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Performance Ranking (performance + ranking)

Distribution by Scientific Domains

Earth and Environmental Science	50%

Selected Abstracts

DIFFERENTIAL PERFORMANCE AMONG LDH-B GENOTYPES IN RANA LESSONAE TADPOLES

EVOLUTION, Issue 5 2000
Hansjürg Hotz
Abstract The European pool frog, Rana lessonae, is widely polymorphic for two common alleles (b, e) at the lactate dehydrogenase-B (LDH-B) locus. We compared fitness-related larval life-history traits among LDH-B genotypes, which originated from segregation in heterozygous parents, in an artificial pond experiment where tadpoles of R. lessonae from a Swiss population were raised together with tadpoles of the hemiclonal hybrid R. esculenta at two densities. In R. lessonae, LDH-B e/e homozygotes at each density had a higher proportion of metamorphs among survivors, reached metamorphosis earlier, and were heavier at metamorphosis than b/b homozygotes; b/e heterozygotes had intermediate values. That e/e individuals were superior to b/b in both time to and mass at metamorphosis is surprising because these two life-history traits are thought to reflect a performance trade-off; e/e genotypes apparently compensated for shorter time to metamorphosis by a higher growth rate. The two alleles showed the same performance ranking when combined in hybrids with a R. ridibunda allele: When R. esculenta from Swiss populations reared in the same ponds had received the e allele rather than the b allele from their R. lessonae parent, they reached metamorphosis earlier, but did not differ in mass at metamorphosis. The degree of linkage disequilibrium in the source population of the eight R. lessonae used as parents of the R. lessonae tadpoles is unknown, so we cannot exclude the possibility that the performance differences are caused by some anonymous tightly linked gene, rather than the LDH-B locus, that constitutes the genomically localized target of natural selection. A causal involvement of LDH-B is plausible, nevertheless, because this enzyme takes part in the central energy-metabolizing processes and has been reported to underlie fitness differences in other animals; also, differential performance of LDH-B genotypes has been observed in R. lessonae larvae from another population. The present results suggest strong directional selection for allele e; the sum of available data, including an independent laboratory experiment, suggests that partial environment-dependent overdominance combined with balancing selection favoring e/e homozygotes under some and b/b homozygotes under other conditions may be partially responsible for the broad maintenance of the LDH-B polymorphism in R. lessonae. [source]

Applying benchmarking and data envelopment analysis (DEA) techniques to irrigation districts in Spain

IRRIGATION AND DRAINAGE, Issue 2 2004
J. A. Rodríguez Díaz
indicateurs de performance; benchmarking; DEA Abstract In this research, the application of data envelopment analysis (DEA) is proposed as a methodology to overcome the problems related to the lack of methodology to assign the correct weightings for the calculation of indexes and to the subjectivity of the interpretations of results. DEA is a linear programming technique to determine the relative efficiencies of a company when the inputs and outputs of production units within the company are known, but the productive process itself is not. In this way, quantitative efficiencies and the weighting of any performance indicator can be assessed and compared, permitting managers to obtain a well-defined performance ranking. This is especially important when managers dispose of a limited budget. The results of the application of this methodology to Andalusian irrigation districts (Spain) are presented and discussed here. This study was used to select the most representative irrigation districts in Andalusia which were then studied in greater depth by applying the performance indicators selected by IPTRID for use by the benchmarking international program. Copyright © 2004 John Wiley & Sons, Ltd. Dans ce travail, l'utilisation de la méthode de ,,data envelopment analysis (DEA),, est analysée en tant que méthodologie capable de résoudre les problèmes liés au manque de méthodologie pour l'attribution des pondérations dans le calcul d'indices composites et à la subjectivité des comparaisons. La DEA est une technique de programmation linéaire pour déterminer les efficiences relatives d'une compagnie. Les moyens utilisés sont la connaissance des intrants et produits de la compagnie, ignorant les processus de production. De cette façon, les gestionnaires peuvent obtenir un large ensemble d'indices de gestion qui se révèle particulièrement important lorsque le gestionnaire dispose d'un budget limité. Les résultats de l'utilisation de cette méthode pour l'irrigation dans la région d'Andalousie (Espagne) sont présentés et discutés dans ce travail. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Preference,performance relationship and influence of plant relatedness on host use by Pityogenes chalcographus L.

AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 4 2009
Coralie Bertheau
Abstract 1Pityogenes chalcographus L. (Coleoptera: Scolytinae) causes damage in European coniferous forests, primarily on Picea abies L. Karst., but is also recorded on other native and exotic Pinaceae species. Estimating the adequacy between adult preference and larval performance of this beetle among its host-range, as well as the influence of plant taxonomic relatedness on these parameters, would provide useful information on the beetle's ability to shift onto novel hosts. 2Choice and no-choice assays were conducted under laboratory conditions. Adult preference and larval performance parameters among two native (Pinus sylvestris L. and Picea abies) and three exotic north American [Pinus contorta Dougl., Picea sitchensis (Bong.) Carr. and Pseudotsuga menziesii Mirbel (Franco)] conifer species were measured. 3Pityogenes chalcographus exhibited a significant positive relationship between preference and performance. Picea abies was both the preferred and the most suitable host species for larval development. The closest relative, P. sitchensis, was the second best choice in terms of preference and performance. Pseudotsuga menziesii occupied an intermediate position for both beetle preference and performance, and Pinus spp. were the least suitable hosts for beetle development. 4Adult preference and larval performance ranking among hosts provides little support to the plant taxonomic relatedness hypothesis. Taxonomic relatedness could play a role on the diet breadth, although only at a limited scale, within the genus Picea. At higher taxonomic levels, other factors such as bark thickness might be decisive. [source]

Potential of meat meal to replace fish meal in extruded dry diets for barramundi, Lates calcarifer (Bloch).

AQUACULTURE RESEARCH, Issue 1 2003

Abstract Juvenile barramundi (,220,280 g start weight) were fed extruded dry-pelleted diets containing varying amounts of fish meal and meat meal in three experiments (E). E1 and E2 were each 66-day farm studies utilizing 16 floating cages (400 fish per cage) in an aerated freshwater pond. E3 examined the same diets as fed in E2 but under controlled water temperature (28 ± 0.7 °C) and photoperiod (12:12) laboratory conditions in a 42-day study involving 24 aquaria (eight fish per aquarium). In all studies, the same 430 g kg,1 crude protein (CP), 15 kJ g,1 digestible energy (DE) control (Ctl) diet (containing 35% Chilean anchovy fish meal) was compared with two high-inclusion meat meal diets and a proprietary diet. The meat meal diets evaluated in E1 were a high-ash (260 g kg,1) meat meal that contained 520 g kg,1 CP and a low-ash (140 g kg,1) meat meal that contained 600 g kg,1 CP when included at either 450 or 400 g kg,1, respectively, in combination with 100 g kg,1 Chilean fish meal in diets that were isonitrogenous and isoenergetic with the Ctl diet. Growth rates and feed conversions were similar (P > 0.05) for all diets. In E2 and E3, the 520 g kg,1 CP meat meal was included at 500 g kg,1 without any marine protein source in diets formulated to provide either 15 or 16.2 kJ g,1 DE and the same CP/DE ratio (29 mg kJ,1) as the Ctl diet. Fish performance ranking of diets was similar in both experiments, with the 16.2 kJ g,1 DE diet supporting better (P < 0.05) growth rates than the Ctl diet and feed conversion ratios equivalent to the Ctl diet but better (P < 0.05) than all other diets. [source]