Rapid, nonparallel genomic evolution of Brassica rapa (field mustard) under experimental drought.

While we know that climate change can potentially cause rapid phenotypic evolution, our understanding of the genetic basis and degree of genetic parallelism of rapid evolutionary responses to climate change is limited. In this study, we combined the resurrection approach with an evolve-and-resequence design to examine genome-wide evolutionary changes following drought. We exposed genetically similar replicate populations of the annual plant Brassica rapa derived from a field population in southern California to four generations of experimental drought or watered conditions in a greenhouse. Genome-wide sequencing of ancestral and descendant population pools identified hundreds of SNPs that showed evidence of rapidly evolving in response to drought. Several of these were in stress response genes, and two were identified in a prior study of drought response in this species. However, almost all genetic changes were unique among experimental populations, indicating that the evolutionary changes were largely nonparallel, despite the fact that genetically similar replicates of the same founder population had experienced controlled and consistent selection regimes. This nonparallelism of evolution at the genetic level is potentially because of polygenetic adaptation allowing for multiple different genetic routes to similar phenotypic outcomes. Our findings help to elucidate the relationship between rapid phenotypic and genomic evolution and shed light on the degree of parallelism and predictability of genomic evolution to environmental change.

Rapid-cycling Brassica rapa evolves even earlier flowering under experimental drought.

PREMISE: Changes in climate can impose selection on populations and may lead to rapid evolution. One such climatic stress is drought, which plant populations may respond to with escape (rapid growth and early flowering) or avoidance (slow growth and efficient water-use). However, it is unclear if drought escape would be a viable strategy for populations that already flower early from prior selection. METHODS: In an experimental evolution study, we subjected rapid-cycling Brassica rapa (RCBr), which was previously selected for early flowering, to four generations of experimental drought or watered conditions. We then grew ancestral and descendant populations concurrently under drought and watered conditions to assess evolution, plasticity, and adaptation. RESULTS: The RCBr populations that evolved under drought had earlier flowering and lower water-use efficiency than the populations that evolved under watered conditions, indicating evolutionary divergence. The drought descendants also had a trend of earlier flowering compared to ancestors, indicating evolution. Evolution of earlier flowering under drought followed the direction of selection and increased fitness and was consistent with studies in natural and experimental populations of this species, suggesting adaptive evolution. CONCLUSIONS: We found rapid adaptive evolution of drought escape in RCBr and little evidence for constraints on flowering time evolution, even though RCBr already flowers extremely early. Our results suggest that some populations may harbor sufficient genetic variation for evolution even after strong selection has occurred. Our study also illustrates the utility of combining artificial selection, experimental evolution, and the resurrection approach to study the evolution of functional traits.

Facial and Lingual Strength and Endurance in Skilled Trumpet Players.

UNLABELLED: Trumpet players produce and manipulate sound through their instrument by articulating the lips, cheeks, and tongue to create a proper airflow. These sustained muscle contractions may result in increased facial and lingual strength and endurance. The purpose of this study was to determine if adult trumpet players who practice at least 6 hrs/wk differed from adult non-trumpet-playing controls in strength and endurance of the lips, cheeks, and tongue. METHODS: This case-control study involved 16 trumpet players, 16 healthy controls balanced for age and sex, and 1 trumpet player 25 years post-Bell's palsy. Strength and endurance of lip, cheek, and tongue muscles were measured using the Iowa Oral Performance Instrument (IOPI Medical, Redmond, WA). Maximum strength was the greatest pressure value of three encouraged trials. Endurance was the length of time the participant was able to sustain 50% of maximum strength. RESULTS: The findings indicate that trumpet players had greater facial strength and endurance, which was objectively quantified using commercially available equipment. The trumpet players had greater cheek strength and greater lip endurance than controls. Tongue strength and endurance did not differ between the trumpet players and controls. Tongue strength was negatively associated with age, which is consistent with previous studies. The trumpet player with a history of Bell's palsy had decreased cheek strength and endurance on his affected side compared to his unaffected side, although this difference was comparable to the differences between right and left cheek strength in trumpet players without a history of facial nerve damage.

Rapid, parallel evolution of field mustard (Brassica rapa) under experimental drought.

Climate change is driving evolutionary and plastic responses in populations, but predicting these responses remains challenging. Studies that combine experimental evolution with ancestor-descendant comparisons allow assessment of the causes, parallelism, and adaptive nature of evolutionary responses, although such studies remain rare, particularly in a climate change context. Here, we created experimental populations of Brassica rapa derived from the same natural population and exposed these replicated populations to experimental drought or watered conditions for four generations. We then grew ancestors and descendants concurrently, following the resurrection approach. Experimental populations under drought showed rapid evolution of earlier flowering time and increased specific leaf area, consistent with a drought escape strategy and observations in natural populations. Evolutionary shifts followed the direction of selection and increased fitness under drought, indicative of adaptive evolution. Evolution to drought also occurred largely in parallel among replicate populations. Further, traits showed phenotypic plasticity to drought, but the direction and effect size of plasticity varied. Our results demonstrate parallel evolution to experimental drought, suggesting that evolution to strong, consistent selection may be predictable. Broadly, our study demonstrates the utility of combining experimental evolution with the resurrection approach to investigate responses to climate change.

The predictive validity of safety climate.

PROBLEM: Safety professionals have increasingly turned their attention to social science for insight into the causation of industrial accidents. One social construct, safety climate, has been examined by several researchers [Cooper, M. D., & Phillips, R. A. (2004). Exploratory analysis of the safety climate and safety behavior relationship. Journal of Safety Research, 35(5), 497-512; Gillen, M., Baltz, D., Gassel, M., Kirsch, L., & Vacarro, D. (2002). Perceived safety climate, job Demands, and coworker support among union and nonunion injured construction workers. Journal of Safety Research, 33(1), 33-51; Neal, A., & Griffin, M. A. (2002). Safety climate and safety behaviour. Australian Journal of Management, 27, 66-76; Zohar, D. (2000). A group-level model of safety climate: Testing the effect of group climate on microaccidents in manufacturing jobs. Journal of Applied Psychology, 85(4), 587-596; Zohar, D., & Luria, G. (2005). A multilevel model of safety climate: Cross-level relationships between organization and group-level climates. Journal of Applied Psychology, 90(4), 616-628] who have documented its importance as a factor explaining the variation of safety-related outcomes (e.g., behavior, accidents). Researchers have developed instruments for measuring safety climate and have established some degree of psychometric reliability and validity. The problem, however, is that predictive validity has not been firmly established, which reduces the credibility of safety climate as a meaningful social construct. The research described in this article addresses this problem and provides additional support for safety climate as a viable construct and as a predictive indicator of safety-related outcomes. METHODS: This study used 292 employees at three locations of a heavy manufacturing organization to complete the 16 item Zohar Safety Climate Questionnaire (ZSCQ) [Zohar, D., & Luria, G. (2005). A multilevel model of safety climate: Cross-level relationships between organization and group-level climates. Journal of Applied Psychology, 90(4), 616-628]. In addition, safety behavior and accident experience data were collected for 5 months following the survey and were statistically analyzed (structural equation modeling, confirmatory factor analysis, exploratory factor analysis, etc.) to identify correlations, associations, internal consistency, and factorial structures. RESULTS: Results revealed that the ZSCQ: (a) was psychometrically reliable and valid, (b) served as an effective predictor of safety-related outcomes (behavior and accident experience), and (c) could be trimmed to an 11 item survey with little loss of explanatory power. IMPACT ON INDUSTRY: Practitioners and researchers can use the ZSCQ with reasonable certainty of the questionnaire's reliability and validity. This provides a solid foundation for the development of meaningful organizational interventions and/or continued research into social factors affecting industrial accident experience.

The prediction of safe lifting behavior: an application of the theory of planned behavior.

PROBLEM: Injuries resulting from lifting are costly, and create significant pain and discomfort. While engineering controls are the most effective means of reducing risks, most organizations continue to rely on manual lifting techniques. The problem, however, is that the use of safe-lifting techniques is inconsistent and managers have a difficult time motivating use of these techniques. Consequently, it is important to understand the factors driving safe-lifting behaviors. METHODS: This study used a survey to apply the theory of planned behavior (Ajzen., I., 1991. The theory of planned behavior. Organization Behavior and Human Processes, 50, 179-211) to safe-lifting among 136 materials management employees at a heavy manufacturing organization. Structural equation modeling and factor analysis were employed to analyze relationships among constructs. RESULTS: Results revealed that perceived behavioral control and intention were the strongest predictors of safe-lifting behavior. Subjective norms, to a lesser degree, were also important influences on intention. Attitudes did not surface as effective direct predictors of safe-lifting behavior, but did affect behavior and intent via mediating factors (subjective norms and perceived behavioral control). Finally, the theory of planned behavior was supported as an effective model explaining safe-lifting behavior, and had potential application for many other safety-related behaviors. IMPACT ON INDUSTRY: Results from this study emphasize the importance of perceived behavioral control as a factor associated with safety-related behavior.