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1.
ALI M GOLMIRZAIE JORGE TENORIO FELIX SERQUÉN RODOMIRO ORTIZ 《The Annals of applied biology》2003,143(2):231-234
Potato cybrids result from the fusion between cytoplasm and nuclear gene donors. Such genetic materials are an alternative means to broaden the breeding pool by non‐sexual gene transfer. Tetrad pollen sterility provides also another source of male sterility with some potential for true potato seed breeding. The objective of this research was to investigate cybrid‐derived offspring for both agronomic and reproductive characteristics in two contrasting Peruvian locations, and to examine new exotic germplasm for tetrad sterility, with the aim of broadening the breeding pool available at the Centro Internacional de la Papa (CIP). The cybrids were derived from fusions between Y‐245.7, a clone with tetrad sterility, and Atzimba. These cybrids were crossed with selected male parents from the CIP breeding population, and their hybrid offspring were tested in La Molina (coastal desert) and Huancayo (cool highlands). In addition, other clones with tetrad sterility were also crossed with selected testers to determine their breeding value. There were significant differences for tuber yield, style length, and berry number among the hybrid offspring, and the genotype by environment interaction was significant for tuber yield and berry number. The top 25% highest yielding cybrid‐derived offspring across both locations showed the same tuber yield although they were significantly different for some of the reproductive characteristics. With the exception of one cybrid, the others did not exhibit segregation for tetrad sterility in their hybrid offspring, which were male fertile. However, the offspring derived from crosses between other sources of tetrad sterility and the same testers all showed tetrad sterility, and some of them had outstanding tuber yield at La Molina. The lack of segregation for tetrad sterility in these new crosses suggests that the non‐cybrid, male sterile, female parents are triplex or quadriplex for the Tr nuclear locus, which interacts with a sensitive cytoplasm (e.g. Trs from S. verrucosum or S. stoloniferum) to produce tetrad sterility in potato. 相似文献
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Raw count data are often used to estimate bird population densities. However, such data do not consider detection probability. As an alternative, methods that model detection probability such as distance-sampling have been proposed. However, standard distance-sampling provides reliable estimates for absolute density only when the underlying assumptions are met. One of the most critical of these assumptions is that animals on a transect line or at an observation point have to be detected with certainty (the g (0) = 1 assumption). We radiotagged nine Orphean Warblers Sylvia hortensis and estimated their short-distance detection probability. Birds were radio-located in 264 cases in single bushes or trees. Their visual detection probability after a 5-min search was only 0.58 (sd = ±0.14, range = 0.38–0.80), although the observer knew the bird's location. Furthermore, we carried out a literature review to assess how the g (0) = 1 assumption is handled in practice. None of the 28 standard distance-sampling papers reviewed contained an estimation of g (0). In 57% of the papers, the g (0) = 1 assumption was not even mentioned. Nevertheless, none of the authors declared their estimates as being relative. Our empirical data show that the g (0) = 1 assumption would be severely violated for a foliage-gleaning bird species at a desert stopover site outside the breeding season. The literature review revealed that the testing of the g (0) = 1 assumption is largely ignored in practice. We strongly suggest that more attention should be paid to the testing of this key assumption, because results may not be reliable when it is violated. If it is not possible to test the g (0) = 1 assumption or g (0) is less than 1, alternative methods should be used. Another possibility is to estimate detection probability by the means of radiotagged individuals. 相似文献
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BÉNÉDICTE N. PONCET DORIS HERRMANN FELIX GUGERLI PIERRE TABERLET ROLF HOLDEREGGER LUDOVIC GIELLY DELPHINE RIOUX WILFRIED THUILLER SERGE AUBERT STÉPHANIE MANEL 《Molecular ecology》2010,19(14):2896-2907
Understanding the genetic basis of adaptation in response to environmental variation is fundamental as adaptation plays a key role in the extension of ecological niches to marginal habitats and in ecological speciation. Based on the assumption that some genomic markers are correlated to environmental variables, we aimed to detect loci of ecological relevance in the alpine plant Arabis alpina L. sampled in two regions, the French (99 locations) and the Swiss (109 locations) Alps. We used an unusually large genome scan [825 amplified fragment length polymorphism loci (AFLPs)] and four environmental variables related to temperature, precipitation and topography. We detected linkage disequilibrium among only 3.5% of the considered AFLP loci. A population structure analysis identified no admixture in the study regions, and the French and Swiss Alps were differentiated and therefore could be considered as two independent regions. We applied generalized estimating equations (GEE) to detect ecologically relevant loci separately in the French and Swiss Alps. We identified 78 loci of ecological relevance (9%), which were mainly related to mean annual minimum temperature. Only four of these loci were common across the French and Swiss Alps. Finally, we discuss that the genomic characterization of these ecologically relevant loci, as identified in this study, opens up new perspectives for studying functional ecology in A. alpina, its relatives and other alpine plant species. 相似文献
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Despite frequent reliance on surveys to document public attitudes towards conservation issues (such as invasive‐species control), only rarely do researchers assess the validity of statements made by the public in response to such surveys. Therefore, how well responses match actual behaviour remains an open question. We conducted a survey asking drivers if they had seen and/or run over (intentionally or not) snakes, native frogs or invasive cane toads (Rhinella marina) on roads in the Northern Territory of Australia. To compare actual driver behaviour to the survey responses, we also carried out field experiments where we quantified the rates at which model snakes, frogs and toads (and controls) were run over on a rural highway. Our results show a discrepancy between survey responses and driver behaviour: for example, 25% of the people we surveyed indicated that they intentionally run over cane toads, yet field experiments showed that model toads were run over no more frequently than expected by chance, or than any other type of model. 相似文献