11 research outputs found
Evolutionary consequences of habitat loss for Pacific anadromous salmonids
Large portions of anadromous salmonid habitat in the western United States has been lost because of dams and other blockages. This loss has the potential to affect salmonid evolution through natural selection if the loss is biased, affecting certain types of habitat differentially, and if phenotypic traits correlated with those habitat types are heritable. Habitat loss can also affect salmonid evolution indirectly, by reducing genetic variation and changing its distribution within and among populations. In this paper, we compare the characteristics of lost habitats with currently accessible habitats and review the heritability of traits which show correlations with habitat/environmental gradients. We find that although there is some regional variation, inaccessible habitats tend to be higher in elevation, wetter and both warmer in the summer and colder in the winter than habitats currently available to anadromous salmonids. We present several case studies that demonstrate either a change in phenotypic or life history expression or an apparent reduction in genetic variation associated with habitat blockages. These results suggest that loss of habitat will alter evolutionary trajectories in salmonid populations and Evolutionarily Significant Units. Changes in both selective regime and standing genetic diversity might affect the ability of these taxa to respond to subsequent environmental perturbations. Both natural and anthropogenic and should be considered seriously in developing management and conservation strategies
Modeling Through Transmission Ultrasonics for Controlling the Fusion Bonding of Composites
Fusion bonding is an attractive technology for joining polymer matrix composites. The advantages of using this technique are good environmental resistance, high strength (ideally that of the parent materials), and the lack of any mechanical fasteners. This study presents a model for predicting the through transmission ultrasonic (TTU) amplitude response of multilayered composite media having a thermal gradient through the thickness, as seen in a fusion bonding process. The received TTU amplitude is predicted as a function of temperature at the interface of interest. The model response to frequency and layer stacking sequence was investigated.</p
EPIC Modeling of Soil Organic Carbon Sequestration in Croplands of Iowa
Depending on management, soil organic carbon (SOC) is a potential source or sink for atmospheric CO2. We used the EPIC model to study impacts of soil and crop management on SOC in corn (Zea mays L.) and soybean (Glycine max L. Merr.) croplands of Iowa. The National Agricultural Statistics Service crops classification maps were used to identify cornâsoybean areas. Soil properties were obtained from a combination of SSURGO and STATSGO databases. Daily weather variables were obtained from first order meteorological stations in Iowa and neighboring states. Data on crop management, fertilizer application and tillage were obtained from publicly available databases maintained by the NRCS, USDA-Economic Research Service (ERS), and Conservation Technology Information Center. The EPIC model accurately simulated state averages of crop yields during 1970â2005 (R2 = 0.87). Simulated SOC explained 75% of the variation in measured SOC. With current trends in conservation tillage adoption, total stock of SOC (0â20 cm) is predicted to reach 506 Tg by 2019, representing an increase of 28 Tg with respect to 1980. In contrast, when the whole soil profile was considered, EPIC estimated a decrease of SOC stocks with time, from 1835 Tg in 1980 to 1771 Tg in 2019. Hence, soil depth considered for calculations is an important factor that needs further investigation. Soil organic C sequestration rates (0â20 cm) were estimated at 0.50 to 0.63 Mg haâ1 yrâ1 depending on climate and soil conditions. Overall, combining land use maps with EPIC proved valid for predicting impacts of management practices on SOC. However, more data on spatial and temporal variation in SOC are needed to improve model calibration and validation
Holocene glacier fluctuations, Waskey Lake, northeastern Ahklun Mountains, southwestern Alaska
Radial growth rate increases in naturally occurring ponderosa pine trees: a late-20th century CO2 fertilization effect?
Homelessness and dog ownership: an investigation into animal empathy, attachment, crime, drug use, health and public opinion
Sex difference in homicide: comparing male and female violent crimes in Korea
The comparison of the South Korean male and female homicide offendersâ characteristics and crime scene behaviours is presented in this study. A total of 537 cases of homicide offenders prosecuted in Korea between 2006 and 2010 were analyzed in terms of offendersâ characteristics, victimâoffender interaction, places of crime, and crime scene actions. Significant differences between male and female offenders were revealed in prior criminal history, offendersâ personal characteristics, choice of victim, crime scene behaviours during and after the homicide, and choice of weapon. The parallel with the gender differences in homicides found in Western countries is discussed as well as the possible explanations for the gender-related characteristics found in this study.N/