Modelling bark beetle disturbances in a large scale forest scenario model to assess climate change impacts and evaluate adaptive management strategies

To study potential consequences of climate-induced changes in the biotic disturbance regime at regional to national scale we integrated a model of Ips typographus (L. Scol. Col.) damages into the large-scale forest scenario model EFISCEN. A two-stage multivariate statistical meta-model was used to upscale stand level damages by bark beetles as simulated in the hybrid forest patch model PICUS v1.41. Comparing EFISCEN simulations including the new bark beetle disturbance module against a 15-year damage time series for Austria showed good agreement at province level (R² between 0.496 and 0.802). A scenario analysis of climate change impacts on bark beetle-induced damages in Austria¿s Norway spruce [Picea abies (L.) Karst.] forests resulted in a strong increase in damages (from 1.33 Mm³ a¿1, period 1990¿2004, to 4.46 Mm³ a¿1, period 2095¿2099). Studying two adaptive management strategies (species change) revealed a considerable time-lag between the start of adaptation measures and a decrease in simulated damages by bark beetle

Differential introgression reveals candidate genes for selection across a spruce (Picea sitchensis × P. glauca) hybrid zone

Differential patterns of introgression between species across ecological gradients provide a fine-scale depiction of extrinsic and intrinsic factors that contribute to the maintenance of species barriers and adaptation across heterogeneous environments. Introgression was examined for 721 individuals collected from the ecological transition zone spanning maritime to continental climates within the Picea sitchensis–Picea glauca contact zone using a panel of 268 candidate gene single nucleotide polymorphisms. Geographic clines showed a strong spatial relationship between allele frequencies and both distance from the ocean along major rivers and mean annual precipitation, indicating a strong role for environmental selection. Interspecific patterns of differentiation using outlier tests revealed three candidate genes that may be targets of long-term divergent selection between the parental species, although contemporary genomic clines within the hybrid zone suggested neutral patterns of introgression for these genes. This study provides a fine-scale analysis of locus-specific introgression, identifying a suite of candidate loci that may be targets of extrinsic or intrinsic selection, with broad application in understanding local adaptation to climate

Polymorphism of postmating reproductive isolation within plant species

Speciation can be viewed as the evolution of reproductive isolation between formerly interbreeding populations. Recent years have seen great advances in our understanding of the genetic mechanisms underlying postmating reproductive isolation during plant speciation. Nevertheless, little is known about the early stages of species divergence and the evolution of reproductive isolation at the within species level. Direct or indirect evidence indicates that intrinsic postzygotic mechanisms are prevalent and often polymorphic among allopatric conspecific populations of plants. We review studies that report direct or indirect evidence for polymorphism of genic (i.e., gene-based) postmating reproductive isolation within species' ranges. Specifically, we focus on three genic mechanisms often held responsible for reproductive isolation between species: Bateson-Dobzhansky-Muller (BDM) incompatibilities and two widespread types of genomic conflict, transmission ratio distortion and cytonuclear interactions. We further highlight the close similarity between reported cases of outbreeding depression among conspecific populations, especially those that correspond to the intrinsic co-adaptation model, and the origin of genetic incompatibilities. This association holds great promise to help improve our understanding of the processes involved in the initial stage of speciation, and it highlights the close (and often overlooked) relationship between evolutionary and conservation biology

Unexpected ancestry of Populus seedlings from a hybrid zone implies a large role for postzygotic selection in the maintenance of species

In the context of potential interspecific gene flow, the integrity of species will be maintained by reproductive barriers that reduce genetic exchange, including traits associated with prezygotic isolation or poor performance of hybrids. Hybrid zones can be used to study the importance of different reproductive barriers, particularly when both parental species and hybrids occur in close spatial proximity. We investigated the importance of barriers to gene flow that act early versus late in the life cycle of European Populus by quantifying the prevalence of homospecific and hybrid matings within a mosaic hybrid zone. We obtained genotypic data for 11,976 loci from progeny and their maternal parents and constructed a Bayesian model to estimate individual admixture proportions and hybrid classes for sampled trees, and for the unsampled pollen parent. Matings that included one or two hybrid parents were common, resulting in admixture proportions of progeny that spanned the whole range of potential ancestries between the two parental species. This result contrasts strongly with the distribution of admixture proportions in adult trees, where intermediate hybrids and each of the parental species are separated into three discrete ancestry clusters. The existence of the full range of hybrids in seedlings is consistent with weak reproductive isolation early in the life cycle of Populus. Instead, a considerable amount of selection must take place between the seedling stage and maturity to remove many hybrid seedlings. Our results highlight that high hybridization rates and appreciable hybrid fitness do not necessarily conflict with the maintenance of species integrity

Live electronics in live performance : a performance practice emerging from the piano+ used in free improvisation

This thesis explores a performance practice within free improvisation. This is not a theory based improvisation – performances do not require specific preparation and the music refrains from repetition of musical structures. It engages in investigative and experimental approaches emerging from holistic considerations of acoustics, interaction and instrument, and also philosophy, psychology, sociopolitics and technology. The performance practice explores modes and approaches to working with the given potentiality of an electronically augmented acoustic instrument and involves the development of a suitably flexible computerised performance system, the piano+, combining extended techniques and real-time electroacoustic processes, which has the acoustic piano at its core. Contingencies of acoustic events and performance gestures – captured by audio analysis and sensors and combined to control the parameter space of computer processes – manipulate the fundamental properties of sound, timbre and time. Spherical abstractions, developed under consideration of Agamben’s potentiality and Sloterdijk’s philosophical theory of spheres, allow a shared metaphor for technical, instrumental, personal, and interpersonal concerns. This facilitates a theoretical approach for heuristic and investigative improvisation where performance is considered ‘Ereignis’ (an event) for sociopolitically aware activities that draw on the situational potentiality and present themselves in fragile and context dependent forms. Ever new relationships can be found and developed, but can equally be lost. Sloterdijk supplied the concept of knowledge resulting from equipping our ‘inner space’, an image suiting non-linearity of thought that transpires from Kuhl’s psychological PSI-theory to explain human motivation and behaviour. The role of technology – diversion and subversion of sound and activity – creates a space between performer and instrument that retains a fundamental pianism but defies expectation and anticipation. Responsibility for one’s actions is required to deal with the unexpected without resorting to preliminary strategies restricting potential discourses, particularly within ensemble situations. This type of performance embraces the ‘Ereignis’.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Regeneration in gap models: priority issues for studying forest responses to climate change

Recruitment algorithms in forest gap models are examined with particular regard to their suitability for simulating forest ecosystem responses to a changing climate. The traditional formulation of recruitment is found limiting in three areas. First, the aggregation of different regeneration stages (seed production, dispersal, storage, germination and seedling establishment) is likely to result in less accurate predictions of responses as compared to treating each stage separately. Second, the relatedassumptions that seeds of all species are uniformly available and that environmental conditions are homogeneous, are likely to cause overestimates of future species diversity and forest migration rates. Third, interactions between herbivores (ungulates and insect pests) and forest vegetation are a big unknown with potentially serious impacts in many regions. Possible strategies for developing better gap model representations for the climate-sensitive aspects of each of these key areas are discussed. A working example of a relatively new model that addresses some of these limitations is also presented for each case. We conclude that better models of regeneration processes are desirable for predicting effects of climate change, but that it is presently impossible to determine what improvements can be expected without carrying out rigorous tests for each new formulation

Live Electronics in Live Performance: A Performance Practice Emerging from the piano+ used in Free Improvisation.

This thesis explores a performance practice within free improvisation. This is not a theory based improvisation – performances do not require specific preparation and the music refrains from repetition of musical structures. It engages in investigative and experimental approaches emerging from holistic considerations of acoustics, interaction and instrument, and also philosophy, psychology, sociopolitics and technology. The performance practice explores modes and approaches to working with the given potentiality of an electronically augmented acoustic instrument and involves the development of a suitably flexible computerised performance system, the piano+, combining extended techniques and real-time electroacoustic processes, which has the acoustic piano at its core. Contingencies of acoustic events and performance gestures – captured by audio analysis and sensors and combined to control the parameter space of computer processes – manipulate the fundamental properties of sound, timbre and time. Spherical abstractions, developed under consideration of Agamben’s potentiality and Sloterdijk’s philosophical theory of spheres, allow a shared metaphor for technical, instrumental, personal, and interpersonal concerns. This facilitates a theoretical approach for heuristic and investigative improvisation where performance is considered ‘Ereignis’ (an event) for sociopolitically aware activities that draw on the situational potentiality and present themselves in fragile and context dependent forms. Ever new relationships can be found and developed, but can equally be lost. Sloterdijk supplied the concept of knowledge resulting from equipping our ‘inner space’, an image suiting non-linearity of thought that transpires from Kuhl’s psychological PSI-theory to explain human motivation and behaviour. The role of technology – diversion and subversion of sound and activity – creates a space between performer and instrument that retains a fundamental pianism but defies expectation and anticipation. Responsibility for one’s actions is required to deal with the unexpected without resorting to preliminary strategies restricting potential discourses, particularly within ensemble situations. This type of performance embraces the ‘Ereignis’

Mating system variation and assortative mating of sympatric bromeliads (Pitcairnia spp.) endemic to neotropical inselbergs

Premise of the study: The mating system is an important component of the complex set of reproductive isolation barriers causing plant speciation. However, empirical evidence showing that the mating system may promote reproductive isolation in co-occurring species is limited. The mechanisms by which the mating system can act as a reproductive isolation barrier are also largely unknown. Methods: Here we studied progeny arrays genotyped with microsatellites and patterns of stigma–anther separation (herkogamy) to understand the role of mating system shifts in promoting reproductive isolation between two hybridizing taxa with porous genomes, Pitcairnia albiflos and P. staminea (Bromeliaceae). Key results: In P. staminea, we detected increased selfing and reduced herkogamy in one sympatric relative to two allopatric populations, consistent with mating system shifts in sympatry acting to maintain the species integrity of P. staminea when in contact with P. albiflos. Conclusions: Mating system variation is a result of several factors acting simultaneously in these populations. We report mating system shifts as one possible reproductive barrier between these species, acting in addition to numerous other prezygotic (i.e., flower phenology and pollination syndromes) and postzygotic barriers (Bateson–Dobzhansky–Muller genetic incompatibilities)

Evaluation of a 3-D rockfall module within a forest patch model

Many slopes in the Alps are prone to rockfall and forests play a vital role in protecting objects such as (rail) roads and infrastructure against rockfall. Decision support tools are required to assess rockfall processes and to quantify the rockfall protection effect of forest stands. This paper presents results of an iterative sequence of tests and improvements of a coupled rockfall and forest dynamics model with focus on the rockfall module. As evaluation data a real-size rockfall experiment in the French Alps and two 2-D rockfall trajectories from Austria and Switzerland were used. Modification of the rebound algorithm and the inclusion of an algorithm accounting for the sudden halt of falling rocks due to surface roughness greatly improved the correspondence between simulated and observed key rockfall variables like run-out distances, rebound heights and jump lengths for the real-size rockfall experiment. Moreover, the observed jump lengths and run-out distances of the 2-D trajectories were well within the stochastic range of variation yielded by the simulations. Based on evaluation results it is concluded that the rockfall model can be employed to assess the protective effect of forest vegetation