Host species,and not environment,predicts variation in blood parasite prevalence,distribution, and diversity along a humidity gradient in northern South America

Environmental factors strongly influence the ecology and evolution of vector‐borne infectious diseases. However, our understanding of the influence of climatic variation on host–parasite interactions in tropical systems is rudimentary. We studied five species of birds and their haemosporidian parasites (Plasmodium and Haemoproteus) at 16 sampling sites to understand how environmental heterogeneity influences patterns of parasite prevalence, distribution, and diversity across a marked gradient in water availability in northern South America. We used molecular methods to screen for parasite infections and to identify parasite lineages. To characterize spatial heterogeneity in water availability, we used weather‐station and remotely sensed climate data. We estimated parasite prevalence while accounting for spatial autocorrelation, and used a model selection approach to determine the effect of variables related to water availability and host species on prevalence. The prevalence, distribution, and lineage diversity of haemosporidian parasites varied among localities and host species, but we found no support for the hypothesis that the prevalence and diversity of parasites increase with increasing water availability. Host species and host × climate interactions had stronger effects on infection prevalence, and parasite lineages were strongly associated with particular host species. Because climatic variables had little effect on the overall prevalence and lineage diversity of haemosporidian parasites across study sites, our results suggest that independent host–parasite dynamics may influence patterns in parasitism in environmentally heterogeneous landscapes.     

Parasite Prevalence Corresponds to Host Life History in a Diverse Assemblage of Afrotropical Birds and Haemosporidian Parasites

Avian host life history traits have been hypothesized to predict rates of infection by haemosporidian parasites. Using molecular techniques, we tested this hypothesis for parasites from three haemosporidian genera (Plasmodium, Haemoproteus, and Leucocytozoon) collected from a diverse sampling of birds in northern Malawi. We found that host life history traits were significantly associated with parasitism rates by all three parasite genera. Nest type and nest location predicted infection probability for all three parasite genera, whereas flocking behavior is an important predictor of Plasmodium and Haemoproteus infection and habitat is an important predictor of Leucocytozoon infection. Parasite prevalence was 79.1% across all individuals sampled, higher than that reported for comparable studies from any other region of the world. Parasite diversity was also exceptionally high, with 248 parasite cytochrome b lineages identified from 152 host species. A large proportion of Plasmodium, Haemoproteus, and Leucocytozoon parasite DNA sequences identified in this study represent new, previously undocumented lineages (n = 201; 81% of total identified) based on BLAST queries against the avian malaria database, MalAvi.     

Loss of forest cover and host functional diversity increases prevalence of avian malaria parasites in the Atlantic Forest

Host phylogenetic relatedness and ecological similarity are thought to contribute to parasite community assembly and infection rates. However, recent landscape level anthropogenic changes may disrupt host-parasite systems by impacting functional and phylogenetic diversity of host communities. We examined whether changes in host functional and phylogenetic diversity, forest cover, and minimum temperature influence the prevalence, diversity, and distributions of avian haemosporidian parasites (genera Haemoproteus and Plasmodium) across 18 avian communities in the Atlantic Forest. To explore spatial patterns in avian haemosporidian prevalence and taxonomic and phylogenetic diversity, we surveyed 2241 individuals belonging to 233 avian species across a deforestation gradient. Mean prevalence and parasite diversity varied considerably across avian communities and parasites responded differently to host attributes and anthropogenic changes. Avian malaria prevalence (termed herein as an infection caused by Plasmodium parasites) was higher in deforested sites, and both Plasmodium prevalence and taxonomic diversity were negatively related to host functional diversity. Increased diversity of avian hosts increased local taxonomic diversity of Plasmodium lineages but decreased phylogenetic diversity of this parasite genus. Temperature and host phylogenetic diversity did not influence prevalence and diversity of haemosporidian parasites. Variation in the diversity of avian host traits that promote parasite encounter and vector exposure (host functional diversity) partially explained the variation in avian malaria prevalence and diversity. Recent anthropogenic landscape transformation (reduced proportion of native forest cover) had a major influence on avian malaria occurrence across the Atlantic Forest. This suggests that, for Plasmodium, host phylogenetic diversity was not a biotic filter to parasite transmission as prevalence was largely explained by host ecological attributes and recent anthropogenic factors. Our results demonstrate that, similar to human malaria and other vector-transmitted pathogens, prevalence of avian malaria parasites will likely increase with deforestation.     

Prevalence patterns of avian haemosporida on Hispaniola

We used PCR to screen for the presence of haemosporidian parasites (Phylum: Apicomplexa; Order: Haemosporida) in avian blood samples, and sequenced the parasite mitochondrial cytochrome b gene from infected hosts, to study patterns in the prevalence of haemosporidians in 1,166 individuals of 50 species in four habitats along an elevation gradient in the Sierra de Bahoruco, Dominican Republic, island of Hispaniola. We found an overall prevalence of 0.44 among species with ≥10 individuals sampled per year, but this varied considerably among species. We found no difference in infection rates between years, between males and females, between second‐year (<1 y old) and older birds, or among members of different foraging guilds. Prevalence differed significantly among migratory, endemic resident, and non‐endemic resident species, with endemics having the highest rates of infection. Prevalence also varied among habitats, decreasing with increasing elevation, but the pattern was confounded by variation in the host species present at each elevation. From 215 sequenced parasites from 17 species of avian hosts, we recovered multiple examples of 12 lineages of Haemoproteus (Parahaemoproteus), two lineages of a Columbiformes‐specific clade of H. (Haemoproteus), and 10 lineages of Plasmodium, with an additional seven lineages sampled only once. A single parasite lineage was responsible for 34.4% of all infections, but five more lineages made up 41.8% of all infections. Several lineages were broadly distributed across multiple host species, but six lineages, all H. (Haemoproteus) or H. (Parahaemoproteus), were recorded from at least five individuals of a single host, suggesting host specialization. The number of host species from which each parasite lineage was recovered varied from one to nine; several host species harbored as many as 5–9 parasite lineages. Longitudinal data suggest that while hosts might harbor the same parasite lineage for more than a year, some hosts appear to clear infections from their circulating blood, while others manifested infections by a different parasite lineage.     

Patterns of parasite abundance and distribution in island populations of Galápagos endemic birds

Parasite life-history characteristics, the environment, and host defenses determine variation in parasite population parameters across space and time. Parasite abundance and distribution have received little attention despite their pervasive effects on host populations and community dynamics. We used analyses of variance to estimate the variability of intensity, prevalence, and abundance of 4 species of lice (Insecta: Phthiraptera) infecting Galápagos doves and Galápagos hawks and 1 haemosporidian parasite (Haemosporida: Haemoproteidae) infecting the doves across island populations throughout their entire geographic ranges. Population parameters of parasites with direct life cycles varied less within than among parasite species, and intensity and abundance did not differ significantly across islands. Prevalence explained a proportion of the variance (34%), similar to infection intensity (33%) and parasite abundance (37%). We detected a strong parasite species-by-island interaction, suggesting that parasite population dynamics is independent among islands. Prevalence (up to 100%) and infection intensity (parasitemias up to 12.7%) of Haemoproteus sp. parasites varied little across island populations.     

Ecology,not distance,explains community composition in parasites of sky-island Audubon’s Warblers

Haemosporidian parasites of birds are ubiquitous in terrestrial ecosystems, but their coevolutionary dynamics remain poorly understood. If species turnover in parasites occurs at a finer scale than turnover in hosts, widespread hosts would encounter diverse parasites, potentially diversifying as a result. Previous studies have shown that some wide-ranging hosts encounter varied haemosporidian communities throughout their range, and vice-versa. More surveys are needed to elucidate mechanisms that underpin spatial patterns of diversity in this complex multi-host multi-parasite system. We sought to understand how and why a community of avian haemosporidian parasites varies in abundance and composition across elevational transects in eight sky islands in southwestern North America. We tested whether bird community composition, environment, or geographic distance explain haemosporidian parasite species turnover in a widespread host that harbors a diverse haemosporidian community, the Audubon’s Warbler (Setophaga auduboni). We tested predictors of infection using generalized linear models, and predictors of bird and parasite community dissimilarity using generalized dissimilarity modeling. Predictors of infection differed by parasite genus: Parahaemoproteus was predicted by elevation and climate, Leucocytozoon varied idiosyncratically among mountains, and Plasmodium was unpredictable, but rare. Parasite turnover was nearly three-fold higher than bird turnover and was predicted by elevation, climate, and bird community composition, but not geographic distance. Haemosporidian communities vary strikingly at fine spatial scales (hundreds of kilometers), across which the bird community varies only subtly. The finer scale of turnover among parasites implies that their ranges may be smaller than those of their hosts. Avian host species should encounter different parasite species in different parts of their ranges, resulting in spatially varying selection on host immune systems. The fact that parasite turnover was predicted by bird turnover, even when considering environmental characteristics, implies that host species or their phylogenetic history plays a role in determining which parasite species will be present in a community.     

Host community similarity and geography shape the diversity and distribution of haemosporidian parasites in Amazonian birds

Identifying the mechanisms driving the distribution and diversity of parasitic organisms and characterizing the structure of parasite assemblages are critical to understanding host–parasite evolution, community dynamics, and disease transmission risk. Haemosporidian parasites of the genera Plasmodium and Haemoproteus are a diverse and cosmopolitan group of bird pathogens. Despite their global distribution, the ecological and historical factors shaping the diversity and distribution of these protozoan parasites across avian communities and geographic regions remain unclear. Here we used a region of the mitochondrial cytochrome b gene to characterize the diversity, biogeographical patterns, and phylogenetic relationships of Plasmodium and Haemoproteus infecting Amazonian birds. Specifically, we asked whether, and how, host community similarity and geography (latitude and area of endemism) structure parasite assemblages across 15 avian communities in the Amazon Basin. We identified 265 lineages of haemosporidians recovered from 2661 sampled birds from 330 species. Infection prevalence varied widely among host species, avian communities, areas of endemism, and latitude. Composition analysis demonstrated that both malarial parasites and host communities differed across areas of endemism and as a function of latitude. Thus, areas with similar avian community composition were similar in their parasite communities. Our analyses, within a regional biogeographic context, imply that host switching is the main event promoting diversification in malarial parasites. Although dispersal of haemosporidian parasites was constrained across six areas of endemism, these pathogens are not dispersal‐limited among communities within the same area of endemism. Our findings indicate that the distribution of malarial parasites in Amazonian birds is largely dependent on local ecological conditions and host evolutionary relationships.     

Diverse avian malaria and other haemosporidian parasites in Andean house wrens: evidence for regional co‐diversification by host‐switching

Recent research has revealed well over 1000 mtDNA lineages of avian haemosporidian parasites, but the extent to which this diversity is caused by host–parasite coevolutionary history or environmental heterogeneity is unclear. We surveyed haemosporidian and host mtDNA in a geographically structured, ecological generalist species, the house wren Troglodytes aedon, across the complex landscape of the Peruvian Andes. We detected deep genetic structure within the house wren across its range, represented by seven clades that were between 3.4–5.7% divergent. From muscle and liver tissue of 140 sampled house wrens we found 23 divergent evolutionary lineages of haemosporidian mtDNA, of which ten were novel and apparently specific to the house wren based on searches of haemosporidian databases. Combined and genus‐specific haemosporidian abundance differed significantly across environments and elevation, with Leucocytozoon parasites strongly associated with montane habitats. We observed spatial stratification of haemosporidians along the west slope of the Andes where five lineages were restricted to non‐overlapping elevational bands. Individual haemosporidian lineages varied widely with respect to host specificity, prevalence, and geographic distribution, with the most host‐generalist lineages also being the most prevalent and widely distributed. Despite the deep divergences within the house wren, we found no evidence for host‐specific co‐diversification with haemosporidians. Instead, host‐specific haemosporidian lineages in the genus Haemoproteus were polyphyletic with respect to the New World parasite fauna and appeared to have diversified by periodic host‐switches involving distantly related avian species within the same region. These host‐specific lineages appeared to have diversified contemporaneously with Andean house wrens. Taken together, these findings suggest a model of diffuse co‐diversification in which host and parasite clades have diversified over the same time period and in the same geographic area, but with parasites having limited or ephemeral host specificity.     

Migratory birds have higher prevalence and richness of avian haemosporidian parasites than residents

Individuals of migratory species may be more likely to become infected by parasites because they cross different regions along their route, thereby being exposed to a wider range of parasites during their annual cycle. Conversely, migration may have a protective effect since migratory behaviour allows hosts to escape environments presenting a high risk of infection. Haemosporidians are one of the best studied, most prevalent and diverse groups of avian parasites, however the impact of avian host migration on infection by these parasites remains controversial. We tested whether migratory behaviour influenced the prevalence and richness of avian haemosporidian parasites among South American birds. We used a dataset comprising ~ 11,000 bird blood samples representing 260 bird species from 63 localities and Bayesian multi-level models to test the impact of migratory behaviour on prevalence and lineage richness of two avian haemosporidian genera (Plasmodium and Haemoproteus). We found that fully migratory species present higher parasite prevalence and higher richness of haemosporidian lineages. However, we found no difference between migratory and non-migratory species when evaluating prevalence separately for Plasmodium and Haemoproteus, or for the richness of Plasmodium lineages. Nevertheless, our results indicate that migratory behaviour is associated with an infection cost, namely a higher prevalence and greater variety of haemosporidian parasites.     

Diversity and host assemblage of avian haemosporidians in different terrestrial ecoregions of Peru

Characterizing the diversity and structure of host–parasite communities is crucial to understanding their eco-evolutionary dynamics. Malaria and related haemosporidian parasites are responsible for fitness loss and mortality in bird species worldwide. However, despite exhibiting the greatest ornithological biodiversity, avian haemosporidians from Neotropical regions are quite unexplored. Here, we analyze the genetic diversity of bird haemosporidian parasites (Plasmodium and Haemoproteus) in 1,336 individuals belonging to 206 bird species to explore for differences in diversity of parasite lineages and bird species across 5 well-differentiated Peruvian ecoregions. We detected 70 different haemosporidian lineages infecting 74 bird species. We showed that 25 out of the 70 haplotypes had not been previously recorded. Moreover, we also identified 81 new host–parasite interactions representing new host records for these haemosporidian parasites. Our outcomes revealed that the effective diversity (as well as the richness, abundance, and Shannon–Weaver index) for both birds and parasite lineages was higher in Amazon basin ecoregions. Furthermore, we also showed that ecoregions with greater diversity of bird species also had high parasite richness, hence suggesting that host community is crucial in explaining parasite richness. Generalist parasites were found in ecoregions with lower bird diversity, implying that the abundance and richness of hosts may shape the exploitation strategy followed by haemosporidian parasites. These outcomes reveal that Neotropical region is a major reservoir of unidentified haemosporidian lineages. Further studies analyzing host distribution and specificity of these parasites in the tropics will provide important knowledge about phylogenetic relationships, phylogeography, and patterns of evolution and distribution of haemosporidian parasites.     

Temporal stability of insular avian malarial parasite communities

Avian malaria is caused by a diverse community of genetically differentiated parasites of the genera Plasmodium and Haemoproteus. Rapid seasonal and annual antigenic allele turnover resulting from selection by host immune systems, as observed in some parasite populations infecting humans, may extend analogously to dynamic species compositions within communities of avian malarial parasites. To address this issue, we examined the stability of avian malarial parasite lineages across multiple time-scales within two insular host communities. Parasite communities in Puerto Rico and St Lucia included 20 and 14 genetically distinct parasite lineages, respectively. Lineage composition of the parasite community in Puerto Rico did not vary seasonally or over a 1 year interval. However, over intervals approaching a decade, the avian communities of both islands experienced an apparent loss or gain of one malarial parasite lineage, indicating the potential for relatively frequent lineage turnover. Patterns of temporal variation of parasite lineages in this study suggest periodic colonization and extinction events driven by a combination of host-specific immune responses, competition between lineages and drift. However, the occasional and ecologically dynamic lineage turnover exhibited by insular avian parasite communities is not as rapid as antigenic allele turnover within populations of human malaria.     

Biogeographical patterns of blood parasite lineage diversity in avian hosts from southern Melanesian islands

Aim (1) To describe the species–area relationships among communities of Plasmodium and Haemoproteus parasites in different island populations of the same host genus (Aves: Zosterops). (2) To compare distance–decay relationships (turnover) between parasite communities and those with potential avian and dipteran hosts, which differ with respect to their movement and potential to disperse parasite species over large distances. Location Two archipelagos in the south‐west Pacific, Vanuatu and New Caledonia (c. 250 km west of Vanuatu) and its Loyalty Islands, with samples collected from a total of 16 islands of varying sizes (328–16,648 km²). Methods We characterized parasite diversity and distribution via polymerase chain reaction (PCR) from avian (Zosterops) blood samples. Bayesian methods were used to reconstruct the parasite phylogeny. In accordance with recent molecular evidence, we treat distinct mitochondrial DNA lineages as equivalent to species in this study. Path analysis and parasite lineage accumulation curves were used to assess the confounding effect of inadequate sampling on the estimation of parasite richness. Species–area and species–distance relationships were assessed using linear regression: distance–decay relationships were assessed using Mantel tests. Results Birds and mosquito species and Plasmodium lineages exhibited significant species–area relationships. However, Plasmodium lineages showed the weakest ‘species–area’ relationship; no relationship was found for Haemoproteus lineages. Avian species richness influenced parasite lineage richness more than mosquito species richness did. Within individual avian host species, the species–area relationship of parasites showed differing patterns. Path analysis indicated that sampling effort was unlikely to have a confounding effect on parasite richness. Distance from mainland (isolation effect) showed no effect on parasite richness. Community similarity decayed significantly with distance for avifauna, mosquito fauna and Plasmodium lineages but not for Haemoproteus lineages. Main conclusions Plasmodium lineages and mosquito species fit the power‐law model with steeper slopes than found for the avian hosts. The lack of species–distance relationship in parasites suggests that other factors, such as the competence of specific vectors and habitat features, may be more important than distance. The decay in similarity with distance suggests that the sampled Plasmodium lineages and their potential hosts were not randomly distributed, but rather exhibited spatially predictable patterns. We discuss these results in the context of the effects that parasite generality may have on distribution patterns.     

Prevalence of malaria and related haemosporidian parasites in two shorebird species with different winter habitat distribution

Parasites can have strong effects on host life-history and behaviour, and result in changes in host population dynamics and community structure. We applied a PCR-based technique and examined prevalence of malaria and related haemosporidian parasites in two arctic breeding shorebird species: the Semipalmated Sandpiper (Calidris pusilla) and the Pectoral Sandpiper (C. melanotos). During the non-breeding season, Semipalmated Sandpipers inhabit coastal marine habitats, whereas Pectoral Sandpipers are found in inland areas. In accordance with the hypothesis that the risk of parasite infection is higher in a species wintering in freshwater areas, we found Plasmodium sp. infection during the breeding season only in Pectoral Sandpipers, whereas Semipalmated Sandpipers were parasite free. However, even in Pectoral Sandpipers sampled in the arctic, prevalence of malaria parasites was very low (<3% of individuals, n = 114). Overall, three different Plasmodium sp. lineages were found, one of which has never been described before.     

Avian host composition,local speciation and dispersal drive the regional assembly of avian malaria parasites in South American birds

Identifying the ecological factors that shape parasite distributions remains a central goal in disease ecology. These factors include dispersal capability, environmental filters and geographic distance. Using 520 haemosporidian parasite genetic lineages recovered from 7,534 birds sampled across tropical and temperate South America, we tested (a) the latitudinal diversity gradient hypothesis and (b) the distance–decay relationship (decreasing proportion of shared species between communities with increasing geographic distance) for this host–parasite system. We then inferred the biogeographic processes influencing the diversity and distributions of this cosmopolitan group of parasites across South America. We found support for a latitudinal gradient in diversity for avian haemosporidian parasites, potentially mediated through higher avian host diversity towards the equator. Parasite similarity was correlated with climate similarity, geographic distance and host composition. Local diversification in Amazonian lineages followed by dispersal was the most frequent biogeographic events reconstructed for haemosporidian parasites. Combining macroecological patterns and biogeographic processes, our study reveals that haemosporidian parasites are capable of circumventing geographic barriers and dispersing across biomes, although constrained by environmental filtering. The contemporary diversity and distributions of haemosporidian parasites are mainly driven by historical (speciation) and ecological (dispersal) processes, whereas the parasite community assembly is largely governed by host composition and to a lesser extent by environmental conditions.     

Host phylogeography and beta diversity in avian haemosporidian (Plasmodiidae) assemblages of the Lesser Antilles

1. We estimated the correlation between host phylogeographical structure and beta diversity of avian haemosporidian assemblages of passerine birds to determine the degree to which parasite communities change with host evolution, expressed as genetic divergence between island populations, and we investigated whether differences among islands in the haemosporidia of a particular host species reflect beta diversity in the entire parasite assemblage, beta diversity in vectors, turnover of bird species and/or geographical distance. 2. We used Mantel tests to assess the significance of partial correlations between host nucleotide difference (based on cytochrome b) and haemosporidian (Haemoproteus spp. and Plasmodium spp.) mitochondrial lineage beta diversity within a given host species and between Plasmodium mitochondrial lineage beta diversity and mosquito and bird species beta diversity (or turnover). Three abundant and widespread host species (Tiaris bicolor, Coereba flaveola and Loxigilla noctis/barbadensis) were included in the study. Haemosporidian lineage beta diversity among nine islands was assessed using the Chao-Jaccard, Chao-S?rensen and Morisita-Horn indices of community similarity. Beta diversity indices of mosquito species and turnover of bird species were calculated from data in published records and field guides. 3. In Loxigilla spp., we found a positive correlation with geographical distance and an unexpected negative correlation between haemosporidian beta diversity and host genetic distance. Tiaris bicolor exhibited a significant positive correlation between haemosporidian beta diversity and beta diversity within the entire parasite assemblage. We did not find significant correlations between parasite beta diversity and mosquito beta diversity or bird species turnover. 4. Host phylogeographical structure does not appear to drive within-host beta diversity of haemosporidian lineages. Instead, the array of parasites on one host can reflect the haemosporidian assemblage on other hosts.     

Migrant birds disperse haemosporidian parasites and affect their transmission in avian communities

Migration has an important impact on the transmission of pathogens. Migratory birds disperse parasites through their routes and may consequently introduce them to new areas and hosts. Hence, haemosporidian parasites, which are among the most prevalent, diverse and important bird pathogens, are potentially dispersed when infecting migrant hosts. Further, migrant hosts could enhance local parasite prevalence and richness by transporting new parasite strains to new areas. Here, we hypothesize and aim to evaluate if 1) migratory birds spread parasite lineages along their routes, and 2) localities crossed by more migratory birds have greater prevalence and richness of haemosporidians. For the first hypothesis, we tested whether parasite lineages found 1) in both migrants and residents, and 2) only in residents, differ in their frequencies of occurrence among localities. For the second hypothesis, we tested for a relationship among localities between the overall local haemosporidian parasite richness and prevalence, and the proportion of migratory bird individuals present in a locality. We combined a dataset on 13 200 bird samples with additional data from the MalAvi database (total: ~2800 sequenced parasites comprising 675 distinct lineages, from 506 host species and 156 localities) from South America, and used Bayesian multi-level models to test our hypotheses. We demonstrate that parasites shared between resident and migratory species are the most spatially widespread, highlighting the potential of migrants to carry and transmit haemosporidians. Further, the presence of migrants in a locality was negatively related to local parasite richness, but not associated with local prevalence. Here, we confirm that migrants can contribute to parasite dispersal and visiting migrants are present in regions with lower Plasmodium prevalence. Also, we observed their presence might raise Haemoproteus community prevalence. Therefore, we demonstrate migrants enhance pathogens spread and their presence may influence parasite community transmission.     

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.     

Avian malaria on Madagascar: prevalence,biodiversity and specialization of haemosporidian parasites

Previous studies about geographic patterns of species diversity of avian malaria parasites and others in the Order Haemosporida did not include the avian biodiversity hotspot Madagascar. Since there are few data available on avian malaria parasites on Madagascar, we conducted the first known large-scale molecular-based study to investigate their biodiversity. Samples (1067) from 55 bird species were examined by a PCR method amplifying nearly the whole haemosporidian cytochrome b gene (1063?bp). The parasite lineages found were further characterized phylogenetically and the degree of specialization was determined with a newly introduced host diversity index (Hd). Our results demonstrate that Madagascar indeed represents a biodiversity hotspot for avian malaria parasites as we detected 71 genetically distinct parasite lineages of the genera Plasmodium and Haemoproteus. Furthermore, by using a phylogenetic approach and including the sequence divergence we suspect that the detected haemosporidian lineages represent at least 29 groups i.e. proposed species. The here presented Hd values for each parasite regarding host species, genus and family strongly support previous works demonstrating the elastic host ranges of some avian parsites of the Order Haemosporida. Representatives of the avian parasite genera Plasmodium and Leucocytozoon tend to more often be generalists than those of the genus Haemoproteus. However, as demonstrated in various examples, there is a large overlap and single parasite lineages frequently deviate from this rule.     

HISTORICAL BIOGEOGRAPHY OF THE BANANAQUIT (COEREBA FLAVEOLA) IN THE CARIBBEAN REGION: A MITOCHONDRIAL DNA ASSESSMENT

We analyzed mitochondrial DNA (mtDNA) restriction-site variation in bananaquit (Coereba flaveola; Aves, Coerebinae) populations sampled on 12 Caribbean islands and at 5 continental localities in Central America and northern South America. Multiple fixed restriction-site differences genetically defined several regional bananaquit populations. An mtDNA clade representing all Jamaican bananaquits was the most divergent; the estimated average sequence divergence (d_xy) between Jamaican and all other mtDNA haplotypes surveyed was 0.027. Three groups of populations, representing Central America, northern South America, and the eastern Antilles (Puerto Rico to Grenada) were nearly equally differentiated among themselves (average d_xy = 0.014), and may represent a single, recent range expansion. Within the eastern Antilles, three geographically restricted haplotype groups were identified: Puerto Rico, north-central Lesser Antilles (U.S. Virgin Islands to St. Lucia), and Grenada–St. Vincent. The evolutionary relationships of these groups were not clear. Genetic homogeneity of the island populations from the U.S. Virgin Islands to St. Lucia suggested a recent spread of a specific north-central Lesser Antillean haplotype through most of those islands. Haplotype variation across this region indicated that this spread may have occurred in two waves, first through the southernmost islands of St. Lucia, Martinique, and Dominica, and more recently from Guadeloupe to the north. The geographic distribution of mtDNA haplotypes, and of bananaquit populations, suggests periods of invasiveness followed by relative geographic quiescence. Although most genetic studies of bird populations have revealed homogeneity over large geographic areas, our findings provide a remarkable counterexample of strong geographic structuring of mtDNA variation over relatively small distances. Furthermore, although the mtDNA data were consistent with several subspecific distinctions, it was clear that named subspecies do not define equally differentiated evolutionary entities.     

Host specificity of avian haemosporidian parasites is unrelated among sister lineages but shows phylogenetic signal across larger clades

Parasites can vary in the number of host species they infect, a trait known as “host specificity”. Here we quantify phylogenetic signal—the tendency for closely related species to resemble each other more than distantly related species—in host specificity of avian haemosporidian parasites (genera Plasmodium, Haemoproteus and Leucocytozoon) using data from MalAvi, the global avian haemosporidian database. We used the genetic data (479 base pairs of cytochrome b) that define parasite lineages to produce genus level phylogenies. Combining host specificity data with those phylogenies revealed significant levels of phylogenetic signal while controlling for sampling effects; phylogenetic signal was higher when the phylogenetic diversity of hosts was taken into account. We then tested for correlations in the host specificity of pairs of sister lineages. Correlations were generally close to zero for all three parasite genera. These results suggest that while the host specificity of parasite sister lineages differ, larger clades may be relatively specialised or generalised.