47 research outputs found
Evolution of Fruit Traits in Ficus Subgenus Sycomorus (Moraceae): To What Extent Do Frugivores Determine Seed Dispersal Mode?
Fig trees are a ubiquitous component of tropical rain forests and exhibit an enormous diversity of ecologies. Focusing on Ficus subgenus Sycomorus, a phenotypically diverse and ecologically important Old World lineage, we examined the evolution of fruit traits using a molecular phylogeny constructed using 5 kilobases of DNA sequence data from 63 species (50% of global diversity). In particular, we ask whether patterns of trait correlations are consistent with dispersal agents as the primary selective force shaping morphological diversity or if other ecological factors may provide a better explanation? Fig colour, size and placement (axial, cauliflorous, or geocarpic) were all highly evolutionarily liable, and the same fruit traits have evolved in different biogeographic regions with substantially different dispersal agents. After controlling for phylogenetic autocorrelation, we found that fig colour and size were significantly associated with fig placement and plant-life history traits (maximum plant height and leaf area, respectively). However, contrary to prevailing assumptions, fig placement correlated poorly with known dispersal agents and appears more likely determined by other factors, such as flowering phenology, nutrient economy, and habitat preference. Thus, plant life-history, both directly and through its influence on fig placement, appears to have played a prominent role in determining fruit traits in these figs
Ultrafast entangling gates between nuclear spins using photo-excited triplet states
The representation of information within the spins of electrons and nuclei
has been powerful in the ongoing development of quantum computers. Although
nuclear spins are advantageous as quantum bits (qubits) due to their long
coherence lifetimes (exceeding seconds), they exhibit very slow spin
interactions and have weak polarisation. A coupled electron spin can be used to
polarise the nuclear spin and create fast single-qubit gates, however, the
permanent presence of electron spins is a source of nuclear decoherence. Here
we show how a transient electron spin, arising from the optically excited
triplet state of C60, can be used to hyperpolarise, manipulate and measure two
nearby nuclear spins. Implementing a scheme which uses the spinor nature of the
electron, we performed an entangling gate in hundreds of nanoseconds: five
orders of magnitude faster than the liquid-state J coupling. This approach can
be widely applied to systems comprising an electron spin coupled to multiple
nuclear spins, such as NV centres, while the successful use of a transient
electron spin motivates the design of new molecules able to exploit
photo-excited triplet states.Comment: 5 pages, 3 figure
A Geospatial Modelling Approach Integrating Archaeobotany and Genetics to Trace the Origin and Dispersal of Domesticated Plants
Background: The study of the prehistoric origins and dispersal routes of domesticated plants is often based on the analysis of either archaeobotanical or genetic data. As more data become available, spatially explicit models of crop dispersal can be used to combine different types of evidence. Methodology/Principal Findings: We present a model in which a crop disperses through a landscape that is represented by a conductance matrix. From this matrix, we derive least-cost distances from the geographical origin of the crop and use these to predict the age of archaeological crop remains and the heterozygosity of crop populations. We use measures of the overlap and divergence of dispersal trajectories to predict genetic similarity between crop populations. The conductance matrix is constructed from environmental variables using a number of parameters. Model parameters are determined with multiple-criteria optimization, simultaneously fitting the archaeobotanical and genetic data. The consilience reached by the model is the extent to which it converges around solutions optimal for both archaeobotanical and genetic data. We apply the modelling approach to the dispersal of maize in the Americas. Conclusions/Significance: The approach makes possible the integrative inference of crop dispersal processes, whil
Adaptive Radiation in Mediterranean Cistus (Cistaceae)
lineage consists of
12 species primarily distributed in Mediterranean habitats and
is herein subject to analysis. lineages), which display asymmetric
characteristics: number of species (2 vs. 10), leaf morphologies
(linear vs. linear to ovate), floral characteristics (small,
three-sepalled vs. small to large, three- or five-sepalled
flowers) and ecological attributes (low-land vs. low-land to
mountain environments). A positive phenotype-environment
correlation has been detected by historical reconstructions of
morphological traits (leaf shape, leaf labdanum content and leaf
pubescence). Ecological evidence indicates that modifications of
leaf shape and size, coupled with differences in labdanum
secretion and pubescence density, appear to be related to
success of new species in different Mediterranean habitats.
Ed Emshwiller
Hanhardt underlines the presence of a moving dancer in Emshwiller's video installation. Artist's statement. Biographical notes