Search

For several years, there have been continuous reports of black flies in Mississippi with evidence of transmission of Leucocytozoon spp. This study was conducted to determine the presence and diversity of Leucocytozoon spp. in black flies captured throughout Mississippi. Thirty-three collections, consisting of 346 specimens, were made during the 2-yr period (2015-2016) at 10 locations around the state. In addition to these systematic biweekly collections, 46 specimens were taken in 10 collections at four additional sites from 2009 to 2014, as well as 388 specimens taken in 14 collections during a severe black fly outbreak during March and April of 2018. Out of 186 pooled samples, 21 samples were positive for haemosporidian DNA. Eighteen of those samples were identified as Leucocytozoon spp. A phylogenetic tree was constructed using the novel sequences along with existing sequences from the MalAvi database. Results showed several of the sequences constructed in this study had high divergence from the existing sequences from the database., (© The Author(s) 2022. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

All organisms encounter pathogens, and birds are especially susceptible to infection by malaria parasites and other haemosporidians. It is important to understand how immune genes, primarily innate immune genes which are the first line of host defense, have evolved across birds, a highly diverse group of tetrapods. Here, we find that innate immune genes are highly conserved across the avian tree of life and that although most show evidence of positive or diversifying selection within specific lineages or clades, the number of sites is often proportionally low in this broader context of putative constraint. Rather, the evidence shows a much higher level of negative or purifying selection in these innate immune genes - rather than adaptive immune genes - which is consistent with birds' long coevolutionary history with pathogens and the need to maintain a rapid response to infection. We further explored avian responses to haemosporidians by comparing differential gene expression in wild birds (1) uninfected with haemosporidians, (2) infected with Plasmodium , and (3) infected with Haemoproteus ( Parahaemoproteus ). We found patterns of significant differential expression with some genes unique to infection with each genus and a few shared between "treatment" groups, but none that overlapped with the genes included in the phylogenetic study.

The vectors of avian malaria (Haemosporida) are an understudied component of wildlife disease ecology. Most studies of avian malaria have focused on the intermediate bird hosts. This bias leaves a significant gap in our knowledge and understanding of the insect hosts. This study investigates the diversity of malaria parasites carried by mosquitoes (Diptera, Culicidae) in the state of Mississippi. With the use of molecular techniques, haemosporidian infection rates were determined and parasites were identified. A total of 27,157 female mosquitoes representing 15 species were captured. Five of those species tested positive for malaria parasites with an overall infection rate of 4 per 1,000 mosquitoes infected. Mosquitoes were shown to harbor Plasmodium and Haemoproteus ( Parahaemoproteus) parasites. A unique lineage of parasites was discovered in Anopheles mosquitoes, potentially representing a new genus of haemosporidian parasites, reinforcing the need to continue investigating this diverse group of parasites.

The diversity of avian malaria parasites is much greater than 20th century morphologists realized and virtually every study in this field in the last 15 years has uncovered previously undocumented diversity at multiple levels within the taxonomic hierarchy. Despite this explosion of knowledge, there remain vast sampling gaps, both geographically and host-taxonomically, which makes characterizing patterns of diversity extremely challenging. Here, we summarize the current state of knowledge of sub-Saharan African avian malaria parasite diversity, focusing on avian hosts endemic to Africa. The relative proportions of the parasite genera included here, Plasmodium, Haemoproteus (including Parahaemoproteus) and Leucocytozoon, varied between regions, in part due to habitat preferences of the insect vectors of these genera, and in part we believe due to sampling bias. Biogeographic regions of sub-Saharan Africa harbour about the same proportion of endemic to shared parasite lineages, but there appears to be no phylogenetic structuring across regions. Our results highlight the sampling problem that must be addressed if we are to have a detailed understanding of parasite diversity in Africa. Without broad sampling within and across regions and hosts, using both molecular tools and microscopy, conclusions about parasite diversity, host-parasite interactions or even transmission dynamics remain extremely limited.

The unicellular blood parasites in the order Haemosporida are highly diverse, infect many vertebrates, are responsible for a large disease burden among humans and animals, and have reemerged as an important model system to understand the evolutionary and ecological dynamics of host-parasite interactions. The phylogenetics and systematics of Haemosporida are limited by poor sampling of different vertebrate host taxa. We surveyed the Haemosporida of wild whooping cranes (Grus americana) and sandhill cranes (Grus canadensis) (Aves: Gruiformes) using a combination of morphological and molecular approaches. We identified Haemoproteus antigonis in blood smears based on published morphological descriptions. Phylogenetic analysis based on partial cytochrome b (cytb) and cytochrome oxidase (coI) sequences placed H. antigonis parasites in a novel clade, distinct from all avian Haemosporida genera for which cytb and/or coI sequences are available. Molecular clock and divergence estimates suggest this crane clade may represent a new genus. This is the first molecular description of H. antigonis and the first report of H. antigonis in wild whooping cranes, an endangered bird in North America. Further sampling of Haemosporida, especially from hosts of the Gruiformes and other poorly sampled orders, will help to resolve the relationship of the H. antigonis clade to other avian Haemosporida genera. Our study highlights the potential of sampling neglected host species to discover novel lineages of diverse parasite groups., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

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.

Hemosporidians are a diverse group of blood parasites that infect terrestrial vertebrates worldwide, but there is variability in parasite prevalence and parasitemia with infections ranging from virtually inconsequential to lethal. In this study, we determined prevalence and parasitemia of avian hemosporidians in the Tufted Titmouse ( Baeolophus bicolor ; n = 81). Plasmodium and Parahaemoproteus were detected and quantified from blood samples using microscopy, polymerase chain reaction (PCR), and quantitative PCR. Thirteen mitochondrial cytochrome b lineages of hemosporidian parasites were found, including generalist and specialist lineages, and the data indicate that prevalence is 69.1% (Plasmodium 89.3%; Parahaemoproteus 7.1%; double infection 3.6%). However, parasitemia was low in all infected birds. Seasonally, parasite prevalence varied significantly, although prevalence and parasitemia were not associated with host sex, age, or health. Observations of infection in this naturally infected bird provide details on host susceptibility that are applicable to the understanding of hemosporidian parasites in other avian hosts.

Malaria parasites have had profound effects on human populations for millennia, but other terrestrial vertebrates are impacted by malaria as well. Entire species of birds have been driven to extinction, and many others are threatened by population declines. Recent studies have shown that host-switching is quite common among malaria parasite lineages, and these switches often involve a significant shift in the environment in which the parasites find themselves, including nucleated vs non-nucleated red blood cells and red vs white blood cells. Therefore, it is important to understand how parasites adapt to these different host environments. The mitochondrial cytochrome b (cyt b) gene shows evidence of adaptive molecular evolution among malaria parasite groups, putatively because of its critical role in the electron transport chain (ETC) in cellular metabolism. Two hypotheses were addressed here: (1) mitochondrial components of the ETC (cyt b and cytochrome oxidase 1 [COI]) should show evidence of adaptive evolution (i.e., selection) and (2) selection should be evident in host switches. Overall we found a signature of constraint (e.g., purifying selection) across the four genes included here, but we also found evidence of positive selection associated with host switches in cyt b and, surprisingly, in (apicoplast) caseinolytic protease C. These results suggest that evidence of selection should be widespread across these parasite genomes.

The avian genus Ficedula has been a model system for studying speciation, genomics, biogeography, and the evolution of migratory behavior. However, no multi-locus molecular phylogenetic hypothesis exists for the genus. We expanded taxon and character sampling over previous studies and produced a robust hypothesis of relationships for the genus. Many previous findings, such as the inclusion of Muscicapella and exclusion of Ficedula monileger from the genus, were verified, but many relationships differed compared to previous work. Some of the differences were due to increased sampling, but others were due to problematic sequence data produced from DNA extracted from historical museum specimens. The new phylogenetic hypothesis resulted in a simpler biogeographic scenario with fewer transitions between regions and fewer transitions between seasonally migratory and resident character states. Notably, all species endemic to the Philippines and Wallacea formed a clade, which included Ficedula dumetoria of the Sunda Shelf and Lesser Sundas. In addition, Ficedula hyperythra was not monophyletic; samples from Philippine populations formed a clade distantly related to a clade that comprised all other sampled populations., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The malaria parasites (Apicomplexa: Haemosporida) of birds are believed to have diversified across the avian host phylogeny well after the origin of most major host lineages. Although many symbionts with direct transmission codiversify with their hosts, mechanisms of species formation in vector-borne parasites, including the role of host shifting, are poorly understood. Here, we examine the hosts of sister lineages in a phylogeny of 181 putative species of malaria parasites of New World terrestrial birds to determine the role of shifts between host taxa in the formation of new parasite species. We find that host shifting, often across host genera and families, is the rule. Sympatric speciation by host shifting would require local reproductive isolation as a prerequisite to divergent selection, but this mechanism is not supported by the generalized host-biting behavior of most vectors of avian malaria parasites. Instead, the geographic distribution of individual parasite lineages in diverse hosts suggests that species formation is predominantly allopatric and involves host expansion followed by local host-pathogen coevolution and secondary sympatry, resulting in local shifting of parasite lineages across hosts.

Delimiting species of malaria parasites (Haemosporida) has become increasingly problematic as new lineages of parasites are identified solely by molecular information, particularly mitochondrial cytochrome b sequence data. In this review, we highlight some of the issues, both historical and contemporary, that have hindered the development of objective criteria to diagnose, delimit and define species of haemosporidians. Defining species is not the focal interest of most researchers, most of whom merely wish to determine whether lineages identified in their samples match those of other researchers, and if so, where and in which host species. Rather than revisiting all the issues with respect to delimiting and naming species, we instead focus on finding a practical near-term resolution to the 'species problem' that utilizes the community's largest resource: mitochondrial cytochrome b DNA sequences. We recommend a standardized procedure to 'tag' these sequences, based on per cent sequence similarity, that will allow researchers to directly assess the novelty, known hosts and geographic distribution of avian malaria parasite lineages.

Malaria parasites (Plasmodium spp.) have plagued humans for millennia. Less well known are related parasites (Haemosporida), with diverse life cycles and dipteran vectors that infect other vertebrates. Understanding the evolution of parasite life histories, including switches between hosts and vectors, depends on knowledge of evolutionary relationships among parasite lineages. In particular, inferences concerning time of origin and trait evolution require correct placement of the root of the evolutionary tree. Phylogenetic reconstructions of the diversification of malaria parasites from DNA sequences have suffered from uncertainty concerning outgroup taxa, limited taxon sampling, and selection on genes used to assess relationships. As a result, inferred relationships among the Haemosporida have been unstable, and questions concerning evolutionary diversification and host switching remain unanswered. A recent phylogeny placed mammalian malaria parasites, as well as avian/reptilian Plasmodium, in a derived position relative to the avian parasite genera Leucocytozoon and Haemoproteus, implying that the ancestral forms lacked merogony in the blood and that their vectors were non-mosquito dipterans. Bayesian, outgroup-free phylogenetic reconstruction using relaxed molecular clocks with uncorrelated rates instead suggested that mammalian and avian/reptilian Plasmodium parasites, spread by mosquito vectors, are ancestral sister taxa, from which a variety of specialized parasite lineages with modified life histories have evolved.

The evolutionary origins of new lineages of pathogens are fundamental to understanding emerging diseases. Phylogenetic reconstruction based on DNA sequences has revealed the sister taxa of human pathogens, but the timing of host-switching events, including the human malaria pathogen Plasmodium falciparum, remains controversial. Here, we establish a rate for cytochrome b evolution in avian malaria parasites relative to its rate in birds. We found that the parasite cytochrome b gene evolves about 60% as rapidly as that of host cytochrome b, corresponding to approximately 1.2% sequence divergence per million years. This calibration puts the origin of P. falciparum at 2.5 million years ago (Ma), the initial radiation of mammalian Plasmodium at 12.8 Ma, and the contemporary global diversity of the Haemosporida across terrestrial vertebrates at 16.2 Ma.

DNA-sequence analyses of avian haemosporidian parasites, primarily of passerine birds, have described the phylogenetic relationships of major groups of these parasites, which are in general agreement with morphological taxonomy. However, less attention has been paid to haemosporidian parasites of non-passerine birds despite morphological and DNA-sequence evidence for unique clades of parasites in these birds. Detection of haemosporidian parasites in the Galapagos archipelago has raised conservation concerns and prompted us to characterise the origins and diversity of these parasites in the Galapagos dove (Zenaida galapagoensis). We used partial mitochondrial cytochrome b (cyt b) and apicoplast caseinolytic protease C (ClpC) genes to develop a phylogenetic hypothesis of relationships of haemosporidian parasites infecting New World Columbiformes, paying special attention to those parasites infecting the endemic Galapagos dove. We identified a well-supported and diverse monophyletic clade of haemosporidian parasites unique to Columbiformes, which belong to the sub-genus Haemoproteus (Haemoproteus). This is a sister clade to all the Haemoproteus (Parahaemoproteus) and Plasmodium parasites so far identified from birds as well as the Plasmodium parasites of mammals and reptiles. Our data suggest that the diverse Haemoproteus parasites observed in Galapagos doves are not endemic to the archipelago and likely represent multiple recent introductions., ((c) 2009 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.)

Haemosporidian parasites of birds and mammals reproduce asexually inside nucleated and nonnucleated host erythrocytes, respectively. Because of these different parasite environments and because bird parasites are paraphyletic, we evaluated whether patterns of parasite molecular evolution differ between host groups. We compared two mitochondrial (mt) genes and one apicoplast gene across mammal Plasmodium, bird Plasmodium, and bird Parahaemoproteus. Using a molecular phylogenetic approach, we show that the parasite mt cytochrome b (cyt b), mt cytochrome oxidase I (COI), and the apicoplast caseinolytic protease C (ClpC) exhibit similar levels of sequence divergence, yet each gene tree presents a strikingly different pattern of internal versus terminal branch lengths. In cyt b, the ratio of nonsynonymous (NS)-to-synonymous substitutions (d(N)/d(S)) is markedly elevated along the internal branch linking mammalian and avian parasites despite the sister relationship between mammal and bird Plasmodium. This is not the case for either COI or ClpC. When NS substitutions are excluded from the parasite cyt b alignment, the resulting phylogenetic tree resembles that of COI (both with and without NS substitutions). The high d(N)/d(S) ratio in the cyt b branch separating avian and mammalian parasites and a mammal-parasite codon bias suggest that adaptive evolution has distinguished mammal and bird parasites.

Haemosporidian parasite diversity among raptorial birds (hawks and owls), as estimated by DNA sequencing, is proving to be greater than previously anticipated from taxonomic assessments based on parasite morphology. Here, we place raptor parasites in a phylogenetic context, including new parasite cytochrome b (cyt b) sequences from North America and Europe and from a variety of host species not previously sampled. Mitochondrial DNA sequences reveal raptor-specific parasite clades within Parahaemoproteus, but not within Plasmodium. We also recovered a strikingly divergent clade of raptor parasites that aligns with neither genus, but groups with both as a sister clade to Leucocytozoon. Different cyt b primer sets recovered additional sequences from 3 of these samples, which grouped with Parahaemoproteus in 2 cases and with Plasmodium in 1 case. Possible explanations (after excluding contamination) include multiple infections, alternative cyt b copies within the mitochondrial genome, and nuclear copies of mitochondrial genes. We believe the latter 2 explanations are unlikely because these divergent cyt b lineages form a single clade and were also recovered with several additional genomic markers.

The avian genus Turdus is one of the most speciose and widespread of passerine genera. We investigated phylogenetic relationships within this genus using mitochondrial DNA sequence data from the ND3, ND2 and cytochrome b genes. Our sampling of Turdus included 60 of the 65 extant species currently recognized, as well as all four species from three genera previously shown to fall inside Turdus (Platycichla, Nesocichla, and Cichlherminia). Phylogenetic trees based on maximum likelihood and maximum parsimony algorithms were congruent. Most of the Turdus taxa sampled fall into one of four clades: an African clade, a Central American-Caribbean clade, a largely South American clade, and a Eurasian clade. Still other taxa are placed either at the base of Turdus, or as links between clades. In no instance is any continent reciprocally monophyletic for the species distributed on it. A general lack of nodal support near the base of the phylogeny seems related to a rapid intercontinental establishment of the major clades within Turdus very early in the history of the genus. The monotypic genus Psophocichla is distantly related to, but clearly the sister of, Turdus rather than a constituent member of it.

Ficedula flycatchers are a group of species with disparate plumages and habits that have proven a challenge for taxonomists since the first description of the genus [Brisson, M.J., 1760. Ornithologia sive synopsis methodica sistens Avium divisionem in ordines. 2: ilxvii, 1-516]. The most recent evaluation was conducted by Vaurie (Vaurie, C., 1953. A generic revision of flycatchers of the tribe Muscicapini. Bull. Amer. Mus. Nat. Hist. 100, 453-538), who used morphological and behavioral characters, as well as distributional data to consider relationships among Ficedula species, between ostensible "groupings" within the genus, and between Ficedula and its presumed sister genera. Since 1953, no study has sought to evaluate relationships among Ficedula species, and only five Palearctic species have been studied to any extent. Here, using three mitochondrial genes, we provide the first assessment of phylogenetic relationships among Ficedula species to include the consideration of presumed subgenera or "groupings," and between Ficedula and its putative sister genera. Our results suggest that Ficedula is not monophyletic; Ficedula solitaris was originally placed in the genus Anthipes, and our results suggest that both solitaris and its sister monileger should be placed in Anthipes, near Niltava. The remaining Ficedula species for which we had samples form a well-supported clade that includes Muscicapella (a monotypic genus of previously uncertain affinities). The genus Tarsiger is the sister genus to Ficedula.