476 research outputs found

    Digital Drapery and Body Schema-tics:Collaborative Authorship in Motion Capture Performance

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    This paper provides a theoretical framework for analyzing motion capture acting for film as a creative professional collaboration between actors and animators. Animators are framed as the draper (rather than the drafter) of the synthespian's digital costume, informed but not overdetermined by the raw data of the motion capture actor's performance. Similarly, the data ensuing from the actor's performance is analyzed in the neuroscientific terms of body image versus body schema, which makes a distinction between the self's physical appearance and the self's capacity for action. The paper concludes that ethnographic research on motion capture acting with this new terminology will provide a holistic view of the collective creative processes in digital cinematic productio

    Quantitative Genetic Effects of Bottlenecks: Experimental Evidence from a Wild Plant Species, Nigella degenii

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    Understanding the genetic consequences of changes in population size is fundamental in a variety of contexts, such as adaptation and conservation biology. In the study presented here, we have performed a replicated experiment with the plant Nigella degenii to explore the quantitative genetic effects of a single-founder bottleneck. In agreement with additive theory, the bottleneck reduced the mean (co)variance within lines and caused stochastic, line-specific changes in the genetic (co)variance structure. However, a significant portion of the (co)variance structure was conserved, and 2 characters—leaf and flower (sepal) size—turned out to be positively correlated in all data sets, indicating a potential for correlated evolution in these characters, even after a severe bottleneck. The hierarchical partitioning of genetic variance for flower size was in good agreement with predictions from additive theory, whereas the remaining characters showed an excess of within-line variance and a deficiency of among-line variance. The latter discrepancies were most likely a result of selection, given the small proportion of lines (23%) that remained viable until the end of the experiment. Our results suggest that bottlenecked populations of N. degenii generally have a lower adaptive potential than the ancestral population but also highlight the idiosyncratic nature of bottleneck effects

    ARTICLE Factors influencing Brown Pelican (Pelecanus occidentalis) foraging movement patterns during the breeding season

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    Abstract: During the breeding season, seabird foraging behaviors are driven by a combination of individual-and external-based factors. This study evaluated how two individual-based factors (body condition and sex) and two external factors (nest stage and colony size), and their interactions, were related to movement. To do so, we used movement data obtained from 22 GPS-tagequipped Brown Pelicans (Pelecanus occidentalis L., 1766) breeding in the northern Gulf of Mexico. In Brown Pelicans, the postegg-hatching phase imposes increased foraging demands on breeding adults relative to the prehatching phase. This study demonstrates that the progression of the breeding period affects the nature and intensity of the relationship between individualbased factors and movement patterns. In particular, birds in relatively lower condition traveled greater distances during foraging trips during the energetically demanding posthatching phase, but not during the incubation stage. Contrary to many seabird species studied to date, neither colony size nor sex appeared to affect Brown Pelican movement patterns. Our results suggest that nest stage is the most important factor influencing foraging movements, and that it may modulate relationships between condition and movement. More refined measures of body condition and foraging behavior will allow further insights into the movement ecology of this seabird

    Invasion of Europe by the western corn rootworm, Diabrotica virgifera virgifera: multiple transatlantic introductions with various reductions of genetic diversity

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    The early stages of invasion involve demographic bottlenecks that may result in lower genetic variation in introduced populations as compared to source population/s. Low genetic variability may decrease the adaptive potential of such populations in their new environments. Previous population genetic studies of invasive species have reported varying levels of losses of genetic variability in comparisons of source and invasive populations. However, intraspecific comparisons are required to assess more thoroughly the repeatability of genetic consequences of colonization events. Descriptions of invasive species for which multiple introductions from a single source population have been demonstrated may be particularly informative. The western corn rootworm (WCR), Diabrotica virgifera virgifera, native to North America and invasive in Europe, offers us an opportunity to analyse multiple introduction events within a single species. We investigated within- and between-population variation at eight microsatellite markers in WCR in North America and Europe to investigate the routes by which WCR was introduced into Europe, and to assess the effect of introduction events on genetic variation. We detected five independent introduction events from the northern USA into Europe. The diversity loss following these introductions differed considerably between events, suggesting substantial variation in introduction, foundation and/or establishment conditions. Genetic variability at evolutionarily neutral loci does not seem to underlie the invasive success of WCR in Europe. We also showed that the introduction of WCR into Europe resulted in the redistribution of genetic variance from the intra- to the interpopulational level contrary to most examples of multiple introductions

    Early detection of population declines: high power of genetic monitoring using effective population size estimators

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    Early detection of population declines is essential to prevent extinctions and to ensure sustainable harvest. We evaluated the performance of two Ne estimators to detect population declines: the two-sample temporal method and a one-sample method based on linkage disequilibrium (LD). We used simulated data representing a wide range of population sizes, sample sizes and number of loci. Both methods usually detect a population decline only one generation after it occurs if Ne drops to less than approximately 100, and 40 microsatellite loci and 50 individuals are sampled. However, the LD method often out performed the temporal method by allowing earlier detection of less severe population declines (Ne approximately 200). Power for early detection increased more rapidly with the number of individuals sampled than with the number of loci genotyped, primarily for the LD method. The number of samples available is therefore an important criterion when choosing between the LD and temporal methods. We provide guidelines regarding design of studies targeted at monitoring for population declines. We also report that 40 single nucleotide polymorphism (SNP) markers give slightly lower precision than 10 microsatellite markers. Our results suggest that conservation management and monitoring strategies can reliably use genetic based methods for early detection of population declines

    Genetic Measures Confirm Familial Relationships and Strengthen Study Design

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    Social structure and behavioral interactions between individuals shape basic biological processes, such as breeding; foraging and predator avoidance; movement and dispersal; and disease transmission. We used a targeted trapping strategy to capture kin groups of white-tailed deer (Odocoileus virginianus) during 2007 and 2008 in Sandhill Wildlife Research Area, Wisconsin, USA, in order to observe social behaviors. Because inferring family relationships from observation of behavior is subjective, we usedmeasures of genetic relatedness and parentage assignment tests to determine that our capture strategy was efficient for capturing related pairs (78% of groups contained 1 dyad of related animals). The results of our genetic tests verified that study animals were related; therefore, our capture strategy was successful and the assumptions of the research design were met. This demonstrates both the utility of a targeted sampling approach, and the importance of genetic techniques to verify relationships among animals, especially when kin association forms a basis for further biological study or management action

    Estimation of effective number of breeders from molecular coancestry of single cohort sample

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    The effective population size, Ne, is an important parameter in population genetics and conservation biology. It is, however, difficult to directly estimate Ne from demographic data in many wild species. Alternatively, the use of genetic data has received much attention in recent years. In the present study, I propose a new method for estimating the effective number of breeders Neb from a parameter of allele sharing (molecular coancestry) among sampled progeny. The bias and confidence interval of the new estimator are compared with those from a published method, i.e. the heterozygote-excess method, using computer simulation. Two population models are simulated; the noninbred population that consists of noninbred and nonrelated parents and the inbred population that is composed of inbred and related parents. Both methods give essentially unbiased estimates of Neb when applied to the noninbred population. In the inbred population, the proposed method gives a downward biased estimate, but the confidence interval is remarkably narrowed compared with that in the noninbred population. Estimate from the heterozygote-excess method is nearly unbiased in the inbred population, but suffers from a larger confidence interval. By combining the estimates from the two methods as a harmonic mean, the reliability is remarkably improved

    Evaluation of experimental genetic management in reintroduced bighorn sheep

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    Positive demographic responses have been reported in several species where the immigration or supplementation of genetically distinct individuals into wild populations has resulted in a genetic rescue effect. However, rarely have researchers incorporated what could be considerable risk of outbreeding depression into planning for genetic management programs. We assess the genetic effects of an experiment in genetic management involving replicate populations of California bighorn sheep (Ovis canadensis californiana) in Oregon, USA, which previously experienced poor productivity and numerical declines. In the experiment, two declining populations were supplemented with ewes from a more genetically diverse population of California bighorn sheep in Nevada. We incorporated analysis of genetic samples representing both experimental populations prior to supplementation, samples from the supplemented individuals, and samples collected from both experimental populations approximately one generation after supplementation. We used genetic analyses to assess the integration of supplemented and resident populations by identifying interpopulation hybrids. Further, we incorporated demographic simulations to assess the risk of outbreeding depression as a result of the experimental augmentation. Finally, we used data from microsatellites and mitochondrial sequences to determine if genetic management increased genetic diversity in the experimental populations. Our analyses demonstrated the success of genetic management by documenting interpopulation hybrids, identifying no evidence for outbreeding depression as a result of contact between the genetically distinct supplemented and resident populations, and by identifying increased population-level metrics of genetic diversity in postsupplementation populations compared with presupplementation levels
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