Sebacinales Everywhere: Previously Overlooked Ubiquitous Fungal Endophytes

Inconspicuous basidiomycetes from the order Sebacinales are known to be involved in a puzzling variety of mutualistic plant-fungal symbioses (mycorrhizae), which presumably involve transport of mineral nutrients. Recently a few members of this fungal order not fitting this definition and commonly referred to as ‘endophytes’ have raised considerable interest by their ability to enhance plant growth and to increase resistance of their host plants against abiotic stress factors and fungal pathogens. Using DNA-based detection and electron microscopy, we show that Sebacinales are not only extremely versatile in their mycorrhizal associations, but are also almost universally present as symptomless endophytes. They occurred in field specimens of bryophytes, pteridophytes and all families of herbaceous angiosperms we investigated, including liverworts, wheat, maize, and the non-mycorrhizal model plant Arabidopsis thaliana. They were present in all habitats we studied on four continents. We even detected these fungi in herbarium specimens originating from pioneering field trips to North Africa in the 1830s/40s. No geographical or host patterns were detected. Our data suggest that the multitude of mycorrhizal interactions in Sebacinales may have arisen from an ancestral endophytic habit by specialization. Considering their proven beneficial influence on plant growth and their ubiquity, endophytic Sebacinales may be a previously unrecognized universal hidden force in plant ecosystems

Task-sensitive cinematography interfaces for interactive 3d learning environments

Interactive 3D learning environments can provide rich problemsolving experiences with unparalleled visual impact. In these environments, students interactively solve problems by directing their avatars to navigate through complex worlds, transport entities from one location to another, and manipulate devices. However, realtime camera control is critical to their successful deployment. To create effective learning experiences, a virtual camera must in realtime “film ” their activities in a manner that most clearly depicts the salient aspects of the tasks students are performing. To address this problem, we have developed the cinematic task modeling framework for automated realtime task-sensitive camera control in 3D environments. Cinematic task models dynamically map the intentional structure of users ’ activities to visual structures that continuously depict the most relevant actions and objects in the environment. By exploiting cinematic task models, a cinematography interface to 3D learning environments can dynamically plan camera positions, view directions, and camera movements that help users perform their tasks. To investigate the effect of the cinematic task modeling framework on student-environment interactions, we have constructed a fullscale cinematography interface and a 3D learning environment testbed. Focus group studies suggest that task-sensitive camera planning significantlyimproves students ’ interactions with complex 3D learning environments

Task-Sensitive Cinematography Interfaces for Interactive 3D Learning Environments

Interactive 3D learning environments can provide rich problem-solving experiences with unparalleled visual impact. In these environments, students interactively solve problems by di-recting their avatars to navigate through complex worlds, transport entities from one location to another, and manip-ulate devices. However, realtime camera control is critical to their successful deployment. To create effective learning experiences, a virtual camera must in realtime “film ” their ac-tivities in a manner that most clearly depicts the salient aspects of the tasks students are performing. To address this problem, we have developed the cinematic task modeling framework for automated realtime task-sensitive camera control in 3D environments. Cinematic task models dynamically map the intentional structure of users ’ activities to visual structures that continuously depict the most relevant actions and objects in the environment. By exploiting cinematic task models, a cinematography interface to 3D learning environments can dynamically plan camera positions, view directions, and cam-era movements that help users perform their tasks. To inves-tigate the effect of the cinematic task modeling framework on student-environment interactions, we have constructed a full-scale cinematography interface and a 3D learning environ-ment testbed. Focus group studies suggest that task-sensitive camera planning significantly improves students ’ interactions with complex 3D learning environments

Phylogeny and biogeography of the American live oaks (Quercus subsection Virentes): a genomic and population genetics approach

The nature and timing of evolution of niche differentiation among closely related species remains an important question in ecology and evolution. The American live oak clade, Virentes, which spans the unglaciated temperate and tropical regions of North America and Mesoamerica, provides an instructive system in which to examine speciation and niche evolution. We generated a fossil-calibrated phylogeny of Virentes using RADseq data to estimate divergence times and used nuclear microsatellites, chloroplast sequences and an intron region of nitrate reductase (NIA-i3) to examine genetic diversity within species, rates of gene flow among species and ancestral population size of disjunct sister species. Transitions in functional and morphological traits associated with ecological and climatic niche axes were examined across the phylogeny. We found the Virentes to be monophyletic with three subclades, including a southwest clade, a southeastern US clade and a Central American/Cuban clade. Despite high leaf morphological variation within species and transpecific chloroplast haplotypes, RADseq and nuclear SSR data showed genetic coherence of species. We estimated a crown date for Virentes of 11 Ma and implicated the formation of the Sea of Cortés in a speciation event ~5 Ma. Tree height at maturity, associated with fire tolerance, differs among the sympatric species, while freezing tolerance appears to have diverged repeatedly across the tropical-temperate divide. Sympatric species thus show evidence of ecological niche differentiation but share climatic niches, while allopatric and parapatric species conserve ecological niches, but diverge in climatic niches. The mode of speciation and/or degree of co-occurrence may thus influence which niche axis plants diverge along