Lack of spatial structure for phenotypic and genetic variation despite high self-fertilization in Aquilegia canadensis (Ranunculaceae).

By reducing genetically effective population size and gene flow, self-fertilization should lead to strong spatial genetic structure (SGS). Although the short-lived plant Aquilegia canadensis produces large, complex, nectar-rich flowers, 75% of seed, on average, are self-fertilized. Previous experimental results are consistent with the fine-scale SGS expected in selfing populations. In contrast, key floral traits show no evidence of SGS, despite a significant genetic basis to phenotypic variation within populations. In this study, we attempt to resolve these contradictory results by hierarchically sampling plants from two plots nested within each of seven rock outcrops distributed over several km, and comparing the spatial pattern of phenotypic variation in four floral traits with neutral genetic variation at 10 microsatellite loci. For both floral and microsatellite variation, we detected only weak hierarchical structuring and no isolation by distance. The spatial pattern of variation in floral traits was on par with microsatellite polymorphisms. These results suggest regular long-distance gene flow via pollen. At much finer spatial scales within plots, estimates of relatedness were higher (albeit very low) between nearest neighbors than random plants, and declined with increasing distance between neighbors, which is consistent with highly localized seed dispersal. High selfing should yield SGS, but strong inbreeding depression in A. canadensis likely erodes SGS so that reproductive plants exhibit weak structure typical of outcrossers, especially given that outcrossing and consequent gene flow in this species are mediated by strong-flying hummingbirds and bumble bees.

Further clinical validation of the walking impairment questionnaire for classification of walking performance in patients with peripheral artery disease.

The purpose of this study was to further validate the Walking Impairment Questionnaire (WIQ) as a self-report tool to aid in the clinical identification of walking ability of patients with peripheral artery disease (PAD). 132 patients with PAD and an ankle brachial index (ABI) ≤0.90 were enrolled; 123 provided complete data for the WIQ and standardized graded treadmill test. The WIQ scores were consistent with reported scores in other studies. The absolute claudication distance (ACD) ranged from 42.3 to 1589.2 meters; the peak walking time (PWT) ranged from 68 to 1800 seconds. Adjusted WIQ scores were positively and moderately associated with the log transformed ACD and PWT (r > .53, P < .001). Based on the area under the curve analysis, an overall WIQ score of 42.5 or less identified low performers (sensitivity 0.90, specificity 0.73); the combined subscale score of distance and stair of 75.5 or more identified high performers (sensitivity 0.41, specificity 0.90). We conclude that WIQ cut-offs appropriately classify walking performance in PAD patients, making this a potentially useful clinical tool. Consideration needs to be given to incorporating a standardized WIQ version into practice guidelines and the use of innovative strategies to facilitate clinical uptake.