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Relative reproductive success and failure are the ultimate determinants of Darwinian fitness. As such, reproductive traits and variation therein have an immediate and considerable impact on the evolutionary trajectory of lineages. Historically, significant attention has been paid to the ecological and evolutionary processes (ultimate factors) that shape the diversity and canalization of reproductive traits within groups to better our understanding of organismal diversity and population or species resilience. In contrast, the physiological systems that mediate variation within and among species (i.e., the proximate factors) in reproductive traits remain a significant black box. To-date, there is comparatively little information about how proximate mechanisms constrain or promote evolutionary potential in reproductive traits. In this mini-review, we focus on litter size in Eutherian mammals as a trait with relatively well-defined diversity (litter sizes are well-described both within and across species) and for which some genetic determinants have been identified. We discuss both the ultimate and potential proximate determinants of litter size with special attention to the breadth of physiological traits that may act as "toggle" switches for evolution of litter size. We close with a brief discussion of the role that physiological plasticity may play in the evolution of litter size and lay out several forward-looking areas for future research.
RESUMO
Microbacteriophage Fizzles has a 62,078-bp linear double-stranded DNA genome sequence, predicted to contain 104 protein-coding genes. Fizzles is a Siphoviridae actinobacteriophage isolated from an ant hill soil sample collected in Stephenville, TX. Microbacteriophage Fizzles has >83.6% nucleotide identity with microbacteriophages Squash and Nike.
RESUMO
PURPOSE: To retrospectively compare the accuracy of interpretation of initial cervical computerized tomography (CCT) by a non-pediatric radiologist (NPR) versus a pediatric radiologist (PR). METHODS: IRB approval and consent waiver were granted to review all injured children from 2010 to 2014 in the trauma registry with CT and magnetic resonance imaging (MRI) of the cervical spine. Patients with negative CCT who subsequently had positive MRI from a single institution comprised the study group. Patients with negative CCT and MRI, matched by age, gender, and severity scores, comprised the control group. The CCTs from both groups were initially interpreted at the time of service by a NPR. Subsequently, a single PR with 20 years of experience blinded to clinical/imaging data reinterpreted these CCT examinations. CT interpretations were then compared with MRI results and evaluated for statistical significance using SSPS software. The data analysis utilized summary statistics, two-tailed binomial test, and univariate χ2 test. Significance for all comparisons was assessed at P < 0.05. RESULTS: The study group was comprised of the 21 patients with negative CCT and positive MRI. Of the cohort included, 76% (16) were male and 24% (5) were female. The age range was 1 month-17 years, with a mean age of 9.7 years. CCT interpretation by NPR had a specificity of 91.7% (sensitivity 71.2%, positive predictive value 81.3%, and negative predictive value 86.3%) compared with results of MRI. Six of the 21 negative CCTs were interpreted by the PR as positive, mainly craniocervical junction injuries, and confirmed by MRI (28.6%, P < .001 compared with the NPR); no control CCT was interpreted by the PR as positive (sensitivity 100%, positive predictive value 100%, and negative predictive value 58.3%). CONCLUSION: In our retrospective study, a pediatric radiologist has improved recognition of pediatric cervical spine injuries on CT compared with non-pediatric radiologist.
