219 Works

An effective mutualism? The role of theoretical studies in ecology and evolution

Maria Servedio
Theoretical models often have fundamentally different goals than do empirical studies of the same topic. Models can test the logic of existing hypotheses, explore the plausibility of new hypotheses, provide expectations that can be tested with data, and address aspects of topics that are currently inaccessible empirically. Theoretical models are common in ecology and evolution, and are generally well-cited, but I show that many citations appearing in non-theoretical studies are general to topic and a...

Data from: Carryover effects and the evolution of polyphenism

David Pfennig, Sofia De La Serna Buzón & Ryan Martin
An individual’s early-life environment and phenotype often influence its traits and performance as an adult. We investigated whether such ‘carryover effects’ are associated with alternative, environmentally induced phenotypes (‘polyphenism’), and, if so, whether they influence polyphenism’s evolution. To do so, we studied spadefoot toads, Spea multiplicata, which have evolved a polyphenism consisting of two, dramatically different forms: a carnivore morph and an omnivore morph. We sampled both morphs from a fast-drying and a slow-drying pond...

Paracoccidioides genomes reveal divergence

Academic Matute
The fungus Paracoccidioides spp. is a prevalent human pathogen endemic to South America. The genus is composed of five species. In this report, we use 37 whole genome sequences to study the allocation of genetic variation in Paracoccidioides. We tested three genome-wide predictions of advanced speciation, namely, that all species should be reciprocally monophyletic, that species pairs should be highly differentiated along the whole genome, and that there should be low rates of interspecific gene...

Data from: A condition-dependent male sexual signal predicts adaptive predator-induced plasticity in offspring

Patrick Kelly
The possibility that sexual selection promotes adaptive evolution in variable environments remains controversial. In particular, where the scale of environmental variation results in parents and their offspring experiencing different environmental conditions, such variation is expected to break down associations between adult sexual traits and adaptive offspring traits. However, when adaptive offspring plasticity in nonsexual traits acts as an indirect benefit of mate choice, then mate choice for males that produce more plastic offspring could promote...

Fine particulate matter and neuroanatomic risk for Alzheimer’s disease in older women

Diana Younan, Xinhui Wang, Ramon Casanova, Ryan Barnard, Sarah Gaussoin, Santiago Saldana, Andrew Petkus, Daniel Beavers, Susan Resnick, JoAnn Manson, Marc Serre, William Vizuete, Victor Henderson, Bonnie Sachs, Joel Salinas, Margaret Gatz, Mark Espeland, Helena Chui, Sally Shumaker, Stephen Rapp & Jiu-Chiuan Chen
Objective: To examine whether late-life exposure to PM2.5 (particulate matter with aerodynamic diameters <2.5-µm) contributes to progressive brain atrophy predictive of Alzheimer’s disease (AD) using a community-dwelling cohort of women (aged 71-89) with up to two brain MRI scans (MRI-1: 2005-6; MRI-2: 2010-11). Methods: AD pattern similarity (AD-PS) scores, developed by supervised machine learning and validated with MRI data from the AD Neuroimaging Initiative, was used to capture high-dimensional gray matter atrophy in brain areas...

Longitudinal white-matter abnormalities in sports-related concussion: a diffusion MRI study of the NCAA-DoD CARE Consortium

Yu-Chien Wu, Jaroslaw Harezlak, Nahla Elsaid, Zikai Lin, Qiuting Wen, Sourajit Mustafi, Larry Riggen, Kevin Koch, Andrew Nencka, Timothy Meier, Andrew Mayer, Yang Wang, Christopher Giza, John DiFiori, Kevin Guskiewicz, Jason Mihalik, Stephen LaConte, Stefan Duma, Steven Broglio, Andrew Saykin, Michael McCrea & Thomas McAllister
Objective To study longitudinal recovery trajectories of white-matter after sports-related concussion (SRC), we performed diffusion tensor imaging (DTI) on collegiate athletes who sustained SRC. Methods Collegiate athletes (n=219, 82 concussed athletes, 68 contact-sport controls, and 69 non-contact-sport controls) were included from the Concussion Assessment, Research and Education (CARE) Consortium. The participants completed clinical assessments and DTI at four time points: 24-48-hours post-injury, asymptomatic state, seven days following return-to-play, and six-months post-injury. Tract-based spatial statistics were...

Extinct plants of North America north of Mexico

Wesley Knapp, Anne Frances, Reed Noss, Robert Naczi, Alan Weakley, George Gann, Bruce Baldwin, James Miller, Patrick McIntyre, Brent Mishler, Gerry Moore, Richard Olmstead, Anna Strong, Daniel Gluesenkamp & Kathryn Kennedy
The recent study by Humphreys et al., reporting extinction of almost 600 plant species globally, represents a groundbreaking effort at compiling direct data on seed plants. We applaud Humphreys et al. for quantifying plant extinctions because they formulate an important and testable hypothesis. However, their study missed many extinctions and rediscoveries of seed plants in the United States and Canada. Our team of experts has been compiling a list of extinct plants of North America...

Data from: Exposure effects beyond the epithelial barrier: trans-epithelial induction of oxidative stress by diesel exhaust particulates in lung fibroblasts in an organotypic human airway model

Samantha Faber, Nicole McNabb, Pablo Ariel, Emily Aungst & Shaun McCullough
In vitro bronchial epithelial monoculture models have been pivotal in defining the adverse effects of inhaled toxicant exposures; however, they are only representative of one cellular compartment and may not accurately reflect the effects of exposures on other cell types. Lung fibroblasts exist immediately beneath the bronchial epithelial barrier and play a central role in lung structure and function, as well as disease development and progression. We tested the hypothesis that in vitro exposure of...

Data from: Identification of candidate loci for adaptive phenotypic plasticity in natural populations of spadefoot toads

Nicholas Levis, Emily Reed, David Pfennig & Martha Burford Reiskind
Phenotypic plasticity allows organisms to alter their phenotype in direct response to changes in the environment. Despite growing recognition of plasticity’s role in ecology and evolution, few studies have probed plasticity’s molecular bases—especially using natural populations. We investigated the genetic basis of phenotypic plasticity in natural populations of spadefoot toads (Spea multiplicata). Spea tadpoles normally develop into an ‘omnivore’ morph that is favored in long-lasting, low-density ponds. However, if tadpoles consume freshwater shrimp or other...

Data from: Elevational differences in developmental plasticity determine phenological responses of grasshoppers to recent climate warming

Lauren B. Buckley, César R. Nufio, Evan M. Kirk & Joel G. Kingsolver
Annual species may increase reproduction by increasing adult body size through extended development, but risk being unable to complete development in seasonally limited environments. Synthetic reviews indicate that most, but not all, species have responded to recent climate warming by advancing the seasonal timing of adult emergence or reproduction. Here, we show that 50 years of climate change have delayed development in high-elevation, season-limited grasshopper populations, but advanced development in populations at lower elevations. Developmental...

Data from: Reproductive isolation with a learned trait in a structured population

Douhan Justin Yeh & Maria R. Servedio
Assortative mating displays and/or preferences can be affected by learning across a wide range of animal taxa, but the specifics of how this learning affects speciation with gene flow are not well understood. We use population genetic models with trait learning to investigate how the identity of the tutor affects the divergence of a self-referent phenotype-matching trait. We find that oblique learning (learning from unrelated individual of the previous generation) and maternal learning mask sexual...

Data from: Abortion legislation, maternal healthcare, fertility, female literacy, sanitation, violence against women, and maternal deaths: a natural experiment in 32 Mexican states

Elard Koch, Monique Chireau, Fernando Pliego, Joseph Stanford, Sebastián Haddad, Byron Calhoun, Paula Aracena, Miguel Bravo, Sebastián Gatica & John Thorp
Objective: To test whether there is an association between abortion legislation and maternal mortality outcomes after controlling for other factors thought to influence maternal health. Design: Population-based natural experiment. Setting and data sources: Official maternal mortality data from 32 federal states of Mexico between 2002 and 2011. Main outcomes: Maternal mortality ratio (MMR), MMR with any abortive outcome (MMRAO) and induced abortion mortality ratio (iAMR). Independent variables: Abortion legislation grouped as less (n=18) or more...

Data from: The geomagnetic environment in which sea turtle eggs incubate affects subsequent magnetic navigation behavior of hatchlings

Matthew J. Fuxjager, Kyla R. Davidoff, Lisa A. Mangiamele & Kenneth J. Lohmann
Loggerhead sea turtle hatchlings (Caretta caretta) use regional magnetic fields as open-ocean navigational markers during trans-oceanic migrations. Little is known, however, about the ontogeny of this behaviour. As a first step towards investigating whether the magnetic environment in which hatchlings develop affects subsequent magnetic orientation behaviour, eggs deposited by nesting female loggerheads were permitted to develop in situ either in the natural ambient magnetic field or in a magnetic field distorted by magnets placed around...

Data from: Genotypic distribution and hepatic fibrosis among HIV/HCV co-infected individuals in Southern China: a retrospective cross-sectional study

Kali Zhou, Fengyu Hu, Charles Wang, Min Xu, Yun Lan, Jamie P. Morano, Stanley M. Lemon, Joseph D. Tucker & Weiping Cai
Background: End-stage liver disease and hepatocellular carcinoma due to hepatitis C virus (HCV) co-infection are increasingly common causes of death among HIV-infected individuals. However, there are few clinical investigations of HIV/HCV co-infected individuals from low and middle-income nations. Here, we compare the epidemiology of HCV-infected and HIV/HCV co-infected individuals in Southern China and examine hepatic fibrosis scores in co-infected individuals. Methods: We conducted a retrospective cross-sectional study of treatment-naïve HIV/HCV co-infected and HCV mono-infected subjects....

Data from: Evolutionary rescue and the coexistence of generalist and specialist competitors: an experimental test

Lisa M. Bono, Catherine L. Gensel, David W. Pfennig, Christina L. Burch & Catharine L. Gensel
Competition for resources is thought to play a critical role in both the origins and maintenance of biodiversity. Although numerous laboratory evolution experiments have confirmed that competition can be a key driver of adaptive diversification, few have demonstrated its role in the maintenance of the resulting diversity. We investigate the conditions that favor the origin and maintenance of alternative generalist and specialist resource-use phenotypes within the same population. Previously, we confirmed that competition for hosts...

Data from: Environmental optimality, not heterogeneity, drives regional and local species richness in lichen epiphytes

Jessica R. Coyle & Allen H. Hurlbert
Aim: We evaluate the scale dependence of species richness–environment relationships with a continent-wide analysis of lichen epiphyte communities. Specifically, our goals are to assess: (1) the dependence of local richness on regional processes, (2) whether species richness is primarily influenced by heterogeneity in environmental conditions or the central tendency of those conditions, and (3) whether the relative influence of these different aspects of the environment differs between local communities and regional species pools. Location: Forests...

Data from: Breakdown of local information processing may underlie isoflurane anesthesia effects

Patricia Wollstadt, Kristin K. Sellers, Lucas Rudelt, Viola Priesemann, Axel Hutt, Flavio Fröhlich, Michael Wibral & Flavio Fröhlich
The disruption of coupling between brain areas has been suggested as the mechanism underlying loss of consciousness in anesthesia. This hypothesis has been tested previously by measuring the information transfer between brain areas, and by taking reduced information transfer as a proxy for decoupling. Yet, information transfer is a function of the amount of information available in the information source—such that transfer decreases even for unchanged coupling when less source information is available. Therefore, we...

Data from: Intraspecific adaptive radiation: competition, ecological opportunity, and phenotypic diversification within species

Nicholas A. Levis, Ryan A. Martin, Kerry A. O'Donnell & David W. Pfennig
Intraspecific variation in resource-use traits can have profound ecological and evolutionary implications. Among the most striking examples are resource polymorphisms, where alternative morphs that utilize different resources evolve within a population. An underappreciated aspect of their evolution is that the same conditions that favor resource polymorphism—competition and ecological opportunity—might foster additional rounds of diversification within already existing morphs. We examined these issues in spadefoot toad tadpoles that develop into either a generalist ‘omnivore’ or a...

Data from: Geographic variation in mimetic precision among different species of coral snake mimics

Christopher K. Akcali & David W. Pfennig
Batesian mimicry is widespread, but whether and why different species of mimics vary geographically in resemblance to their model is unclear. We characterized geographic variation in mimetic precision among four Batesian mimics of coral snakes. Each mimic occurs where its model is abundant (i.e., in “deep sympatry”), rare (i.e., at the sympatry/allopatry boundary or “edge sympatry”), and absent (i.e., in allopatry). Geographic variation in mimetic precision was qualitatively different among these mimics. In one mimic,...

Data from: Archipelagic genetics in a widespread Caribbean anole

Robert Graham Reynolds, Tanner R. Strickland, Jason J. Kolbe, Bryan G. Falk, Gad Perry, Liam J. Revell & Jonathan B. Losos
Aim We examine the influence of fluctuating sea levels in a land-bridge archipelago on the apportioning of intraspecific genetic diversity and divergence in the widespread Puerto Rican crested anole (Anolis cristatellus). We compare three alternative scenarios for genetic diversification in an archipelagic species that contrast the relative influences of periodic isolation versus island connectedness driven by fluctuating sea levels. Our approach combines information from geography and population genetics to assess the influence of island size,...

Data from: Evolution of plasticity and adaptive responses to climate change along climate gradients

Joel G. Kingsolver & Lauren B. Buckley
The relative contributions of phenotypic plasticity and adaptive evolution to the responses of species to recent and future climate change are poorly understood. We combine recent (1960–2010) climate and phenotypic data with microclimate, heat balance, demographic and evolutionary models to address this issue for a montane butterfly, Colias eriphyle, along an elevational gradient. Our focal phenotype, wing solar absorptivity, responds plastically to developmental (pupal) temperatures and plays a central role in thermoregulatory adaptation in adults....

Data from: Genetic accommodation in the wild: evolution of gene expression plasticity during character displacement

Nicholas A. Levis, Antonio Serrato-Capuchina & David W. Pfennig
Ecological character displacement is considered crucial in promoting diversification, yet relatively little is known of its underlying mechanisms. We examined whether evolutionary shifts in gene expression plasticity (‘genetic accommodation’) mediate character displacement in spadefoot toads. Where Spea bombifrons and S. multiplicata occur separately in allopatry (the ancestral condition), each produces alternative, diet-induced, larval ecomorphs: omnivores, which eat detritus, and carnivores, which specialize on shrimp. By contrast, where these two species occur together in sympatry (the...

Data from: How stabilizing selection and nongenetic inheritance combine to shape the evolution of phenotypic plasticity

Nicholas A. Levis & David W. Pfennig
Relatively little is known about whether and how nongenetic inheritance interacts with selection to impact the evolution of phenotypic plasticity. Here, we empirically evaluated how stabilizing selection and a common form of nongenetic inheritance––maternal environmental effects––jointly influence the evolution of phenotypic plasticity in natural populations of spadefoot toads. We compared populations that previous field work has shown to have evolved conspicuous plasticity in resource-use phenotypes (‘resource polyphenism’) with those that, owing to stabilizing selection favouring...

Data from: Nitrogen transformations differentially affect nutrient-limited primary production in lakes of varying trophic state

J. Thad Scott, Mark J. McCarthy & Hans W. Paerl
The concept of lakes “evolving” phosphorus (P) limitation has persisted in limnology despite limited direct evidence. Here, we developed a simple model to broadly characterize nitrogen (N) surpluses and deficits relative to P in lakes, and compared the magnitude of this imbalance to estimates of N gains and losses through biological N transformations. The model suggested that approximately half of oligotrophic lakes in the US had a stoichiometric N deficit, but almost 90% of the...

Data from: Comparison of cerebral blood volume and plasma volume in untreated intracranial tumors

Soha Bazyar, Joana Ramalho, Cihat Eldeniz, Hongyu An, Yueh Lee & Yueh Z. Lee
Purpose: Plasma volume and blood volume are imaging-derived parameters that are often used to evaluation intracranial tumors. Physiologically, these parameters are directly related, but their two different methods of measurements, T1-dynamic contrast enhanced (DCE)- and T2-dynamic susceptibility contrast (DSC)-MR utilize different model assumptions and approaches. This poses the question of whether the interchangeable use of T1-DCE-MRI derived fractionated plasma volume (vp) and relative cerebral blood volume (rCBV) assessed using DSC-MRI, particularly in glioblastoma, is reliable,...

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