165 Works

Data from: Genetic drift and selection in many-allele range expansions

Bryan T. Weinstein, Maxim O. Lavrentovich, Wolfram Moebius, Andrew W. Murray, David R. Nelson & Wolfram Möbius
We experimentally and numerically investigate the evolutionary dynamics of four competing strains of E. coli with differing expansion velocities in radially expanding colonies. We compare experimental measurements of the average fraction, correlation functions between strains, and the relative rates of genetic domain wall annihilations and coalescences to simulations modeling the population as a one-dimensional ring of annihilating and coalescing random walkers with deterministic biases due to selection. The simulations reveal that the evolutionary dynamics can...

Competition for resources can promote the divergence of social learning phenotypes

R. Tucker Gilman, Fern Johnson & Marco Smolla
Social learning occurs when animals acquire knowledge or skills by observing or interacting with others, and is the fundamental building block of culture. Within populations, some individuals use social learning more frequently than others, but why social learning phenotypes differ among individuals is poorly understood. We modelled the evolution of social learning frequency in a system where foragers compete for resources and there are many different foraging options to learn about. Social learning phenotypes diverged...

Divalent cations bind to phosphoinositides to induce ion and isomer specific propensities for nano-cluster initiation in bilayer membranes

Ravi Radhakrishnan, Ryan Bradley, Paul Janmey & David Slochower
We report all-atom molecular dynamics simulations of physiologically composed asymmetric bilayers containing phosphoinositides in the presence of monovalent and divalent cations. We have characterized the molecular mechanism by which these divalent cations interact with phosphoinositides. Calcium desolvates more readily, consistent with single-molecule calculations, and forms a network of ionic-like bonds that serve as a "molecular glue'' that allows a single ion to coordinate with up to three phosphatidylinositol-(4,5)-bisphosphate lipids. The phosphatidylinositol-(3,5)-bisphosphate isomer shows no such...

Wolbachia-infected ant colonies have increased reproductive investment and an accelerated life cycle

Rohini Singh & Timothy Linksvayer
Wolbachia is a widespread group of maternally-transmitted endosymbiotic bacteria that often manipulates the reproductive strategy and life history of its hosts to favor its own transmission. Wolbachia mediated phenotypic effects are well characterized in solitary hosts, although evidence of similar effects are rare in eusocial insects, such as ants. The invasive pharaoh ant, Monomorium pharaonis, shows natural variation in Wolbachia infection between colonies and can be readily bred under laboratory conditions. We previously showed that...

Data from: Ant collective behavior is heritable and shaped by selection

Justin Troy Walsh, Simon Garnier & Timothy Arnold Linksvayer
Collective behaviors are widespread in nature and usually assumed to be strongly shaped by natural selection. However, the degree to which variation in collective behavior is heritable and has fitness consequences -- the two prerequisites for evolution by natural selection -- is largely unknown. We used a new pharaoh ant ( Monomorium pharaonis ) mapping population to estimate the heritability, genetic correlations, and fitness consequences of three collective behaviors (foraging, aggression, and exploration) as well...

Data from: Cholesterol and ORP1L dependent clustering of dynein on endolysosmes in cells 2 revealed by super resolution microscopy

Melike Lakadamyali & Shreyasi Thakur
The sub-cellular positioning of endolysosomes is crucial for regulating their function. Particularly, the positioning of endolysosomes between the cell periphery versus the peri-nuclear region impacts autophagy, mTOR (mechanistic target of rapamycin) signaling and other processes. The mechanisms that regulate the positioning of endolysosomes at these two locations are still being uncovered. Here, using quantitative super-resolution microscopy in intact cells, we show that the retrograde motor dynein forms nano-clusters on endolysosomal membranes containing 1-2 dyneins, with...

Did shell-crushing predators drive the evolution of ammonoid septal shape?

Erynn Johnson, Briana DiMarco, David Peterman, Aja Carter & Warren Allmon
For centuries, paleontologists have sought functional explanations for the uniquely complex internal walls (septa) of ammonoids, extinct shelled cephalopods. Ammonoid septa developed increasingly complex fractal margins, unlike any modern shell morphologies, throughout more than 300 million years of evolution. Some have suggested these morphologies provided increased resistance to shell-crushing predators. We perform the first physical compression experiments on model ammonoid septa using controlled, theoretical morphologies generated by computer-aided design and 3D printing. These biomechanical experiments...

Data from: Complex disease and phenotype mapping in the domestic dog

Jessica J. Hayward, Marta G. Castelhano, Kyle C. Oliveira, Elizabeth Corey, Cheryl Balkman, Tara L. Baxter, Margret L. Casal, Sharon A. Center, Meiying Fang, Susan J. Garrison, Sara E. Kalla, Pavel Korniliev, Michael I. Kotlikoff, N. Sydney Moise, Laura M. Shannon, Kenneth W. Simpson, Nathan B. Sutter, Rory J. Todhunter & Adam R. Boyko
The domestic dog is becoming an increasingly valuable model species in medical genetics, showing particular promise to advance our understanding of cancer and orthopaedic disease. Here we undertake the largest canine genome-wide association study to date, with a panel of over 4,200 dogs genotyped at 180,000 markers, to accelerate mapping efforts. For complex diseases, we identify loci significantly associated with hip dysplasia, elbow dysplasia, idiopathic epilepsy, lymphoma, mast cell tumour and granulomatous colitis; for morphological...

Data from: Selection biases the prevalence and type of epistasis along adaptive trajectories

Jeremy A. Draghi & Joshua B. Plotkin
The contribution to an organism's phenotype from one genetic locus may depend upon the status of other loci. Such epistatic interactions among loci are now recognized as fundamental to shaping the process of adaptation in evolving populations. Although little is known about the structure of epistasis in most organisms, recent experiments with bacterial populations have concluded that antagonistic interactions abound and tend to de-accelerate the pace of adaptation over time. Here, we use the NK...

Data from: Detecting epistasis from an ensemble of adapting populations

David M. McCandlish, Jakub Otwinowski & Joshua B. Plotkin
The role that epistasis plays during adaptation remains an outstanding problem, which has received considerable attention in recent years. Most of the recent empirical studies are based on ensembles of replicate populations that adapt in a fixed, laboratory controlled condition. Researchers often seek to infer the presence and form of epistasis in the fitness landscape from the time-evolution of various statistics averaged across the ensemble of populations. Here we provide a rigorous analysis of what...

Data from: Biophysically inspired model for functionalized nanocarrier adhesion to cell surface: roles of protein expression and mechanical factors

N. Ramakrishnan, Richard W. Tourdot, David M. Eckmann, Portonovo S. Ayyaswamy, Vladimir M. Muzykantov & Ravi Radhakrishnan
In order to achieve selective targeting of affinity–ligand coated nanoparticles to the target tissue, it is essential to understand the key mechanisms that govern their capture by the target cell. Next-generation pharmacokinetic (PK) models that systematically account for proteomic and mechanical factors can accelerate the design, validation and translation of targeted nanocarriers (NCs) in the clinic. Towards this objective, we have developed a computational model to delineate the roles played by target protein expression and...

Data from: Strategic use of affiliative vocalizations by wild female baboons

Joan B. Silk, Robert M. Seyfarth & Dorothy L. Cheney
Although vocal production in non-human primates is highly constrained, individuals appear to have some control over whether to call or remain silent. We investigated how contextual factors affect the production of grunts given by wild female chacma baboons, Papio ursinus, during social interactions. Females grunted as they approached other adult females 28% of the time. Supporting previous research, females were much more likely to grunt to mothers with young infants than to females without infants....

Data from: An inversion supergene in Drosophila underpins latitudinal clines in survival traits

Esra Durmaz, Clare Benson, Martin Kapun, Paul Schmidt & Thomas Flatt
Chromosomal inversions often contribute to local adaptation across latitudinal clines, but the underlying selective mechanisms remain poorly understood. We and others have previously shown that a clinal inversion polymorphism in Drosophila melanogaster, In(3R)Payne, underpins body size clines along the North American and Australian east coasts. Here we ask whether this polymorphism also contributes to clinal variation in other fitness-related traits, namely survival traits (lifespan, survival upon starvation, and survival upon cold shock). We generated homokaryon...

Data from: ASSET: analysis of sequences of synchronous events in massively parallel spike trains

Emiliano Torre, Carlos Canova, Michael Denker, Goerge Gerstein, Moritz Helias, Sonja Grün & George Gerstein
With the ability to observe the activity from large numbers of neurons simultaneously using modern recording technologies, the chance to identify sub-networks involved in coordinated processing increases. Sequences of synchronous spike events (SSEs) constitute one type of such coordinated spiking that propagates activity in a temporally precise manner. The synfire chain was proposed as one potential model for such network processing. Previous work introduced a method for visualization of SSEs in massively parallel spike trains,...

Data from: Stimulation-based control of dynamic brain networks

Sarah Feldt Muldoon, Fabio Pasqualetti, Shi Gu, Matthew Cieslak, Scott T. Grafton, Jean M. Vettel & Danielle S. Bassett
The ability to modulate brain states using targeted stimulation is increasingly being employed to treat neurological disorders and to enhance human performance. Despite the growing interest in brain stimulation as a form of neuromodulation, much remains unknown about the network-level impact of these focal perturbations. To study the system wide impact of regional stimulation, we employ a data-driven computational model of nonlinear brain dynamics to systematically explore the effects of targeted stimulation. Validating predictions from...

Data from: Comparing radiomic classifiers and classifier ensembles for detection of peripheral zone prostate tumors on T2-weighted MRI: a multi-site study

Satish E. Viswanath, Prathyush V. Chirra, Michael C. Yim, Neil M. Rofsky, Andrei S. Purysko, Mark A. Rosen, Nicolas B. Bloch & Anant Madabhushi
Background: For most computer-aided diagnosis (CAD) problems involving prostate cancer detection via medical imaging data, the choice of classifier has been largely ad hoc, or been motivated by classifier comparison studies that have involved larger synthetic datasets. More significantly, it is currently unknown how classifier choices and trends generalize across multiple institutions, due to heterogeneous acquisition and intensity characteristics (especially when considering MR imaging data). In this work, we empirically evaluate and compare a number...

Data from: A clinal polymorphism in the insulin signaling transcription factor foxo contributes to life-history adaptation in Drosophila

Esra Durmaz, Subhash Rajpurohit, Nicolas Betancourt, Daniel K. Fabian, Martin Kapun, Paul Schmidt & Thomas Flatt
A fundamental aim of adaptation genomics is to identify polymorphisms that underpin variation in fitness traits. In D. melanogaster latitudinal life-history clines exist on multiple continents and make an excellent system for dissecting the genetics of adaptation. We have previously identified numerous clinal SNPs in insulin/insulin-like growth factor signaling (IIS), a pathway known from mutant studies to affect life history. However, the effects of natural variants in this pathway remain poorly understood. Here we investigate...

Data from: Imputation of canine genotype array data using 365 whole-genome sequences improves power of genome-wide association studies

Jessica J. Hayward, Michelle E. White, Michael Boyle, Laura M Shannon, Margret L. Casal, Marta G. Castelhano, Sharon A. Center, Vicki N. Meyers-Wallen, Kenneth W. Simpson, Nathan B. Sutter, Rory J. Todhunter & Adam R. Boyko
Genomic resources for the domestic dog have improved with the widespread adoption of a 173k SNP array platform and updated reference genome. SNP arrays of this density are sufficient for detecting genetic associations within breeds but are underpowered for finding associations across multiple breeds or in mixed-breed dogs, where linkage disequilibrium rapidly decays between markers, even though such studies would hold particular promise for mapping complex diseases and traits. Here we introduce an imputation reference...

Auditory cortex shapes sounds responses in the inferior colliculus

Jennifer Blackwell, Winnie Rao, Mariella DeBiasi & Maria Geffen
The extensive feedback from the auditory cortex (AC) to the inferior colliculus (IC) supports critical aspects of auditory behavior, but has not been extensively characterized. Previous studies demonstrated that activity in IC is altered by focal electrical stimulation and pharmacological inactivation of AC, but these methods lack the ability to selectively manipulate projection neurons. We measured the effects of selective optogenetic modulation of cortico-collicular feedback projections on IC sound responses in mice. Activation of feedback...

Data from: Population structure of the Chagas disease vector, Triatoma infestans, at the urban-rural interface

Erica A. Foley, Camilo E. Khatchikian, Josephine Hwang, Jenny Ancca-Juárez, Katty Borrini-Mayori, Victor R. Quispe-Machaca, Michael Z. Levy & Dustin Brisson
The increasing rate of biological invasions resulting from human transport or human-mediated changes to the environment have had devastating ecologic and public health consequences. The kissing bug, Triatoma infestans, has dispersed through the Peruvian city of Arequipa. The biological invasion of this insect has resulted in a public health crisis, putting thousands of residents of this city at risk of infection by Trypanosoma cruzi and subsequent development of Chagas disease. Here we show that populations...

Data from: The effect of population bottlenecks on mutation rate evolution in asexual populations

Yevgeniy Raynes, Angela L. Halstead & Paul D. Sniegowski
In the absence of recombination, a mutator allele can spread through a population by hitchhiking with beneficial mutations that appear in its genetic background. Theoretical studies over the past decade have shown that the survival and fixation probability of beneficial mutations can be severely reduced by population size bottlenecks. Here, we use computational modelling and evolution experiments with the yeast S. cerevisiae to examine whether population bottlenecks can affect mutator dynamics in adapting asexual populations....

Data from: Phenotypic correlation between queen and worker brood care supports the role of maternal care in the evolution of eusociality

Justin T. Walsh, Lisa Signorotti, Timothy A. Linksvayer & Patrizia D'Ettorre
Cooperative brood care by siblings, a defining feature of eusociality, is hypothesized to be evolutionarily derived from maternal care via shifts in the timing of the expression of genes underlying maternal care. If sibling and maternal care share a genetic basis, the two behaviors are expected to be genetically and phenotypically correlated. We tested this prediction in the black garden ant Lasius niger by quantifying the brood retrieval rate of queens and their first and...

Cellular dataset for: The anterior Hox gene ceh-13 and elt-1/GATA activate the posterior Hox genes nob-1 and php-3 to specify posterior lineages in the C. elegans embryo

Amanda Zacharias, John Isaac Murray, Elicia Preston, Jeremy Crawford, Jonathan Rumley, Prativa Amom, Breana Anderson, Priya Sivaramakrishnan, Shaili Patel, Barrington Bennett, Teddy Lavon & Felicia Peng
Hox transcription factors play a conserved role in specifying positional identity during animal development, with posterior Hox genes typically repressing the expression of more anterior Hox genes. Here, we dissect the regulation of the posterior Hox genes nob-1 and php-3 in the nematode C. elegans. We show that nob-1 and php-3 are co-expressed in gastrulation-stage embryos in cells that previously expressed the anterior Hox gene ceh-13. This expression is controlled by several partially redundant transcriptional...

Neuronal activity in sensory cortex predicts the specificity of learning

Maria Geffen, Katherine Wood, Christopher Angeloni, Karmi Oxman & Claudia Clopath
Learning to avoid dangerous signals while preserving normal responses to safe stimuli is essential for everyday behavior and survival. Following identical experiences, subjects exhibit fear specificity ranging from high (specializing fear to only the dangerous stimulus) to low (generalizing fear to safe stimuli), yet the neuronal basis of fear specificity remains unknown. Here, we identified the neuronal code that underlies inter-subject variability in fear specificity using longitudinal imaging of neuronal activity before and after differential...

The rheological behavior of CO2 ice: application to glacial flow on Mars

Andrew Cross, David L. Goldsby, Travis F. Hager & Isaac B. Smith
Vast amounts of solid CO2 reside in topographic basins of the south polar layered deposits (SPLD) on Mars and exhibit morphological features indicative of glacial flow. Previous experimental studies showed that coarse-grained CO2 ice is 1–2 orders of magnitude weaker than water ice under Martian polar conditions. Here we present data from a series of deformation experiments on high-purity, fine-grained CO2 ice over a broader range of temperatures than previously explored (158–213 K). The experiments...

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