REVIEWS
“A fascinating treatment of coevolution using the very interesting and apt model system of lice-host associations. The authors assemble and consider a great deal of research to achieve a broad synthesis—for instance, linking microevolution and macroevolution, taking a community ecology approach to host-parasite coevolution, and reflecting on geographic structure as part of the coevolutionary process. As an insect-plant person I was very much taken in, and I left the book with a new appreciation for what these systems can teach us about coevolution. The scholarship is exceptional. Thorough, carefully documented, well-substantiated, and with flashes of humor, Coevolution of Life on Hosts will become a bible for students of lice-host interactions, but it should appeal to anybody with an interest in coevolution and has the potential to be a crossover work that stimulates thought and progress in many fields.”
— Kelley J. Tilmon, South Dakota State University, editor of "Specialization, Speciation & Radiation: The Evolutionary Biology of Herbivorous Insects"
“Clayton, Bush, and Johnson’s writing has a way of sneaking up on you, drawing you further and further into the fascinating world of lice, their unfortunate hosts (count us among The Chosen, of course), and evolution’s hand on all participants, be they willing or unwilling. This may be a book intended for biologists, but I would call it a page-turner for just about anyone who—forgive the pun—itches to learn more about little creatures that make their living by sucking and chewing on bigger creatures. Let me just say this: I know for sure it’s a treasure trove for at least one cartoonist.”
— Gary Larson, creator of "The Far Side" TM
“It's a lousy world out there! . . . Parasites and their hosts constitute fascinating examples of ecological and evolutionary interactions, as evidenced by the interest that people as far away from the field as cartoonist Gary Larson pay to the lives of these critters. Hence there is every reason to consider these organisms to be model systems of coevolution. Clayton and his collaborators Bush and Johnson have together with their many students done an impressive job by filling out many of the gaps of knowledge on coevolution, thereby accidentally filling an academic niche in the same way as many ectoparasites squeeze into empty spaces on the host to make their living. . . . This is an exciting book that will direct many students towards the study of lice and other parasites, and thereby spread an interest in coevolution at large—as large as this topic deserves.”
— Trends in Ecology & Evolution
“Clayton and Bush and Johnson make it abundantly clear that external parasites and their hosts are excellent subjects for evolutionary studies. . . . The authors cite many such studies in context, as the book refers, where appropriate, to evolutionary theory from Darwin through Dobzhansky, Wright, and other more recent authors, and include about 1,000 references in their 50-page ‘Literature Cited’ section. They also attempt to describe, illustrate, and define such terms as coevolution and coadaptation. For its subject matter, the book is readable, with some quotations from various sources and some humor. There are abundant illustrations, mostly charts but some pictures of organisms; some plates, including color; graphs and tables, all of good quality; and many text boxes explaining ideas. . . . A useful resource for collections on evolutionary experimentation and theory. . . . Recommended.”
— M. LaBar, Southern Wesleyan University, Choice
“This is not only a book about lice and host adaptations and counter-adaptations, this is a book about how one tests for the role of coevolution by studying a fascinating system. It is the way the authors lay out the logic and rationale for the tests and comparisons they present that will make this book timeless. . . . There is no question that the culmination of decades of work by Clayton, Bush, and Johnson has provided a rich tapestry woven together in Coevolution of Life on Hosts. Champions and skeptics of coevolution alike will find a wealth of studies and ideas that are sure to generate deep thought. In my opinion, Clayton, Bush, and Johnson have shown us that coevolution is a continual and important source of selection between interacting lineages.”
— David M. Althoff, Syracuse University, Evolution
TABLE OF CONTENTS
Preface
Part I. Background
1. Introduction to coevolution - Dale H. Clayton, Sarah E. Bush, Kevin P. Johnson
DOI: 10.7208/chicago/9780226302300.003.0001
[coadaptation, co-diversification, co-evolution, geographic mosaic, reciprocal selection, heritability]
This chapter provides an overview of basic principles of coevolutionary biology, including both microevolutionary (ecological) and macroevolutionary (historical) approaches and their integration. It defines the main terminology used in coevolutionary biology. It discusses the relationship between coadaptation, codiversification, and coevolution. The chapter considers the relationship of reciprocal phenotypic selection to coadaptive responses of heritable traits. It introduces the geographic mosaic theory of coevolution and considers the central roles of dispersal and population structure, as well as GxGxE interactions. Chapter 1 briefly reviews the fossil evidence for coevolution. It introduces co-phylogenetic approaches and the cospeciation - host-switching continuum. The chapter concludes by considering why permanent parasites are unusually tractable model systems for studies of coevolution, and by introducing the concept of “ecological replicates.” (pages 3 - 24)
This chapter is available at:
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2. Biology of lice: overview - Dale H. Clayton, Sarah E. Bush, Kevin P. Johnson
DOI: 10.7208/chicago/9780226302300.003.0002
[specificity, permanent, obligate, model, fossil, endosymbiont]
This chapter provides an introduction to the biology of lice and their hosts, particularly for readers with little or no knowledge of their biology. Lice are unusually good model systems for work that attempts to bridge micro- and macro-evolutionary approaches to coevolution. The chapter reviews the basic systematics, morphology, physiology, behaviour, and ecology of both bird and mammal lice. It reviews the “permanent” life cycle of lice and the role of this life cycle in making lice such useful models for coevolutionary studies. The chapter covers the fossil record for lice, as well as patterns of host specificity and basic population biology. It considers the endosymbiotic bacteria that help lice to metabolize the host materials on which the lice feed. Chapter 1 concludes with a review of the community ecology of lice, and a section about human lice. (pages 25 - 41)
This chapter is available at:
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3. Effects of lice on hosts - Dale H. Clayton, Sarah E. Bush, Kevin P. Johnson
DOI: 10.7208/chicago/9780226302300.003.0003
[fitness, virulence, selection, vector]
This chapter reviews data relevant to the effects of lice on host fitness, including aspects of host condition, survival, and reproductive success. The chapter includes four nonexclusive categories: 1) effects of lice on domesticated hosts (both mammals and birds), 2) effects of lice on wild hosts (mammals and birds), 3) effects of lice on mate choice and sexual selection, and 4) costs of resistance to lice. Examples are provided of both the proximal effects of lice on hosts, such as blood loss or feather damage, as well as the ultimate effects of lice on host fitness. The indirect role of lice as vectors or intermediate hosts of pathogens of hosts is also considered in some detail. The chapter concludes with a section on host tolerance, which is an alternative strategy that does not reduce parasite fitness, and therefore does not select for parasite escape. (pages 42 - 58)
This chapter is available at:
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Part II. Coadaptation
4. Adaptations for resisting lice - Dale H. Clayton, Sarah E. Bush, Kevin P. Johnson
DOI: 10.7208/chicago/9780226302300.003.0004
[avoidance, tolerance, resistance, defense, adaptation]
In this chapter we review adaptation of birds and mammals for combatting lice and reducing their effects on host fitness. Some of these adaptations appear to be specific to lice, while others are also effective against other ectoparasites. Overall, birds and mammals have three broad strategies for combating lice: 1) avoidance, 2) tolerance, and 3) resistance. Although individual hosts cannot choose their parents, they can attempt to choose a louse-free mate, which is an example of the first strategy. Louse-mediated mate choice was reviewed in Chapter 3. The second strategy - tolerance of small infestations of lice – was also reviewed at the conclusion of the last chapter. In this chapter, adaptations for resisting lice, which is the third and most common defense strategy, are reviewed. Resistance adaptations include molting of plumage or pelage, endogenous chemical resistance, maintenance behavior, and immunological responses. The chapter concludes by considering the genetics of resistance. (pages 61 - 84)
This chapter is available at:
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5. Counter- adaptations of lice - Dale H. Clayton, Sarah E. Bush, Kevin P. Johnson
DOI: 10.7208/chicago/9780226302300.003.0005
[counter-adaptation, escape, attachment, locomotion]
Lice and other permanent parasites complete their entire life cycle on the body of the host. This “host or bust” strategy provides ready access to food and shelter, but it comes with a cost. Over evolutionary time, lice have lost the ability to disperse easily away from the host, or to survive for long off the host. They have evolved morphological, physiological, and behavioral adaptations for 1) attachment to the host, 2) locomotion on the host, and 3) escape from host defense. The three classes of adaptations are intertwined; however, the third category includes the most apparent and best-studied counter-adaptations. In this chapter, adaptations for attachment and locomotion are discussed. A variety of counter-adaptations coevolved by lice for circumventing host defense are highlighted. (pages 85 - 105)
This chapter is available at:
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6. Competition and coadaptation - Dale H. Clayton, Sarah E. Bush, Kevin P. Johnson
DOI: 10.7208/chicago/9780226302300.003.0006
[competition, displacement, local extinction, community, limiting resource, coadaptation]
The preceding chapters of the book focused on interactions between hosts and parasites. This chapter focuses on competitive interactions between different species of parasites, and the role of the host in mediating those interactions. Parasites do not live in isolation, but are members of diverse parasite communities that share hosts. While no individual harbors all parasites known from that host species, most individuals support more than one species of parasite at a time. The presence of a given parasite species can have a negative effect on other parasites due to competition for limiting resources in or on the shared host. Even parasites that exploit very different parts of a host's body may compete, because each host individual is ultimately a single resource. Interspecific competition can lead to the coadaptation of traits that reduce the intensity of competition. Thus, in addition to coevolving with the host species, parasites coevolve with other parasites that share that same host species. The chapter begins by considering competition between parasite species, in general. It then provides a more detailed overview of competition between species of lice. (pages 106 - 122)
This chapter is available at:
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Part III. Hosts as islands
7. Dispersal - Dale H. Clayton, Sarah E. Bush, Kevin P. Johnson
DOI: 10.7208/chicago/9780226302300.003.0007
[transmission, vertical, horizontal, gene flow]
Dispersal is the movement of individuals away from their place of birth. Dispersal governs gene flow and thus population genetic structure. It is of central importance to ecology and evolution. Local adaptation of parasites is governed by the dispersal rates of parasites in relation to those of the hosts. Limited dispersal contributes to population subdivision, divergence, and ultimately the process of diversification. Hence, data on dispersal are required to interpret coevolutionary dynamics in both micro- and macroevolutionary time. In this chapter, three major modes of dispersal by lice are reviewed. These modes of dispersal can be considered as forms of transmission: 1) Vertical transmission (movement of lice directly from parent hosts to their offspring); 2) Direct horizontal transmission (movement of lice between individual hosts that are in direct contact); and 3) Indirect horizontal transmission (movement of lice between individual hosts that are not in direct contact). (pages 125 - 137)
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8. Population structure - Dale H. Clayton, Sarah E. Bush, Kevin P. Johnson
DOI: 10.7208/chicago/9780226302300.003.0008
[gene flow, population subdivision, deme, metapopulation]
Populations are seldom uniform; they tend to be subdivided, with gene frequencies unevenly distributed across landscapes. In this chapter, determinants of population structure in parasites are first reviewed. Lice turn out to be excellent models for studies of population structure. Population genetic structure arises largely because of limitations to dispersal and gene flow. Population variation in parasites is influenced by the rate of parasite dispersal at three scales: dispersal among host individuals, among host populations, and among host species. If most dispersal consists of vertical transmission from parent hosts to their offspring, then parasites living on individual hosts and their progeny will accumulate genetic differences, contributing to population genetic structure. If horizontal transmission is common, however, it will tend to erode population genetic structure among host individuals. It is essential to have information regarding the dispersal ecology of parasites in order to interpret parasite population structure. (pages 138 - 152)
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Part IV. Codiversification
9. Cophylogenetic dynamics - Dale H. Clayton, Sarah E. Bush, Kevin P. Johnson
DOI: 10.7208/chicago/9780226302300.003.0009
[cophylogenetics, cospeciation, host switching, congruence, duplication, cohesion, sorting events, macroevolution]
Interacting groups with patterns of codiversification are powerful arenas for testing the influence of selection, dispersal, and other processes on lineage diversification. When reproduction in one group is linked to reproduction in another group, codiversification may occur. For example, parasite dispersal is often linked to host dispersal, with barriers to host movement also influencing the movement of their parasites. This linkage of host and parasite dispersal is particularly common in permanent parasites, such as lice, which complete all stages of their life cycle on the body of the host. If barriers to movement contribute to lineage diversification in both host and parasite, then they will codiversify. If codiversification is simultaneous, then the host and parasite may undergo cospeciation. In this chapter we review the five main macroevolutionary events that govern patterns of cophylogenetic history. These processes are cospeciation, host switching, duplication, sorting events, and parasite cohesion. Each of these processes can influence copylogenetic patterns in different ways. (pages 155 - 175)
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10. Comparative cophylogenetics of lice - Dale H. Clayton, Sarah E. Bush, Kevin P. Johnson
DOI: 10.7208/chicago/9780226302300.003.0010
[macroevolution, cophylogenetics, lice, comparative analysis]
Cophylogenetic patterns are central to the study of coevolution in the broad sense because they document codiversification, which is the correlated diversification of interacting lineages. In the last chapter, the macroevolutionary events that govern the cophylogenetic dynamics of codiversifying groups were reviewed. Given the complexity of these processes, it can be difficult to identify ecological or other factors influencing macroevolutionary events and cophylogenetic processes. Comparisons of related groups of organisms can be very helpful. This comparative approach has the power to pinpoint ecological or other differences between groups that may be responsible for different patterns of codiversification. In this chapter, the comparative approach is applied to groups of lice with different cophylogenetic histories. These case studies illustrate some of the ways in which to integrate cophylogenetic analyses with ecological data. They also illustrate the importance of understanding the basic natural history of the system being studied. (pages 176 - 191)
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11. Coadaptive diversification of lice - Dale H. Clayton, Sarah E. Bush, Kevin P. Johnson
DOI: 10.7208/chicago/9780226302300.003.0011
[adaptive radiation, coadaptation, diversification, competition, ecomorph]
Coadaptive diversification occurs when one of two interacting lineages diversifies in response to coadaptation between those lineages. This chapter reviews evidence suggesting that bird lice have undergone coadaptive diversification. For example, coadaptation between lice and their hosts can trigger the diversification of lice across different host species. Lineages of feather lice on different host species live largely in isolation, punctuated by occasional dispersal between hosts. The isolation causes lice to diverge in behavior and morphology in response to interactions with their respective host species. This, in turn, leads to coadaptive diversification of lice across host species. Lice also compete with other species of lice, further contributing to the coadaptive radiation of lice. Divergence and speciation, followed by periodic dispersal, may also result in divergent lineages coming into secondary contact with former conspecifics, triggering even more competition and diversification. In summary, the distribution of feather louse ecomorphs across the feather louse phylogeny is a consequence of infrequent dispersal events, followed by the repeated, independent evolution of similar ecomorphs. (pages 192 - 206)
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Part V. Synthesis
12. Coevolution of life on hosts - Dale H. Clayton, Sarah E. Bush, Kevin P. Johnson
DOI: 10.7208/chicago/9780226302300.003.0012
[codiversification, coadaptation, coevolution, cospeciation, microevolution, macroevolution]
This chapter summarizes the book using a graphical framework that integrates the coadaption and codiversification ends of coevolution with five “zones” of coevolution. This framework can be applied to any host-parasite system. Indeed, it can be used with any coevolving system. Differences in the five coevolutionary zones are operational, yet subtle. Delineating these different zones helps to clarify the ways in which dispersal and selection influence the adapation, coadapation, diversification, and codiversification of interacting groups. Coevolution in this framework varies from a purely microevolutionary focus in the case of coadapation, to a purely macroevolutionary focus in the case of codiversification. These extremes are first considered in more detail. Then the three combinations of adaptation and diversification that comprise the middle portions of the framework are discussed. The importance of integrating phylogenetic, comparative, and experimental approaches cannot be overstated in studies of coevolution, or evolutionary ecology in general. (pages 209 - 224)
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Literature cited
Index
