Defensive Mutualism In Microbial Symbiosis

Anemones and fish, ants and acacia trees, fungus and trees, buffaloes and oxpeckers--each of these unlikely duos is an inimitable partnership in which the species' coexistence is mutually beneficial. More specifically, they represent examples of defensive mutualism, when one species receives protection against predators or parasites in exchange for

Taking account of developments over the last decade, this 2nd edition addresses advances in the field and the emergence of fields such as cellular microbiology, immunoparasitology and cytobiology which have revealed new aspects of symbiosis.

This volume summarizes recent advances in our understanding of the mechanisms that produce successful symbiotic partnerships involving microorganisms. It begins with a basic introduction to the nature of and mechanistic benefits derived from symbiotic associations. Taking that background knowledge as the starting point, the next sections include chapters that examine representative examples of coevolutionary associations that have developed between species of microbes, as well as associations between microbes and plants. The authors conclude with a section covering a broad range of associations between microbes and invertebrate animals, in which they discuss the spectrum of hosts, with examples ranging from bryozoans and corals to nematodes, arthropods, and cephalopods. Join the authors on this journey of understanding!

Insects display a staggering diversity of behaviors. Studying these systems provides insights into a wide range of ecological, evolutionary, and behavioral questions including the genetics of behavior, phenotypic plasticity, chemical communication, and the evolution of life-history traits. This accessible text offers a new approach that provides the reader with the necessary theoretical and conceptual foundations, at different hierarchical levels, to understand insect behavior. The book is divided into three main sections: mechanisms, ecological and evolutionary consequences, and applied issues. The final section places the preceding chapters within a framework of current threats to human survival - climate change, disease, and food security - before providing suggestions and insights as to how we can utilize an understanding of insect behavior to control and/or ameliorate them. Each chapter provides a concise, authoritative review of the conceptual, theoretical, and methodological foundations of each topic.

The Arthur M. Sackler Colloquia of the National Academy of Sciences address scientific topics of broad and current interest, cutting across the boundaries of traditional disciplines. Each year, four or five such colloquia are scheduled, typically two days in length and international in scope. Colloquia are organized by a member of the Academy, often with the assistance of an organizing committee, and feature presentations by leading scientists in the field and discussions with a hundred or more researchers with an interest in the topic. Colloquia presentations are recorded and posted on the National Academy of Sciences Sackler colloquia website and published on CD-ROM. These Colloquia are made possible by a generous gift from Mrs. Jill Sackler, in memory of her husband, Arthur M. Sackler.

The associations between insects and microorganisms, while pervasive and of paramount ecological importance, have been relatively poorly understood. The third book in this set, Insect Symbiosis, Volume 3, complements the previous volumes in exploring this somewhat uncharted territory. Like its predecessors, Volume 3 illustrates how symbiosis resear

Bacteria have been the dominant forms of life on Earth for the past 3.5 billion years. They rapidly evolve, constantly changing their genetic architecture through horizontal DNA transfer and other mechanisms. Consequently, it can be difficult to define individual species and determine how they are related. Written and edited by experts in the field, this collection from Cold Spring Harbor Perspectives in Biology examines how bacteria and other microbes evolve, focusing on insights from genomics-based studies. Contributors discuss the origins of new microbial populations, the evolutionary and ecological mechanisms that keep species separate once they have diverged, and the challenges of constructing phylogenetic trees that accurately reflect their relationships. They describe the organization of microbial genomes, the various mutations that occur, including the birth of new genes de novo and by duplication, and how natural selection acts on those changes. The role of horizontal gene transfer as a strong driver of microbial evolution is emphasized throughout. The authors also explore the geologic evidence for early microbial evolution and describe the use of microbial evolution experiments to examine phenomena like natural selection. This volume will thus be essential reading for all microbial ecologists, population geneticists, and evolutionary biologists.

Microbes influence the evolutionary trajectories of animals through symbiosis, which ranges from parasitic to mutualistic associations. Fungus-growing ants engage in multiple microbial symbioses, including an obligate mutualism with a fungus, Leucoagaricus spp., which is the ants' main food source and is cultivated into structures known as 'fungus gardens.' In addition, Escovopsis is a system-specific fungal parasite that destroys Leucoagaricus hyphae. The interactions between the ants, Leucoagaricus, and Escovopsis represent ancient co-evolving symbioses with well-described roles. However, other microbial symbioses within the system are less explored. Metagenomic studies revealed a consistent bacterial community in fungus gardens dominated by Proteobacteria, but the specific functional roles of most of these bacteria are unknown. Likewise, one metagenomic study found bacteriophage in fungus gardens, yet virus presence and dynamics are poorly described. Overall, the goal of my research is to investigate the function and diversity of the understudied secondary bacterial and viral communities present within the multipartite symbiosis of fungus-growing ants. In this dissertation, I use interdisciplinary approaches to assess the functional capacity of bacteria that associate with fungus gardens and to explore viral diversity in the fungus-growing ant system for the first time. In Chapter 2, I explore the ability of fungus garden bacteria to detoxify plant secondary compounds that are harmful to the fungal mutualist, Leucoagaricus spp. Using methods including isolation of bacterial and fungal strains, phenotypic and genomic analyses, and gas-chromatography to quantify toxin degradation, I concluded that plant secondary compound detoxification is a polymicrobial process that includes multiple fungus garden bacterial community members and the fungal mutualist. These microbial associations enable leaf-cutter ants to be the successful generalist herbivores that they are. In Chapter 3, I describe the role of fungus garden-associated bacteria in the genus Burkholderia as potential defensive symbionts that protect the ants against the parasitic fungus Escovopsis. Using selective isolations of bacteria in the family Burkholderiaceae, genomic analysis, competitive bioassays, and analytical chemistry techniques, I found that Burkholderia sp. can inhibit Escovopsis via the production of two synergistic or additive antifungals, pyrrolnitrin and burkholdine1213. In Chapter 4, I performed virus-enriched metagenomic and metatranscriptomic sequencing of fungus-growing ants and Leucoagaricus spp. to identify viruses that associate with the system. Here, I identified 34 eukaryotic viruses that associate with either ant or fungal tissue, with certain viruses demonstrating evolutionary congruence with ant host phylogeny. Overall, my work sheds light on the secondary microbial interactions and functions within the fungus-growing ant system. Together, these studies enhance our knowledge of how fungus-growing ants associate with a diversity of microbes to succeed in the presence of biotic stressors, underscoring the importance of symbiotic microbes on the evolution and ecology of their host.

This volume focuses on those instances when benign and even beneficial relationships between microbes and their hosts opportunistically change and become detrimental toward the host. It examines the triggering events which can factor into these changes, such as reduction in the host’s capacity for mounting an effective defensive response due to nutritional deprivation, coinfections and seemingly subtle environmental influences like the amounts of sunlight, temperature, and either water or air quality. The effects of environmental changes can be compounded when they necessitate a physical relocation of species, in turn changing the probability of encounter between microbe and host. The change also can result when pathogens, including virus species, either have modified the opportunist or attacked the host’s protective natural microflora. The authors discuss these opportunistic interactions and assess their outcomes in both aquatic as well as terrestrial ecosystems, highlighting the impact on plant, invertebrate and vertebrate hosts.

Parasites are a masterful work of evolutionary art. The tiny mite Histiostoma laboratorium, a parasite of Drosophila, launches itself, in an incredible display of evolutionary engineering, like a surface-to-air missile at a fruit fly far above its head. Gravid mussels such as Lampsilis ventricosa undulate excitedly as they release their parasitic larval offspring, conning greedy predators in search of a tasty meal into hosting the parasite. The Art of Being a Parasite is an extensive collection of these and other wonderful and weird stories that illuminate the ecology and evolution of interactions between species. Claude Combes illustrates what it means to be a parasite by considering every stage of its interactions, from invading to reproducing and leaving the host. An accessible and engaging follow-up to Combes's Parasitism, this book will be of interest to both scholars and nonspecialists in the fields of biodiversity, natural history, ecology, public health, and evolution.