Search results for "reference"
showing 10 items of 2491 documents
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…
Macrophytes in boreal streams: Characterizing and predicting native occurrence and abundance to assess human impact
2016
Abstract Macrophytes are a structurally and functionally essential element of stream ecosystems and therefore indispensable in assessment, protection and restoration of streams. Modelling based on continuous environmental gradients offers a potential approach to predict natural variability of communities and thereby improve detection of anthropogenic community change. Using data from minimally disturbed streams, we described natural macrophyte assemblages in pool and riffle habitats separately and in combination, and explored their variation across large scale environmental gradients. Specifically, we developed RIVPACS-type models to predict the presence and abundance of macrophyte taxa at …
An annotated checklist of the leech (Annelida: Hirudinida) species of the Moulouya River basin, Morocco, with several new distribution records and a …
2019
A historical overview of the leech fauna of Morocco, based on both literature data, museum collections and new material, sampled in more than 100 sites in the Moulouya River basin (eastern region of Morocco), is provided. Twenty species from five families and ten genera are currently known, of which Helobdella europea Kutschera, 1987, is a new record for the country and North Africa as a whole. Herein, we add many new distribution records. The current list will need to be revised as new species distributions are recorded in the region. Notes on the species distribution are given along with comments on their habitat preferences. A concise biogeographic analysis outlines the similarities in t…
Honeybees prefer novel insect-pollinated flower shapes over bird-pollinated flower shapes
2019
AbstractPlant–pollinator interactions have a fundamental influence on flower evolution. Flower color signals are frequently tuned to the visual capabilities of important pollinators such as either bees or birds, but far less is known about whether flower shape influences the choices of pollinators. We tested European honeybee Apis mellifera preferences using novel achromatic (gray-scale) images of 12 insect-pollinated and 12 bird-pollinated native Australian flowers in Germany; thus, avoiding influences of color, odor, or prior experience. Independent bees were tested with a number of parameterized images specifically designed to assess preferences for size, shape, brightness, or the number…
Size-assortative pairing in Gammarus pulex (Crustacea: Amphipoda): a test of the prudent choice hypothesis.
2010
6 pages; International audience; Positive assortative mating is a widespread phenomenon in the animal kingdom. Several hypotheses have been proposed to explain this reproductive pattern in natural populations, but growing evidence suggests that assortative mating most often results from sexual mating preferences. Recently, conditiondependent mate choice in the face of costly competition for mates has been proposed to explain assortative mating in natural populations. Variation in competitive ability may generate variation in both the strength and the direction of mate preference, resulting in assortative mating with respect to individual quality if low-quality competitors are less choosy, o…
European catfish (Silurus glanis) as a freshwater apex predator drives ecosystem via its diet adaptability
2017
AbstractApex predators play a key role in ecosystem stability across environments but their numbers in general are decreasing. By contrast, European catfish (Silurus glanis), the European freshwater apex predator, is on the increase. However, studies concerning apex predators in freshwaters are scarce in comparison to those in terrestrial and marine ecosystems. The present study combines stomach content and stable isotope analyses with diet preferences of catfish to reveal its impact on the ecosystem since stocking. Catfish niche width is extremely wide in comparison to the typical model predator, Northern pike (Esox lucius). Catfish and pike have different individual dietary specialization…
The Strategic Reference Gene: an organismal theory of inclusive fitness
2019
How to define and use the concept of inclusive fitness is a contentious topic in evolutionary theory. Inclusive fitness can be used to calculate selection on a focal gene, but it is also applied to whole organisms. Individuals are then predicted to appear designed as if to maximise their inclusive fitness, provided that certain conditions are met (formally when interactions between individuals are 'additive'). Here we argue that applying the concept of inclusive fitness to organisms is justified under far broader conditions than previously shown, but only if it is appropriately defined. Specifically, we propose that organisms should maximise the sum of their offspring (including any accrued…
Assortative mating by size without a size-based preference: the female-sooner norm as a mate-guarding criterion.
2013
7 pages; International audience; The study of size-assortative mating, or homogamy, is of great importance in speciation and sexual selection. However, the proximate mechanisms that lead to such patterns are poorly understood. Homogamy is often thought to come from a directional preference for larger mates. However, many constraints affect mating preferences and understanding the causes of size assortment requires a precise evaluation of the pair formation mechanism. Mate-guarding crustaceans are a model group for the study of homogamy. Males guard females until moult and reproduction. They are also unable to hold a female during their own moult and tend to pair with females closer to moult…
Out in the open : behavior’s effect on predation risk and thermoregulation by aposematic caterpillars
2020
Abstract Warning coloration should be under strong stabilizing selection but often displays considerable intraspecific variation. Opposing selection on color by predators and temperature is one potential explanation for this seeming paradox. Despite the importance of behavior for both predator avoidance and thermoregulation, its role in mediating selection by predators and temperature on warning coloration has received little attention. Wood tiger moth caterpillars, Arctia plantaginis, have aposematic coloration, an orange patch on the black body. The size of the orange patch varies considerably: individuals with larger patches are safer from predators, but having a small patch is beneficia…
Low-Power, Subthreshold Reference Circuits for the Space Environment : Evaluated with -rays, X-rays, Protons and Heavy Ions
2019
The radiation tolerance of subthreshold reference circuits for space microelectronics is presented. The assessment is supported by measured results of total ionization dose and single event transient radiation-induced effects under &gamma