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.     

Evolutionary relationships, cospeciation, and host switching in avian malaria parasites

We used phylogenetic analyses of cytochrome b sequences of malaria parasites and their avian hosts to assess the coevolutionary relationships between host and parasite lineages. Many lineages of avian malaria parasites have broad host distributions, which tend to obscure cospeciation events. The hosts of a single parasite or of closely related parasites were nonetheless most frequently recovered from members of the same host taxonomic family, more so than expected by chance. However, global assessments of the relationship between parasite and host phylogenetic trees, using Component and ParaFit, failed to detect significant cospeciation. The event-based approach employed by TreeFitter revealed significant cospeciation and duplication with certain cost assignments for these events, but host switching was consistently more prominent in matching the parasite tree to the host tree. The absence of a global cospeciation signal despite conservative host distribution most likely reflects relatively frequent acquisition of new hosts by individual parasite lineages. Understanding these processes will require a more refined species concept for malaria parasites and more extensive sampling of parasite distributions across hosts. If parasites can disperse between allopatric host populations through alternative hosts, cospeciation may not have a strong influence on the architecture of host-parasite relationships. Rather, parasite speciation may happen more often in conjunction with the acquisition of new hosts followed by divergent selection between host lineages in sympatry. Detailed studies of the phylogeographic distributions of hosts and parasites are needed to characterize these events.     

Within-population variation in prevalence and lineage distribution of avian malaria in blue tits, Cyanistes caeruleus

The development of molecular genetic screening techniques for avian blood parasites has revealed many novel aspects of their ecology, including greatly elevated diversity and complex host-parasite relationships. Many previous studies of malaria in birds have treated single study populations as spatially homogeneous with respect to the likelihood of transmission of malaria to hosts, and we have very little idea whether any spatial heterogeneity influences different malaria lineages similarly. Here, we report an analysis of variation in the prevalence and cytochrome b lineage distribution of avian malaria infection with respect to environmental and host factors, and their interactions, in a single blue tit (Cyanistes caeruleus) population. Of 11 Plasmodium and Haemoproteus cytochrome b lineages found in 997 breeding individuals, the three most numerous (pSGS1, pTURDUS1 and pBT7) were considered separately, in addition to analyses of all avian malaria lineages pooled. Our analyses revealed marked spatial differences in the prevalence and distribution of these lineages, with local prevalence of malaria within the population ranging from over 60% to less than 10%. In addition, we found several more complex patterns of prevalence with respect to local landscape features, host state, parasite genotype, and their interactions. We discuss the implications of such heterogeneity in parasite infection at a local scale for the study of the ecology and evolution of infectious diseases in natural populations. The increased resolution afforded by the combination of molecular genetic and geographical information systems (GIS) tools has the potential to provide many insights into the epidemiology, evolution and ecology of these parasites in the future.     

Resource predictability and specialization in avian malaria parasites

We tested the hypothesis that avian haemosporidian (malaria) parasites specialize on hosts that can be characterized as predictable resources at a site in Amazonian Ecuador. We incorporated host phylogenetic relationship and relative abundance in assessing parasite specialization, and we examined associations between parasite specialization and three host characteristics – abundance, mass and longevity – using quantile regression, phylogenetic logistic regression and t‐tests. Hosts of specialist malaria parasite lineages were on average more abundant than hosts of generalist parasite lineages, but the relationship between host abundance and parasite specialization was not consistent across analyses. We also found support for a positive association between parasite specialization and host longevity, but this also was not consistent across analyses. Nonetheless, our findings suggest that the predictability of a host resource may play a role in the evolution of specialization. However, we also discuss two alternative explanations to the resource predictability hypothesis for specialization: (i) that interspecific interactions among the parasites themselves might constrain some parasites to a specialist strategy, and (ii) that frequent encounters with multiple host species, mediated by blood‐sucking insects, might promote generalization within this system.     

Host-parasite associations and host-specificity in haemoparasites of reed bed passerines

The host specificity and host sharing of avian haemoparasites (genera Haemoproteus and Plasmodium) is still poorly known, although they infect a large proportion of several studied bird populations. This study used molecular techniques to detect haemoparasites in marsh warblers and in other passerines that feed in reed beds, at 4 sites in Portugal. The host-specificity of the parasite lineages was analysed and compared with other cases described in the literature to assess whether apparent host specificity changes according to the studied system. Nine lineages of Haemoproteus and 15 of Plasmodium were found, of which only 10 Plasmodium were proven to have local transmission. Each lineage was confined to a distinct set of host species. The distribution of parasites in the host species was non-nested, meaning that specialist lineages did not always share hosts with generalists. The most prevalent lineages were those with a wider host range, indicating that the ability to infect more hosts will enhance a parasite's prevalence in its entire host range. We also found that in our areas, a specialist parasite (H. MW1) appears to have a more generalist character than described in the literature, suggesting that a parasite's apparent specialization can depend on the type of host species sampled.     

Host specialization and geographic localization of avian malaria parasites: a regional analysis in the Lesser Antilles

We recovered 26 genetically distinct avian malaria parasite lineages, based on cytochrome b sequences, from a broad survey of terrestrial avifauna of the Lesser Antilles. Here we describe their distributions across host species within a regional biogeographic context. Most parasite lineages were recovered from a few closely related host species. Specialization on one host species and distribution across many hosts were both rare. Geographic patterns of parasite lineages indicated limited dispersal and frequent local extinction. The central islands of the archipelago share similar parasite lineages and patterns of infection. However, the peripheral islands harbor well-differentiated parasite communities, indicating long periods of isolation. Nonetheless, 20 of 26 parasite lineages were recovered from at least one of three other geographic regions, the Greater Antilles, North America, and South America, suggesting rapid dispersal relative to rate of differentiation. Six parasite lineages were restricted to the Lesser Antilles, primarily to endemic host species. Host differences between populations of the same parasite lineage suggest that host preference may evolve more rapidly than mitochondrial gene sequences. Taken together, distributions of avian malarial parasites reveal evidence of coevolution, host switching, extinction, and periodic recolonization events resulting in ecologically dynamic as well as evolutionarily stable patterns of infection.     

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.     

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 and evolutionary relationships of haematozoan parasites in native versus introduced populations of common myna Acridotheres tristis

The success of introduced species is frequently explained by their escape from natural enemies in the introduced region. We tested the enemy release hypothesis with respect to two well studied blood parasite genera (Plasmodium and Haemoproteus) in native and six introduced populations of the common myna Acridotheres tristis. Not all comparisons of introduced populations to the native population were consistent with expectations of the enemy release hypothesis. Native populations show greater overall parasite prevalence than introduced populations, but the lower prevalence in introduced populations is driven by low prevalence in two populations on oceanic islands (Fiji and Hawaii). When these are excluded, prevalence does not differ significantly. We found a similar number of parasite lineages in native populations compared to all introduced populations. Although there is some evidence that common mynas may have carried parasite lineages from native to introduced locations, and also that introduced populations may have become infected with novel parasite lineages, it may be difficult to differentiate between parasites that are native and introduced, because malarial parasite lineages often do not show regional or host specificity.     

Cross-species infection of blood parasites between resident and migratory songbirds in Africa

We studied the phylogeny of avian haemosporidian parasites, Haemoproteus and Plasmodium, in a number of African resident and European migratory songbird species sampled during spring and autumn in northern Nigeria. The phylogeny of the parasites was constructed through sequencing part of their mitochondrial cytochrome b gene. We found eight parasite lineages, five Haemoproteus and three Plasmodium, infecting multiple host species. Thus, 44% of the 18 haemospiridian lineages found in this study were detected in more than one host species, indicating that host sharing is a more common feature than previously thought. Furthermore, one of the Plasmodium lineages infected species from different host families, Sylviidae and Ploceidae, expressing exceptionally large host range. We mapped transmission events, e.g. the occurrence of the parasite lineages in resident bird species in Europe or Africa, onto a phylogenetic tree. This yielded three clades, two Plasmodium and one Haemoproteus, in which transmission seems to occur solely in Africa. One Plasmodium clade showed European transmission, whereas the remaining two Haemoproteus clades contained mixes of lineages of African, European or unknown transmission. The mix of areas of transmission in several branches of the phylogenetic tree suggests that transmission of haemosporidian parasites to songbirds has arisen repeatedly in Africa and Europe. Blood parasites could be viewed as a cost of migration, as migratory species in several cases were infected with parasite lineages from African resident species. This cost of migration could have considerable impact on the evolution of migration and patterns of winter distribution in migrating birds.     

Diversification and host switching in avian malaria parasites

The switching of parasitic organisms to novel hosts, in which they may cause the emergence of new diseases, is of great concern to human health and the management of wild and domesticated populations of animals. We used a phylogenetic approach to develop a better statistical assessment of host switching in a large sample of vector-borne malaria parasites of birds (Plasmodium and Haemoproteus) over their history of parasite-host relations. Even with sparse sampling, the number of parasite lineages was almost equal to the number of avian hosts. We found that strongly supported sister lineages of parasites, averaging 1.2% sequence divergence, exhibited highly significant host and geographical fidelity. Event-based matching of host and parasite phylogenetic trees revealed significant cospeciation. However, the accumulated effects of host switching and long distance dispersal cause these signals to disappear before 4% sequence divergence is achieved. Mitochondrial DNA nucleotide substitution appears to occur about three times faster in hosts than in parasites, contrary to findings on other parasite-host systems. Using this mutual calibration, the phylogenies of the parasites and their hosts appear to be similar in age, suggesting that avian malaria parasites diversified along with their modern avian hosts. Although host switching has been a prominent feature over the evolutionary history of avian malaria parasites, it is infrequent and unpredictable on time scales germane to public health and wildlife management.     

Diversification by host switching and dispersal shaped the diversity and distribution of avian malaria parasites in Amazonia

Understanding how pathogens and parasites diversify through time and space is fundamental to predicting emerging infectious diseases. Here, we use biogeographic, coevolutionary and phylogenetic analyses to describe the origin, diversity, and distribution of avian malaria parasites in the most diverse avifauna on Earth. We first performed phylogenetic analyses using the mitochondrial cytochrome b (cyt b) gene to determine relationships among parasite lineages. Then, we estimated divergence times and reconstructed ancestral areas to uncover how landscape evolution has shaped the diversification of Parahaemoproteus and Plasmodium in Amazonia. Finally, we assessed the coevolutionary patterns of diversification in this host–parasite system to determine how coevolution may have influenced the contemporary diversity of avian malaria parasites and their distribution among Amazonian birds. Biogeographic analysis of 324 haemosporidian parasite lineages recovered from 4178 individual birds provided strong evidence that these parasites readily disperse across major Amazonian rivers and this has occurred with increasing frequency over the last five million years. We also recovered many duplication events within areas of endemism in Amazonia. Cophylogenetic analyses of these blood parasites and their avian hosts support a diversification history dominated by host switching. The ability of avian malaria parasites to disperse geographically and shift among avian hosts has played a major role in their radiation and has shaped the current distribution and diversity of these parasites across Amazonia.     

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.     

High lineage diversity and host sharing of malarial parasites in a local avian assemblage

Bird populations often have high prevalences of the haemosporidians Haemoproteus spp. and Plasmodium spp., but the extent of host sharing and host switching among these parasite lineages and their avian hosts is not well known. While sampling within a small geographic region in which host individuals are likely to have been exposed to the same potential parasite lineages, we surveyed highly variable mitochondrial DNA from haemosporidians isolated from 14 host taxa representing 4 avian families (Hirundinidae, Parulidae, Emberizidae, and Fringillidae). Analyses of cytochrome b sequences from 83 independent infections identified 29 unique haplotypes, representing 2 well-differentiated Haemoproteus spp. lineages and 6 differentiated Plasmodium spp. lineages. A phylogenetic reconstruction of relationships among these lineages provided evidence against host specificity at the species and family levels, as all haemosporidian lineages recovered from 2 or more host individuals (2 Haemoproteus and 3 Plasmodium lineages) were found in at least 2 host families. We detected a similar high level of host sharing; the 3 most intensively sampled host species each harbored 4 highly differentiated haemosporidian lineages. These results indicate that some Haemoproteus spp. and Plasmodium spp. lineages exhibit a low degree of host specificity, a phenomenon with implications for ecological and evolutionary interactions among these parasites and their hosts.     

Host specificity in avian blood parasites: a study of Plasmodium and Haemoproteus mitochondrial DNA amplified from birds

A fragment of the mitochondrial cytochrome b gene of avian malaria (genera Haemoproteus and Plasmodium) was amplified from blood samples of 12 species of passerine birds from the genera Acrocephalus, Phylloscopus and Parus. By sequencing 478 nucleotides of the obtained fragments, we found 17 different mitochondrial haplotypes of Haemoproteus or Plasmodium among the 12 bird species investigated. Only one out of the 17 haplotypes was found in more than one host species, this exception being a haplotype detected in both blue tits (Parus caeruleus) and great tits (Parus major). The phylogenetic tree which was constructed grouped the sequences into two clades, most probably representing Haemoproteus and Plasmodium, respectively. We found two to four different parasite mitochondrial DNA (mtDNA) haplotypes in four bird species. The phylogenetic tree obtained from the mtDNA of the parasites matched the phylogenetic tree of the bird hosts poorly. For example, the two tit species and the willow warbler (Phylloscopus trochilus) carried parasites differing by only 0.6% sequence divergence, suggesting that Haemoproteus shift both between species within the same genus and also between species in different families. Hence, host shifts seem to have occurred repeatedly in this parasite host system. We discuss this in terms of the possible evolutionary consequences for these bird species.     

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 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.     

Host and habitat specialization of avian malaria in Africa

Studies of both vertebrates and invertebrates have suggested that specialists, as compared to generalists, are likely to suffer more serious declines in response to environmental change. Less is known about the effects of environmental conditions on specialist versus generalist parasites. Here, we study the evolutionary strategies of malaria parasites (Plasmodium spp.) among different bird host communities. We determined the parasite diversity and prevalence of avian malaria in three bird communities in the lowland forests in Cameroon, highland forests in East Africa and fynbos in South Africa. We calculated the host specificity index of parasites to examine the range of hosts parasitized as a function of the habitat and investigated the phylogenetic relationships of parasites. First, using phylogenetic and ancestral reconstruction analyses, we found an evolutionary tendency for generalist malaria parasites to become specialists. The transition rate at which generalists become specialists was nearly four times as great as the rate at which specialists become generalists. We also found more specialist parasites and greater parasite diversity in African lowland rainforests as compared to the more climatically variable habitats of the fynbos and the highland forests. Thus, with environmental changes, we anticipate a change in the distribution of both specialist and generalist parasites with potential impacts on bird communities.     

Relative migration rates and local adaptation in a mosquito-protozoan interaction

Theory predicts that the direction of local adaptation depends on the relative migration rates of hosts and parasites. Here we measured relative migration rates and tested for local adaptation in the interaction between a tree hole mosquito (Ochlerotatus sierrensis) and a protozoan parasite (Lambornella clarki). We found strong support for the hypothesis that the host migrates more than its parasite. Hosts colonized artificial tree holes in the field at a much higher rate than the parasite. Field releases of the parasite demonstrated that it colonizes and persists in natural tree holes where it was previously absent, suggesting that parasite distribution is limited by its migratory ability. Although the host migrates more than its parasite, we found no evidence for local adaptation by hosts and some evidence for local adaptation by parasites. Other life history traits of the host and parasite may also influence patterns in local adaptation, particularly parasite virulence and host dormancy.     

Global warming will reshuffle the areas of high prevalence and richness of three genera of avian blood parasites

The importance of parasitism for host populations depends on local parasite richness and prevalence: usually host individuals face higher infection risk in areas where parasites are most diverse, and host dispersal to or from these areas may have fitness consequences. Knowing how parasites are and will be distributed in space and time (in a context of global change) is thus crucial from both an ecological and a biological conservation perspective. Nevertheless, most research articles focus just on elaborating models of parasite distribution instead of parasite diversity. We produced distribution models of the areas where haemosporidian parasites are currently highly diverse (both at community and at within‐host levels) and prevalent among Iberian populations of a model passerine host: the blackcap Sylvia atricapilla; and how these areas are expected to vary according to three scenarios of climate change. On the basis of these models, we analysed whether variation among populations in parasite richness or prevalence are expected to remain the same or change in the future, thereby reshuffling the geographic mosaic of host‐parasite interactions as we observe it today. Our models predict a rearrangement of areas of high prevalence and richness of parasites in the future, with Haemoproteus and Leucocytozoon parasites (today the most diverse genera in blackcaps) losing areas of high diversity and Plasmodium parasites (the most virulent ones) gaining them. Likewise, the prevalence of multiple infections and parasite infracommunity richness would be reduced. Importantly, differences among populations in the prevalence and richness of parasites are expected to decrease in the future, creating a more homogeneous parasitic landscape. This predicts an altered geographic mosaic of host‐parasite relationships, which will modify the interaction arena in which parasite virulence evolves.