The genomic bases of morphological divergence and reproductive isolation driven by ecological speciation in Senecio(Asteraceae)

Ecological speciation, driven by adaptation to contrasting environments, provides an attractive opportunity to study the formation of distinct species, and the role of selection and genomic divergence in this process. Here, we focus on a particularly clear-cut case of ecological speciation to reveal the genomic bases of reproductive isolation and morphological differences between closely related Senecio species, whose recent divergence within the last ~200 000 years was likely driven by the uplift of Mt. Etna (Sicily). These species form a hybrid zone, yet remain morphologically and ecologically distinct, despite active gene exchange. Here, we report a high-density genetic map of the Senecio genome and map hybrid breakdown to one large and several small quantitative trait loci (QTL). Loci under diversifying selection cluster in three 5 cM regions which are characterized by a significant increase in relative (FST), but not absolute (dXY), interspecific differentiation. They also correspond to some of the regions of greatest marker density, possibly corresponding to ‘cold-spots’ of recombination, such as centromeres or chromosomal inversions. Morphological QTL for leaf and floral traits overlap these clusters. We also detected three genomic regions with significant transmission ratio distortion (TRD), possibly indicating accumulation of intrinsic genetic incompatibilities between these recently diverged species. One of the TRD regions overlapped with a cluster of high species differentiation, and another overlaps the large QTL for hybrid breakdown, indicating that divergence of these species may have occurred due to a complex interplay of ecological divergence and accumulation of intrinsic genetic incompatibilities

Domain Wall Spacetimes: Instability of Cosmological Event and Cauchy Horizons

The stability of cosmological event and Cauchy horizons of spacetimes associated with plane symmetric domain walls are studied. It is found that both horizons are not stable against perturbations of null fluids and massless scalar fields; they are turned into curvature singularities. These singularities are light-like and strong in the sense that both the tidal forces and distortions acting on test particles become unbounded when theses singularities are approached.Comment: Latex, 3 figures not included in the text but available upon reques

Hydrodynamics and Flow

In this lecture note, we present several topics on relativistic hydrodynamics and its application to relativistic heavy ion collisions. In the first part we give a brief introduction to relativistic hydrodynamics in the context of heavy ion collisions. In the second part we present the formalism and some fundamental aspects of relativistic ideal and viscous hydrodynamics. In the third part, we start with some basic checks of the fundamental observables followed by discussion of collective flow, in particular elliptic flow, which is one of the most exciting phenomenon in heavy ion collisions at relativistic energies. Next we discuss how to formulate the hydrodynamic model to describe dynamics of heavy ion collisions. Finally, we conclude the third part of the lecture note by showing some results from ideal hydrodynamic calculations and by comparing them with the experimental data.Comment: 40 pages, 35 figures; lecture given at the QGP Winter School, Jaipur, India, Feb.1-3, 2008; to appear in Springer Lecture Notes in Physic

Phenomenology of the Lense-Thirring effect in the Solar System

Recent years have seen increasing efforts to directly measure some aspects of the general relativistic gravitomagnetic interaction in several astronomical scenarios in the solar system. After briefly overviewing the concept of gravitomagnetism from a theoretical point of view, we review the performed or proposed attempts to detect the Lense-Thirring effect affecting the orbital motions of natural and artificial bodies in the gravitational fields of the Sun, Earth, Mars and Jupiter. In particular, we will focus on the evaluation of the impact of several sources of systematic uncertainties of dynamical origin to realistically elucidate the present and future perspectives in directly measuring such an elusive relativistic effect.Comment: LaTex, 51 pages, 14 figures, 22 tables. Invited review, to appear in Astrophysics and Space Science (ApSS). Some uncited references in the text now correctly quoted. One reference added. A footnote adde

The physiology and biochemistry of the pollen-stigma interaction in Brassica

SIGLEAvailable from British Library Document Supply Centre- DSC:D178537 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Genomic architecture of phenotypic divergence between two hybridizing plant species along an elevational gradient

Knowledge of the genetic basis of phenotypic divergence between species and how such divergence is caused and maintained is crucial to an understanding of speciation and the generation of biodiversity. The hybrid zone between Senecio aethnensis and S. chrysanthemifolius on Mount Etna, Sicily, provides a well-studied example of species divergence in response to conditions at different elevations, despite hybridization and gene flow. Here, we investigate the genetic architecture of divergence between these two species using a combination of quantitative trait locus (QTL) mapping and genetic differentiation measures based on genetic marker analysis. A QTL architecture characterized by physical QTL clustering, epistatic interactions between QTLs, and pleiotropy was identified, and is consistent with the presence of divergent QTL complexes resistant to gene flow. A role for divergent selection between species was indicated by significant negative associations between levels of interspecific genetic differentiation at mapped marker gene loci and map distance from QTLs and hybrid incompatibility loci. Within-species selection contributing to interspecific differentiation was evidenced by negative associations between interspecific genetic differentiation and genetic diversity within species. These results show that the two Senecio species, while subject to gene flow, maintain divergent genomic regions consistent with local selection within species and selection against hybrids between species which, in turn, contribute to the maintenance of their distinct phenotypic differences

Testing predictions for symmetry, variability and chronology of backed artefact production in Australia\u27s Western Desert

The Backed Artefact Symmetry Index (BASI) provides a measure with which to describe geometric variation in Australian backed artefacts, and Peter Hiscock has suggested that desert versions of this artefact type will be more symmetrical than their coastal counterparts. The re-excavated Serpent\u27s Glen (Karnatukul) site and nearby site of Wirrili have produced a large assemblage of backed artefacts. These Western Desert assemblages allow for the testing of BASI. The backed artefacts demonstrate significantly more variability than predicted, demonstrating that all technological debates benefit from larger well-dated assemblages. The signalling information observed in these sites\u27 pigment art repertoires, combined with this versatility in the toolkits, increases our understanding of the complexity of middle and late Holocene highly mobile foragers in the Australian arid zone