Evolution of ultraviolet vision in the largest avian radiation - the passerines

<p>Abstract</p> <p>Background</p> <p>Interspecific variation in avian colour vision falls into two discrete classes: violet sensitive (VS) and ultraviolet sensitive (UVS). They are characterised by the spectral sensitivity of the most shortwave sensitive of the four single cones, the SWS1, which is seemingly under direct control of as little as one amino acid substitution in the cone opsin protein. Changes in spectral sensitivity of the SWS1 are ecologically important, as they affect the abilities of birds to accurately assess potential mates, find food and minimise visibility of social signals to predators. Still, available data have indicated that shifts between classes are rare, with only four to five independent acquisitions of UV sensitivity in avian evolution.</p> <p>Results</p> <p>We have classified a large sample of passeriform species as VS or UVS from genomic DNA and mapped the evolution of this character on a passerine phylogeny inferred from published molecular sequence data. Sequencing a small gene fragment has allowed us to trace the trait changing from one stable state to another through the radiation of the passeriform birds. Their ancestor is hypothesised to be UVS. In the subsequent radiation, colour vision changed between UVS and VS at least eight times.</p> <p>Conclusions</p> <p>The phylogenetic distribution of SWS1 cone opsin types in Passeriformes reveals a much higher degree of complexity in avian colour vision evolution than what was previously indicated from the limited data available. Clades with variation in the colour vision system are nested among clades with a seemingly stable VS or UVS state, providing a rare opportunity to understand how an ecologically important trait under simple genetic control may co-evolve with, and be stabilised by, associated traits in a character complex.</p

An experimental test for indirect benefits in Drosophila melanogaster

BACKGROUND: Despite much empirical attention, tests for indirect benefits of mate choice have rarely considered the major components of sexual and nonsexual offspring fitness relevant to a population. Here we use a novel experimental design to test for the existence of any indirect benefits in a laboratory adapted population of D. melanogaster. Our experiment compared the fitness (mating success, longevity, and productivity) of individuals possessing genomes that derived two generations previously from males that were either entirely successful (studs) or wholly unsuccessful (duds) at achieving mates in three subsequent rounds of mating trials. RESULTS: Males from the stud treatment were 30% more successful on average at securing mates than males from the dud treatment. In contrast, we found no difference between treatments in measures of productivity or of longevity when measured in a mixed-sex environment. In the absence of females, however, males in the stud treatment outlived males in the dud treatment. CONCLUSION: Our results suggest that mating with successful males in this population provides an indirect benefit to females and that, at least in this environment, the benefit arises primarily through the production of more attractive male offspring. However, it is unclear whether this represents solely a traditional sexy sons benefit or whether there is an additional good genes component (with male offspring simply allocating their surplus condition to traits that enhance their mating success). The lack of any detectable differences in female fitness between the two treatments suggests the former, although the longevity advantage of males in the stud treatment when females were absent is consistent with the latter. Determining the effect of this indirect benefit on the evolution of female mate preferences (or resistance) will require comparable data on the direct costs of mating with various males, and an understanding of how these costs and benefits integrate across generations and vary among environments

Évaluation de l’impact économique du crédit d’impôt pour la compétitivité et l’emploi (CICE)

À la suite de la remise au Premier ministre du Rapport Gallois, le gouvernement a décidé, pour relancer la compétitivité et l'emploi en France, la création du Crédit d'impôt pour la compétitivité et l'emploi (CICE). Ouvert à toutes les entreprises, le CICE sera égal à 6 % de la masse salariale, hors cotisations patronales, correspondant aux salaires de moins de 2,5 SMIC. Représentant 20 milliards d'euros, son financement reposera pour moitié sur des économies supplémentaires sur les dépenses publiques, dont le détail n'a pas été précisé, et pour moitié sur des recettes fiscales : une réforme de la TVA à compter du 1er janvier 2014 et un renforcement de la fiscalité écologique. Le CICE diminuerait en moyenne de 2,6 % le coût du travail du secteur marchand : l'impact sectoriel le plus fort sur le coût du travail serait dans la construction (-3,0 %), l'industrie (-2,8 %) et les services marchands (-2,4 %). Le CICE représenterait 1,8 % de la valeur ajoutée des entreprises industrielles, 1,9 % de la valeur ajoutée de la construction et 1,3 % de celle des services marchands. Globalement, le CICE pèse pour 1,4 % dans la valeur ajoutée des entreprises du secteur marchand. Selon notre évaluation, réalisée à l'aide du modèle e-mod.fr, le CICE devrait permettre de créer, cinq ans après sa mise en place, environ 150 000 emplois faisant baisser le taux de chômage de 0,6 point et il générerait un gain de croissance de 0,1 point de PIB en 2018

Load control speed screw conveyer

<p>The flight paths of two blue bottle flies (<i>Calliphora vomitoria</i>) sampled from high-speed video (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0151099#pone.0151099.s002" target="_blank">S1 Movie</a>): A) at the rate of the visual system of a human (40 frames/s) and B) at the rate of a pied flycatcher (120 frames/s) at a light intensity of approximately 500 cdm^-2. The flycatcher refreshes visual input almost three times faster, resulting in a much more detailed view of the flight paths of the flies.</p

Comparative genomics reveals insights into avian genome evolution and adaptation

Birds are the most species-rich class of tetrapod vertebrates and have wide relevance across many research fields. We explored bird macroevolution using full genomes from 48 avian species representing all major extant clades. The avian genome is principally characterized by its constrained size, which predominantly arose because of lineage-specific erosion of repetitive elements, large segmental deletions, and gene loss. Avian genomes furthermore show a remarkably high degree of evolutionary stasis at the levels of nucleotide sequence, gene synteny, and chromosomal structure. Despite this pattern of conservation, we detected many non-neutral evolutionary changes in protein-coding genes and noncoding regions. These analyses reveal that pan-avian genomic diversity covaries with adaptations to different lifestyles and convergent evolution of traits

Effects of Post-Glacial Range Expansions and Population Bottlenecks on Species Richness

This thesis relates modern speciation theory to the effects of sudden changes in the range and size of populations. Special reference is made to the climatic oscillations during the Quaternary ice ages. A meta-analysis of laboratory experiments showed that support for allopatric speciation is weak, especially for the peripatric type of allopatric speciation. Furthermore, factors traditionally believed to increase the likelihood of speciation have had little effect on the generation of reproductive isolation in speciation experiments. However, the method of testing reproductive isolation appeared important, in the sense that experimentally derived sister populations were likely to demonstrate reproductive isolation from each other but not from the unaffected mother population. Raw data from mating tests showed that the poor isolation between mother and daughter populations was an effect of asymmetric mate preferences towards males from the mother population. This suggests that peripatric speciation can be effective in generating reproductive isolation between sister populations. The proposed mechanism is that males become less attractive to females by losing certain secondary sexual traits during population bottlenecks, and that females shift their preferences towards other male traits. Support for this mode of speciation is found in the widespread bird genus Motacilla (wagtails). This genus is characterised by extensive plumage variation and contains a large number of widely distributed taxa in the northern parts of its distribution. This thesis shows that taxonomic diversity of wagtails is inversely related to complexity in song and to diversity in molecular and mitochondrial markers. The northern taxa seem to be descendants of southern populations, which were subjected to bottlenecks during expansions into re-opened habitats after the last ice age. The bottlenecks would not only reduce genetic diversity but also inhibit cultural transmission of song to the leading edge of colonisers, allowing sexual selection on other traits, such as plumage. Rapid plumage differentiation among wagtail taxa appears to be a recurrent process and has lead to convergent evolution, making the currently recognised species Motacilla flava (Yellow Wagtail) polyphyletic