Dale Clayton

University of Utah | UOU · Department of Biology

Environmental factors such as temperature and humidity influence the distribution of free‐living organisms. As climates change, the distributions of these organisms change along with their associated parasites, mutualists and commensals. Less studied, however, is the possibility that environmental conditions may directly influence the distribution...

Evolution results from the interaction of stochastic and deterministic processes that create a web of historical contingency, shaping gene content and organismal function. To understand the scope of this interaction, we examine the relative contributions of stochasticity, determinism, and contingency in shaping gene inactivation in 34 lineages of e...

Birds have a diverse community of "permanent" arthropods that complete their entire life cycle on the body of the host. Because some of these arthropods are parasites that reduce host fitness, birds control them by grooming, which consists of preening with the beak and scratching with the feet. Although preening is the primary component of grooming...

Divergent natural selection should lead to adaptive radiation - that is, the rapid evolution of phenotypic and ecological diversity originating from a single clade. The drivers of adaptive radiations have often been conceptualized through the concept of "adaptive landscapes"; yet formal empirical estimates of adaptive landscapes for natural adaptiv...

Co‐parasitism is ubiquitous and has important consequences for the ecology and evolution of wild host populations. Studies of parasite co‐infections remain limited in scope, with few experimental tests of the fitness consequences of multiple parasites, especially in natural populations. We measured the separate and combined effects of Philornis seg...

Animals defend themselves against parasites in many ways. Defenses, such as physiological immune responses, are capable of clearing some infections. External parasites that do not feed on blood, however, are not controlled by the physiological immune system. Instead, ectoparasites like feather-feeding lice (Phthiraptera: Ischnocera) are primarily c...

Animals have evolved a variety of adaptations to care for their body surfaces, such as grooming behavior, which keeps the integument clean, parasite-free, and properly arranged. Despite extensive research on the grooming of mammals, birds, and arthropods, the survival value of grooming has never been directly measured in natural populations. We mon...

The term terroir is used in viticulture to emphasize how the biotic and abiotic characteristics of a local site influence grape physiology and thus the properties of wine. In ecology and evolution, such terroir (i.e., the effect of space or "site") is expected to play an important role in shaping phenotypic traits. Just how important is the pure sp...

Adaptive radiation is an important mechanism of organismal diversification and can be triggered by new ecological opportunities. Although poorly studied in this regard, parasites are an ideal group in which to study adaptive radiations because of their close associations with host species. Both experimental and comparative studies suggest that the...

Adaptive radiation is an important mechanism of organismal diversification, and can be triggered by new ecological opportunities. Although poorly studied in this regard, parasites present an ideal system to study adaptive radiations because of their close associations with host species. Both experimental and comparative studies suggest that the ect...

Anthropogenic changes to the environment challenge animal populations to adapt to new conditions and unique threats. While the study of adaptation has focused on genetic variation, epigenetic mechanisms may also be important. DNA methylation is sensitive to environmental stressors, such as parasites and pesticides, which may affect gene expression...

A recent paper in this journal concerning parasites of rock pigeons (Columba livia) published by Ali and colleagues exemplifies a growing trend of misidentified parasites in the literature, despite increased online resources that should help facilitate accurate identification. In the Ali et al. paper, a pigeon louse in the genus Columbicola (Phthir...

The pigeon louse Columbicola columbae is a longstanding and important model for studies of ectoparasitism and host-parasite coevolution. However, a deeper understanding of its evolution and capacity for rapid adaptation is limited by a lack of genomic resources. Here, we present a high-quality draft assembly of the C. columbae genome, produced usin...

The pigeon louse Columbicola columbae is a longstanding and important model for studies of ectoparasitism and host-parasite coevolution. However, a deeper understanding of its evolution and capacity for rapid adaptation is limited by a lack of genomic resources. Here, we present a high-quality draft assembly of the C. columbae genome, produced usin...

Grooming by birds is thought to serve essential anti-parasite functions. While preening has been well studied, little is known about the function of scratching in birds. We conducted a series of experiments to determine the effectiveness of scratching for controlling feather lice (Columbicola columbae) on Rock Pigeons (Columba livia). First, we use...

Allopreening occurs when 1 bird preens another bird. The behavior is normally directed at the head and neck of the recipient, i.e., regions that the bird cannot self-preen. Studies of penguins, pigeons, and other groups of birds suggest that allopreening plays a role in the control of ectoparasites, such as ticks and feather lice. However, it is no...

Organisms allocate limited resources to competing activities such as reproduction, growth, and defense against parasites and predators. The introduction of a novel parasite may create new life history trade-offs. As hosts increase their investment in self-maintenance or defense, the cost of parasitism may carry over to other aspects of host biology...

Birds can adjust investment in reproduction by altering the sex ratios of their broods. When one sex is more costly to raise than the other, producing either more male or female offspring can lower the costs of reproduction. Biasing sex ratios can also be advantageous if the expected fitness of male versus female offspring differs. Here, we investi...

Disruptive natural selection within populations exploiting different resources is considered to be a major driver of adaptive radiation and the production of biodiversity. Fitness functions, which describe the relationships between trait variation and fitness, can help to illuminate how this disruptive selection leads to population differentiation....

Darwin argued that differential natural selection across environments leads to the evolution of reproductive isolation and speciation. More recently, this process has been dubbed “ecological speciation.” Although simple in principle, mechanisms that link adaptation and reproductive isolation have seldom been demonstrated. We triggered diversificati...

Table A1. Linear mixed model (LMM) summary comparing the luminosity of lice on pigeons with normal preening. Table A2. Linear mixed model (LMM) summary comparing the luminosity of lice on pigeons with impaired preening. Table A3. Mean luminosity of lice from white, grey, and black pigeons with normal preening over the course of the four‐year expe...

Adaptive radiation occurs when the members of a single lineage evolve different adaptive forms in response to selection imposed by competitors or predators. Iconic examples include Darwin's finches, Caribbean anoles, and Hawaiian silverswords, all of which live on islands. Although adaptive radiation is thought to be an important generator of biodi...

When confronted with a parasite or pathogen, hosts can defend themselves by resisting or tolerating the attack. While resistance can be diminished when resources are limited, it is unclear how robust tolerance is to changes in environmental conditions. Here, we investigate the sensitivity of tolerance in a single host population living in a highly...

The chewing louse subgenus Cicchinella new subgenus is erected and described for species of Guimaraesiella Eichler, 1949, parasitizing Old World babblers (Leiothrichidae, Pellorneidae, Timaliidae). The subgenus is divided into three species groups based on chaetotaxy, head and genitalia of both sexes. Two species are redescribed: Guimaraesiella (Ci...

Ecological speciation occurs when local adaptation generates reproductive isolation as a by-product of natural selection. Although ecological speciation is a fundamental source of diversification, the mechanistic link between natural selection and reproductive isolation remains poorly understood, especially in natural populations. Here we show that...

Adaptive radiation occurs when the members of a single lineage evolve different adaptive forms in response to selection imposed by competitors or predators. Iconic examples include Darwin's finches, Caribbean anoles, and Hawaiian silverswords, all of which live on islands. Parasites, which live on host 'islands', show macroevolutionary patterns con...

Darwin’s finches are an iconic example of adaptive radiation. The size and shape of the beaks of different finch species are diversified for feeding on different size seeds and other food resources. However, beaks also serve other functions, such as preening for the control of ectoparasites. In diverse groups of birds, the effectiveness of preening...

During the summer of 2015, 52 passerine birds, representing 16 genera and 19 species were captured at a field site in the High Tatra Mountains, Tatranská Javorina, Slovakia. These birds were examined for ectoparasites, including chewing lice (Phthiraptera: Ischnocera), fleas (Siphonaptera), flies (Diptera: Hippoboscidae), and feather mites (Acari)....

Birds have many kinds of internal and external parasites, including viruses, bacteria and fungi, as well as protozoa, helminths and arthropods. Because parasites have negative effects on host fitness, selection favours the evolution of anti-parasite defences, many of which involve behaviour. We provide a brief review of anti-parasite behaviours in...

Dispersal is a fundamental component of the life history of most species. Dispersal influences fitness, population dynamics, gene flow, genetic drift, and population genetic structure. Even small differences in dispersal can alter ecological interactions and trigger an evolutionary cascade. Linking such ecological processes with evolutionary patter...

1. Harrison's rule, which predicts that large‐bodied species of hosts have large‐bodied species of parasites, has been documented in a wide diversity of parasites. 2. Harrison's rule has been most thoroughly studied in avian feather lice, which escape from host defence (preening) by hiding in the feathers. Lice that are unable to hide are selective...

Twelve new species of chewing lice in the genus Priceiella Gustafsson & Bush, 2017, are described from Old World “babblers” (Leiothrichidae, Paradoxornithiidae, Pellorneidae and Timaliidae). Eight species belong to the subgenus Thescelovora Gustafsson & Bush, 2017: Priceiella (Thescelovora) calcicola n. sp. from Turdinus crispifrons crispifrons; Pr...

The muscid genus Philornis comprises approximately 50 described species of flies, nearly all of which are obligate parasites of nestling birds. Philornis species are native to the Neotropics and widely distributed from Florida to Argentina. Most research on this group has focused on P. downsi, which was introduced to the Gal´apagos Islands in the l...

Background The molecular basis of evolutionary change is assumed to be genetic variation. However, growing evidence suggests that epigenetic mechanisms, such as DNA methylation, may also be involved in rapid adaptation to new environments. An important first step in evaluating this hypothesis is to test for the presence of epigenetic variation betw...

The Vegetarian Finch, Platyspiza crassirostris, is a relatively unstudied Darwin's finch that appears to be in decline in the Galapagos Islands. We monitored 11 nests of Vegetarian Finches during 2013 and 2014 on Santa Cruz Island, Galapagos, and found that 10 of these were infested with an invasive parasitic fly, Philornis downsi. This is the firs...

Introduced parasites threaten host populations around the world. For example, introduced parasitic nest flies (Philornis downsi) have contributed to the decline of several species of Darwin's finches in the Galápagos Islands. Introduced parasites are thought to have severe effects on native hosts because the hosts do not have effective defenses aga...

Parasitic "wing lice" (Phthiraptera: Columbicola) and their dove and pigeon hosts are a well-recognized model system for coevolutionary studies at the intersection of micro- and macroevolution. Selection on lice in microevolutionary time occurs as pigeons and doves defend themselves against lice by preening. In turn, behavioral and morphological ad...

For birds, the first line of defence against ectoparasites is preening. The effectiveness of self-preening for ectoparasite control is well known. By contrast, the ectoparasite control function of allopreening - in which one birds preens another - has not been rigorously tested. We infested captive pigeons with identical numbers of parasitic lice,...

Behavior is usually the first line of defense against parasites. Antiparasite behaviors, such as grooming, or outright avoidance, have been shown to reduce the risk of parasitism in a wide variety of host–parasite systems. However, despite the central importance of antiparasite behavior, little is known about the extent to which prior exposure to p...

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...

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 indi...

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...

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. Th...

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,...

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 p...

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...

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, behavi...

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 b...

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...

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)...

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 cho...

Introduced pathogens and other parasites are often implicated in host population‐level declines and extinctions. However, such claims are rarely supported by rigorous real‐time data. Indeed, the threat of introduced parasites often goes unnoticed until after host populations have declined severely. The recent introduction of the parasitic nest fly,...

Introduced parasites threaten native host species that lack effective defenses. Such parasites increase the risk of extinction, particularly in small host populations like those on islands. If some host species are tolerant to introduced parasites, this could amplify the risk of the parasite to vulnerable host species. Recently, the introduced para...

Introduced parasites threaten native host species that lack effective defenses. Such parasites increase the risk of extinction, particularly in small host populations, like those on islands. If some host species are tolerant to introduced parasites, this could amplify the risk of the parasite to vulnerable host species. Recently, the introduced par...

We studied diverse antigen binding in hosts and the outcome of parasitism.We used captive bred F1 descendants of feral rock pigeons (Columba livia) challenged with blood feeding flies (Hippoboscidae) and a protozoan parasite (Haemoproteus). Enzyme-linked immunosorbent assays (ELISAs) and immunoblots were used to test (1) if pre-infection IgY antige...

The prevailing theory for the molecular basis of evolution involves genetic mutations that ultimately generate the heritable phenotypic variation on which natural selection acts. However, epigenetic transgenerational inheritance of phenotypic variation may also play an important role in evolutionary change. A growing number of studies have demonstr...

Transmission of insect-borne diseases is shaped by the interactions among parasites, vectors, and hosts. Any factor that alters movement of infected vectors from infected to uninfeced hosts will in turn alter pathogen spread. In this paper, we study one such pathogen-vector-host system, avian malaria in pigeons transmitted by fly ectoparasites, whe...

Introduced parasites are a threat to biodiversity when naïve hosts lack effective defenses against such parasites [1]. Several parasites have recently colonized the Galápagos Islands, threatening native bird populations [2]. For example, the introduced parasitic nest fly Philornis downsi (Diptera: Muscidae) has been implicated in the decline of end...

Blood-feeding arthropods can harm their hosts in many ways, such as through direct tissue damage and anemia, but also by distracting hosts from foraging or watching for predators. Blood-borne pathogens transmitted by arthropods can further harm the host. Thus, effective behavioral and immunological defenses against blood-feeding arthropods may prov...

Ecological immunology aims to explain variation among hosts in the strength and efficacy of immunological defenses. However, a shortcoming has been the failure to link host immune responses to actual parasites under natural conditions. Here, we present one of the first experimental demonstrations of a parasite-induced immune response in a wild bird...

Two methods commonly used to quantify ectoparasites on live birds are visual examination and dust-ruffling. Visual examination provides an estimate of ectoparasite abundance based on an observer's timed inspection of various body regions on a bird. Dust-ruffling involves application of insecticidal powder to feathers that are then ruffled to dislod...

Background Many groups of insects have obligate bacterial symbionts that are vertically transmitted. Such associations are typically characterized by the presence of a monophyletic group of bacteria living in a well-defined host clade. In addition the phylogeny of the symbiotic bacteria is typically congruent with that of the host, signifying co-sp...

Abstract ABSTRACT: Feather mites are a diverse group of ectosymbionts that occur on most species of birds. Although Darwin's finches are a well-studied group of birds, relatively little is known about their feather mites. Nearly 200 birds across 9 finch species, and from 2 locations on Santa Cruz Island, Galápagos, were dust-ruffled during the 2009...

Like many parasites, avian haematozoa are often found at lower infection intensities in older birds than young birds. One explanation, known as the ''selection'' hypothesis, is that infected young birds die before reaching adulthood, thus removing the highest infection intensities from the host population. We tested this hypothesis in the field by...

Many parasites, such as those that cause malaria, depend on an insect vector for transmission between vertebrate hosts. Theory predicts that parasites should have little or no effect on the transmission ability of vectors, e.g., parasites should not reduce vector life span as this will limit the temporal window of opportunity for transmission. Howe...

Birds combat ectoparasites with many defences but the first line of defence is grooming behaviour, which includes preening with the bill and scratching with the feet. Preening has been shown to be very effective against ectoparasites. However, most tests have been with feather lice, which are relatively slow moving. Less is known about the effectiv...

Preening is a bird's first line of defense against harmful ectoparasites. Ectoparasites, in turn, have evolved adaptations for avoiding preening such as hardened exoskeletons and escape behavior. Earlier work suggests that some groups of ectoparasites, such as feather lice, leave hiding places in feathers that are exposed to direct sunlight, making...

Reciprocal selective effects between coevolving species are often influenced by interactions with the broader ecological community. Community-level interactions may also influence macroevolutionary patterns of coevolution, such as cospeciation, but this hypothesis has received little attention. We studied two groups of ecologically similar feather...