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Neopomacentrus filamentosus, a common damselfish on the Indo–Australian archipelago, undergoes significant shifts in size and mitochondrial genetic structure upon larval settlement and metamorphosis to juvenile stages. We characterized five polymorphic microsatellite loci in order to study temporal genetic shifts within a single generation of N. filamentosus sampled first as larval settlers then again as demersal juvenile recruits. All loci were extremely polymorphic and exhibited high levels of heterozygosity. While all loci from the larval samples conformed to Hardy – Weinberg expectations, significant heterozygote deficiencies were seen in two loci in the juvenile samples, likely due to extreme size‐selective mortality imposed post‐settlement. 相似文献
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R F Sturrock 《International journal for parasitology》1973,3(2):165-174
Growth curves, calculated for field populations of B. glabrata, were not materially affected by habitat, altitude or season. A mean growth curve was therefore used to estimate the age-frequency distribution of snails in successive field samples. These data permitted the construction of ecological life tables and the estimation of r, the intrinsic rate of natural increase (or decrease) of the different populations. The calculated values of r were inserted in a simple model of unlimited population growth but the resultant curves poorly represented the observed data. A model for unlimited growth was more satisfactory for pond and marsh populations but, apparently, immigration made it less satisfactory for stream and banana drain populations. Nevertheless, r may still be of value in predicting repopulation rates in certain habitats after a mollusciciding which does not kill the entire snail population. 相似文献
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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
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《Saudi Journal of Biological Sciences》2020,27(6):1573-1579
Supplementation of the growing substrate by nitrogenous additives has been known to improve the production of oyster mushroom (Pleurotus ostreatus (Jacq. ex Fr.) P. Kumm. (1871)). However, the application of nano-additives has not been reported in such cultivation yet. The study investigated the effect of nano-urea added in two different doses (3 g and 5 g per kg substrate), once (at spawning or after first flush) or twice (at spawning and after first flush) to the growing substrate consisting of wheat straw and spent oyster substrate (1:1, w/w). Results showed that the application of nano-urea once has induced the highest number of mushroom flushes (four flushes) despite the dose applied. Contrarily to early findings, where high doses of nitrogen have caused inhibition of mushroom growth and production, nano-urea application has had better effects when applied twice. With 5 g/kg, it induced the shortest period between the first and the third flush (15 days). With 3 g/kg, it resulted in the highest biological and economic yields at the third flush (332.7 g/bag and 283.1 g/bag respectively), in total (973.4 g/bag and 854.0 g/bag respectively), the highest biological efficiency (109.6%), and pileus diameter/stipe length ratio (2.8). Experimental findings of the current study may be potentially applied at commercial scale. 相似文献
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Detailed palynological studies in two adjoining French Pyrenean valleys, complemented by the study of archives, demonstrate that under similar climatic conditions, the forest history of each valley from the Bronze Age to present time was essentially determined by socio-economical constraints, possibly modified by natural characteristics such as topography. The studies show why the expansion of Fagus (beech) at c. 4000 B.P. was asynchronous on the northern slope of the Pyrenees and emphasize the effects of the human impact on the recent lowering of the tree-line.A contribution to the 8th IPC, Aix-en-Provence, 1992 相似文献
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