Striving to do good things: teaching humanities in Canadian medical schools.

We provide the results of a systematic key-informant review of medical humanities curricula at fourteen of Canada's seventeen medical schools. This survey was the first of its kind. We found a wide diversity of views among medical educators as to what constitutes the medical humanities, and a lack of consensus on how best to train medical students in the field. In fact, it is not clear that consensus has been attempted - or is even desirable - given that Canadian medical humanities programs are largely shaped by individual educators' interests, experience and passions. This anarchic approach to teaching the medical humanities contrasts sharply with teaching in the clinical sciences where national accreditation processes attempt to ensure that doctors graduating from different schools have roughly the same knowledge (or at least have passed the same exams). We argue that medical humanities are marginalized in Canadian curricula because they are considered to be at odds philosophically with the current dominant culture of evidence-based medicine (EBM). In such a culture where adhering to a consensual standard is a measure of worth, the medical humanities - which defy easy metrical appraisal - are vulnerable. We close with a plea for medical education to become more comfortable in the borderlands between EBM and humanities approaches.

POLYTOMIES AND THE POWER OF PHYLOGENETIC INFERENCE.

Although phylogenetic hypotheses can provide insights into mechanisms of evolution, their utility is limited by our inability to differentiate simultaneous speciation events (hard polytomies) from rapid cladogenesis (soft polytomies). In the present paper, we tested the potential for statistical power analysis to differentiate between hard and soft polytomies in molecular phytogenies. Classical power analysis typically is used a priori to determine the sample size required to detect a particular effect size at a particular level of significance (a) with a certain power (1 - ß). A posteriori, power analysis is used to infer whether failure to reject a null hypothesis results from lack of an effect or from insufficient data (i.e., low power). We adapted this approach to molecular data to infer whether polytomies result from simultaneous branching events or from insufficient sequence information. We then used this approach to determine the amount of sequence data (sample size) required to detect a positive branch length (effect size). A worked example is provided based on the auklets (Charadriiformes: Alcidae), a group of seabirds among which relationships are represented by a polytomy, despite analyses of over 3000 bp of sequence data. We demonstrate the calculation of effect sizes and sample sizes from sequence data using a normal curve test for difference of a proportion from an expected value and a t-test for a difference of a mean from an expected value. Power analyses indicated that the data for the auklets should be sufficient to differentiate speciation events that occurred at least 100,000 yr apart (the duration of the shortest glacial and interglacial events of the Pleistocene), 2.6 million years ago.

Sequence variation in the guillemot (Alcidae: Cepphus) mitochondrial control region and its nuclear homolog.

We describe sequence variation in the mitochondrial control region and its nuclear homolog in three species and seven subspecies of guillemots (Cepphus spp.). Nuclear homologs of the 5' end of the control region were found in all individuals. Nuclear sequences were approximately 50% divergent from their mitochondrial counterparts and formed a distinct phylogenetic clade; the mitochondrial-nuclear introgression event must have predated the radiation of Cepphus. As in other vertebrates, the guillemot control region has a relatively conserved central block flanked by hypervariable 5' and 3' ends. Mean pairwise interspecific divergence values among control regions were lower than those in other birds. All individuals were heteroplasmic for the number of simple tandem nucleotide repeats (A(n)C) at the 3' end of the control region. Phylogenetic analyses suggest that black guillemots are basal to pigeon and spectacled guillemots, but evolutionary relationships among subspecies remain unresolved, possibly due to incomplete lineage sorting. Describing molecular variation in nuclear homologs of mitochondrial genes is of general interest in phylogenetics because, if undetected, the homologs may confound interpretations of mitochondrial phylogenies.