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Evolution In Changing Environments

Author: Richard Levins
Publisher: Princeton University Press
ISBN: 9780691080628
Size: 21.51 MB
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Professor Levins, one of the leading explorers in the field of integrated population biology, considers the mutual interpenetration and joint evolution of organism and environment, occurring on several levels at once. Physiological and behavioral adaptations to short-term fluctuations of the environment condition the responses of populations to long-term changes and geographic gradients. These in turn affect the way species divide the environments among themselves in communities, and, therefore, the numbers of species which can coexist. Environment is treated here abstractly as pattern: patchiness, variability, range, etc. Populations are studied in their patterns: local heterogeneity, geographic variability, faunistic diversity, etc.

Microbial Evolution In Changing Environments

Author: Peter L. Conlin
Size: 28.42 MB
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Chapter 1. Compensatory mutations play a critical role in the evolution of drug resistance in microorganisms. Most directly, they serve to alleviate the fitness cost commonly associated with initial drug resistance mutations. Here we use experimental evolution to examine adaptation to the cost of rifampicin resistance in an antibiotic-free environment, and ask whether compensatory mutations that restore fitness back to ancestral levels could also be further increasing the level of drug tolerance in these resistant isolates. We suggest that the identity of the initial resistance conferring mutations may influence the relative frequency at which drug tolerance increases during compensatory evolution through epistatic interactions. Chapter 2. The evolutionary transition to multicellularity likely began with the formation of simple undifferentiated cellular groups. Such groups evolve readily in diverse lineages of extant unicellular taxa, suggesting that there are few genetic barriers to this first key step. In this chapter, we focus on how the transition to multicellularity may be stabilized against evolutionary reversion when environmental conditions change and tip the balance of selection back in favor of unicellularity. Using mathematical modeling, we show how multicellular adaptations can act as evolutionary "ratchets", limiting the potential for reversion to unicellularity. Chapter 3. Evolutionary transitions in individuality (ETIs) occur when formerly autonomous organisms evolve to become parts of a new, ‘higher-level’ organism. Here we explore the key role that simple multicellular life cycles in facilitating this transition. Specifically, we use mathematical models to compute how canonical early life cycles vary in their ability to fix beneficial mutations via mathematical modeling. Building on our prevous work (Chapter 2), we show how life cycles that lack a persistent single-cell stage and develop clonally are far more likely to fix ‘ratcheting’ mutations that limit evolutionary reversion to the pre-ETI state. Chapter 4. Phenotypic plasticity is the ability of a single genotype to produce different phenotypes in response to changes in the environment. Theory suggests that the adaptive value of plasticity depends on the degree of environmental heterogeneity and the existence of environmental cues that provide reliable information about selective conditions. We tested this prediction using experimental evolution. We find that temporally varying selection can favor the evolution of phenotypic plasticity in experimental populations of yeast when selection is predictable but that plasticity is lost when selection in unpredictable. Chapter 5. Fitness trade-offs, while central to all of life history theory, are thought to take on a particularly important role during major evolutionary transitions such as the evolution of multicellularity. Specifically, trade-offs between survival and reproduction may drive increases in complexity and cellular differentiation. Here we used computer simulations of digital mulitcellular organisms to explore how trade-offs could promote the evolution of multicellular complexity. Chapter 6. In this chapter, we review how game theory can be a useful first step in modeling and understanding interactions among bacteria that produce and resist antibiotics. We introduce the basic features of evolutionary game theory and explore model microbial systems that correspond to some classical games. Each game discussed defines a different category of social interaction with different resulting population dynamics (exclusion, coexistence, bistability, cycling). We then explore how the framework can be extended to incorporate some of the complexity of natural microbial communities.

Virtual Plants Modeling Plant Architecture In Changing Environments

Author: Katrin Kahlen
Publisher: Frontiers Media SA
ISBN: 2889450929
Size: 64.68 MB
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Plant architecture is a major determinant of the resource use efficiency of crops. The architecture of a plant shows ontogenetic structural changes which are modified by multiple environmental factors: Plant canopies are exposed to natural fluctuations in light quantity and the dynamically changing canopy architecture induces local variations in light quality. Changing temperature conditions or water availability during growth additionally affect plant architecture and thus crop productivity, because plants have various options to adapt their architecture to the available resources. Meeting the challenge of ensuring food security we must understand the plant’s mechanisms for integrating and responding to an orchestra of environmental factors. ‘Virtual plants’ describe plant architecture in silico. Virtual plants have the potential to help us understanding the complex feedback processes between canopy architecture, multiple environmental factors and crop productivity. As a research tool, they have become increasingly popular within the last decade due to their great power of realistically visualizing the plant’s architecture. This Research Topic highlights current research carried out on modeling plant architecture in changing environments.

The Evolution Of Genetic And Epigenetic Diversity In Changing Environments

Author: Oana Carja
Size: 34.55 MB
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The production and maintenance of genetic and phenotypic diversity under temporally fluctuating selection has been a major focus of study in population genetics for more than five decades. In this thesis, I use analytical and computational models to gain insight into the relative roles of genetic and epigenetic diversity in adaptation to changing selection. The different chapters provide complimentary perspectives on the signatures of environmental volatility in the patterns of variation. Chapter 2 explores the evolution of epigenetic variation and its role in adaptation under changing selection pressures. Chapter 3 investigates the effect of recombination on the geometric mean principle under different environmental regimens and fitness landscapes. Two chapters of this thesis, Chapter 4 and Chapter 5 explore the evolution of phenotypic switching, a phenomenon widely documented in viruses, yeast and bacteria, where offspring can express a phenotype different from those of their parents. These chapters highlight the interplay of spatial and temporal environmental variability, offering new insights into how migration can influence the evolution of stochastic switching rates, epigenetic inheritance, and sources of phenotypic variation. Chapter 6 compares and contrasts how fluctuating selection shapes the rates of recombination, mutation and migration, highlighting surprising similarities in their evolutionary dynamics to changing selection. This chapter offers new insights into the role of the environmental duration, shape and randomness in predicting the long-term evolutionary advantage of the forces of recombination, mutation and migration. The models and analyses presented here provide a more complete understanding of the role of genetic and epigenetic diversity in adaptation to changing selection pressures.

Environment Development And Evolution

Author: Thomas Pradeu
Publisher: MIT Press
ISBN: 9780262083195
Size: 78.41 MB
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Leading researchers in evolutionary developmental biology seek linkages between, and a synthesis of, development, physiology, endocrinology, ecology, and evolution. Evolutionary developmental biology, also known as evo-devo or EDB, seeks to find links between development and evolution by opening the "black box" of development's role in evolution and in the evolution of developmental mechanisms. In particular, this volume emphasizes the roles of the environment and of hormonal signaling in evo-devo. It brings together a group of leading researchers to analyze the dynamic interaction of environmental factors with developmental and physiological processes and to examine how environmental signals are translated into phenotypic change, from the molecular and cellular level to organisms and groups of organisms. Taken together, these chapters demonstrate the crucial roles of those processes of genetic, developmental, physiological, and hormonal change that underpin evolutionary change in development, morphology, physiology, behavior, and life-history. Part I investigates links between environmental signals and developmental processes that could be preserved over evolutionary time. Several contributors evaluate the work of the late Ryuichi Matsuda, especially his emphasis on the role of the external environment in genetic change and variability ("pan-environmentalism"). Other contributors in part I analyze different aspects of environmental-genetic-evolutionary linkages, including the importance of alternate ontogenies in evolution and the paradox of stability over long periods of evolutionary time. Part II examines the plasticity that characterizes much of development, with contributors discussing such topics as gene regulatory networks and heterochronicity. Part III analyzes the role of hormones and metamorphosis in the evolution of such organisms with alternate life-history stages as lampreys, amphibians, and insects.

Organized Business Interests In Changing Environments

Author: J. Grote
Publisher: Springer
ISBN: 0230594913
Size: 42.25 MB
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A book on the path dependent and path creating structures and attitudes of business interest associations in a world of Europeanization and internationalization of markets. It includes empirical data on relational information used for network analytic purposes – drawn from hundreds of interviews with CEOs.

Terrestrial Photosynthesis In A Changing Environment

Author: Jaume Flexas
Publisher: Cambridge University Press
ISBN: 1107377676
Size: 36.69 MB
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Understanding how photosynthesis responds to the environment is crucial for improving plant production and maintaining biodiversity in the context of global change. Covering all aspects of photosynthesis, from basic concepts to methodologies, from the organelle to whole ecosystem levels, this is an integrated guide to photosynthesis in an environmentally dynamic context. Focusing on the ecophysiology of photosynthesis – how photosynthesis varies in time and space, responds and adapts to environmental conditions and differs among species within an evolutionary context – the book features contributions from leaders in the field. The approach is interdisciplinary and the topics covered have applications for ecology, environmental sciences, agronomy, forestry and meteorology. It also addresses applied fields such as climate change, biomass and biofuel production and genetic engineering, making a valuable contribution to our understanding of the impacts of climate change on the primary productivity of the globe and on ecosystem stability.

European Energy Policies In A Changing Environment

Author: Francis McGowan
Publisher: Springer Science & Business Media
ISBN: 3642614922
Size: 59.92 MB
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Across the European Union, energy policy remains a highly controversial issue, despite the relative stability of energy markets and the lack of concern of energy availabilities and prices which marked previous debates on the issue. The debates on nuclear power in Germany, on the coal industry in the UK indicate the continuing resonance of energy policy as a source of dispute at the national level. Moreover, while the urgency which the 1970s energy crises brought to policy discussions may no longer exist, the emergence of new issues, such as the environment and economic liberalisation, have offered new challenges for energy policy. These issues also arise in a European setting. Early in 1995 the European Commission published a Green Paper on Energy Policy -indeed, as the manuscript was completed the Commission was finalising a White Paper -and the issue will be on the agenda of the 1996 Intergovernmental Conference. The outcome of these discussions is far from clear, but there is no doubt that, in one way or another the European Union will help to shape national energy policies for many years to come.