Rethinking phylogenetic comparative methods, bioRxiv, 2017-12-06
As a result of the process of descent with modification, closely related species tend to be similar to one another in a myriad different ways. In statistical terms, this means that traits measured on one species will not be independent of traits measured on others. Since their introduction in the 1980s, phylogenetic comparative methods (PCMs) have been framed as a solution to this problem. In this paper, we argue that this way of thinking about PCMs is deeply misleading. Not only has this sowed widespread confusion in the literature about what PCMs are doing but has led us to develop methods that are susceptible to the very thing we sought to build defenses against --- unreplicated evolutionary events. Through three Case Studies, we demonstrate that the susceptibility to singular events is indeed a recurring problem in comparative biology that links several seemingly unrelated controversies. In each Case Study we propose a potential solution to the problem. While the details of our proposed solutions differ, they share a common theme unifying hypothesis testing with data-driven approaches (which we term phylogenetic natural history) to disentangle the impact of singular evolutionary events from that of the factors we are investigating. More broadly, we argue that our field has, at times, been sloppy when weighing evidence in support of causal hypotheses. We suggest that one way to refine our inferences is to re-imagine phylogenies as probabilistic graphical models; adopting this way of thinking will help clarify precisely what we are testing and what evidence supports our claims.
biorxiv evolutionary-biology 100-200-users 2017Assessing the Landscape of U.S. Postdoctoral Salaries, bioRxiv, 2017-12-04
AbstractPurposePostdocs make up a significant portion of the biomedical workforce. However, data about the postdoctoral position are generally scarce, including salary data. The purpose of this study was to request, obtain and interpret actual salaries, and the associated job titles, for postdocs at U.S. public institutions.MethodologyFreedom of Information Act Requests were submitted to U.S. public institutions estimated to have at least 300 postdocs according to the National Science Foundation’s Survey of Graduate Students and Postdocs. Salaries and job titles of postdoctoral employees as of December 1st, 2016 were requested.FindingsSalaries and job titles for over 13,000 postdocs at 52 public U.S. institutions and 1 private institution around the date of December 1st, 2016 were received, and individual postdoc names were also received for approximately 7,000 postdocs. This study shows evidence of gender-related salary discrepancies, a significant influence of job title description on postdoc salary, and a complex relationship between salaries and the level of institutional NIH funding.ValueThese results provide insights into the ability of institutions to collate actual payroll-type data related to their postdocs, highlighting difficulties faced in tracking, and reporting data on this population. Ultimately, these types of efforts, aimed at increasing transparency, may lead to improved tracking and support for postdocs at all U.S. institutions.
biorxiv scientific-communication-and-education 100-200-users 2017Oxford Nanopore sequencing in a research-based undergraduate course, bioRxiv, 2017-12-01
AbstractBackgroundNanopore sequencing is a third generation genomic sequencing method that offers real time sequencing of DNA samples. Nanopore sequencing is an excellent tool for teaching because it involves cutting-edge sequencing methods and also helps students to develop a research mindset, where students can learn to identify and resolve problems that arise during an experiment.ResultsWe, as a group of undergraduate biology students, were able to use nanopore sequencing to analyze a sample of pupfish DNA. We were able to accomplish this without computer science backgrounds and only some basic DNA extraction training. Although there were issues, such as inconsistent results across runs, we found it useful as a research learning experience and an application of the skills we learned.ConclusionsAs students, it was exciting to be able to experience this technology first hand and apply what we learned in the classroom. Nanopore sequencing holds potential for DNA sequencing of large fragments in real time. It allows students to be acquainted with novel technologies and the theories behind them. However, as with all new techniques, it does not have the same established support, and when students run into difficulties while using nanopore sequencing, it is often difficult to identify what went wrong.
biorxiv genomics 100-200-users 2017Community-driven data analysis training for biology, bioRxiv, 2017-11-30
AbstractThe primary problem with the explosion of biomedical datasets is not the data itself, not computational resources, and not the required storage space, but the general lack of trained and skilled researchers to manipulate and analyze these data. Eliminating this problem requires development of comprehensive educational resources. Here we present a community-driven framework that enables modern, interactive teaching of data analytics in life sciences and facilitates the development of training materials. The key feature of our system is that it is not a static but a continuously improved collection of tutorials. By coupling tutorials with a web-based analysis framework, biomedical researchers can learn by performing computation themselves through a web-browser without the need to install software or search for example datasets. Our ultimate goal is to expand the breadth of training materials to include fundamental statistical and data science topics and to precipitate a complete re-engineering of undergraduate and graduate curricula in life sciences.
biorxiv bioinformatics 100-200-users 2017Laminar-specific cortical dynamics in human visual and sensorimotor cortices, bioRxiv, 2017-11-29
AbstractLower frequency, feedback, activity in the alpha and beta range is thought to predominantly originate from infragranular cortical layers, whereas feedforward signals in the gamma range stem largely from supragranular layers. Distinct anatomical and spectral channels may therefore play specialized roles in communication within hierarchical cortical networks; however, empirical evidence for this organization in humans is limited. We leverage high precision MEG to test this proposal, directly and non-invasively, in human participants during visually guided actions. Visual alpha activity mapped onto deep cortical laminae, whereas visual gamma activity predominantly arose from superficial laminae. This laminar-specificity was echoed in sensorimotor beta and gamma activity. Visual gamma activity scaled with task demands in a way compatible with feedforward signaling. For sensorimotor activity, we observed a more complex relationship with feedback and feedforward processes. Distinct frequency channels thus operate in a laminar-specific manner, but with dissociable functional roles across sensory and motor cortices.
biorxiv neuroscience 100-200-users 2017A design framework and exemplar metrics for FAIRness, bioRxiv, 2017-11-28
Abstract“FAIRness” - the degree to which a digital resource is Findable, Accessible, Interoperable, and Reusable - is aspirational, yet the means of reaching it may be defined by increased adherence to measurable indicators. We report on the production of a core set of semi-quantitative metrics having universal applicability for the evaluation of FAIRness, and a rubric within which additional metrics can be generated by the community. This effort is the output from a stakeholder-representative group, founded by a core of FAIR principles’ co-authors and drivers. We now seek input from the community to more broadly discuss their merit.
biorxiv scientific-communication-and-education 100-200-users 2017