Combining geometric morphometrics, molecular phylogeny, and micropaleontology to assess evolutionary patterns in Mallomonas (Synurophyceae: Heterokontophyta).

Synurophytes, also known as scaled chrysophytes, are ecologically important algae that produce an array of siliceous structures upon which their taxonomy is based. Despite occupying a key position within the photosynthetic heterokonts, the evolutionary history of synurophytes remains poorly constrained. Here, modern and Middle Eocene siliceous scales of the morphotaxon Mallomonas insignis are used as a model to investigate synurophyte evolutionary patterns. Structural details of scale morphology were examined comparatively with scanning electron microscopy and scored for geometric morphometric analyses to assess the stability of shape characters. Although consistent size differences exist (modern scales are larger than Eocene counterparts), the populations cannot be differentiated on the basis of shape or microstructural detail, implying considerable evolutionary stasis in scale morphology. A time-calibrated relaxed molecular clock analysis using a three-gene concatenated data set (27 strains) suggests that the M. insignis lineage predates the available fossil record, having diverged from closest congeneric taxa in the Cretaceous (≥94 Ma). However, the molecular analysis also implies that considerable genetic variability is present within several morphotaxa of Mallomonas, implying that substantial genetic variability has arisen despite the retention of uniform scale morphologies, and resulting in the widespread occurrence of cryptic taxa. Results from the synurophyte lineage are consistent with the notion of protracted ghost ranges (>10 Ma) implied by the molecular phylogenies of other algal groups, together pointing to the paucity of the fossil record of these organisms on these timescales.

High anxiety, young age and long waits increase the need for preoperative sedatives in children.

OBJECTIVE: This prospective, observational study aimed to identify children likely to require sedation preoperatively by measuring anxiety levels using the modified Yale Preoperative Anxiety Scale (mYPAS). Other possible predictive factors for preoperative sedation were also investigated. METHODS: A total of 455 patients aged 2-12 years scheduled for surgery requiring general anaesthesia were enrolled in the study. Patients' anxiety levels were measured using the mYPAS in a preoperative holding area just before patients were separated from their parents or guardians and entered the operating theatre. Anaesthetists blindedto the mYPAS assessments judged whether the child could be separated and enter the operating theatre without a sedative. The ability of the mYPAS to predict the need for preoperative sedation was analysed by receiver operating characteristic (ROC) curve analysis. RESULTS: The optimum mYPAS cut-off for requiring sedatives was 41.7 according to ROC curve analysis. Multivariate logistic regression analysis showed that age, mYPAS>40 and waiting time were independent predictors of the requirement for sedative administration. CONCLUSIONS: High anxiety levels, young age and long waits contributed to the need for preoperative sedation in children.