Kirsten Brown

A test of the chromosomal rearrangement model of speciation in Drosophila pseudoobscura.

Abstract Recent studies suggest that chromosomal rearrangements play a significant role in speciation by preventing recombination and maintaining species persistence despite interspecies gene flow. Factors conferring adaptation or reproductive isolation are maintained in rearranged regions in the face of hybridization, while such factors are eliminated from collinear regions. As a direct test of this rearrangement model, we evaluated the genetic basis of hybrid male sterility in a sympatric species pair, Drosophila pseudoobscura pseudoobscura and D. persimilis, and an allopatric species pair, D. pseudoobscura bogotana and D. persimilis. Our results are consistent with the proposed model: virtually all of the sterility factors in the former pair are associated with three inverted regions, whereas sterility factors are present in the collinear regions in the latter pair. These findings indicate recombination and selection may have eliminated sterility factors outside the inverted regions between D. p. pseudoobscura and D. persimilis, suggesting chromosomal rearrangements may facilitate species persistence despite hybridization.

Anatomical knowledge retention in third-year medical students prior to obstetrics and gynecology and surgery rotations

Surgical anatomy is taught early in medical school training. The literature shows that many physicians, especially surgical specialists, think that anatomical knowledge of medical students is inadequate and nesting of anatomical sciences later in the clinical curriculum may be necessary. Quantitative data concerning this perception of an anatomical knowledge deficit are lacking, as are specifics as to what content should be reinforced. This study identifies baseline areas of strength and weakness in the surgical anatomy knowledge of medical students entering surgical rotations. Third‐year medical students completed a 20–25‐question test at the beginning of the General Surgery and Obstetrics and Gynecology rotations. Knowledge of inguinal anatomy (45.3%), orientation in abdominal cavity (38.8%), colon (27.7%), and esophageal varices (12.8%) was poor. The numbers in parentheses are the percentage of questions answered correctly per topic. In comparing those scores to matched test items from this cohort as first‐year students in the anatomy course, the drop in retention overall was very significant (P = 0.009) from 86.9 to 51.5%. Students also scored lower in questions relating to pelvic organs (46.7%), urogenital development (54.0%), pulmonary development (17.8%), and pregnancy (17.8%). These data showed that indeed, knowledge of surgical anatomy is poor for medical students entering surgical clerkships. These data collected will be utilized to create interactive learning modules, aimed at improving clinically relevant anatomical knowledge retention. These modules, which will be available to students during their inpatient surgical rotations, connect basic anatomy principles to clinical cases, with the ultimate goal of closing the anatomical knowledge gap. Anat Sci Educ 7: 461–468.

A Meta-analysis of Anatomy Laboratory Pedagogies.

The debate regarding anatomy laboratory teaching approaches is ongoing and controversial. To date, the literature has yielded only speculative conclusions because of general methodological weaknesses and a lack of summative empirical evidence. Through a meta‐analysis, this study compared the effectiveness of instructional laboratory approaches used in anatomy education to objectively and more conclusively synthesize the existing literature. Studies published between January 1965 and December 2015 were searched through five databases. Titles and abstracts of the retrieved records were screened using eligibility criteria to determine their appropriateness for study inclusion. Only numerical data were extracted for analysis. A summary effect size was estimated to determine the effects of laboratory pedagogies on learner performance and perceptions data were compiled to provide additional context. Of the 3,035 records screened, 327 underwent full‐text review. Twenty‐seven studies, comprising a total of 7,731 participants, were included in the analysis. The meta‐analysis detected no effect (standardized mean difference = −0.03; 95% CI = −0.16 to 0.10; P = 0.62) on learner performance. Additionally, a moderator analysis detected no effects (P ≥ 0.16) for study design, learner population, intervention length, or specimen type. Across studies, student performance on knowledge examinations was equivalent regardless of being exposed to either dissection or another laboratory instructional strategy. This was true of every comparison investigated (i.e., dissection vs. prosection, dissection vs. digital media, dissection vs. models/modeling, and dissection vs. hybrid). In the context of short‐term knowledge gains alone, dissection is no better, and no worse, than alternative instructional modalities. Clin. Anat. 31:122–133, 2018.

Selective pressures in the human bony pelvis: Decoupling sexual dimorphism in the anterior and posterior spaces.

OBJECTIVES Sexual dimorphism in the human bony pelvis is commonly assumed to be related to the intensity of obstetrical selective pressures. With intense obstetrical selective pressures, there should be greater shape dimorphism; with minimal obstetrical selective pressures, there should be reduced shape dimorphism. This pattern is seen in the nondimorphic anterior spaces and highly dimorphic posterior spaces. Decoupling sexual dimorphism in these spaces may in turn be related to the differential influence of other selective pressures, such as biomechanical ones. MATERIALS AND METHODS The relationship between sexual dimorphism and selective pressures in the human pelvis was examined using five skeletal samples (total female n = 101; male n = 103). Pelvic shape was quantified by collecting landmark coordinate data on articulated pelves. Euclidean distance matrix analysis was used to extract the distances that defined the anterior and posterior pelvic spaces. Sex and body mass were used as proxies for obstetrical and biomechanical selective pressures, respectively. RESULTS MANCOVA analyses demonstrate significant effects of sex and body mass on distances in both the anterior and the posterior spaces. A comparison of the relative contribution of shape variance attributed to each of these factors suggests that the posterior space is more influenced by sex, and obstetrics by proxy, whereas the anterior space is more influenced by body mass, and biomechanics by proxy. CONCLUSIONS Although the overall shape of the pelvis has been influenced by obstetrical and biomechanical selective pressures, there is a differential response within the pelvis to these factors. These results provide new insight into the ongoing debate on the obstetrical dilemma hypothesis.

Curricular response to increase recall and transfer of anatomical knowledge into the obstetrics/gynecology clerkship.

Deficits in retention of anatomy knowledge from the preclinical years to clinical application on the wards have been well documented in the medical education literature. We developed and evaluated a web and laboratory‐based curriculum to address deficits in anatomy knowledge retention and to increase anatomy knowledge recall through repetition and application of clinical concepts during the obstetrics and gynecology (Ob/Gyn) core clinical clerkship. Using principles of adult learning and instructional design, a curriculum was designed consisting of (1) interactive, case‐based e‐modules reviewing clinically relevant anatomical topics and (2) a hands‐on laboratory session reinforcing the content of the e‐modules, with the practice of clinical techniques using anatomical cadaveric dissections. The curriculums effectiveness was evaluated by using multiple choice testing and comparing baseline and final test scores. For questions testing content directly covered in this curriculum, mean final scores increased by 14.3% (P < 0.001). In contrast, for questions not directly addressed in this curriculum, mean final scores did not increase significantly, only by 6.0% (P = 0.31). Questions related to the uterus showed the greatest gains in final scores (30.3% improvement, P = 0.002). A curriculum with web‐based preparatory material and a hands‐on gross anatomy laboratory session effectively addresses deficits in anatomy retention and improves anatomical knowledge recall for medical students on a clinical clerkship. In the future, the authors plan to conduct a multicenter study to further evaluate the ability of this curriculum to improve clinically relevant anatomical knowledge. Anat Sci Educ 9: 337–343.

Breaking with tradition: A scoping meta-analysis analyzing the effects of student-centered learning and computer-aided instruction on student performance in anatomy: Effectiveness of Student Centered and Computer-Aided Learning in Anatomy

While prior meta‐analyses in anatomy education have explored the effects of laboratory pedagogies and histology media on learner performance, the effects of student‐centered learning (SCL) and computer‐aided instruction (CAI) have not been broadly evaluated. This research sought to answer the question, “How effective are student‐centered pedagogies and CAI at increasing student knowledge gains in anatomy compared to traditional didactic approaches?” Relevant studies published within the past 51 years were searched using five databases. Predetermined eligibility criteria were applied to the screening of titles and abstracts to discern their appropriateness for study inclusion. A summary effect size was estimated to determine the effects of SCL and CAI on anatomy performance outcomes. A moderator analysis of study features was also performed. Of the 3,035 records screened, 327 underwent full‐text review. Seven studies, which comprised 1,564 participants, were included in the SCL analysis. An additional 19 studies analyzed the effects of CAI in the context of 2,570 participants. Upon comparing SCL to traditional instruction, a small positive effect on learner performance was detected (standardized mean difference (SMD = 0.24; [CI = 0.07, 0.42]; P = 0.006). Likewise, students with CAI exposure moderately outscored those with limited or no access to CAI (SMD = 0.59; [CI = 0.20, 0.98]; P = 0.003). Further analysis of CAI studies identified effects (P ≤ 0.001) for learner population, publication period, interventional approach, and intervention frequency. Overall, learners exposed to SCL and supplemental CAI outperformed their more classically‐trained peers as evidenced by increases in short‐term knowledge gains. Anat Sci Educ.