Brandon Robert Tearse

Multilocus Patterns of Nucleotide Diversity and Divergence Reveal Positive Selection at Candidate Genes Related to Cold-hardiness in Coastal Douglas-fir (Pseudotsuga menziesii var. menziesii)

Forest trees exhibit remarkable adaptations to their environments. The genetic basis for phenotypic adaptation to climatic gradients has been established through a long history of common garden, provenance, and genecological studies. The identities of genes underlying these traits, however, have remained elusive and thus so have the patterns of adaptive molecular diversity in forest tree genomes. Here, we report an analysis of diversity and divergence for a set of 121 cold-hardiness candidate genes in coastal Douglas fir (Pseudotsuga menziesii var. menziesii). Application of several different tests for neutrality, including those that incorporated demographic models, revealed signatures of selection consistent with selective sweeps at three to eight loci, depending upon the severity of a bottleneck event and the method used to detect selection. Given the high levels of recombination, these candidate genes are likely to be closely linked to the target of selection if not the genes themselves. Putative homologs in Arabidopsis act primarily to stabilize the plasma membrane and protect against denaturation of proteins at freezing temperatures. These results indicate that surveys of nucleotide diversity and divergence, when framed within the context of further association mapping experiments, will come full circle with respect to their utility in the dissection of complex phenotypic traits into their genetic components.

TreeGenes: A Forest Tree Genome Database

The Dendrome Project and associated TreeGenes database serve the forest genetics research community through a curated and integrated web-based relational database. The research community is composed of approximately 2 000 members representing over 730 organizations worldwide. The database itself is composed of a wide range of genetic data from many forest trees with focused efforts on commercially important members of the Pinaceae family. The primary data types curated include species, publications, tree and DNA extraction information, genetic maps, molecular markers, ESTs, genotypic, and phenotypic data. There are currently ten main search modules or user access points within this PostgreSQL database. These access points allow users to navigate logically through the related data types. The goals of the Dendrome Project are to (1) provide a comprehensive resource for forest tree genomics data to facilitate gene discovery in related species, (2) develop interfaces that encourage the submission and integration of all genomic data, and to (3) centralize and distribute existing and novel online tools for the research community that both support and ease analysis. Recent developments have focused on increasing data content, functional annotations, data retrieval, and visualization tools. TreeGenes was developed to provide a centralized web resource with analysis and visualization tools to support data storage and exchange.

A phylogeographical analysis of the range disjunction for foxtail pine (Pinus balfouriana, Pinaceae): the role of Pleistocene glaciation

Biogeographical patterns within the California Floristic Province have been greatly affected by geological and climatic events. Here, we investigate the phylogeography of foxtail pine (Pinus balfouriana) in an effort to date its range disjunction using molecular data and to further our understanding of phylogeographical patterns for plants within the California Floristic Province. The distribution of foxtail pine is characterized by a 500‐km disjunction separating populations located in the Klamath Mountains from those in the southern Sierra Nevada. Previous authors suggested that this disjunction occurred approximately 4000–8000 years ago during the Holocene Xerotherm when western North America became warmer and drier. Those dates, however, are inconsistent with the morphological differences that separate regional populations into formally recognized subspecies. Using the coalescent‐based isolation with migration model and DNA sequence data from the chloroplast, mitochondrial, and nuclear genomes, we evaluate several hypotheses addressing the timing of this range disjunction and its effects on subsequent patterns of gene flow. Results from all three genomes are largely consistent with Middle to Early Pleistocene divergence dates. Those dates correspond to the Sherwin glaciation, which was the largest Pleistocene glacial episode in the Sierra Nevada. Gene flow, moreover, was only documented using data from the chloroplast genome, suggesting that low levels of long‐distance pollen dispersal (Nem < 0.5) have occurred since this divergence event. These results are extended to a discussion of the biogeographical development of subalpine forests in California.

DnaSAM: Software to perform neutrality testing for large datasets with complex null models

Patterns of DNA sequence polymorphisms can be used to understand the processes of demography and adaptation within natural populations. High‐throughput generation of DNA sequence data has historically been the bottleneck with respect to data processing and experimental inference. Advances in marker technologies have largely solved this problem. Currently, the limiting step is computational, with most molecular population genetic software allowing a gene‐by‐gene analysis through a graphical user interface. An easy‐to‐use analysis program that allows both high‐throughput processing of multiple sequence alignments along with the flexibility to simulate data under complex demographic scenarios is currently lacking. We introduce a new program, named DnaSAM, which allows high‐throughput estimation of DNA sequence diversity and neutrality statistics from experimental data along with the ability to test those statistics via Monte Carlo coalescent simulations. These simulations are conducted using the ms program, which is able to incorporate several genetic parameters (e.g. recombination) and demographic scenarios (e.g. population bottlenecks). The output is a set of diversity and neutrality statistics with associated probability values under a user‐specified null model that are stored in easy to manipulate text file.

Comme il Faut 2 : a fully realized model for socially-oriented gameplay

Social games---common patterns of character interactions that modify the social environment of the story world---provide a useful abstraction when authoring a story composed of interactive characters, making it possible to create games with deep possibility spaces that are about social interaction (which would be intractable if hand-authoring all the options). In this paper, we detail the workings of a major new version of our social artificial intelligence system, Comme il Faut, that enables social game play in interactive media experiences. The workings of Comme il Faut 2 are shown, with running examples, from both knowledge representation and process perspectives. Finally, the paper concludes with a plan for evaluating and demonstrating Comme il Faut 2 through an implementation of an interactive media experience that consists of a playable social space.

MINSTREL Remixed: a rational reconstruction

In this paper, we introduce Minstrel Remixed, a rational reconstruction of MINSTREL by Scott Turner. In addition to recreating the landmark story generation system for public usage we also introduce a number of modifications that were made during the reconstruction that allow for investigation into the inner workings of the system. Additionally we introduce Minstrel Remixed as a platform for use in Interactive Narrative applications and provide a number of concrete examples.

Skald: Minstrel Reconstructed

Scott Turners Minstrel is considered a landmark story-generation system, cited as an important system in our fields history for the quality of its output. Other influential systems such as Meehans Tale-Spin have inspired modern successors, but although a few systems have followed Minstrels case-based approach, none of them use its “imaginative recall” technique. This paper details Skald, a publicly-released rational reconstruction of Minstrel that enables exploration of Turners work and discovery of new implications for future research. A key finding is a brittleness only hinted at in Turners publications: the story library, story templates, and the recall system must be tailored to one another for Turners original system to function. We show that this can be ameliorated through a number of techniques, however, from adding differential costs to transformations to removing the least-successful author-level actions. Another key finding is that Turners original “boredom” system limited leverage of the story library. An alternative and its results are presented here. What emerges from this work is a different picture of the original Minstrel than that currently present in the literature, as well as a new system, Skald, that sets the stage for future research to explore Turners ideas for story generation.