Plant-herbivore interactions are a central topic in evolutionary ecology. Historically, their study has been a cornerstone for coevolutionary theory. Starting from classic ecological studies at the phenotypic level, it has since expanded to molecular and genomic approaches. After a historical perspective, the book’s subsequent chapters cover a wide range of topics: from populations to ecosystems; plant- and herbivore-focused studies; in natural and in man-modified ecosystems; and both micro- and macro-evolutionary levels. All chapters include valuable background information and empirical evidence. Given its scope, the book will be of interest to both students and researchers, and will hopefully stimulate further research in this exciting field of evolutionary biology.

This book examines an important paradigm shift in biology: Plants and animals, traditionally viewed as individuals, are now considered to be complex systems and host to a plethora of microorganisms. After first presenting historical aspects of microbiota research, bacterial compositions of individual microbiomes and the critical analysis of current methods, the book discusses how microbial communities inside the human body are profoundly affected by numerous factors, such as macro- and micro-nutrients, physical exercise, antibiotics, gender and age. As described by current research, the author highlights how microbiomes contribute to the fitness of the host by providing nutrients, inhibiting pathogens, aiding in the storage of fat during pregnancy, and contributing to development and behavior. The author not only focusses on prokaryotic components in microbiomes, but also addresses single-cell eukaryotes and viruses. This follow-up to the successful book The Hologenome Concept: Human, Animal and Plant Microbiota, published in 2013, provides a contemporary overview of microbiomes. It appeals to anyone working in the life sciences and biomedicine.

This book focuses on the importance and roles of seed microbiomes in sustainable agriculture by exploring the diversity of microbes vectored on and within seeds of both cultivated and non-cultivated plants. It provides essential insights into how seeds can be adapted to enhance microbiome vectoring, how damaged seed microbiomes can be assembled again and how seed microbiomes can be conserved. Plant seeds carry not only embryos and nutrients to fuel early seedling growth, but also microbes that modulate development, soil nutrient acquisition, and defense against pathogens and other stressors. Many of these microbes (bacteria and fungi) become endophytic, entering into the tissues of plants, and typically exist within plants without inducing negative effects. Although they have been reported in all plants examined to date, the extent to which plants rely on seed vectored microbiomes to enhance seedling competitiveness and survival is largely unappreciated. How microbes function to increase the fitness of seedlings is also little understood. The book is a unique and important resource for researchers and students in microbial ecology and biotechnology. Further, it appeals to applied academic and industrial agriculturists interested in increasing crop health and yield.

The One Health concept, introduced at the beginning of the 2000s, is a worldwide strategy for promoting multidisciplinary partnerships and information in all facets of health care sciences, perceiving the interrelationship between humans, animals, plants, and their common environment. Recent advances in DNA sequencing technology and computational biology have revolutionized the field of the microbiome. Information surrounding uncultured microorganisms provides a comprehensive analysis of the relationships between an animal, the environment, and human's microbiota, including various disease correlations. In this Research Topic, we are interested in exploring how environmental stress effects bacterial communities, and how those changes relate to human health and pathobiont transmission in experimental and big data analysis.

The evolution of metazoans has been accompanied by new interfaces with the microbial environment that include biological barriers and surveillance by specialized cell types. Increasingly complex organisms require increased capacities to confront pathogens, achieved by co-evolution of recognition mechanisms and regulatory pathways. Two distinct but interactive forms of immunity have evolved. Innate immunity, shared by all metazoans, is traditionally viewed as simple and non-specific. Adaptive immunity possesses the capacity to anticipate new infectious challenges and recall previous exposures; the most well-understood example of such a system, exhibited by lymphocytes of vertebrates, is based on somatic gene alterations that generate extraordinary specificity in discrimination of molecular structures. Our understanding of immune phylogeny over the past decades has tried to reconcile immunity from a vertebrate standpoint. While informative, such approaches cannot completely address the complex nature of selective pressures brought to bear by the complex microbiota (including pathogens) that co-exist with all metazoans. In recent years, comparative studies (and new technologies) have broadened our concepts of immunity from a systems-wide perspective. Unexpected findings, e.g., genetic expansions of innate receptors, high levels of polymorphism, RNA-based forms of generating diversity, adaptive evolution and functional divergence of gene families and the recognition of novel mediators of adaptive immunity, prompt us to reconsider the very nature of immunity. Even fundamental paradigms as to how the jawed vertebrate adaptive immune system should be structured for “optimal” recognition potential have been disrupted more than once (e.g., the discovery of the multicluster organization and germline joining of immunoglobulin genes in sharks, gene conversion as a mechanism of somatic diversification, absence of IgM or MHC II in certain teleost fishes). Mechanistically, concepts of innate immune memory, often referred to as “trained memory,” have been realized further, with the development of new discoveries in studies of epigenetic regulation of somatic lineages. Immune systems innovate and adapt in a taxon-specific manner, driven by the complexity of interactions with microbial symbionts (commensals, mutualists and pathogens). Immune systems are shaped by selective forces that reflect consequences of dynamic interactions with microbial environments as well as a capacity for rapid change that can be facilitated by genomic instabilities. We have learned that characterizing receptors and receptor interactions is not necessarily the most significant component in understanding the evolution of immunity. Rather, such a subject needs to be understood from a more global perspective and will necessitate re-consideration of the physical barriers that afford protection and the developmental processes that create them. By far, the most significant paradigm shifts in our understanding of immunity and the infection process has been that microbes no longer are considered to be an automatic cause or consequence of illness, but rather integral components of normal physiology and homeostasis. Immune phylogeny has been shaped not only by an arms race with pathogens but also perhaps by mutualistic interactions with resident microbes. This Research Topic updates and extends the previous eBook on Changing Views of the Evolution of Immunity and contains peer-reviewed submissions of original research, reviews and opinions.