INFLUENCE OF GROOMING ON PERMANENT ARTHROPOD ASSOCIATES OF BIRDS: CATTLE EGRETS, LICE, AND MITES.

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, scratching is essential for controlling arthropods on the head and neck, which cannot be preened. Several unrelated groups of birds have evolved comb-like pectinate claws on the middle toenail of each foot. We tested the role of these claws in the control of arthropods by experimentally removing teeth from the claws of captive western cattle egrets (Bubulcus ibis) infested with chewing lice (Insecta: Phthiraptera), feather mites (Acari: Sarcoptiformes), and nasal mites (Acari: Mesostigmata). After a period of 4 mo, we compared the abundance of arthropods on experimental birds to that of control birds with intact teeth. We used video to quantify the grooming rates of the captive birds, which groomed twice as much as wild birds. Experimental and control birds did not differ significantly in grooming time. Both groups virtually eradicated the chewing lice, but not feather mites or nasal mites. We found no support for the hypothesis that pectinate claws increase the efficiency of arthropod control by grooming. Experiments with wild birds are needed to test the hypothesis further under conditions in which birds devote less time to grooming.

Co-parasitism in the face of predation: Effects of natural enemies on a neotropical mockingbird.

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 seguyi nest flies and shiny cowbirds Molothrus bonariensis on the fitness of a shared host, the chalk-browed mockingbird (Mimus saturninus) in Argentina. Using a two-factor experimental approach, we manipulated the presence of nest flies and cowbirds in mockingbird nests and assessed their effects on mockingbird haemoglobin levels, begging and provisioning rates, body size, and fledging success. We also monitored rates of nest predation in relation to parasitism by flies and cowbirds. Nest flies reduced the haemoglobin concentration, body size, and fledging success of mockingbirds, likely because mockingbirds did not compensate for parasitism by begging more or feeding their nestlings more. Cowbirds also reduced the fledging success of mockingbirds, even though they had no detectable effect on haemoglobin or body size. Nests with cowbirds, which beg more than mockingbirds, attracted more nest predators. There was no significant interaction between the effects of flies and cowbirds on any component of mockingbird fitness. The combined effects of nest flies and cowbirds were strictly additive. In summary, we show that nest flies and cowbirds both reduce host fitness, but do not have interactive effects in co-parasitized nests. Our results further suggest that predators exacerbate the effects of nest flies and cowbirds on their hosts. Our study shows that the fitness consequences of co-parasitism are complex, especially in the context of community-level interactions.

El co-parasitismo es ubicuo y tiene consecuencias importantes para la ecología y la evolución de las poblaciones de hospedadores silvestres. Los estudios de coinfecciones por parásitos poseen un alcance limitado, con pocos trabajos experimentales que analicen las consecuencias del parasitismo múltiple sobre la eficacia biológica, especialmente en poblaciones naturales. Medimos los efectos separados y combinados de las moscas de los nidos Philornis seguyi y el tordo renegrido (Molothrus bonariensis) sobre la eficacia biológica de un hospedador compartido, la calandria grande (Mimus saturninus) en Argentina. Utilizando un enfoque experimental de dos factores, manipulamos la presencia de moscas de nido y tordos en los nidos de calandrias y evaluamos sus efectos sobre los niveles de hemoglobina, las tasas de solicitud de alimento y aprovisionamiento, el tamaño corporal y el éxito de supervivencia de los pichones de calandria. También monitoreamos las tasas de depredación de nidos en relación con el parasitismo de moscas y tordos. Las moscas de los nidos redujeron la concentración de hemoglobina, el tamaño corporal y el éxito de supervivencia de los pichones de calandrias, probablemente porque las calandrias no compensaron el parasitismo solicitando más alimento o alimentando más a sus pichones. Los tordos también redujeron el éxito de supervivencia de las calandrias, aunque no tuvieron un efecto detectable sobre la hemoglobina o el tamaño corporal. Los nidos con tordos, quienes solicitaron más alimento más que las calandrias, atrajeron a más depredadores de nidos. El aumento de la depredación de nidos asociado a la alta intensidad de solicitud de alimento puede explicar por qué las calandrias en Argentina no solicitan más alimento en respuesta al parasitismo de las moscas. No hubo una interacción significativa entre los efectos de las moscas y los tordos en ningún componente de la eficacia biológica de las calandrias. Los efectos combinados de las moscas de los nidos y los tordos fueron estrictamente aditivos. En resumen, mostramos que las moscas de los nidos y los tordos reducen la eficacia biológica del hospedador, pero no tienen efectos interactivos en los nidos co-parasitados. Nuestros resultados sugieren además que los depredadores exacerban los efectos de las moscas de los nidos y los tordos sobre sus hospedadores. Nuestro estudio muestra que las consecuencias del co-parasitismo sobre la eficacia biológica son complejas, especialmente en el contexto de las interacciones a nivel comunitario.

DOES PREENING BEHAVIOR REDUCE THE PREVALENCE OF AVIAN FEATHER LICE (PHTHIRAPTERA: ISCHNOCERA)?

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 controlled by behavioral defenses such as preening. Here we test the hypothesis that birds able to preen are capable of clearing infestations of feather lice. We experimentally manipulated preening ability in a captive population of rock pigeons (Columba livia) that were infested with identical numbers of feather lice (Columbicola columbae or Campanulotes compar or both). We then monitored the feather louse infestations for 42 wk. Birds with impaired preening remained infested throughout the experiment; in contrast, the prevalence of lice on birds that could preen normally decreased by 50%. These data indicate that it is indeed possible for birds to clear themselves of feather lice, and perhaps other ectoparasites, by preening. We note, however, that captive birds spend more time preening than wild birds, and that they are less likely to be reinfested than wild birds. Thus, additional studies are necessary to determine under what circumstances wild birds can clear themselves of ectoparasites by preening.

Grooming Time Predicts Survival: American Kestrels, Falco sparverius, on a Subtropical Island.

AbstractAnimals 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 monitored grooming and survival in a population of marked American kestrels (Falco sparverius) on San Salvador Island, Bahamas. We found a strong association between time spent grooming and survival over a 2-year period. The quadratic relationship we show is consistent with stabilizing natural selection on grooming time. To our knowledge, this is the first evidence for a correlation between grooming time and survival in a natural population. Grooming time may predict the survival of many animal taxa, but additional studies are needed to determine the shape and strength of the relationship among birds, mammals, and arthropods.

Chewing lice of the Brueelia-complex (Phthiraptera: Ischnocera) parasitic on members of the Campephagidae (Aves: Passeriformes), with description of a new subgenus and 14 new species.

Fourteen new species of chewing lice in the Brueelia-complex are described, from hosts in the Campephagidae. In addition, Malardifax a new subgenus of Guimaraesiella Eichler, 1949 is described for the species occurring on minivets (Campephagidae: Pericrocotus). The new species and their hosts are: Guimaraesiella (Guimaraesiella) nouankaoensis n. sp. from Coracina caledonica seiuncta Mayr Ripley, 1941 and C. caledonica thilenii (Neumann, 1915); Guimaraesiella (Guimaraesiella) sphagmotica n. sp. from Coracina caeruleogrisea strenua (Schlegel, 1871) and C. caeruleogrisea adamsoni Mayr Rand, 1936; Indoceoplanetes (Capnodella) kamphaengphetensis n. sp. from Lalage melaschistos avensis (Blyth, 1852); Indoceoplanetes (Capnodella) saucia n. sp. from Edolisoma montanum montanum (Meyer, 1874); Indoceoplanetes (Capnodella) subarcens n. sp. from Edolisoma melas melas (Lesson, 1828); Indoceoplanetes (Indoceoplanetes) cinitemnina n. sp. from Edolisoma melas melas (Lesson, 1828); Indoceoplanetes (Indoceoplanetes) ephippiformis n. sp. from Edolisoma montanum montanum (Meyer, 1874); Indoceoplanetes (Indoceoplanetes) fodincana n. sp. from Coracina papuensis oriomo Mayr Rand, 1936, C. papuensis angustifrons (Salvadori, 1876), and C. papuensis elegans (Ramsay, 1881); Indoceoplanetes (Indoceoplanetes) incisoma n. sp. from Coracina macei siamensis (Baker, 1918) and C. macei rexpineti (Swinhoe, 1863); Indoceoplanetes (Indoceoplanetes) microgenitalis n. sp. from Coracina caeruleogrisea strenua (Schlegel, 1871); Indoceoplanetes (Indoceoplanetes) pterophora n. sp. from Coracina macei nipalensis (Hodgson, 1836); Indoceoplanetes (Indoceoplanetes) saburrata n. sp. from Coracina lineata ombriosa (Rothschild Hartert, 1905); Indoceoplanetes (Indoceoplanetes) wandoensis n. sp. from Coracina novaehollandiae melanops (Latham, 1802); and Indoceoplanetes (Indoceoplanetes) zambica n. sp. from Coracina pectoralis (Jardine Selby, 1828). Checklists and keys to the louse species of the Brueelia-complex parasitic on campephagid hosts are provided.

Differential Functional Responses of Neutrophil Subsets in Severe COVID-19 Patients.

Neutrophils play a significant role in determining disease severity following SARS-CoV-2 infection. Gene and protein expression defines several neutrophil clusters in COVID-19, including the emergence of low density neutrophils (LDN) that are associated with severe disease. The functional capabilities of these neutrophil clusters and correlation with gene and protein expression are unknown. To define host defense and immunosuppressive functions of normal density neutrophils (NDN) and LDN from COVID-19 patients, we recruited 64 patients with severe COVID-19 and 26 healthy donors (HD). Phagocytosis, respiratory burst activity, degranulation, neutrophil extracellular trap (NET) formation, and T-cell suppression in those neutrophil subsets were measured. NDN from severe/critical COVID-19 patients showed evidence of priming with enhanced phagocytosis, respiratory burst activity, and degranulation of secretory vesicles and gelatinase and specific granules, while NET formation was similar to HD NDN. COVID LDN response was impaired except for enhanced NET formation. A subset of COVID LDN with intermediate CD16 expression (CD16Int LDN) promoted T cell proliferation to a level similar to HD NDN, while COVID NDN and the CD16Hi LDN failed to stimulate T-cell activation. All 3 COVID-19 neutrophil populations suppressed stimulation of IFN-γ production, compared to HD NDN. We conclude that NDN and LDN from COVID-19 patients possess complementary functional capabilities that may act cooperatively to determine disease severity. We predict that global neutrophil responses that induce COVID-19 ARDS will vary depending on the proportion of neutrophil subsets.

Descriptions of six new species of slender-bodied chewing lice of the Resartor-group (Phthiraptera: Ischnocera: Brueelia-complex).

Six new species of chewing lice in the Resartor-group (Brueelia-complex) are described and illustrated. They are: Aratricerca cerata n. sp. ex Zosterops capensis Sundevall, 1850; Aratricerca macki n. sp. ex Melidectes princeps Mayr Gilliard, 1951 and Ptiloprora perstriata perstriata (de Vis, 1898); Aratricerca madagascariensis n. sp. ex Randia pseudozosterops Delacour Berlioz, 1931; Turdinirmoides janigai n. sp. ex Prunella collaris nipalensis (Blyth, 1843) and P. collaris fennelli Deignan, 1964; Turdinirmoides rozsai n. sp. ex Carpodacus subhimachala (Hodgson, 1836); and Timalinirmus curvus n. sp. ex Yuhina castaniceps plumbeiceps (Godwin-Austen, 1877). A key to the species of Aratricerca, Turdinirmoides and Timalinirmus is provided.

Long-distance dispersal of pigeons and doves generated new ecological opportunities for host-switching and adaptive radiation by their parasites.

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 ectoparasitic wing lice of pigeons and doves have adaptively radiated, leading to differences in body size and overall coloration. Here, we show that long-distance dispersal by dove hosts was central to parasite diversification because it provided new ecological opportunities for parasites to speciate after host-switching. We further show that among extant parasite lineages host-switching decreased over time, with cospeciation becoming the more dominant mode of parasite speciation. Taken together, our results suggest that host dispersal, followed by host-switching, provided novel ecological opportunities that facilitated adaptive radiation by parasites.

A specific low-density neutrophil population correlates with hypercoagulation and disease severity in hospitalized COVID-19 patients.

SARS coronavirus 2 (SARS-CoV-2) is a novel viral pathogen that causes a clinical disease called coronavirus disease 2019 (COVID-19). Although most COVID-19 cases are asymptomatic or involve mild upper respiratory tract symptoms, a significant number of patients develop severe or critical disease. Patients with severe COVID-19 commonly present with viral pneumonia that may progress to life-threatening acute respiratory distress syndrome (ARDS). Patients with COVID-19 are also predisposed to venous and arterial thromboses that are associated with a poorer prognosis. The present study identified the emergence of a low-density inflammatory neutrophil (LDN) population expressing intermediate levels of CD16 (CD16Int) in patients with COVID-19. These cells demonstrated proinflammatory gene signatures, activated platelets, spontaneously formed neutrophil extracellular traps, and enhanced phagocytic capacity and cytokine production. Strikingly, CD16Int neutrophils were also the major immune cells within the bronchoalveolar lavage fluid, exhibiting increased CXCR3 but loss of CD44 and CD38 expression. The percentage of circulating CD16Int LDNs was associated with D-dimer, ferritin, and systemic IL-6 and TNF-α levels and changed over time with altered disease status. Our data suggest that the CD16Int LDN subset contributes to COVID-19-associated coagulopathy, systemic inflammation, and ARDS. The frequency of that LDN subset in the circulation could serve as an adjunct clinical marker to monitor disease status and progression.

A MISIDENTIFICATION CRISIS PLAGUES SPECIMEN-BASED RESEARCH: A CASE FOR GUIDELINES WITH A RECENT EXAMPLE (ALI ET AL., 2020).

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 (Phthiraptera: Ischnocera) is misidentified as Menopon gallinae, which is a parasite of chickens (Gallus gallus) and their relatives; moreover, this louse is from an entirely different suborder of lice (Phthiraptera: Amblycera). Another louse is misidentified as Goniodes dissimilis, another parasite of chickens and junglefowl. In addition, photographs of cestodes from pigeons in the same paper are not sufficient to confirm identification. Misidentifications are fueled, in part, by increasing pressure to publish coupled with a decrease in taxonomic expertise. We consider the downstream consequences of misidentification and suggest guidelines for authors, reviewers, and editors that could help to improve the reliability of specimen-based research.

The assembled and annotated genome of the pigeon louse Columbicola columbae, a model ectoparasite.

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 using a combination of Oxford Nanopore, Illumina, and Hi-C technologies. The final assembly is 208 Mb in length, with 12 chromosome-size scaffolds representing 98.1% of the assembly. For gene model prediction, we used a novel clustering method (wavy_choose) for Oxford Nanopore RNA-seq reads to feed into the MAKER annotation pipeline. High recovery of conserved single-copy orthologs (BUSCOs) suggests that our assembly and annotation are both highly complete and highly accurate. Consistent with the results of the only other assembled louse genome, Pediculus humanus, we find that C. columbae has a relatively low density of repetitive elements, the majority of which are DNA transposons. Also similar to P. humanus, we find a reduced number of genes encoding opsins, G protein-coupled receptors, odorant receptors, insulin signaling pathway components, and detoxification proteins in the C. columbae genome, relative to other insects. We propose that such losses might characterize the genomes of obligate, permanent ectoparasites with predictable habitats, limited foraging complexity, and simple dietary regimes. The sequencing and analysis for this genome were relatively low cost, and took advantage of a new clustering technique for Oxford Nanopore RNAseq reads that will be useful to future genome projects.

A new subgenus and eight new species of Guimaraesiella Eichler, 1949 (Phthiraptera: Ischnocera: Philopteridae: Brueelia-complex).

The species of the chewing louse genus Guimaraesiella Eichler, 1949 parasitic on drongos (Dicruridae) are reviewed and placed in the new subgenus Dicrurobates, which is described herein together with eight new species, including one species from non-dicrurid hosts. The new species are: Guimaraesiella (Dicrurobates) carbonivora n. sp. from Dicrurus bracteatus carbonarius Bonaparte, 1850; Guimaraesiella (Dicrurobates) latitemporalis n. sp. from Dicrurus hottentottus brevirostris (Cabanis, 1851) and Dicrurus hottentottus ssp. (Linnaeus, 1766); Guimaraesiella (Dicrurobates) lurida n. sp. from Dicrurus leucophaeus Vieillot, 1817; Guimaraesiella (Dicrurobates) luzonica n. sp. from Dicrurus balicassius (Linnaeus, 1766); Guimaraesiella (Dicrurobates) nana n. sp. from Dicrurus hottentottus samarensis Vaurie, 1947; Guimaraesiella (Dicrurobates) regis n. sp. from Dicrurus annectans (Hodgson, 1836), Dicrurus paradiseus paradiseus (Linnaeus, 1766) and Dicrurus paradiseus rangoonensis (Gould, 13836); Guimaraesiella (Dicrurobates) transvaalensis n. sp. from Dicrurus adsimilis apivorus Clancey, 1976; and Guimaraesiella (Dicrurobates) campanula n. sp. from Oriolus larvatus rolleti Salvadori, 1864 and Prionops plumatus poliocephalus (Stanley, 1814). Also, Guimaraesiella (Dicrurobates) sexmaculata (Piaget, 1880) and Guimaraesiella (Dicrurobates) dicruri (Ansari, 1955) are redescribed and illustrated. A key to identify adults of all 10 species included in the subgenus is provided.

Is Allopreening a Stimulus-Driven Defense Against Ectoparasites?

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 not known whether allopreening increases in response to increases in parasite load, or whether it is a programmed response that occurs independently of parasite load. We conducted a laboratory experiment using wild-caught rock pigeons (Columba livia) to test the relationship between ectoparasite load and allopreening rate. We added feather lice (Columbicola columbae) to captive pigeons and tested for changes in allopreening rates compared to control birds with no lice added. Allopreening rates did not change in response to the addition of lice. Interestingly, however, our data revealed a negative correlation between allopreening and self-preening rates.

The Genus Brueelia (Phthiraptera: Ischnocera: Philopteridae) of North American Jays and Allies (Aves: Passeriformes: Corvidae), with Descriptions of Five New Species.

Five new species of chewing lice in the genus Brueelia Kéler, 1936 , are described from North American jays and allies. They are Brueelia mexicana n. sp. from Aphelocoma woodhouseii cyanotis Ridgway, 1887 ; Brueelia bonnevillensis n. sp. from Aphelocoma woodhouseii nevadae Pitelka, 1945 ; Brueelia diblasiae n. sp. from Cyanocitta stelleri frontalis ( Ridgway, 1873 ); Brueelia tempestwilliamsae n. sp. from Gymnorhinus cyanocephala Wied-Neuwied, 1841 ; Brueelia mcnewae n. sp. from Nucifraga columbiana ( Wilson, 1811 ). An identification key to the Brueelia on corvid hosts is provided.

The genera and species of the Brueelia-complex (Phthiraptera: Philopteridae) described by Mey (2017).

Two large taxonomic revisions of chewing lice belonging to the Brueelia-complex were published independently in 2017: Gustafsson Bush (August 2017) and Mey (September 2017). However, Mey (2017) was incorrectly dated "Dezember 2016" on the title page. These two publications described many of the same taxonomic units under different names and therefore, the names in Gustafsson and Bush (2017) have priority over the synonyms in Mey (2017). Here we clarify some of the resulting taxonomic confusion.                Firstly, we confirm the availability of the genera Guimaraesiella Eichler, 1949 and Acronirmus Eichler, 1953, as well as the status of Nitzschinirmus Mey Barker, 2014 as a junior synonym of Guimaraesiella.                Nine genera were described and simultaneously placed as juniors synonyms by Mey (2017: 182). We agree with his synonymy in seven of them: Australnirmus Mey, 2017 under Saepocephalum Gustafsson Bush, 2017; Couanirmus Mey, 2017 under Couala Gustafsson Bush, 2017; Estrildinirmus Mey, 2017 under Mirandofures Gustafsson Bush, 2017; Harpactiacus Mey, 2017 under Harpactrox Gustafsson Bush, 2017; Leiothrichinirmus Mey, 2017 under Resartor Gustafsson Bush, 2017; Manucodiacus Mey, 2017 under Manucodicola Gustafsson Bush, 2017, and Protonirmus Mey, 2017 under Ceratocista Gustafsson Bush, 2017. Furthermore, Mey (2017) described and placed Pomatostomiacus as an absolute junior synonym of Sychraella Gustafsson Bush, 2017; here, we argue that Pomatostomiacus is actually a junior synonym of Anarchonirmus Gustafsson Bush, 2017. Also, Mey (2017) described and placed Timalinirmus as a probable junior synonym of Turdinirmoides Gustafsson Bush, 2017; here we argue that Timalinirmus is a valid genus.We place ten more genera from Mey (2017) as junior synonyms, as follows: Callaenirmus Mey, 2017 and Philemoniellus Mey, 2017 under Guimaraesiella Eichler, 1949; Carpodaciella Mey, 2017 under Turdinirmoides Gustafsson Bush, 2017; Cinclosomatiellum Mey, 2017 under Maculinirmus Zlotorzycka, 1964; Koanirmus Mey, 2017 and Tesonirmus Mey, 2017 under Couala Gustafsson Bush, 2017; Garrulaxeus Mey, 2017 under Priceiella (Camurnirmus) Gustafsson Bush, 2017; Lycocoranirmus Mey, 2017 under Corvonirmus Eichler, 1944; Neosittiella Mey, 2017 and Plesionirmus Mey, 2017 under Brueelia Kéler, 1936.                We accept Melinirmus Mey, 2017 as valid, and Mohoaticus Mey, 2017 as a valid subgenus of Guimaraesiella Eichler, 1949. Also, we provisionally accept Ptilononirmus Mey, 2017 as valid but, until a proper redescription determines its true status, we categorize Ptilononirmus as genus inquirenda.                We accept most species described by Mey (2017) as valid, except for two which we place as junior synonyms: Callaenirmus kokakophilus Mey, 2017 under Brueelia callaeincola Valim Palma, 2015, and Mohoaticus pteroacariphagus Mey, 2017 under Guimaraesiella (Mohoaticus) diaprepes (Kellogg Chapman, 1902). We agree with Mey's assessment that four of his new species are junior synonyms of previously described taxa. Furthermore, among the species (subspecies) described by Mey (2017) as new, we establish 31 new generic (subgeneric) combinations, and we regard 16 species as species inquirenda, and three as incertae sedis.

Brueelia (Phthiraptera: Ischnocera: Philopteridae) of North American Nine-Primaried Oscines (Aves: Passeriformes: Passerida) with Descriptions of Nine New Species.

Nine new species of chewing lice in the genus Brueelia Kéler, 1936 , are described from North American hosts. They are Brueelia thorini n. sp. from Haemorhous mexicanus frontalis (Say, 1822) and Haemorhous mexicanus potosinus Griscom, 1928; Brueelia straseviciusi n. sp. from Haemorhous purpureus (Gmelin, 1789); Brueelia mattsonae n. sp. from Coccothraustes vespertinus brooksi (Grinnell, 1917); Brueelia novemstriata n. sp. from Icterus wagleri wagleri Sclater, 1857, and I. parisorum Bonaparte, 1838; Brueelia benkmani n. sp. from Pheucticus melanocephalus (Swainson, 1827); Brueelia arizonae n. sp. from Passerina caerulea (Linnaeus, 1758); Brueelia hellstromi n. sp. from Piranga ludoviciana (Wilson, 1811); Brueelia dolorosa n. sp. from Spinus pinus pinus (Wilson, 1810); and Brueelia melancholica n. sp. from Spinus tristis (Linnaeus, 1758). Brueelia limbata ( Burmeister, 1838 ) is redescribed and illustrated from North American material. A key for these North American species is provided.

Five New Species of Guimaraesiella (Phthiraptera: Ischnocera) from Broadbills (Aves: Passeriformes: Calyptomenidae: Eurylaimidae).

Five new species of Guimaraesiella Eichler, 1949 are described and illustrated from hosts in the Eurylaimidae and Calyptomenidae. They are Guimaraesiella corydoni n. sp. from Corydon sumatranus laoensis Meyer de Schauensee, 1929 ; Guimaraesiella latirostris n. sp. from Eurylaimus ochromalus Raffles, 1822 ; Guimaraesiella cyanophoba n. sp. from Cymbirhynchus macrorhynchus malaccensis Salvadori, 1874 and C. m. siamensis Meyer de Schauensee and Ripley, 1940 ; Guimaraesiella altunai n. sp. from Calyptomena viridis caudacuta Swainson, 1838 ; and Guimaraesiella forcipata n. sp. from Eurylaimus steerii steerii Sharpe, 1876 . These represent the first species of Guimaraesiella described from the Calyptomenidae and Eurylaimidae, as well as the first species of this genus described from the Old World suboscines.

Rapid experimental evolution of reproductive isolation from a single natural population.

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 experimental evolution of parasite body size over 4 y (approximately 60 generations) leads to reproductive isolation in natural populations of feather lice on birds. When lice are transferred to pigeons of different sizes, they rapidly evolve differences in body size that are correlated with host size. These differences in size trigger mechanical mating isolation between lice that are locally adapted to the different sized hosts. Size differences among lice also influence the outcome of competition between males for access to females. Thus, body size directly mediates reproductive isolation through its influence on both intersexual compatibility and intrasexual competition. Our results confirm that divergent natural selection acting on a single phenotypic trait can cause reproductive isolation to emerge from a single natural population in real time.

Host defense triggers rapid adaptive radiation in experimentally evolving parasites.

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 biodiversity, most studies concern groups that have already diversified. Here, we take the opposite approach. We experimentally triggered diversification in the descendants of a single population of host-specific parasites confined to different host "islands." We show rapid adaptive divergence of experimentally evolving feather lice in response to preening, which is a bird's main defense against ectoparasites. We demonstrate that host defense exerts strong phenotypic selection for crypsis in lice transferred to different colored rock pigeons (Columba livia). During four years of experimental evolution (∼60 generations), the lice evolved heritable differences in color. Strikingly, the observed color differences spanned the range of phenotypes found among congeneric lice adapted to other species of birds. To our knowledge, this is the first real-time demonstration that microevolution is fast enough to simulate millions of years of macroevolutionary change. Our results further indicate that host-mediated selection triggers rapid divergence in the adaptive radiation of parasites, which are among the most diverse organisms on Earth.

Annual environmental variation influences host tolerance to parasites.

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 variable environment. We manipulated the abundance of an invasive parasitic fly, Philornis downsi, in nests of Galápagos mockingbirds ( Mimus parvulus) over four field seasons and measured host fitness in response to parasitism. Mockingbird tolerance to P. downsi varied significantly among years and decreased when rainfall was limited. Video observations indicate that parental provisioning of nestlings appears key to tolerance: in drought years, mockingbirds likely do not have sufficient resources to compensate for the effects of P. downsi. These results indicate that host tolerance is a labile trait and suggest that environmental variation plays a major role in mediating the consequences of host-parasite interactions.