103 Works

Environmental stress gradients regulate the relative importance of predator density- and trait-mediated indirect effects in oyster reef communities

Jessica Pruett & Marc Weissburg
Predators affect community structure by influencing prey density and traits, but the importance of these effects often is difficult to predict. We measured the strength of blue crab predator effects on mud crab prey consumption of juvenile oysters across a flow gradient that inflicts both physical and sensory stress to determine how the relative importance of top predator density-mediated indirect effects (DMIEs) and trait-mediated indirect effects (TMIEs) change within systems. Overall, TMIEs dominated in relatively...

Sensitivity analysis of the maximum entropy production method to model evaporation in boreal and temperate forests

Audrey Maheu, Pierre-Erik Isabelle, Laure Viens, Daniel F. Nadeau, François Anctil & Jingfeng Wang
The maximum entropy production (MEP) approach has been little used to simulate evaporation in forests and its sensitivity to input variables has yet to be systematically evaluated. This study addresses these shortcomings. First, we show that the MEP model performed well in simulating evaporation during the snow-free period at six sites in temperate and boreal forests (0.68 ≤ NSE ≤ 0.82). Second, we computed a sensitivity coefficient S representing the proportion of change in the...

Data from: Nanotransfection-based vasculogenic cell reprogramming drives functional recovery in a mouse model of ischemic stroke

Luke Lemmerman, Maria Balch, Jordan Moore, Diego Alzate-Correa, Maria Rincon-Benavides, Ana Salazar-Puerta, Surya Gnyawali, Hallie Harris, William Lawrence, Lilibeth Ortega-Pineda, Lauren Wilch, Ian Risser, Aidan Maxwell, Silvia Duarte-Sanmiguel, Daniel Dodd, Gina Guio-Vega, Dana McTigue, William Arnold, Shahid Nimjee, Chandan Sen, Savita Khanna, Cameron Rink, Natalia Higuita-Castro & Daniel Gallego-Perez
Ischemic stroke causes vascular and neuronal tissue deficiencies that could lead to significant functional impairment and/or death. Although progenitor-based vasculogenic cell therapies have shown promise as a potential rescue strategy following ischemic stroke, current approaches face major hurdles. Here we used fibroblasts nanotransfected with Etv2, Foxc2, and Fli1 (EFF), to drive reprogramming-based vasculogenesis, intracranially, as a potential therapy for ischemic stroke. Perfusion analyses suggest that intracranial delivery of EFF-nanotransfected fibroblasts led to a dose-dependent increase...

Dimensional analysis of spring-wing systems reveals performance metrics for resonant flapping-wing flight

Nicholas Gravish, James Lynch, Jeff Gau & Simon Sponberg
Flapping-wing insects, birds, and robots are thought to offset the high power cost of oscillatory wing motion by using elastic elements for energy storage and return. Insects possess highly resilient elastic regions in their flight anatomy that may enable high dynamic efficiency. However, recent experiments highlight losses due to damping in the insect thorax that could reduce the benefit of those elastic elements. We performed experiments on, and simulations of a dynamically-scaled robophysical flapping model...

The evolution of two distinct strategies of moth flight

Brett Aiello
Across insects, wing shape and size have undergone dramatic divergence even in closely related sister groups. However, we do not know how morphology changes in tandem with kinematics to support body weight within available power and how the specific force production patterns are linked to differences in behavior. Hawkmoths and wild silkmoths are diverse sister families with divergent wing morphology. Using 3d kinematics and quasi-steady aerodynamic modeling, we compare the aerodynamics and the contributions of...

Data from: Virulent disease epidemics can increase host density by depressing foraging of hosts

Rachel Penczykowski, Marta Shocket, Jessica Housley Ochs, Brian Lemanski, Hema Sundar, Meghan Duffy & Spencer Hall
All else equal, parasites that harm host fitness should depress densities of their hosts. However, parasites that alter host traits may increase host density via indirect ecological interactions. Here, we show how depression of foraging rate of infected hosts can produce such a hydra effect. Using a foraging assay, we quantified reduced foraging rates of a zooplankton host infected with a virulent fungal parasite. We then parameterized a dynamical model of hosts, parasites, and resources...

Machine learning to extract muscle fascicle length changes from dynamic ultrasound images in real-time

Luis Rosa
B-mode ultrasound has become one-off, if not the main way of measuring muscle fascicle fiber lengths non-invasively. Yet, the gold standard for tracking these is still time-intensive hand-tracking, and even with semi-automated approaches, the process takes time and has to be done post hoc. Hence, towards greatly improving current processing capabilities by tracking these muscle fasicle lengths in real-time, we trained and optimized machine learning models with collected B-mode ultrasound data. We focused on soleus...

Data from: Poor resource quality lowers transmission potential by changing foraging behaviour

Rachel M. Penczykowski, Brian C. P. Lemanski, Robert Drew Sieg, Spencer R. Hall, Jessica Housley Ochs, Julia Kubanek & Meghan A. Duffy
Resource quality can have conflicting effects on the spread of disease. High quality resources could hinder disease spread by promoting host immune function. Alternatively, high quality food might enhance the spread of disease through other traits of hosts or parasites. Thus, to assess how resource quality shapes epidemics, we need to delineate mechanisms by which food quality affects key epidemiological traits. Here, we disentangle effects of food quality on ‘transmission potential’ – a key component...

Data from: Environmental changes drive the temporal stability of semi-arid natural grasslands through altering species asynchrony

Zhuwen Xu, Haiyan Ren, Mai-He Li, Jasper Van Ruijven, Xingguo Han, Shiqiang Wan, Hui Li, Qiang Yu, Yong Jiang & Lin Jiang
Stability is an important property of ecological systems, many of which are experiencing increasing levels of anthropogenic environmental changes. However, how these environmental changes influence ecosystem stability remains poorly understood. We conducted an 8-year field experiment in a semi-arid natural grassland to explore the effects of two common environmental changes, precipitation and nitrogen enrichment, on the temporal stability of plant above-ground biomass. A split-plot design, with precipitation as the main plot factor and nitrogen as...

Data from: Species ecological similarity modulates the importance of colonization history for adaptive radiation

Jiaqi Tan, Xian Yang & Lin Jiang
Adaptive radiation is an important evolutionary process, through which a single ancestral lineage rapidly gives rise to multiple newly formed lineages that specialize in different niches. In the first-arrival hypothesis, David Lack emphasized the importance of species colonization history for adaptive radiation, suggesting that the earlier arrival of a diversifying species would allow it to radiate to a greater extent. Here, we report on the first rigorous experimental test of this hypothesis, using the rapidly...

Data from: Predator identity influences metacommunity assembly

Nicole K. Johnston, Zhichao Pu & Lin Jiang
1.Predation is among the most important biotic factors influencing natural communities, yet we have a rather rudimentary understanding of its role in modulating metacommunity assembly. 2.We experimentally examined the effects of two different predators (a generalist and a specialist) on metacommunity assembly, using protist microcosm metacommunities that varied in predator identity, dispersal among local communities, and the history of species colonization into local communities. 3.Generalist predation resulted in reduced α diversity and increased β diversity...

Data from: Fluc­tu­a­tion domains in adap­tive evo­lu­tion

Carl Boettiger, Jonathan Dushoff & Joshua S. Weitz
We derive an expression for the variation between parallel trajectories in phenotypic evolution, extending the well known result that predicts the mean evolutionary path in adaptive dynamics or quantitative genetics. We show how this expression gives rise to the notion of fluctuation domains–parts of the fitness landscape where the rate of evolution is very predictable (due to fluctuation dissipation) and parts where it is highly variable (due to fluctuation enhancement). These fluctuation domains are determined...

Data from: Intoxicated copepods: ingesting toxic phytoplankton leads to risky behaviour

Rachel S. Lasley-Rasher, Kathryn Nagel, Aakanksha Angra & Jeannette Yen
Understanding interactions between harmful algal bloom (HAB) species and their grazers is essential for determining mechanisms of bloom proliferation and termination. We exposed the common calanoid copepod, Temora longicornis to the harmful algal bloom species Alexandrium fundyense and examined effects on copepod survival, ingestion, egg production and swimming behaviour. A. fundyense was readily ingested by T. longicornis and significantly altered copepod swimming behaviour without affecting copepod survival or fitness. A. fundyense caused T. longicornis to...

Data from: Plant functional diversity modulates global environmental change effects on grassland productivity

Zhuwen Xu, Mai-He Li, Niklaus E. Zimmermann, Shaopeng Li, Hui Li, Haiyan Ren, Hao Sun, Xingguo Han, Yong Jiang, Lin Jiang & Shao-Peng Li
1. Although much research has explored changes in ecosystem functions associated with global environmental changes, the mechanistic pathways behind the observed changes remain poorly understood. 2. Using an 11-year experiment that increased growing season precipitation and nitrogen deposition in a temperate steppe, we explored the relative importance of direct and indirect environmental change effects on plant primary productivity. 3. We show that increases in water and nitrogen availability influenced plant productivity via both direct and...

Data from: Spatial storage effect promotes biodiversity during adaptive radiation

Jiaqi Tan, Jennifer B. Rattray, Xian Yang & Lin Jiang
Many ecological communities are enormously diverse. Variation in environmental conditions over time and space provides opportunities for temporal and spatial storage effects to operate, potentially promoting species coexistence and biodiversity. While several studies have provided empirical evidence supporting the significance of the temporal storage effect for coexistence, empirical tests of the role of the spatial storage effect are rare. In particular, we know little about how the spatial storage effect contributes to biodiversity over evolutionary...

Data from: Species colonisation, not competitive exclusion, drives community overdispersion over long-term succession

Shao-Peng Li, Marc W. Cadotte, Scott J. Meiners, Zheng-Shuang Hua, Lin Jiang & Wen-Sheng Shu
Ecological communities often transition from phylogenetic and functional clustering to overdispersion over succession as judged by space-for-time substitution studies. Such a pattern has been generally attributed to the increase in competitive exclusion of closely related species with similar traits through time, although colonisation and extinction have rarely been examined. Using 44 years of uninterrupted old-field succession in New Jersey, USA, we confirmed that phylogenetic and functional clustering decreased as succession unfolded, but the transition was...

Data from: Temperature-regulated guest admission and release in microporous materials

Gang Kevin Li, Jin Shang, Qinfen Gu, Rohan V. Awati, Nathan Jensen, Andrew Grant, Xueying Zhang, David S. Sholl, Jefferson Z. Liu, Paul A. Webley & Eric F. May
While it has long been known that some highly adsorbing microporous materials suddenly become inaccessible to guest molecules below certain temperatures, previous attempts to explain this phenomenon have failed. Here we show that this anomalous sorption behaviour is a temperature-regulated guest admission process, where the pore-keeping group’s thermal fluctuations are influenced by interactions with guest molecules. A physical model is presented to explain the atomic-level chemistry and structure of these thermally regulated micropores, which is...

Data from: How do morphological sharpness measures relate to puncture performance in viperid snake fangs?

Stephanie B. Crofts, Yang Lai, Yuhang Hu & Philip S.L. Anderson
It makes intuitive sense that you need a sharp tool to puncture through a tough material. The typical approach to evaluating sharpness in biological puncturing tools is to treat morphological measurements as a proxy for puncture ability. However there are multiple approaches to measuring sharpness, and the relative influence of morphology on function remains unclear. Our goal is to determine what aspects of tip morphology have the greatest impact on puncture ability, using a) viper...

Data from: Resource addition drives taxonomic divergence and phylogenetic convergence of plant communities

Xian Yang, Guoyong Li, Shao-Peng Li, Qianna Xu, Huanhuan Song, Danyu Sun, Mingxing Zhong, Zhenxing Zhou, Jian Song, Jingyi Ru, Shiqiang Wan & Lin Jiang
1. Anthropogenic environmental changes are known to affect the Earth’s ecosystems. However, how these changes influence assembly trajectories of the impacted communities remains a largely open question. 2. In this study, we investigated the effect of elevated nitrogen (N) deposition and increased precipitation on plant taxonomic and phylogenetic β-diversity in a 9-year field experiment in the temperate semi-arid steppe of Inner Mongolia, China. 3. We found that both N and water addition significantly increased taxonomic...

Data from: Force encoding in muscle spindles during stretch of passive muscle

Kyle P. Blum, Boris Lamotte D’Incamps, Daniel Zytnicki & Lena H. Ting
Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs) of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle...

Data from: Evolution of altruistic cooperation among nascent multicellular organisms

Jordan G. Gulli, Matthew D. Herron & William C. Ratcliff
Cooperation is a classic solution to hostile environments that limit individual survival. In extreme cases this may lead to the evolution of new types of biological individuals (e.g., eusocial super-organisms). We examined the potential for inter-individual cooperation to evolve via experimental evolution, challenging nascent multicellular ‘snowflake yeast’ with an environment in which solitary multicellular clusters experienced low survival. In response, snowflake yeast evolved to form cooperative groups composed of thousands of multicellular clusters that typically...

Indirect actuation reduces flight power requirements in Manduca sexta via elastic energy exchange

Jeff Gau, Nick Gravish & Simon Sponberg
In many insects, wing movements are generated indirectly via exoskeletal deformations. Measurements of inertial and aerodynamic power suggest that elastic recovery of energy between wingstrokes might reduce power requirements of flight. We tested three questions. 1) Can the thorax itself provide significant energy return? 2) Does a simple damped elastic model describe the bulk mechanical behavior? and 3) Are different regions of the thorax specialized for elastic energy exchange? We measured deformation mechanics of the...

Data from: Consistently positive effect of species diversity on ecosystem, but not population, temporal stability

Qianna Xu
Despite much recent progress, our understanding of diversity-stability relationships across different study systems remains incomplete. In particular, recent theory clarified that within-species population stability and among-species asynchronous population dynamics combine to determine ecosystem temporal stability, but their relative importance in modulating diversity-ecosystem temporal stability relationships in different ecosystems remains unclear. We addressed this issue with a meta-analysis of empirical studies of ecosystem and population temporal stability in relation to species diversity across a range of...

Data from: Synergistic effects of nitrogen and CO2 enrichment on alpine grassland biomass and community structure

Juntao Zhu, Yangjian Zhang, Xian Yang, Ning Chen & Lin Jiang
Global environmental change is altering Earth’s ecosystems. However, much research has focused on ecosystem-level responses, and we know substantially less about community-level responses to global change stressors. Here we conducted a 6-year field experiment in a high-altitude (4600 m above sea level) alpine grassland on the Tibetan Plateau to explore the effects of nitrogen (N) addition and rising atmospheric CO2 concentration on plant communities. Our results showed that N and CO2 enrichment had synergistic effects...

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  • Georgia Institute of Technology
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