
crops, has been the main vector of invertebrate introductions, whereas vertebrates were mostly released for stocking purposes.
Overall stock enhancement (47.92%) and culture (37.5%) prevailed over the other pathways. Seventeen and 7 species of our list
are included among the 100 worst invasive species of Europe (DAISIE) and of the world (IUCN), respectively. For some (but
not all) non-indigenous species recorded in Italy the multilevel impact exerted on the recipient communities and ecosystems
is known, even if rarely quantified, but knowledge on their chronic impact is still missing. Additional research is needed
to provide criteria for prioritizing intervention against well established invaders and identify which new potential invader
should be targeted as “unwanted”. 相似文献
10.
Comparative phylogeography of two co‐distributed but ecologically distinct rainbowfishes of far‐northern Australia 下载免费PDF全文
Andrew T. Mather Jeffrey O. Hanson Lisa C. Pope Cynthia Riginos 《Journal of Biogeography》2018,45(1):127-141