Search results for " Size"
showing 10 items of 2281 documents
Sexing birds using discriminant function analysis: a critical appraisal.
2011
9 pages; International audience; Discriminant function analysis (DFA) based on morphological measurements is a quick, inexpensive, and efficient method for sex determination in field studies on cryptically monomorphic bird species. However, behind the apparent standardization and relative simplicity of DFA lie subtle differences and pitfalls that have been neglected in some studies. Most of these concerns directly affect assessment of the discriminant performance, a parameter of crucial importance in practice because it provides a measure of the quality of an equation that may be used in later field studies. Using results from 141 published studies and simulations based on a large data set …
An Algebraic Derivation of Chao’s Estimator of the Number of Species in a Community Highlights the Condition Allowing Chao to Deliver Centered Estima…
2014
Anne Chao proposed a very popular, nonparametric estimator of the species richness of a community, on the basis of a limited size sampling of this community. This expression was originally derived on a statistical basis as a lower-bound estimate of the number of missing species in the sample and provides accordingly a minimal threshold for the estimation of the total species richness of the community. Hereafter, we propose an alternative, algebraic derivation of Chao’s estimator, demonstrating thereby that Chao’s formulation may also provide centered estimates (and not only a lower bound threshold), provided that the sampled communities satisfy a specific type of SAD (species abundance dist…
Factors influencing infection patterns of trophically transmitted parasites among a fish community: host diet, host-parasite compatibility or both?
2011
20 pages; International audience; Parasite infection patterns were compared with the occurrence of their intermediate hosts in the diet of nine sympatric fish species in a New Zealand lake. Stomach contents and infection levels of three gastrointestinal helminth species were examined from the entire fish community. The results highlighted some links between fish host diet and the flow of trophically transmitted helminths. Stomach contents indicated that all but one fish species were exposed to these helminths through their diet. Host feeding behaviour best explained infection patterns of the trematode Coitocaecum parvum among the fish community. Infection levels of the nematode Hedruris spi…
An ecological multi-Level theory of competition for resources used to analyse density-dependence effects in fruit production
2014
International audience; Lescourret and Génard (2003) developed a multi-level theory of competition for resources applied to fruit production, considering that any collection of unit parts (cells or seeds in a fruit, fruits in an infructescence or in a tree...) can form a population and the population is subject to competition, whatever the level of organization. The principles of the theory are that the mass of each unit decreases when the number of units in the population increases and that the total mass of the population increases as the number of units increases until it reaches a maximum, after which it decreases. A three-parameter model based on that theory was used to analyse the lev…
Medium-size droplets of methyl ricinoleate are reduced by cell-surface activity in the gamma-decalactone production by Yarrowia lipolytica.
2000
International audience; Size of methyl ricinoleate droplets during biotransformation into gamma-decalactone by Yarrowia lipolytica was measured in both homogenized and non-homogenized media. In non-homogenized but shaken medium, droplets had an average volume surface diameter d32 of 2.5 microm whereas it was 0.7 microm in homogenized and shaken medium. But as soon as yeast cells were inoculated, both diameters became similar at about 0.7 microm and did not vary significantly until the end of the culture. The growth of Y. lipolytica in both media was very similar except for the lag phase which was lowered in homogenized medium conditions.
Evolutionary Changes after Translational Challenges Imposed by Horizontal Gene Transfer
2019
International audience; Genes acquired by horizontal gene transfer (HGT) may provide the recipient organism with potentially new functions, but proper expression level and integration of the transferred genes in the novel environment are not granted. Notably, transferred genes can differ from the receiving genome in codon usage preferences, leading to impaired translation and reduced functionality. Here, we characterize the genomic and proteomic changes undergone during experimental evolution of Escherichia coli after HGT of three synonymous versions, presenting very different codon usage preference, of an antibiotic resistance gene. The experimental evolution was conducted with and without…
The effects of different combinations of fixed and moving bed bioreactors on rainbow trout (Oncorhynchus mykiss) growth and health, water quality and…
2019
Abstract The effect of bioreactor design on nitrification efficiency has been well studied, but less is known about the overall impacts on water quality. Besides nitrification, submerged fixed bed bioreactors (FBBR) trap fine solid particles, whereas moving bed bioreactors (MBBR) grind solids, possibly increasing solids and particle accumulation in the system. In this experiment, the effects of different combinations of fixed bed and moving bed bioreactors on water quality, solids removal, particle size distribution, fish health based on histopathological changes and nitrification efficiency were studied in laboratory scale recirculating aquaculture systems (RAS) with rainbow trout (Oncorhy…
<p><strong>A new species of the genus <em>Glischrochilus</em> Reitter (Coleoptera: Nitidulidae: Cryptarchinae) from China<…
2016
The cosmopolitan genus Glischrochilus Reitter, 1873 (Nitidulidae: Cryptarchinae) is distributed in Holarctic and Oriental regions. According to the most recent catalogue (Jelinek & Audisio 2007), 32 species are known from the Palaearctic region. In China the genus is represented by 13 species, most of which were described by Jelinek (1975, 1982, 1999) and Lason (2009).
Density and reproductive characteristics of female brown bears in the Cantabrian Mountains, NW Spain
2018
Here we present annual nearest-neighbour distances (as a proxy of density) between females with cubs-of-the-year (hereafter FCOY) and reproductive characteristics of brown bears Ursus arctos in the Cantabrian Mountains (NW Spain), from 1989 to 2017. FCOY nearest-neighbour distances and reproduction parameters of 19 focal females followed over several consecutive years (from 2004 to 2017) were obtained from bears inhabiting the western sector of the Cantabrian Mountains, where most of the bear population resides. In contrast, general reproductive characteristics were studied in the whole Cantabrian Mountains (western and eastern sectors together) on a sample of 362 litter sizes and 695 cubs.…
Testing macroecological abundance patterns:the relationship between local abundance and range size, range position and climatic suitability among Eur…
2020
Aim A fundamental question in macroecology centres around understanding the relationship between species' local abundance and their distribution in geographical and climatic space (i.e. the multi-dimensional climatic space or climatic niche). Here, we tested three macroecological hypotheses that link local abundance to the following range properties: (a) the abundance-range size relationship, (b) the abundance-range centre relationship and (c) the abundance-suitability relationship. Location Europe. Taxon Vascular plants. Methods Distribution range maps were extracted from the Chorological Database Halle to derive information on the range and niche sizes of 517 European vascular plant speci…