Search results for "NIST"
showing 10 items of 13738 documents
Spontaneous hybridizations between oilseed rape and wild radish
1998
The occurence of spontaneous hybridization between Brassica napus (oilseed rape) and Raphanus raphanistrum (wild radish) was investigated under different density conditions in cages and open-field experiments. Hybrids with wild radish as the seed parent were identified by screening for herbicide resistance belonging to rape. Small seed size and intermediate morphology were used to screen for hybrids with rape as the seed parent. Leaf isozyme patterns and flow cytometry provided confirmation of hybrids. Wild radish in an oilseed rape field produced as many as three interspecific hybrids per 100 plants. This is the first report of such a spontaneous event. The frequency of hybrids is expected…
Drosophila Evolution over Space and Time (DEST) : A New Population Genomics Resource
2021
Drosophila melanogaster is a leading model in population genetics and genomics, and a growing number of whole-genome datasets from natural populations of this species have been published over the last years. A major challenge is the integration of disparate datasets, often generated using different sequencing technologies and bioinformatic pipelines, which hampers our ability to address questions about the evolution of this species. Here we address these issues by developing a bioinformatics pipeline that maps pooled sequencing (Pool-Seq) reads from D. melanogaster to a hologenome consisting of fly and symbiont genomes and estimates allele frequencies using either a heuristic (PoolSNP) or a…
Pulsed-resource dynamics increase the asymmetry of antagonistic coevolution between a predatory protist and a prey bacterium
2011
Temporal resource fluctuations could affect the strength of antagonistic coevolution through population dynamics and costs of adaptation. We studied this by coevolving the prey bacterium Serratia marcescens with the predatory protozoa Tetrahymena thermophila in constant and pulsed-resource environments for approximately 1300 prey generations. Consistent with arms race theory, the prey evolved to be more defended, whereas the predator evolved to be more efficient in consuming the bacteria. Coevolutionary adaptations were costly in terms of reduced prey growth in resource-limited conditions and less efficient predator growth on nonliving resource medium. However, no differences in mean coevol…
Climate Change: Negationism, Skepticism, and Misinformation
2021
Resumen: El objetivo de este artículo es examinar los principales lineamientos antagonistas sobre el cambio climático. Para ello, se ofrece una aproximación teórica a las narrativas y repertorios sustantivos que sostienen los fundamentos de la negación y se diferencia conceptualmente entre negacionistas, climatoescépticos y contrarios climáticos. Estos repertorios son la negación de las evidencias científicas, la negación económica y la negación política. Finalmente, se hace referencia a la difusión de información errónea y tóxica como estrategia organizada y deliberada. Como principal conclusión se abordan los emergentes programas de alfabetización climática para neutralizar la desinformac…
The role of male coloration in the outcome of staged contests in the European common wall lizard (Podarcis muralis)
2016
Colour signals play a key role in regulating the intensity and outcome of animal contests. Males of the common wall lizard (Podarcis muralis) show conspicuous ventrolateral ultraviolet (UV)-blue and black patches. In addition, some populations express a striking ventral colour polymorphism (i.e., discrete orange, white and yellow morphs). In this study, we set out to evaluate the potential signalling function of these colour patches by staging pairwise combats between 60 size-matched adult lizards (20 per morph). Combats were held in a neutral arena, with each lizard facing rivals from the three morphs in a tournament with a balanced design. We then calculated a fighting ability ranking usi…
Costs and Benefits of Experimentally Induced Changes in the Allocation of Growth versus Immune Function under Differential Exposure to Ectoparasites
2010
Background Ecological immunology has focused on the costs of investment in immunocompetence. However, understanding optimal resource allocation to immune defence requires also identification of its benefits, which are likely to occur only when parasites are abundant. Methodology We manipulated the abundance of parasitic hen fleas in blue tit (Cyanistes caeruleus) nests, and supplemented their hosts, the nestlings, with methionine (a sulphur amino acid enhancing cell-mediated immunity) during day 3–6. We found a significant interaction between these two experimental factors on the development of immune defences and growth rates. Only in parasitized nests did methionine supplementation boost …
Experimental size-selective harvesting affects behavioral types of a social fish
2019
In most fisheries, larger fish experience substantially higher mortality than smaller fish. Body length, life history, and behavioral traits are often correlated, such that fisheries-induced changes in size or life history can also alter behavioral traits. However, empirical evidence regarding how size-selective harvesting alters the evolution of behavioral traits in exploited stocks is scarce. We used experimental lines of Zebrafish Danio rerio that were exposed to positively size-selective, negatively size-selective, or random harvest over five generations. Our aim was to investigate whether simulated fishing changed the mean personality of the surviving females five generations after ini…
From habitat use to social behavior: natural history of a voiceless poison frog, Dendrobates tinctorius
2019
AbstractDescriptive studies of natural history have always been a source of knowledge on which experimental work and scientific progress rely. Poison frogs are a well-studied group of small Neotropical frogs with diverse parental behaviors, distinct calls, and bright colors that warn predators about their toxicity; and a showcase of advances in fundamental biology through natural history observations. The dyeing poison frog, Dendrobates tinctorius, is emblematic of the Guianas region, widespread in the pet-trade, and increasingly popular in research. This species shows several unusual behaviors, such as the lack of advertisement calls and the aggregation around tree-fall gaps, which remain …
Social learning within and across predator species reduces attacks on novel aposematic prey
2020
Abstract To make adaptive foraging decisions, predators need to gather information about the profitability of prey. As well as learning from prey encounters, recent studies show that predators can learn about prey defences by observing the negative foraging experiences of conspecifics. However, predator communities are complex. While observing heterospecifics may increase learning opportunities, we know little about how social information use varies across predator species.Social transmission of avoidance among predators also has potential consequences for defended prey. Conspicuous aposematic prey are assumed to be an easy target for naïve predators, but this cost may be reduced if multipl…
Decoupled nonlinear adaptive control of position and stiffness for pneumatic soft robots
2020
This article addresses the problem of simultaneous and robust closed-loop control of joint stiffness and position, for a class of antagonistically actuated pneumatic soft robots with rigid links and compliant joints. By introducing a first-order dynamic equation for the stiffness variable and using the additional control degree of freedom, embedded in the null space of the pneumatic actuator matrix, an innovative control approach is introduced comprising an adaptive compensator and a dynamic decoupler. The proposed solution builds upon existing adaptive control theory and provides a technique for closing the loop on joint stiffness in pneumatic variable stiffness actuators. Under a very mi…