Population genomics of Drosophila suzukii reveal longitudinal population structure and signals of migrations in and out of the continental United States.

Drosophila suzukii, or spotted-wing drosophila, is now an established pest in many parts of the world, causing significant damage to numerous fruit crop industries. Native to East Asia, D. suzukii infestations started in the United States a decade ago, occupying a wide range of climates. To better understand invasion ecology of this pest, knowledge of past migration events, population structure, and genetic diversity is needed. In this study, we sequenced whole genomes of 237 individual flies collected across the continental United States, as well as several sites in Europe, Brazil, and Asia, to identify and analyze hundreds of thousands of genetic markers. We observed strong population structure between Western and Eastern US populations, but no evidence of any population structure between different latitudes within the continental United States, suggesting that there are no broad-scale adaptations occurring in response to differences in winter climates. We detect admixture from Hawaii to the Western United States and from the Eastern United States to Europe, in agreement with previously identified introduction routes inferred from microsatellite analysis. We also detect potential signals of admixture from the Western United States back to Asia, which could have important implications for shipping and quarantine policies for exported agriculture. We anticipate this large genomic dataset will spur future research into the genomic adaptations underlying D. suzukii pest activity and development of novel control methods for this agricultural pest.

Rapid Global Spread of wRi-like Wolbachia across Multiple Drosophila.

Maternally transmitted Wolbachia, Spiroplasma, and Cardinium bacteria are common in insects [1], but their interspecific spread is poorly understood. Endosymbionts can spread rapidly within host species by manipulating host reproduction, as typified by the global spread of wRi Wolbachia observed in Drosophila simulans [2, 3]. However, because Wolbachia cannot survive outside host cells, spread between distantly related host species requires horizontal transfers that are presumably rare [4-7]. Here, we document spread of wRi-like Wolbachia among eight highly diverged Drosophila hosts (10-50 million years) over only about 14,000 years (5,000-27,000). Comparing 110 wRi-like genomes, we find ≤0.02% divergence from the wRi variant that spread rapidly through California populations of D. simulans. The hosts include both globally invasive species (D. simulans, D. suzukii, and D. ananassae) and narrowly distributed Australian endemics (D. anomalata and D. pandora) [8]. Phylogenetic analyses that include mtDNA genomes indicate introgressive transfer of wRi-like Wolbachia between closely related species D. ananassae, D. anomalata, and D. pandora but no horizontal transmission within species. Our analyses suggest D. ananassae as the Wolbachia source for the recent wRi invasion of D. simulans and D. suzukii as the source of Wolbachia in its sister species D. subpulchrella. Although six of these wRi-like variants cause strong cytoplasmic incompatibility, two cause no detectable reproductive effects, indicating that pervasive mutualistic effects [9, 10] complement the reproductive manipulations for which Wolbachia are best known. "Super spreader" variants like wRi may be particularly useful for controlling insect pests and vector-borne diseases with Wolbachia transinfections [11].

Using the Readiness for Clerkship and Residency Surveys to Evaluate the Effectiveness of Four MD Programs: A Cross-Institutional Generalizability Study.

PURPOSE: The importance of confidence for learning and performance makes learners' perceptions of readiness for the next level of training valuable indicators of curricular success. The "Readiness for Clerkship" (RfC) and "Readiness for Residency" (RfR) surveys have been shown to provide reliable ratings of the relative effectiveness of various aspects of training. This study examines the generalizability of those results. METHOD: Surveys were administered at four medical schools approximately four months after the start of clerkship and eight months after the start of residency during 2013-2015. Collected data were anonymized. A total of 647 medical students and 483 residents participated. RESULTS: Reliabilities of G = 0.8 could be obtained with only 6 to 12 medical students and 8 to 15 residents. Within MD programs, no meaningful differences in item ratings were observed across cohorts. Residents in each school consistently rated themselves higher than clerks on the majority of Medical Expert and Communicator competencies common to both surveys. Similar strengths and weaknesses were identified across programs, but differences were observed on five clerkship items and one residency item. CONCLUSIONS: Across four MD programs, the RfC and RfR surveys provided reliable ratings of the relative effectiveness of aspects of training with small numbers of respondents. The capacity of these surveys to efficiently identify perceived strengths and weaknesses held by cohorts of learners may, thereby, facilitate program improvement.

Readiness for Residency: A Survey to Evaluate Undergraduate Medical Education Programs.

BACKGROUND: Health professions programs continue to search for meaningful and efficient ways to evaluate the quality of education they provide and support ongoing program improvement. Despite flaws inherent in self-assessment, recent research suggests that aggregated self-assessments reliably rank aspects of competence attained during preclerkship MD training. Given the novelty of those observations, the purpose of this study was to test their generalizability by evaluating an MD program as a whole. METHOD: The Readiness for Residency Survey (RfR) was developed and aligned with the published Readiness for Clerkship Survey (RfC), but focused on the competencies expected to be achieved at graduation. The RfC and RfR were administered electronically four months after the start of clerkship and six months after the start of residency, respectively. Generalizability and decision studies examined the extent to which specific competencies were achieved relative to one another. RESULTS: The reliability of scores assigned by a single resident was G = 0.32. However, a reliability of G = 0.80 could be obtained by averaging over as few as nine residents. Whereas highly rated competencies in the RfC resided within the CanMEDS domains of professional, communicator, and collaborator, five additional medical expert competencies emerged as strengths when the program was evaluated after completion by residents. CONCLUSIONS: Aggregated resident self-assessments obtained using the RfR reliably differentiate aspects of competence attained over four years of undergraduate training. The RfR and RfC together can be used as evaluation tools to identify areas of strength and weakness in an undergraduate medical education program.