Geographic variation in malarial parasite lineages in the common yellowthroat (Geothlypis trichas)

Stronger population differentiation at infection-sensing than infection-clearing innate immune loci in songbirds: Different selective regimes for different defenses

Parasite-mediated selection is widespread at loci involved in immune defense, but different defenses may experience different selective regimes. For defenses involved in clearing infections, purifying selection favoring a single most efficacious allele likely predominates. However, for defenses involved in sensing and recognizing infections, evolutionary arms races may make positive selection particularly important. This could manifest primarily within populations (e.g., balancing selection maintaining variation) or among them (e.g., spatially varying selection enhancing population differences in allele frequencies). We genotyped three toll-like receptors (TLR; involved in sensing infections) and three avian beta-defensins (involved in clearing infections) in 96 song sparrows (Melospiza melodia) from three breeding populations that differ in disease resistance. Variation-based indicators of selection (proportion of variable sites, proportion of nonsynonymous SNPs, proportion of sites bearing signatures of positive or purifying selection, rare allele frequencies) did not differ appreciably between the two locus types. However, differentiation was generally higher at infection-sensing than infection-clearing loci. Allele frequencies differed markedly at TLR3, driven by a variant predicted to alter protein function. Geographically structured variants at infection-sensing loci may reflect local adaptation to spatially heterogeneous parasite communities. Selective regimes experienced by infection-sensing versus infection-clearing loci may differ primarily due to parasite-mediated population differentiation.

Drivers of community turnover differ between avian hemoparasite genera along a North American latitudinal gradient

The latitudinal diversity gradient (LDG) is an established macroecological pattern, but is poorly studied in microbial organisms, particularly parasites. In this study, we tested whether latitude, elevation, and host species predicted patterns of prevalence, alpha diversity, and community turnover of hemosporidian parasites. We expected parasite diversity to decrease with latitude, alongside the diversity of their hosts and vectors. Similarly, we expected infection prevalence to decrease with latitude as vector abundances decrease. Lastly, we expected parasite community turnover to increase with latitudinal distance and to be higher between rather than within host species. We tested these hypotheses by screening blood and tissue samples of three closely related avian species in a clade of North American songbirds (Turdidae: Catharus, n = 466) across 17.5° of latitude. We used a nested PCR approach to identify parasites in hemosporidian genera that are transmitted by different dipteran vectors. Then, we implemented linear-mixed effects and generalized dissimilarity models to evaluate the effects of latitude, elevation, and host species on parasite metrics. We found high diversity of hemosporidian parasites in Catharus thrushes (n = 44 lineages) but no evidence of latitudinal gradients in alpha diversity or prevalence. Parasites in the genus Leucocytozoon were most prevalent and lineage rich in this study system; however, there was limited turnover with latitude and host species. Contrastingly, Plasmodium parasites were less prevalent and diverse than Leucocytozoon parasites, yet communities turned over at a higher rate with latitude and host species. Leucocytozoon communities were skewed by the dominance of one or two highly prevalent lineages with broad latitudinal distributions. The few studies that evaluate the hemosporidian LDG do not find consistent patterns of prevalence and diversity, which makes it challenging to predict how they will respond to global climate change.

Host dispersal and landscape conversion are associated with the composition of haemosporidian parasites of the golden-winged warbler

Understanding factors that influence the spatial and temporal distributions of blood parasites is important to help predict how host species and their parasites may respond to global change. Factors that may influence parasite distributions are land cover and host dispersal patterns, which may result in exposure of a host to novel parasites, or escape from parasites of their origin. We screened golden-winged warblers from across the United States and Canada for blood parasites, and investigated whether land-use patterns or host dispersal affected the prevalence and composition of haemosporidian assemblages. Parasite prevalence varied strongly with study area, and areas with high agricultural cover had a significantly higher prevalence of Leucocytozoon and Parahaemoproteus parasites. Lineages of Parahaemoproteus and Leucocytozoon were genetically differentiated among study areas, and prevalence and composition of parasite assemblages indicated an increase in parasite prevalence and accumulation of unique parasite lineages from the southeast to the northwest. This matches the historical range expansion and natal dispersal patterns of golden-winged warblers, and suggests that golden-winged warblers may have been sensitive to novel parasites as they dispersed. The high prevalence and diversity of parasite lineages in the north-west extent of their breeding range (Manitoba) indicates that this population may face unique pressures.

Malaria infection status of European Robins seems to associate with timing of autumn migration but not with actual condition

Avian malaria parasites can negatively affect many aspects of the life of the passerines. Though these parasites may strongly affect the health and thus migration patterns of the birds also during autumn, previous studies on avian malaria focused mainly on the spring migration and the breeding periods of the birds. We investigated whether the prevalence of blood parasites varies in relation to biometrical traits, body condition and arrival time in the European Robin (Erithacus rubecula) during autumn migration. We found no sex or age related differences in avian malaria prevalence and no relationship between infection status and body size or actual condition of the birds was found either. However, the timing of autumn migration differed marginally between infected and non-infected juveniles, so that parasitized individuals arrived later at the Hungarian stopover site. This is either because avian malaria infections adversely affect the migration timing or migration speed of the birds, or because later arriving individuals come from more distant populations with possibly higher blood parasite prevalence. The possible delay that parasites cause in the arrival time of the birds during autumn migration could affect the whole migratory strategy and the breeding success of the birds in the next season.

Age and infection history are revealed by different ornaments in a warbler

Female preference for older or more disease-resistant males are both possible outcomes of parasite-mediated sexual selection, but the extent to which infection alters the development of ornaments to yield signals of male age and health has rarely been explored. In a longitudinal study of 61 male common yellowthroats (Geothlypis trichas), age-related increases in the size of the melanin-based mask and carotenoid-based bib were not correlated among young males, likely owing to differences in how blood parasites affect ornament development. Infection with trypanosomes and hemosporidians in a male's first breeding season was associated with slower growth of the mask; uninfected males attained large masks in their second breeding season, while infected males attained large masks in their third breeding season. In contrast, the bib size of males increased every year regardless of infection. As a consequence, different populations of males are identified by the largest ornaments-older males in the case of bib and a combination of older males and young, uninfected males in the case of mask. Although mask is thus the more informative trait with respect to male health, females prefer large bibs in our population. If infection is opportunistic, young, uninfected males may not possess good genes for parasite resistance but simply good luck, and it may benefit females to prefer older males who are more likely to have withstood prior episodes of selection. A "pure" signal of age may be a more reliable signal of resistance to parasites than an ornament whose expression is modulated by infection.

Immune profiles vary seasonally, but are not significantly related to migration distance or natal dispersal, in a migratory songbird

A central tenet of ecoimmunology is that an organism's environment shapes its optimal investment in immunity. For example, the benefits of acquired (relatively pathogen specific) versus innate (nonspecific) immune defenses are thought to vary with the risk of encountering familiar versus unfamiliar pathogens. Because pathogen communities vary geographically, individuals that travel farther during seasonal migration or natal dispersal are predicted to have higher exposure to novel pathogens, and lower exposure to familiar pathogens, potentially favoring investment in innate immunity. During the breeding season, migratory animals' exposure to familiar pathogens should increase, potentially favoring investment in acquired immunity. We hypothesized that song sparrows Melospiza melodia adjust their constitutive immune profiles in response to risk of encountering novel versus familiar pathogens. We predicted that individuals migrating longer distances (inferred from stable hydrogen isotope analysis of claws) and less philopatric individuals (inferred from microsatellite assignment testing) would rely more heavily on acquired than innate defenses. We also predicted that reliance on acquired defenses would increase throughout the early breeding season. Consistent with trade-offs between acquired and innate defenses, levels of immunoglobulin Y (acquired) varied negatively with macrophage phagocytosis activity (innate). Levels of acquired relative to innate immunity did not vary significantly with migration distance or philopatry, but increased throughout the early breeding season. Macrophage phagocytosis was not significantly repeatable between years. Song sparrows appear to shift from innate defenses immediately after migration to acquired defenses with increasing time at the breeding grounds. These patterns highlight the plasticity of constitutive immune defenses in migratory animals.

Prevalence and diversity of avian Haemosporida infecting songbirds in southwest Michigan

Avian blood parasites from the genera Plasmodium, Haemoproteus, and Leucocytozoon (Haemosporida) affect hosts in numerous ways. They influence species interactions, host behavior, reproductive success, and cause pathology and mortality in birds. The Great Lakes region of North America has extensive aquatic and wetland habitat and supports a diverse vector community. Here we describe the community of bird-infecting Haemosporida in southwest Michigan and their host associations by measuring parasite prevalence, diversity, and host breadth across a diverse community of avian hosts. Over 700 songbirds of 55 species were screened for Haemosporida infection across southwest Michigan, including 11 species that were targeted for larger sample sizes. In total, 71 parasite lineages infected over 40% of birds. Of these, 42 were novel, yet richness estimates suggest that approximately half of the actual parasite diversity in the host community was observed despite intensive sampling of multiple host species. Parasite prevalence varied among parasite genera (7-24%) and target host species (0-85%), and parasite diversity was consistently high across most target species. Host breadth varied widely across the most prevalent parasite lineages, and we detected around 60% of host species richness for these parasite lineages. We report many new lineages and novel host-parasite associations, but substantial parasite diversity remains undiscovered in the Midwest.

Haemoparasites of the pied flycatcher: inter-population variation in the prevalence and community composition

The prevalence and community composition of haemoparasites can substantially differ among avian host populations, which may lead to different selection pressures. Therefore, information about these parameters is crucial for understanding, e.g. the inter-population variation in host life history traits. Here, we molecularly screened a population of a long-distance migrant, the pied flycatcher Ficedula hypoleuca, from central Poland for the presence of three genera of blood parasites: Haemoproteus, Plasmodium and Trypanosoma. The infection rate in this population was the highest for haemosporidians (86·8%) and one of the highest for trypanosomes (39·7%) among the thus far screened breeding populations of this species. The haemosporidian community was composed of six Haemoproteus/Plasmodium lineages, and the trypanosome community - 4 species and a parasite assigned to genus level. Trypanosomes were dominated by T. culicavium, a recently described species, corroborating the prediction that insectivorous songbirds are vertebrate hosts of this parasite. Host sex and age did not explain variation in infection incidence except for the higher trypanosome infection rates in males. A comparison of the study population with three other breeding populations previously screened molecularly for haemosporidians showed some geographic differences. This study confirms the importance of examining local parasite communities across a host distribution range.

Population Differences at MHC Do Not Explain Enhanced Resistance of Song Sparrows to Local Parasites

Infectious disease represents an emerging threat to natural populations, particularly when hosts are more susceptible to novel parasites (allopatric) than to parasites from the local area (sympatric). This pattern could arise through evolutionary processes (host populations become adapted to their local parasites and genetically differentiated from other populations at immune-related loci) and/or through ecological interactions (host individuals develop resistance to local parasites through previous exposure). The relative importance of these candidate mechanisms remains unclear. In jawed vertebrates, genes of the major histocompatibility complex (MHC) play a fundamental role in immunity and are compelling candidates for spatially varying selection. We recently showed that song sparrows (Melospiza melodia) are more susceptible to allopatric than to sympatric strains of malaria (Plasmodium). In the current study, to determine whether population differences at MHC explain this pattern, we characterized the peptide-binding regions of MHC (classes I and II) of birds that did or did not become infected in the previous experiment. We recovered up to 4 alleles per individual at class I, implying at least 2 loci, and up to 26 alleles per individual at class II, implying at least 13 loci. Individuals with more class I alleles were less likely to become infected by Plasmodium, consistent with parasite-mediated balancing selection. However, we found no evidence for population genetic differentiation at either class of MHC, based on 36 individuals sequenced. Resistance to sympatric parasites previously described for this system likely stems from individuals' prior immune experience, not from population differentiation and locally protective alleles at MHC.

Age-specific patterns of infection with haemosporidians and trypanosomes in a warbler: implications for sexual selection

Although the selective loss of individuals susceptible to disease can favor the evolution of female preference for older males, the interrelationship between age, infection, longevity, and mating success remains poorly characterized in natural populations. In a longitudinal study of 61 male common yellowthroats (Geothlypis trichas), we found that the probability of infection with hematozoa increased as males aged from 1 to 5 years. Despite a significant, negative association between infection and longevity that partially masked age-effects, the odds that a male was infected with Trypanosoma, Plasmodium, or Leucocytozoon increased 71-212% per year. Nearly 75% of males in their first breeding season were either uninfected or infected with only a single parasite, while 50% of older males were infected with at least two parasites and 16% were infected with all three. No males escaped infection after their second breeding season. Older males were also more likely to sire extra-pair young (EPY) and, as a consequence, infection with multiple parasites was associated with a fourfold increase in the odds of producing EPY. Unlike younger males, 80% of the oldest males had a history of either surviving chronic infection or recovering. Combined with previous work showing higher diversity at the major histocompatibility complex among older males, our results suggest that the song and plumage traits that signal male age in common yellowthroats also, perforce, signal resistance to parasites. By preferring older males, females may obtain good genes for disease resistance even in the absence of any effect of infection on male ornamentation.

Intra-individual changes in haemosporidian infections over the nesting period in great tit females

Prevalence of haemosporidian parasites in bird populations varies temporally both between years and within a year. In contrast to variation at the population level, relatively little is known about variation in infection attributes at the individual level, especially in non-migratory species. We examined intra-individual changes in the presence and identity of haemosporidian parasites (genera Plasmodium and Haemoproteus) over the course of the nesting period in females of great tits (Parus major)—a species considered to be resident over much of its distribution range. Birds were sampled during two stages of the nesting period: nest building and nestling rearing. The mean time interval between sampling occasions was 43 days. Between the first and second samplings, 30.6% of females gained at least one parasite lineage and 18.5% lost the lineage. Haemoproteus gains were over three times more common than Plasmodium gains. The probability of the lineage gain decreased with the date of the first sampling, was higher in individuals in better body condition and differed between years, but was not associated with the host age. The probability of the lineage loss was not explained by any of the considered parameters except for year. These results indicate that in a large proportion of a population, infection attributes (presence/absence and/or parasite identity) may change over the nesting period and the occurrence of such changes may be associated with the individual quality. Consequently, this phenomenon should be taken into account to correctly interpret parasite-mediated effects.

Diversity and distribution of avian malaria and related haemosporidian parasites in captive birds from a Brazilian megalopolis

BACKGROUND

The role of zoos in conservation programmes has increased significantly in last decades, and the health of captive animals is essential to guarantee success of such programmes. However, zoo birds suffer from parasitic infections, which often are caused by malaria parasites and related haemosporidians. Studies determining the occurrence and diversity of these parasites, aiming better understanding infection influence on fitness of captive birds, are limited.

METHODS

In 2011-2015, the prevalence and diversity of Plasmodium spp. and Haemoproteus spp. was examined in blood samples of 677 captive birds from the São Paulo Zoo, the largest zoo in Latin America. Molecular and microscopic diagnostic methods were used in parallel to detect and identify these infections.

RESULTS

The overall prevalence of haemosporidians was 12.6%. Parasites were mostly detected by the molecular diagnosis, indicating that many birds harbour subclinical or abortive infections. In this project, birds of 17 orders (almost half of all the orders currently accepted in taxonomy of birds), 29 families, and 122 species, were tested, detecting positive individuals in 27% of bird species. Birds from the Anatidae were the most prevalently infected (64.7% of all infected animals). In all, infections with parasites of the genus Plasmodium (overall prevalence 97.6%) predominated when compared to those of the genus Haemoproteus (2.4%). In total, 14 cytochrome b (cytb) lineages of Plasmodium spp. and 2 cytb lineages of Haemoproteus spp. were recorded. Eight lineages were new. One of the reported lineages was broad generalist while others were reported in single or a few species of birds. Molecular characterization of Haemoproteus ortalidum was developed.

CONCLUSION

This study shows that many species of birds are at risk in captivity. It is difficult to stop haemosporidian parasite transmission in zoos, but is possible to reduce the infection rate by treating the infected animals or/and while keeping them in facilities free from mosquitoes. Protocols of quarantine should be implemented whenever an animal is transferred between bird maintaining institutions. This is the first survey of haemosporidians in captive birds from different orders maintained in zoos. It is worth emphasizing the necessity of applying practices to control these parasites in management and husbandry of animals in captivity.

Distribution and Prevalence of Haemosporidian Parasites in the Northern Cardinal (Cardinalis cardinalis)

Avian haemosporidian parasites provide a model system for understanding ecological and evolutionary host-parasite interactions. The diversity and distribution of these parasites remains incomplete, and, here, we provide the first range-wide assessment of avian haemosporidians in a continentally distributed host, the Northern Cardinal ( Cardinalis cardinalis ). Based on molecular techniques, we show geographical differences in prevalence and lineage diversity between host subspecies and identify several novel lineages. We use phylogenetic reconstruction to show where these lineages fit into the expanding evolutionary tree of avian haemosporidian lineages. All except 1 subspecies of Northern Cardinal are highly parasitized by a wide diversity of Plasmodium and Parahaemoproteus. Compared to published studies that used microscopy to determine prevalence in this host, we find a much higher number of infected individuals (67.4% vs. 45% or less). Consistent with previous studies, Parahaemoproteus from the Northern Cardinal was found to be highly host specific and geographically structured, whereas Plasmodium was less host specific and geographically unstructured.

Differential prevalence and diversity of haemosporidian parasites in two sympatric closely related non-migratory passerines

Haemosporidian parasites infecting birds show distinct heterogeneity in their distribution among host species. However, despite numerous studies on the prevalence and diversity of parasite communities across species, very little is known on patterns of differences between them. Such data is lacking because up to date the majority of studies explored the patterns of variation in infections in different years, different time of sampling within a year or a breeding cycle, different study sites or was based on a small sample size, all of which may affect the estimates of prevalence and parasite diversity. Here, the prevalence, richness and diversity of haemosporidian parasites from the genera Plasmodium and Haemoproteus were studied in two closely related non-migratory hole-nesting passerines: Great Tits and Blue Tits. Birds were sampled in sympatrically breeding populations during two seasons at the same stage of their breeding cycle - late nestling care. Great Tits were more prevalently infected with Plasmodium and Haemoproteus parasites (97·1 vs 71·2%), harboured a higher proportion of multiple infections (26·2 vs 3·2%) and had a more diverse parasite community (11 vs 5 parasite lineages) than Blue Tits. Observed differences between two host species are discussed with reference to their breeding densities and immunological and behavioural characteristics.

Local parasite lineage sharing in temperate grassland birds provides clues about potential origins of Galapagos avian Plasmodium

Oceanic archipelagos are vulnerable to natural introduction of parasites via migratory birds. Our aim was to characterize the geographic origins of two Plasmodium parasite lineages detected in the Galapagos Islands and in North American breeding bobolinks (Dolichonyx oryzivorus) that regularly stop in Galapagos during migration to their South American overwintering sites. We used samples from a grassland breeding bird assemblage in Nebraska, United States, and parasite DNA sequences from the Galapagos Islands, Ecuador, to compare to global data in a DNA sequence registry. Homologous DNA sequences from parasites detected in bobolinks and more sedentary birds (e.g., brown‐headed cowbirds Molothrus ater, and other co‐occurring bird species resident on the North American breeding grounds) were compared to those recovered in previous studies from global sites. One parasite lineage that matched between Galapagos birds and the migratory bobolink, Plasmodium lineage B, was the most common lineage detected in the global MalAvi database, matching 49 sequences from unique host/site combinations, 41 of which were of South American origin. We did not detect lineage B in brown‐headed cowbirds. The other Galapagos‐bobolink match, Plasmodium lineage C, was identical to two other sequences from birds sampled in California. We detected a close variant of lineage C in brown‐headed cowbirds. Taken together, this pattern suggests that bobolinks became infected with lineage B on the South American end of their migratory range, and with lineage C on the North American breeding grounds. Overall, we detected more parasite lineages in bobolinks than in cowbirds. Galapagos Plasmodium had similar host breadth compared to the non‐Galapagos haemosporidian lineages detected in bobolinks, brown‐headed cowbirds, and other grassland species. This study highlights the utility of global haemosporidian data in the context of migratory bird–parasite connectivity. It is possible that migratory bobolinks bring parasites to the Galapagos and that these parasites originate from different biogeographic regions representing both their breeding and overwintering sites.

Different ornaments signal male health and MHC variation in two populations of a warbler

Male traits that signal health and vigour are used by females to choose better quality mates, but in some cases the male trait selected by females differs among populations. Multiple male traits can be maintained through female mate choice if both traits are equally honest indicators of male quality, but tests of this prediction are rare. By choosing males based on such traits, females could gain direct benefits from males (assistance with parental care), but when females choose extra-pair mates based on these traits, females gain only male sperm, and potentially indirect genetic benefits for their offspring. In common yellowthroats (Geothylpis trichas), female choice of extra-pair mates targets two different plumage ornaments: the black mask in a Wisconsin population and the yellow bib in a New York population. Previously, we found that the black mask in Wisconsin is related to greater major histocompatibility complex (MHC) class II variation, which in turn signals better survival and disease resistance. In this study, we examined the signalling function of the yellow bib in New York to test whether it signals the same aspects of male quality as the black mask in Wisconsin. As predicted, we found that the yellow bib in New York is most closely associated with MHC variation, which also signals survival and resistance to blood parasites. Thus, the ornament preferred by females differs between the two populations, but the different ornaments signal similar aspects of male health and genetic quality, specifically information regarding MHC variation and potential indirect genetic benefits to females.

Coevolutionary patterns and diversification of avian malaria parasites in African sunbirds (Family Nectariniidae)

The coevolutionary relationships between avian malaria parasites and their hosts influence the host specificity, geographical distribution and pathogenicity of these parasites. However, to understand fine scale coevolutionary host–parasite relationships, robust and widespread sampling from closely related hosts is needed. We thus sought to explore the coevolutionary history of avianPlasmodiumand the widespread African sunbirds, family Nectariniidae. These birds are distributed throughout Africa and occupy a variety of habitats. Considering the role that habitat plays in influencing host-specificity and the role that host-specificity plays in coevolutionary relationships, African sunbirds provide an exceptional model system to study the processes that govern the distribution and diversity of avian malaria. Here we evaluated the coevolutionary histories using a multi-gene phylogeny for Nectariniidae and avianPlasmodiumfound in Nectariniidae. We then assessed the host–parasite biogeography and the structuring of parasite assemblages. We recoveredPlasmodiumlineages concurrently in East, West, South and Island regions of Africa. However, severalPlasmodiumlineages were recovered exclusively within one respective region, despite being found in widely distributed hosts. In addition, we inferred the biogeographic history of these parasites and provide evidence supporting a model of biotic diversification in avianPlasmodiumof African sunbirds.

Prevalence, transmission, and genetic diversity of blood parasites infecting tundra-nesting geese in Alaska

A total of 842 blood samples collected from five species of tundra-nesting geese in Alaska was screened for haemosporidian parasites using molecular techniques. Parasites of the genera Leucocytozoon Danilewsky, 1890, Haemoproteus Kruse, 1890, and Plasmodium Marchiafava and Celli, 1885 were detected in 169 (20%), 3 (<1%), and 0 (0%) samples, respectively. Occupancy modeling was used to estimate prevalence of Leucocytozoon parasites and assess variation relative to species, age, sex, geographic area, year, and decade. Species, age, and decade were identified as important in explaining differences in prevalence of Leucocytozoon parasites. Leucocytozoon parasites were detected in goslings sampled along the Arctic Coastal Plain using both historic and contemporary samples, which provided support for transmission in the North American Arctic. In contrast, lack of detection of Haemoproteus and Plasmodium parasites in goslings (n = 238) provided evidence to suggest that the transmission of parasites of these genera may not occur among waterfowl using tundra habitats in Alaska, or alternatively, may only occur at low levels. Five haemosporidian genetic lineages shared among different species of geese sampled from two geographic areas were indicative of interspecies parasite transmission and supported broad parasite or vector distributions. However, identical Leucocytozoon and Haemoproteus lineages on public databases were limited to waterfowl hosts suggesting constraints in the range of parasite hosts.

New host and lineage diversity of avian haemosporidia in the northern Andes

The northern Andes, with their steep elevational and climate gradients, are home to an exceptional diversity of flora and fauna, particularly rich in avian species that have adapted to divergent ecological conditions. With this diversity comes the opportunity for parasites to exploit a wide breadth of avian hosts. However, little research has focused on examining the patterns of prevalence and lineage diversity of avian parasites in the Andes. Here, we screened a total of 428 birds from 19 species (representing nine families) and identified 133 infections of avian haemosporidia (31%), including lineages of Plasmodium, Haemoproteus, and Leucocytozoon. We document a higher prevalence of haemosporidia at higher elevations and lower temperatures, as well as an overall high diversity of lineages in the northern Andes, including the first sequences of haemosporidians reported in hummingbirds (31 sequences found in 11 species within the family Trochilidae). Double infections were distinguished using PHASE, which enables the separation of distinct parasite lineages. Results suggest that the ecological heterogeneity of the northern Andes that has given rise to a rich diversity of avian hosts may also be particularly conducive to parasite diversification and specialization.

Distribution, prevalence and host specificity of avian malaria parasites across the breeding range of the migratory lark sparrow (Chondestes grammacus)

The lark sparrow (Chondestes grammacus) is a ground-nesting passerine that breeds across much of the central North American steppe and sand barrens. Through genotyping and sequencing of avian malaria parasites we examined levels of malaria prevalence and determined the distribution of Haemoproteus and Plasmodium lineages across the breeding range of the lark sparrow. Analysis of 365 birds collected from five breeding locations revealed relatively high levels of malaria prevalence in adults (80 %) and juveniles (46 %), with infections being primarily of Haemoproteus (91 % of sequenced samples). Levels of genetic diversity and genetic structure of malaria parasites with respect to the avian host populations revealed distinct patterns for Haemoproteus and Plasmodium, most likely as a result of their distinct life histories, host specificity, and transmission vectors. With the exception of one common Haemoproteus haplotype detected in all populations, all other haplotypes were either population-specific or shared by two to three populations. A hierarchical analysis of molecular variance of Haemoproteus sequences revealed that 15-18 % of the genetic variation can be explained by differences among host populations/locations (p < 0.001). In contrast to the regional patterns of genetic differentiation detected for the lark sparrow populations, Haemoproteus parasites showed high levels of population-specific variation and no significant differences among regions, which suggests that the population dynamics of the parasites may be driven by evolutionary processes operating at small spatial scales (e.g., at the level of host populations). These results highlight the potential effects of host population structure on the demographic and evolutionary dynamics of parasites.

Multiple lineages of Avian malaria parasites (Plasmodium) in the Galapagos Islands and evidence for arrival via migratory birds

Haemosporidian parasites in the genus Plasmodium were recently detected through molecular screening in the Galapagos Penguin (Spheniscus mendiculus). We summarized results of an archipelago-wide screen of 3726 endemic birds representing 22 species for Plasmodium spp. through a combination of molecular and microscopy techniques. Three additional Plasmodium lineages were present in Galapagos. Lineage A-infected penguins, Yellow Warblers (Setophaga petechia aureola), and one Medium Ground Finch (Geospiza fortis) and was detected at multiple sites in multiple years [corrected]. The other 3 lineages were each detected at one site and at one time; apparently, they were transient infections of parasites not established on the archipelago. No gametocytes were found in blood smears of infected individuals; thus, endemic Galapagos birds may be dead-end hosts for these Plasmodium lineages. Determining when and how parasites and pathogens arrive in Galapagos is key to developing conservation strategies to prevent and mitigate the effects of introduced diseases. To assess the potential for Plasmodium parasites to arrive via migratory birds, we analyzed blood samples from 438 North American breeding Bobolinks (Dolichonyx oryzivorus), the only songbird that regularly migrates through Galapagos. Two of the ephemeral Plasmodium lineages (B and C) found in Galapagos birds matched parasite sequences from Bobolinks. Although this is not confirmation that Bobolinks are responsible for introducing these lineages, evidence points to higher potential arrival rates of avian pathogens than previously thought. Linajes Múltiples de Parásitos de Malaria Aviar (Plasmodium) en las Islas Galápagos y Evidencia de su Arribo por Medio de Aves Migratorias.

Plasmodium (Novyella) nucleophilum from an Egyptian Goose in São Paulo Zoo, Brazil: microscopic confirmation and molecular characterization

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An Egyptian Goose (Alopochen aegyptiacus) died in São Paulo Zoo, Brazil.

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Plasmodium (Novyella) nucleophilum was identified, using microscopy and PCR.

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The first assignment of the cytb gene sequence to P. nucleophilum is reported.

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Phylogenetic position of P. nucleophilum was determined.

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This sequence will assist in barcoding of this Plasmodium species in other birds.

Plasmodium (Novyella) nucleophilum was identified using microscopy and PCR, in an Egyptian Goose (Alopochen aegyptiacus) that died in São Paulo Zoo, Brazil. This parasite is characterized by elongated gametocytes, small meronts with scant cytoplasm, less than eight merozoites and mainly for having all the stages appressed to the nuclei of infected erythrocytes. Additionally, Plasmodium (Haemamoeba) sp. was identified by microscopy in the same blood sample. The latter parasite lacks nucleophilic blood stages and is characterized by large roundish trophozoites, each with a large prominent centrally collated vacuole. This co-infection was not confirmed by PCR amplification of the mitochondrial cytochrome b (cytb) gene and sequencing; only one Plasmodium sp. cytb sequence was detected in the blood sample. Since parasitemia of P. nucleophilum (2.4%) was much higher than that of P. (Haemamoeba) sp. (0.2%), PCR may have favored the amplification of the cytb sequence of the former. Phylogenetic analysis is in agreement with this conclusion because the reported cytb sequence was positioned in the same branch of sequences of several Novyella species. This is the first assignment of the mitochondrial cytb gene sequence to P. nucleophilum. The P. (Haemamoeba) parasite is particularly similar to Plasmodium (Haemamoeba) tejerai, because its advanced trophozoites and young erythrocytic meronts possess a large vacuole with prominent pigment granules arranged around it, the characteristic features of development in this species. For definitive identification of P. (Haemamoeba) species, mature meronts and gametocytes are required; however, these were absent from the thin blood smear. Representative images of the blood stages of P. nucleophilum and P. (Haemamoeba) sp. are provided. Together with microscopy data, the P. nucleophilum cytb sequence will assist in molecular identification (barcoding) of this Plasmodium species in other birds.

Evaluation of blood and muscle tissues for molecular detection and characterization of hematozoa infections in northern pintails (Anas acuta) wintering in California

Information on the molecular detection of hematozoa from different tissue types and multiple years would be useful to inform sample collection efforts and interpret results of meta-analyses or investigations spanning multiple seasons. In this study, we tested blood and muscle tissue collected from northern pintails (Anas acuta) during autumn and winter of different years to evaluate prevalence and genetic diversity of Leucocytozoon, Haemoproteus, and Plasmodium infections in this abundant waterfowl species of the Central Valley of California. We first compared results for paired blood and wing muscle samples to assess the utility of different tissue types for molecular investigations of haemosporidian parasites. Second, we explored inter-annual variability of hematozoa infection in Central Valley northern pintails and investigated possible effects of age, sex, and sub-region of sample collection on estimated parasite detection probability and prevalence. We found limited evidence for differences between tissue types in detection probability and prevalence of Leucocytozoon, Haemoproteus, and Plasmodium parasites, which supports the utility of both sample types for obtaining information on hematozoan infections. However, we detected 11 haemosporidian mtDNA cyt b haplotypes in blood samples vs. six in wing muscle tissue collected during the same sample year suggesting an advantage to using blood samples for investigations of genetic diversity. Estimated prevalence of Leucocytozoon parasites was greater during 2006-2007 as compared to 2011-2012 and four unique haemosporidian mtDNA cyt b haplotypes were detected in the former sample year but not in the latter. Seven of 15 mtDNA cyt b haplotypes detected in northern pintails had 100% identity with previously reported hematozoa lineages detected in waterfowl (Haemoproteus and Leucocytozoon) or other avian taxa (Plasmodium) providing support for lack of host specificity for some parasite lineages.

Hidden haemosporidian infections in Ruffs (Philomachus pugnax) staging in Northwest Europe en route from Africa to Arctic Europe

In their African freshwater wintering habitats, shorebirds show a high prevalence of blood parasites, whereas no parasites are detected elsewhere along the migration route. We looked at two genera of haemosporidian parasites, Haemoproteus and Plasmodium, in the long-distance migrating Ruff (Philomachus pugnax) along a geographical/seasonal gradient to verify the infection pattern and examine possible hidden organ infections at European staging areas. We amplified parasite DNA from blood of 53 healthy birds wintering in Mali, 53 samples of seven organ tissues (spleen, liver, kidneys, heart, lungs, brain, and pectoral muscle) from healthy individuals caught during spring migration, and 18 weak birds found sick in summer in The Netherlands. We confirm that Ruffs wintering in Africa carried blood infections and that some infections developed into hidden organ infections during spring migration. Moreover, sick birds either had new infections (in one juvenile) or relapses (in an adult harboring an African lineage). Our results suggest that some parasites develop latency. This strategy may be beneficial for the parasite as it may take control over reappearance in the blood to help further transmission.

North American transmission of hemosporidian parasites in the Swainson's thrush (Catharus ustulatus), a migratory songbird

The geographic structuring of parasite communities across the range of a single host species can illuminate patterns of host-population connectivity. To determine the location of parasite transmission in a Neotropical migrant bird species, we sampled adult and hatch-year (HY) birds across the breeding and wintering range of the Swainson's thrush (SWTH), an abundant passerine with a migratory divide. We examined the phylogenetic relationships among cytochrome b lineages of the avian blood parasite genera Haemoproteus, Plasmodium, and Leucocytozoon and determined the transmission location of unique lineages. We found that Haemoproteus and Plasmodium lineages are transmitted on California breeding grounds, whereas Leucocytozoon transmission occurs on Alaskan breeding grounds. The presence of hemosporidians on wintering grounds and shared lineages between the SWTH and resident species suggests that transmission of some of these lineages occurs on both breeding and wintering grounds. We emphasize that the sampling of HY birds and local resident heterospecifics will supplement vector studies to determine the key players in hemosporidian host switching and range-expansion events.

Biogeography of avian blood parasites (Leucocytozoon spp.) in two resident hosts across Europe: phylogeographic structuring or the abundance-occupancy relationship?

Relationships between hosts and parasites represent complex co-evolving systems that can vary both temporally and spatially. This variation may result in different phylogeographic outcomes, ranging from highly geographically structured parasite populations comprised of specialist lineages that are locally abundant but have restricted global occupancy to geographically unstructured parasite populations consisting of widespread parasites. Here, we present results from a large biogeographic study of the Leucocytozoon blood parasites of two nonmigrant bird species, conducted at nine sites across Europe. The aim was to determine whether the parasite lineages of the two hosts were phylogeographically structured across Europe. Employing molecular methods, we found a large diversity of parasites, and although overall prevalence varied greatly, the parasites were not genetically structured. Several measures of local parasite abundance were associated with the number of sites that the lineage occurred in, which is consistent with the macroecological phenomenon of the abundance-occupancy relationship. Taken together, our results show that parasite dispersal is somewhat uncoupled to that of the host in this system: we suggest that broad host and/or vector preference may play an important role in determining the distribution of these parasites and in affecting host-parasite coevolution in this system.