BackgroundConvergent evolution, the repeated evolution of similar phenotypes in independent lineages, provides natural replicates to study mechanisms of evolution. Cases of convergent evolution might have the same underlying developmental and genetic bases, implying that some evolutionary trajectories might be predictable. In a classic example of convergent evolution, most freshwater populations of threespine stickleback fish have independently evolved a reduction of gill raker number to adapt to novel diets. Gill rakers are a segmentally reiterated set of dermal bones important for fish feeding. A previous large quantitative trait locus (QTL) mapping study using a marine × freshwater F2 cross identified QTL on chromosomes 4 and 20 with large effects on evolved gill raker reduction.ResultsBy examining skeletal morphology in adult and developing sticklebacks, we find heritable marine/freshwater differences in gill raker number and spacing that are specified early in development. Using the expression of the Ectodysplasin receptor (Edar) gene as a marker of raker primordia, we find that the differences are present before the budding of gill rakers occurs, suggesting an early change to a lateral inhibition process controlling raker primordia spacing. Through linkage mapping in F2 fish from crosses with three independently derived freshwater populations, we find in all three crosses QTL overlapping both previously identified QTL on chromosomes 4 and 20 that control raker number. These two QTL affect the early spacing of gill raker buds.ConclusionsCollectively, these data demonstrate that parallel developmental genetic features underlie the convergent evolution of gill raker reduction in freshwater sticklebacks, suggesting that even highly polygenic adaptive traits can have a predictable developmental genetic basis.

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The incidence of developing AKI as a consequence of AUGIB in the elderly is very common. Those with AKI tend to have a more complicated clinical course in the hospital.

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INTRODUCTION: The incidence of peptic ulcer disease (PUD) has been decreasing over time with Helicobacter pylori eradication and use of acid-suppressing therapies. However, PUD remains a common cause of hospitalization in the United States. We aimed to evaluate contemporary national trends in the incidence, treatment patterns, and outcomes for PUD-related hospitalizations and compare care delivery by hospital rurality. METHODS: Data from the National Inpatient Sample were used to estimate weighted annual rates of PUD-related hospitalizations. Temporal trends were evaluated by joinpoint regression and expressed as annual percent change with 95% confidence intervals (CIs). We determined the proportion of hospitalizations requiring endoscopic and surgical interventions, stratified by clinical presentation and rurality. Multivariable logistic regression was used to assess independent predictors of in-hospital mortality and postoperative morbidity. RESULTS: There was a 25.8% reduction (P < 0.001) in PUD-related hospitalizations from 2005 to 2014, although the rate of decline decreased from −7.2% per year (95% CI: 13.2% to −0.7%) before 2008 to −2.1% per year (95% CI: 3.0% to −1.1%) after 2008. In-hospital mortality was 2.4% (95% CI: 2.4%–2.5%). Upper endoscopy (84.3% vs 78.4%, P < 0.001) and endoscopic hemostasis (26.1% vs 16.8%, P < 0.001) were more likely to be performed in urban hospitals, whereas surgery was performed less frequently (9.7% vs 10.5%, P < 0.001). In multivariable logistic regression, patients managed in urban hospitals were at higher risk for postoperative morbidity (odds ratio 1.16 [95% CI: 1.04–1.29]), but not death (odds ratio 1.11 [95% CI: 1.00–1.23]). DISCUSSION: The rate of decline in hospitalization rates for PUD has stabilized over time, although there remains significant heterogeneity in treatment patterns by hospital rurality.