Search results for " selection"
showing 10 items of 1271 documents
Effect of the host plant on the immunity of a phytophagous insect : influence of grape variety on the ability of the European grapevine moth to defen…
2013
In tritrophic interactions involving phytophagous insects, host plants and natural enemies, trophic levels are highly dependent on each other. Host plant may strongly affect directly phytophagous insect and indirectly natural enemies growing on these phytophagous insects. When a natural enemy attacks a phytophagous insect, the host immune system constitutes the last chance for the host to survive to an infection. A great variation of insect immune system is generally found in populations for susceptibility to pathogens, suggesting that variable selection pressures may have shaped and driven adaptation of immune traits. This project aims to determine the influence of both host plant and natu…
Male coloration and species recognition in sympatric flycatchers
1994
Currently favoured views for explaining ornaments in males emphasize female preference such that females benefit from increased offspring production, good genes of the offspring, or the attractiveness of sons. Results from long-term studies in the pied flycatcher Ficedula hypoleuca suggest that factors associated with species recognition may also be important for male coloration. In sympatry the collared flycatcher F. albicollis is dominant in competition for nesting sites over the pied flycatcher. Bright pied flycatcher males resemble collared flycatcher males and suffer from interspecific interference, whereas dull and female-like males can acquire nesting sites close to those of the coll…
Overestimation of the strength of size-assortative pairing in taxa with cryptic diversity: a case of Simpson's paradox.
2015
5 pages; International audience; Size-assortative pairing is one of the most common pairing patterns observed in nature and it probably occurs in many taxa with cryptic diversity. Observed patterns of size-assortative pairing in natural populations may thus be influenced by the co-occurrence of noninterbreeding cryptic groups of individuals living in sympatry. To quantify this potential bias, we sampled amphipods from the Gammarus pulex/Gammarus fossarum crustacean species complex in rivers containing two sympatric and morphologically cryptic groups, i.e. molecular operational taxonomic units (MOTUs). Within each river, MOTUs did not interbreed and differed in mean body size. We measured th…
Ecological differentiation and reproductive isolation of two closely related sympatric species of Oenanthe (Apiaceae)
2010
Oenanthe conioides is a lower Elbe endemic plant species growing in the freshwater tidal zone around Hamburg (Germany). Its closest relative Oenanthe aquatica is widely distributed in Eurasia and grows in calm and shallow freshwater. The two species differ in habitat requirements but are otherwise sympatrically distributed, suggesting that ecological divergence has to be maintained in the face of gene flow. In the present study, we investigated ecological differentiation and reproductive isolation in these two species. An amplified fragment length polymorphism analysis found clear genetic differentiation between the two species implying reproductive isolation. A reciprocal transplantation e…
What do we need to know about speciation?
2011
Speciation has been a major focus of evolutionary biology research in recent years, with many important advances. However, some of the traditional organising principles of the subject area no longer provide a satisfactory framework, such as the classification of speciation mechanisms by geographical context into allopatric, parapatric and sympatry classes. Therefore, we have asked where speciation research should be directed in the coming years. Here, we present a distillation of questions about the mechanisms of speciation, the genetic basis of speciation and the relationship between speciation and diversity. Our list of topics is not exhaustive; rather we aim to promote discussion on rese…
Selection on size and secondary sexual characters of the damselfly Calopteryx splendens when sympatric with the congener Calopteryx virgo
2011
Male mating success is often determined by body size or secondary sexual characters because of female mate choice or competition for females. In addition to intraspecific interactions, interspecific interactions may interfere with intraspecific selection. In this study, we investigated sexual selection on size and sexual characters of male banded demoiselle ( Calopteryx splendens (Harris, 1780)) in wild populations sympatric with the beautiful demoiselle ( Calopteryx virgo (L., 1758)). As secondary sexual characters, male C. splendens have pigmented wing spots whose size appears to be under positive selection. Male C. virgo resemble male C. splendens that have the largest wing spots, leadi…
Urban monitoring using multi-temporal SAR and multi-spectral data
2006
In some key operational domains, the joint use of synthetic aperture radar (SAR) and multi-spectral sensors has shown to be a powerful tool for Earth observation. In this paper, we analyze the potentialities of combining interferometric SAR and multi-spectral data for urban area characterization and monitoring. This study is carried out following a standard multi-source processing chain. First, a pre-processing stage is performed taking into account the underlying physics, geometry, and statistical models for the data from each sensor. Second, two different methodologies, one for supervised and another for unsupervised approaches, are followed to obtain features that optimize the urban rela…
Genome-wide analyses reveal population structure and identify candidate genes associated with tail fatness in local sheep from a semi-arid area.
2021
Abstract Under a climate change perspective, the genetic make-up of local livestock breeds showing adaptive traits should be explored and preserved as a priority. We used genotype data from the ovine 50 k Illumina BeadChip for assessing breed autozygosity based on runs of homozygosity (ROH) and fine-scale genetic structure and for detecting genomic regions under selection in 63 Tunisian sheep samples. The average genomic inbreeding coefficients based on ROH were estimated at 0.017, 0.021, and 0.024 for Barbarine (BAR, n = 26), Noire de Thibar (NDT, n = 23), and Queue fine de l'Ouest (QFO, n = 14) breeds, respectively. The genomic relationships among individuals based on identity by state (I…
Predictors of early scaffold thrombosis: results from the multicenter prospective German-Austrian ABSORB RegIstRy.
2018
BACKGROUND In randomized clinical trials, the risk of thrombotic events with the absorb bioresorbable vascular scaffold (BVS) was significantly higher than with metallic drug-eluting stents. We evaluated predictors of scaffold thrombosis in the large-scale, multicenter German-Austrian ABSORB RegIstRy. METHODS AND RESULTS 3178 patients with treatment of 4252 lesions using 5020 scaffolds were included. Follow-up rate at 6 months was 97.4%. Forty-five (1.42%) patients experienced definite/probable scaffold thrombosis during follow-up. Multiple regression analysis showed implantation of absorb BVS in bifurcation lesions [odds ratio (OR): 4.43; 95% confidence interval (CI): 1.69-11.59; P=0.0024]…
Seven Shades of Grey: A Follow-Up Study on the Molecular Basis of Coat Colour in Indicine Grey Cattle Using Genome-Wide SNP Data
2022
Shades of grey and brown are a dominant component in mammal coat colours, representing a fundamental trait involved in a great number of processes including cryptism, sexual selection and signalling. The genetic mechanisms of the grey colouration in mammals are very complex and controlled by hundreds of genes whose effects and interactions are still largely unclear. In this study, we adopted a robust multi-cohort Fst outlier approach based on pairwise contrasts between seven grey indicine cattle breeds and both taurine and indicine non-grey cattle breeds in order to find genomic regions potentially related to the grey colouration. On the basis of three main drawn settings, built in order to…