Predicting metabolic adaptation from networks of mutational paths

Mapping Intimacies ◽

10.1101/115170 ◽

2017 ◽

Author(s):

Christos Josephides ◽

Peter S. Swain

Keyword(s):

Adaptive Evolution ◽

Evolutionary Dynamics ◽

Evolutionary Model ◽

Metabolic Adaptation ◽

Long Term Outcomes ◽

Reliable Prediction ◽

Graph Theoretic ◽

Incomplete Observations ◽

Trade Offs

Competition for substrates is a ubiquitous selection pressure faced by microbes, yet intracellular trade-offs can prevent cells from metabolizing every type of available substrate. Adaptive evolution is constrained by these trade-offs, but their consequences for the repeatability and predictability of evolution are unclear. Here we develop an eco-evolutionary model with a metabolic trade-off to generate networks of mutational paths in microbial communities and show that these networks have descriptive and predictive information about the evolving communities. We find that long-term outcomes, including community collapse, diversity, and cycling, have characteristic evolutionary dynamics that determine the entropy, or repeatability, of mutational paths. Although reliable prediction of evolutionary outcomes from environmental conditions is difficult, graph-theoretic properties of the mutational networks enable accurate prediction even from incomplete observations. In conclusion, we present a novel methodology for analyzing adaptive evolution and report that the dynamics of adaptation are a key variable for predictive success.

Download Full-text

The role of ventromedial prefrontal cortex in reward valuation and future thinking during intertemporal choice

10.1101/2021.03.15.435400 ◽

2021 ◽

Author(s):

Elisa Ciaramelli ◽

Flavia De Luca ◽

Donna Kwan ◽

Jenkin N. Y. Mok ◽

Francesca Bianconi ◽

...

Keyword(s):

Prefrontal Cortex ◽

Reward Magnitude ◽

Intertemporal Choice ◽

Ventromedial Prefrontal Cortex ◽

Future Thinking ◽

Long Term Outcomes ◽

Trade Offs ◽

Reward Valuation

Intertemporal choices require trade-offs between short-term and long-term outcomes. Ventromedial prefrontal cortex (vmPFC) damage causes steep discounting of future rewards (delay discounting; DD) and impoverished episodic future thinking (EFT). The role of vmPFC in reward valuation, EFT, and their interaction during intertemporal choice is still unclear. Here, twelve patients with lesions to vmPFC and forty-one healthy controls chose between smallerimmediate and larger-delayed rewards while we manipulated reward magnitude and the availability of EFT cues. In the EFT condition, participants imagined personal events to occur at the delays associated with the larger-delayed rewards. We found that DD was steeper in vmPFC patients compared to controls, and not modulated by reward magnitude. However, EFT cues downregulated DD in vmPFC patients as well as controls. These findings indicate that vmPFC integrity is critical for the valuation of (future) rewards, but not to instill EFT in intertemporal choice.

Download Full-text

Functional and evolutionary trade-offs co-occur between two consolidated memory phases in Drosophila melanogaster

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2012.1457 ◽

2012 ◽

Vol 279 (1744) ◽

pp. 4015-4023 ◽

Cited By ~ 14

Author(s):

Fabrice Lagasse ◽

Celine Moreno ◽

Thomas Preat ◽

Frederic Mery

Keyword(s):

Evolutionary Dynamics ◽

Functional Relationship ◽

Learning Task ◽

Long Term Memory ◽

Phenotypic Traits ◽

Trade Offs ◽

Memory Phase ◽

Fitness Benefits ◽

Benefits And Costs

Memory is a complex and dynamic process that is composed of different phases. Its evolution under natural selection probably depends on a balance between fitness benefits and costs. In Drosophila , two separate forms of consolidated memory phases can be generated experimentally: anaesthesia-resistant memory (ARM) and long-term memory (LTM). In recent years, several studies have focused on the differences between these long-lasting memory types and have found that, at the functional level, ARM and LTM are antagonistic. How this functional relationship will affect their evolutionary dynamics remains unknown. We selected for flies with either improved ARM or improved LTM over several generations, and found that flies selected specifically for improvement of one consolidated memory phase show reduced performance in the other memory phase. We also found that improved LTM was linked to decreased longevity in male flies but not in females. Conversely, males with improved ARM had increased longevity. We found no correlation between either improved ARM or LTM and other phenotypic traits. This is, to our knowledge, the first evidence of a symmetrical evolutionary trade-off between two memory phases for the same learning task. Such trade-offs may have an important impact on the evolution of cognitive capacities. On a neural level, these results support the hypothesis that mechanisms underlying these forms of consolidated memory are, to some degree, antagonistic.

Download Full-text

Adaptation

Eco-evolutionary Dynamics ◽

10.23943/princeton/9780691145433.003.0003 ◽

2016 ◽

Author(s):

Andrew P. Hendry

Keyword(s):

Genetic Variation ◽

Adaptive Evolution ◽

Evolutionary Dynamics ◽

Natural Populations ◽

Phenotypic Change ◽

Adaptive Landscapes ◽

Local Environments ◽

Short And Long Term ◽

Different Populations

This chapter outlines how to conceptualize and predict adaptive evolution based on information about selection and genetic variation. It introduces and explains adaptive landscapes, a concept that has proven useful in guiding the understanding of evolution. The chapter also reviews empirical data to answer fundamental questions about adaptation in nature, including to what extent short- and long-term evolution is predictable, how fast is phenotypic change, to what extent is adaptation constrained by genetic variation, and how well adapted natural populations are to their local environments. Moving beyond selection and adaptation within populations, the chapter shows how eco-evolutionary dynamics will be shaped by biological diversity: that is, different populations and species have different effects on their environment.

Download Full-text

The role of ventromedial prefrontal cortex in reward valuation and future thinking during intertemporal choice

eLife ◽

10.7554/elife.67387 ◽

2021 ◽

Vol 10 ◽

Author(s):

Elisa Ciaramelli ◽

Flavia De Luca ◽

Donna Kwan ◽

Jenkin Mok ◽

Francesca Bianconi ◽

...

Keyword(s):

Prefrontal Cortex ◽

Reward Magnitude ◽

Intertemporal Choice ◽

Ventromedial Prefrontal Cortex ◽

Future Thinking ◽

Long Term Outcomes ◽

Trade Offs ◽

Reward Valuation

Intertemporal choices require trade-offs between short-term and long-term outcomes. Ventromedial prefrontal cortex (vmPFC) damage causes steep discounting of future rewards (delay discounting [DD]) and impoverished episodic future thinking (EFT). The role of vmPFC in reward valuation, EFT, and their interaction during intertemporal choice is still unclear. Here, 12 patients with lesions to vmPFC and 41 healthy controls chose between smaller-immediate and larger-delayed hypothetical monetary rewards while we manipulated reward magnitude and the availability of EFT cues. In the EFT condition, participants imagined personal events to occur at the delays associated with the larger-delayed rewards. We found that DD was steeper in vmPFC patients compared to controls, and not modulated by reward magnitude. However, EFT cues downregulated DD in vmPFC patients as well as controls. These findings indicate that vmPFC integrity is critical for the valuation of (future) rewards, but not to instill EFT in intertemporal choice.

Download Full-text

Regional neutrality evolves through local adaptive niche evolution

10.1101/326348 ◽

2018 ◽

Author(s):

Mathew A. Leibold ◽

Mark C. Urban ◽

Luc De Meester ◽

Christopher A. Klausmeier ◽

Joost Vanoverbeke

Keyword(s):

Adaptive Evolution ◽

Evolutionary Dynamics ◽

Biological Diversity ◽

Regional Scale ◽

Niche Differentiation ◽

Priority Effects ◽

Local Conditions ◽

Stable Coexistence ◽

Landscape Level

AbstractJoost Vanoverbeke, Department of Biology, Katholieke Universiteit Leuven, Leuven, Belgium. Abstract: Biodiversity in natural systems can be maintained either because niche differentiation among competitors facilitates stable coexistence or because equal fitness among neutral species allows for their long-term co-occurrence despite a slow drift toward extinction. Whereas the relative importance of these two ecological mechanisms has been well-studied in the absence of evolution, the role of local adaptive evolution in maintaining biological diversity through these processes is less clear. Here we study the contribution of local adaptive evolution to coexistence in a landscape of interconnected patches subject to disturbance. Under these conditions, early colonists to empty patches following disturbance can often adapt to novel local conditions sufficiently fast to prevent successful colonization by other pre-adapted species. Over the long term, the iteration of these local-scale priority effects results in niche convergence of species at the regional scale even though species tend to monopolize local patches. Thus, the dynamics evolve from stable coexistence through niche differentiation to neutral co-occurrence at the landscape level while still maintaining strong local niche differentiation. Our model results show that neutrality can emerge at the regional scale from local, niche-based adaptive evolution, potentially resolving why ecologists often observe neutral distribution patterns at the landscape level despite strong niche divergence among local communities. Our results also demonstrate how local adaptive evolution can shape cryptic eco-evolutionary dynamics and thus alter the regional mechanisms that determine biological diversity and resistance to disturbance.

Download Full-text

Treating symptomatic infections and the co-evolution of virulence and drug resistance

10.1101/2020.02.29.970905 ◽

2020 ◽

Cited By ~ 2

Author(s):

Samuel Alizon

Keyword(s):

Evolutionary Dynamics ◽

Adaptive Dynamics ◽

Drug Resistant ◽

Treatment Rate ◽

Virulence Evolution ◽

Trade Offs ◽

Virulent Strains ◽

Host Mortality ◽

Parameter Values

AbstractAntimicrobial therapeutic treatments are by definition applied after the onset of symptoms, which tend to correlate with infection severity. Using mathematical epidemiology models, I explore how this link affects the coevolutionary dynamics between the virulence of an infection, measured via host mortality rate, and its susceptibility to chemotherapy. I show that unless resistance pre-exists in the population, drug-resistant infections are initially more virulent than drug-sensitive ones. As the epidemic unfolds, virulence is more counter-selected in drug-sensitive than in drug-resistant infections. This difference decreases over time and, eventually, the exact shape of genetic trade-offs govern long-term evolutionary dynamics. Using adaptive dynamics, I show that two types of evolutionary stable strategies (ESS) may be reached in the context of this simple model and that, depending on the parameter values, an ESS may only be locally stable. In general, the more the treatment rate increases with virulence, the lower the ESS value. Overall, both on the short-term and long-term, having treatment rate depend on infection virulence tend to favour less virulent strains in drug-sensitive infections. These results highlight the importance of the feedbacks between epidemiology, public health policies and parasite evolution, and have implications for the monitoring of virulence evolution.

Download Full-text

Traumatic Brain Injury: A Trauma Surgeon's Perspective

Perspectives on Neurophysiology and Neurogenic Speech and Language Disorders ◽

10.1044/nnsld22.3.82 ◽

2012 ◽

Vol 22 (3) ◽

pp. 82-89

Author(s):

Oscar D. Guillamondegui

Keyword(s):

Traumatic Brain Injury ◽

Brain Injury ◽

Multidisciplinary Approach ◽

Trauma Team ◽

The United States ◽

Long Term Outcomes ◽

Term Care ◽

Injured Brain ◽

The Moment

Traumatic brain injury (TBI) is a serious epidemic in the United States. It affects patients of all ages, race, and socioeconomic status (SES). The current care of these patients typically manifests after sequelae have been identified after discharge from the hospital, long after the inciting event. The purpose of this article is to introduce the concept of identification and management of the TBI patient from the moment of injury through long-term care as a multidisciplinary approach. By promoting an awareness of the issues that develop around the acutely injured brain and linking them to long-term outcomes, the trauma team can initiate care early to alter the effect on the patient, family, and community. Hopefully, by describing the care afforded at a trauma center and by a multidisciplinary team, we can bring a better understanding to the armamentarium of methods utilized to treat the difficult population of TBI patients.

Download Full-text