Using parasites to infer host population history: a new rationale for parasite conservation

Population genomics of seal lice provides insights into the postglacial history of northern European seals

Genetic analyses of host-specific parasites can elucidate the evolutionary histories and biological features of their hosts. Here, we used population-genomic analyses of ectoparasitic seal lice (Echinophthirius horridus) to shed light on the postglacial history of seals in the Arctic Ocean and the Baltic Sea region. One key question was the enigmatic origin of relict landlocked ringed seal populations in lakes Saimaa and Ladoga in northern Europe. We found that that lice of four postglacially diverged subspecies of the ringed seal (Pusa hispida) and Baltic gray seal (Halichoerus grypus), like their hosts, form genetically differentiated entities. Using coalescent-based demographic inference, we show that the sequence of divergences of the louse populations is consistent with the geological history of lake formation. In addition, local effective population sizes of the lice are generally proportional to the census sizes of their respective seal host populations. Genome-based reconstructions of long-term effective population sizes revealed clear differences among louse populations associated with gray versus ringed seals, with apparent links to Pleistocene and Holocene climatic variation as well as to the isolation histories of ringed seal subspecies. Interestingly, our analyses also revealed ancient gene flow between the lice of Baltic gray and ringed seals, suggesting that the distributions of Baltic seals overlapped to a greater extent in the past than is the case today. Taken together, our results demonstrate how genomic information from specialized parasites with higher mutation and substitution rates than their hosts can potentially illuminate finer scale population genetic patterns than similar data from their hosts.

How many threatened lice are there? An approximation to the red list of the Spanish Phthiraptera

Although the idea of conserving parasites as part of biodiversity is not new, these in general and lice in particular, are not included in the threatened list of invertebrate fauna. Assuming that the conservation status of a lice species is similar to that of its host, the number of threatened lice within the Spanish entomofauna was estimated based on the known host-lice assemblages. The lice parasitizing many of the Spanish birds and mammals are unknown. Overall, I found 6 extinct (EX) species; 4 critically endangered (CR); 15 endangered (EN), 7 vulnerable (VU) and 1 species near threatened (NT), at regional level. Since the status of hosts varies through time and space, it, (together with those of their lice, must be periodically updated. In addition to a number of reasons that justify the conservation of parasites, lice deserve being conserved, particularly, because of their scientific value.

Heterocheilus floridensis sp. n. (Nematoda: Heterocheilidae) from the West Indian manatee Trichechus manatus (Trichechidae, Sirenia) in Florida, USA

Morphological data are used to describe a new nematode species, Heterocheilus floridensis sp. n. (Heterocheilidae) from the digestive tract of the Florida manatee Trichechus manatus latirostris (Harlan) (Trichechidae, Sirenia) from Florida, USA. Examination by light and scanning electron microscopy revealed that the new species differs from the related Heterocheilus tunicatus Diesing, 1839 mainly by having dentigerous ridges on the inner surface of the lips, a median unpaired papilla located anterior to the cloaca, and a considerably larger body size. Sequence data for subunits I and II of mitochondrial cytochrome oxidase gene, 18S small subunit and 28S ribosomal RNA genes were provided for molecular characterisation of the new species. However, the current unavailability of homologous sequence data for congeneric specimens precluded a molecular assessment of the morphological species hypothesis, and ascaridoid phylogenetic hypotheses could not be advanced. Specimens of Heterocheilus sp. collected from the Antillean manatee Trichechus manatus manatus Linnaeus in Puerto Rico, on loan from the US National Museum of Natural History, were morphologically consistent with the new species, so apparently all congeneric nematodes reported from both subspecies of the West Indian manatee Trichechus manatus Linnaeus and previously identified as H. tunicatus belong rather to H. floridensis sp. n. Heterocheilus hagenbecki (Khalil et Vogelsang, 1932) Sprent 1980 is here considered to be a species inquirenda. A key to valid species of Heterocheilus Diesing, 1839 is provided.

Loss of species and genetic diversity during colonization: Insights from acanthocephalan parasites in northern European seals

Studies on host-parasite systems that have experienced distributional shifts, range fragmentation, and population declines in the past can provide information regarding how parasite community richness and genetic diversity will change as a result of anthropogenic environmental changes in the future. Here, we studied how sequential postglacial colonization, shifts in habitat, and reduced host population sizes have influenced species richness and genetic diversity of Corynosoma (Acanthocephala: Polymorphidae) parasites in northern European marine, brackish, and freshwater seal populations. We collected Corynosoma population samples from Arctic, Baltic, Ladoga, and Saimaa ringed seal subspecies and Baltic gray seals, and then applied COI barcoding and triple-enzyme restriction-site associated DNA (3RAD) sequencing to delimit species, clarify their distributions and community structures, and elucidate patterns of intraspecific gene flow and genetic diversity. Our results showed that Corynosoma species diversity reflected host colonization histories and population sizes, with four species being present in the Arctic, three in the Baltic Sea, two in Lake Ladoga, and only one in Lake Saimaa. We found statistically significant population-genetic differentiation within all three Corynosoma species that occur in more than one seal (sub)species. Genetic diversity tended to be high in Corynosoma populations originating from Arctic ringed seals and low in the landlocked populations. Our results indicate that acanthocephalan communities in landlocked seal populations are impoverished with respect to both species and intraspecific genetic diversity. Interestingly, the loss of genetic diversity within Corynosoma species seems to have been less drastic than in their seal hosts, possibly due to their large local effective population sizes resulting from high infection intensities and effective intra-host population mixing. Our study highlights the utility of genomic methods in investigations of community composition and genetic diversity of understudied parasites.

DO PARASITIC LICE EXHIBIT ENDEMISM IN PARALLEL WITH THEIR AVIAN HOSTS? A COMPARISON ACROSS NORTHERN AMAZONIAN AREAS OF ENDEMISM

Areas of endemism are the smallest units in biogeography and can be defined as biologically unique areas comprising taxa with common geographic limits to their distributions. High beta diversity within Amazonia is often related to turnover among these areas. For decades, evolutionary biologists have tried to comprehend the mechanisms generating and maintaining the spatial structure and high diversity of free-living Amazonian organisms, particularly birds. However, few studies have tried to analyze these patterns among their parasites. Host and parasite associations involve shared history that may allow us to better understand the fine-scale evolutionary history of the host. Here we compare the coevolutionary patterns among 2 avian host species with distinct patterns of genetic structure in northern Amazonia, Dendrocincla fuliginosa (Aves: Dendrocolaptidae) and Dixiphia pipra (Aves: Pipridae), and their ectoparasitic lice (Insecta: Phthiraptera), Furnaricola sp. ex Dendrocincla fuliginosa, Myrsidea sp. ex Dixiphia pipra, and Tyranniphilopterus sp. ex Dixiphia pipra. We obtained sequences of the mitochondrial gene cytochrome oxidase subunit I from hosts and parasites collected on opposite banks of the Negro and Japurá rivers, which delimit 3 areas of endemism in northern Amazonia: Napo, Jau, and Guiana. Our results demonstrate that the Negro River is a geographical barrier for both Furnaricola sp. and its avian host, Dendrocincla fuliginosa. Phylogenies of both hosts, Dendrocincla fuliginosa, and the parasites, Furnaricola sp., show monophyletic clades on opposite margins of the river that are not sister taxa. These clades have a mean uncorrected p-distance of 17.8% for Furnaricola sp. and 6.0% for Dendrocincla fuliginosa. Thus, these parasite clades constitute distinct evolutionary lineages and may even be distinct species. In contrast, Dixiphia pipra has no population structure associated with either river. Accordingly, data from their lice Myrsidea sp. indicate weak support for different clades on opposite margins of the Negro River, whereas data from their lice Tyranniphilopterus sp. indicate weak structure across the Japurá. This study is a first step toward understanding the effects of biogeographic history on permanent ectoparasites and suggests that host biogeographic history is to some extent a determinant of the parasite's history. Furthermore, the parasite's evolutionary history is an additional source of information about their hosts' evolution in this highly diverse region of northern Amazonia.

Molecular phylogenetics of the sucking louse genus Lemurpediculus (Insecta: Phthiraptera), ectoparasites of lemurs, with descriptions of three new species

Sucking lice live in intimate association with their hosts and often display a high degree of host specificity. The present study investigated sucking lice of the genus Lemurpediculus from six mouse lemur (Microcebus) and two dwarf lemur (Cheirogaleus) species endemic to the island of Madagascar, considered a biodiversity hotspot. Louse phylogenetic trees were created based on cytochrome C oxidase subunit I (COI), elongation factor 1α (EF1α) and internal transcribed spacer 1 (ITS1) sequences. While clustering according to host species was generally observed for COI and ITS1, suggesting high host specificity of the examined lice, EF1α sequences alone did not distinguish between lice of different Microcebus species, possibly due to rather recent divergence. As bootstrap support for basal tree structure was rather low, further data are necessary to resolve the evolutionary history of louse-mouse lemur associations. Three new species of sucking lice are described: Lemurpediculus zimmermanni sp. Nov. From Microcebus ravelobensis, Lemurpediculus gerpi sp.nov. from Microcebus gerpi, and Lemurpediculus tsimanampesotsae sp. nov. from Microcebus griseorufus. These new species are compared with all known congeneric species and identifying features are illustrated for all known species of Lemurpediculus.

A century of parasitology in fisheries and aquaculture

Fish parasitological research associated with fisheries and aquaculture has expanded remarkably over the past century. The application of parasites as biological tags has been one of the fields in which fish parasitology has generated new insight into fish migration and stock assessments worldwide. It is a well-established discipline whose methodological issues are regularly reviewed and updated. Therefore, no concepts or case-studies will be repeated here; instead, we summarize some of the main recent findings and achievements of this methodology. These include the extension of its use in hosts other than bony fishes; the improvements in the selection of parasite tags; the recognition of the host traits affecting the use of parasite tags; and the increasingly recognized need for integrative, multidisciplinary studies combining parasites with classical methods and modern techniques, such as otolith microchemistry and genetics. Archaeological evidence points to the existence of parasitic problems associated with aquaculture activities more than a thousand years ago. However, the main surge of research within aquaculture parasitology occurred with the impressive development of aquaculture over the past century. Protozoan and metazoan parasites, causing disease in domesticated fish in confined environments, have attracted the interest of parasitologists and, due to their economic importance, funding was made available for basic and applied research. This has resulted in a profusion of basic knowledge about parasite biology, physiology, parasite-host interactions, life cycles and biochemistry. Due to the need for effective control methods, various solutions targeting host-parasite interactions (immune responses and host finding), genetics and pharmacological aspects have been in focus.

Traveler Mites: Population Genetic Structure of the Wing Mites Periglischrus paracaligus (Acari: Mesostigmata: Spinturnicidae)

Wing mites of the genus Periglischrus are ectoparasites exclusively associated with phyllostomid bats. These mites show high host specificity and have been studied to understand the evolutionary history of their bat hosts mainly by using a morphological variation. Through a phylogeographic approach, we analyzed the genetic diversity and population genetic structure of the ectoparasite Periglischrus paracaligus Herrin and Tipton which parasitizes Leptonycteris yerbabuenae Martínez and Villa (lesser long-nosed bat) in Mexico. By the implementation of a multilocus approach, we found that P. paracaligus populations were diverse for haplotype diversity, and had values ranging from 0.5 to 1. No genetic structuring in the P. paracaligus parasites was observed along with the distribution of the host, L. yerbabuenae, in Mexico, nor when populations or regions were compared, but our results revealed a process of historical demographic expansion in all the analyzed markers. We discuss possible scenarios that could explain the lack of population structure in the light of the data analyzed for the parasites and the biology of L. yerbabuenae, such as the interplay between parasite and host traits being responsible for the genetic make-up of parasite populations. We also inferred its phylogenetic position among wing mites parasitizing the two other species of Leptonycteris bats. Long-nosed bats' monophyly helps to explain the observed presence of distinctive clades in the wing mite's phylogeny in specific association with each long-nosed bat host species.

High levels of inbreeding with spatial and host-associated structure in lice of an endangered freshwater seal

Host-specialist parasites of endangered large vertebrates are in many cases more endangered than their hosts. In particular, low host population densities and reduced among-host transmission rates are expected to lead to inbreeding within parasite infrapopulations living on single host individuals. Furthermore, spatial population structures of directly-transmitted parasites should be concordant with those of their hosts. Using population genomic approaches, we investigated inbreeding and population structure in a host-specialist seal louse (Echinophthirius horridus) infesting the Saimaa ringed seal (Phoca hispida saimensis), which is endemic to Lake Saimaa in Finland, and is one of the most endangered pinnipeds in the world. We conducted genome resequencing of pairs of lice collected from 18 individual Saimaa ringed seals throughout the Lake Saimaa complex. Our analyses showed high genetic similarity and inbreeding between lice inhabiting the same individual seal host, indicating low among-host transmission rates. Across the lake, genetic differentiation among individual lice was correlated with their geographic distance, and assignment analyses revealed a marked break in the genetic variation of the lice in the middle of the lake, indicating substantial population structure. These findings indicate that movements of Saimaa ringed seals across the main breeding areas of the fragmented Lake Saimaa complex may in fact be more restricted than suggested by previous population-genetic analyses of the seals themselves.

Correlated population genetic structure in a three-tiered host-parasite system. The potential for coevolution and adaptive divergence

Three subspecies of Northern Bahamian Rock Iguanas, Cyclura cychlura, are currently recognized: C. c. cychlura, restricted to Andros Island, and C. c. figginsi and C. c. inornata, native to the Exuma Island chain. Populations on Andros are genetically distinct from Exuma Island populations, yet genetic divergence among populations in the Exumas is inconsistent with the two currently recognized subspecies from those islands. The potential consequences of this discrepancy might include the recognition of a single subspecies throughout the Exumas rather than two. That inference also ignores evidence that populations of C. cychlura are potentially adaptively divergent. We compared patterns of population relatedness in a three-tiered host-parasite system: C. cychlura iguanas, their ticks (genus Amblyomma, preferentially parasitizing these reptiles), and Rickettsia spp. endosymbionts (within tick ectoparasites). Our results indicate that while C. c. cychlura on Andros is consistently supported as a separate clade, patterns of relatedness among populations of C. c. figginsi and C. c. inornata within the Exuma Island chain are more complex. The distribution of the hosts, different tick species, and Rickettsia spp., supports the evolutionary independence of C. c. inornata. Further, these patterns are also consistent with two independent evolutionarily significant units within C. c. figginsi. Our findings suggest coevolutionary relationships between the reptile hosts, their ectoparasites, and rickettsial organisms, suggesting local adaptation. This work also speaks to the limitations of using neutral molecular markers from a single focal taxon as the sole currency for recognizing evolutionary novelty in populations of endangered species.

Host Associations of Ectoparasites of the Gray Mouse Lemur, Microcebus murinus, in Northwestern Madagascar

Eight species of ectoparasites were collected during 225 gray mouse lemur, Microcebus murinus (J. F. Miller), captures, in Ankarafantsika National Park, Madagascar, in 2010-2011. The ixodid tick, Haemaphysalis lemuris Hoogstraal, was the most common ectoparasite and was mostly represented by nymphs. Other ectoparasites recorded include the polyplacid sucking louse, Lemurpediculus madagascariensis Durden, Kessler, Radespiel, Zimmermann, Hasiniaina, and Zohdy; the ixodid tick, Haemaphysalis simplex Neumann; an undescribed laelapid mite in the genus Aetholaelaps; another laelapid belonging to the genus Androlaelaps; the chigger mite Schoutedenichia microcebi Stekolnikov; an undescribed species of atopomelid mite in the genus Listrophoroides; and an undescribed species of psoroptid mite in the genus Cheirogalalges. Except for the 2 species of ticks and 1 species of chigger, these ectoparasites may be host-specific to M. murinus. Total tick (H. lemuris and H. simplex) infestation was significantly greater in August than October, whereas louse (L. madagascariensis) infestation was significantly greater in October. There was no significant difference in tick infestations between male and female lemurs, but male lemurs had significantly more lice than female lemurs. Reproductive status was not a significant predictor of tick infestation in males and females.

Host conservation through their parasites: molecular surveillance of vector-borne microorganisms in bats using ectoparasitic bat flies

Most vertebrates host a wide variety of haematophagous parasites, which may play an important role in the transmission of vector-borne microorganisms to hosts. Surveillance is usually performed by collecting blood and/or tissue samples from vertebrate hosts. There are multiple methods to obtain samples, which can be stored for decades if properly kept. However, blood sampling is considered an invasive method and may possibly be harmful to the sampled individual. In this study, we investigated the use of ectoparasites as a tool to acquire molecular information about the presence and diversity of infectious microorganism in host populations. We tested the presence of three distinct vector-borne microorganisms in both bat blood and bat flies: Bartonella bacteria, malaria-like Polychromophilus sp. (Apicomplexa), and Trypanosoma sp. (Kinetoplastea). We detected the presence of these microorganisms both in bats and in their bat flies, with the exception of Trypanosoma sp. in South African bat flies. Additionally, we found Bartonella sp. in bat flies from one population in Spain, suggesting its presence in the host population even if not detected in bats. Bartonella and Polychromophilus infection showed the highest prevalence in both bat and bat fly populations. Single, co- and triple infections were also frequently present in both. We highlight the use of haematophagous ectoparasites to study the presence of infectious microorganism in host blood and its use as an alternative, less invasive sampling method.

Circumpolar diversification of the Ixodes uriae tick virome

Ticks (order: Ixodida) are a highly diverse and ecologically important group of ectoparasitic blood-feeding organisms. One such species, the seabird tick (Ixodes uriae), is widely distributed around the circumpolar regions of the northern and southern hemispheres. It has been suggested that Ix. uriae spread from the southern to the northern circumpolar region millions of years ago and has remained isolated in these regions ever since. Such a profound biographic subdivision provides a unique opportunity to determine whether viruses associated with ticks exhibit the same evolutionary patterns as their hosts. To test this, we collected Ix. uriae specimens near a Gentoo penguin (Pygoscelis papua) colony at Neko harbour, Antarctica, and from migratory birds—the Razorbill (Alca torda) and the Common murre (Uria aalge)—on Bonden island, northern Sweden. Through meta-transcriptomic next-generation sequencing we identified 16 RNA viruses, seven of which were novel. Notably, we detected the same species, Ronne virus, and two closely related species, Bonden virus and Piguzov virus, in both hemispheres indicating that there have been at least two cross-circumpolar dispersal events. Similarly, we identified viruses discovered previously in other locations several decades ago, including Gadgets Gully virus, Taggert virus and Okhotskiy virus. By identifying the same or closely related viruses in geographically disjunct sampling locations we provide evidence for virus dispersal within and between the circumpolar regions. In marked contrast, our phylogenetic analysis revealed no movement of the Ix. uriae tick hosts between the same locations. Combined, these data suggest that migratory birds are responsible for the movement of viruses at both local and global scales.

As host populations diverge, so may those microorganisms, including viruses, that are dependent on those hosts. To examine this key issue in host-microbe evolution we compared the co-phylogenies of the seabird tick, Ixodes uriae, and their RNA viruses sampled from the far northern and southern hemispheres. Despite the huge geographic distance between them, phylogeographic analysis reveals that the same and closely related viruses were found both within and between the northern and southern circumpolar regions, most likely reflecting transfer by virus-infected migratory birds. In contrast, genomic data suggested that the Ix. uriae populations were phylogenetically distinct between the northern and southern hemispheres. This work emphasises the importance of migratory birds and ticks as vectors and sources of virus dispersal and introduction at both the local and global scales.

Unveiling patterns of genetic variation in parasite–host associations: an example with pinworms and Neotropical primates

Patterns of genetic variation among populations can reveal the evolutionary history of species. Pinworm parasites are highly host specific and form strong co-evolutionary associations with their primate hosts. Here, we describe the genetic variation observed in four Trypanoxyuris species infecting different howler and spider monkey subspecies in Central America to determine if historical dispersal processes and speciation in the host could explain the genetic patterns observed in the parasites. Mitochondrial (cox1) and ribosomal (28S) DNA were analysed to assess genetic divergence and phylogenetic history of these parasites. Sequences of the 28S gene were identical within pinworms species regardless of host subspecies. However, phylogenetic analyses, haplotype relationships and genetic divergence with cox1 showed differentiation between pinworm populations according to host subspecies in three of the four Trypanoxyuris species analysed. Haplotype separation between host subspecies was not observed in Trypanoxyuris minutus, nor in Trypanoxyuris atelis from Ateles geoffoyi vellerosus and Ateles geoffoyi yucatanensis. Levels of genetic diversity and divergence in these parasites relate with such estimates reported for their hosts. This study shows how genetic patterns uncovered in parasitic organisms can reflect the host phylogenetic and biogeographic histories.

Viruses as indicators of contemporary host dispersal and phylogeography: an example of feline immunodeficiency virus (FIVP le ) in free-ranging African lion (Panthera leo)

Measuring contemporary dispersal in highly mobile terrestrial species is challenging, especially when species are characterized by low levels of population differentiation. Directly transmitted viruses can be used as a surrogate for traditional methods of tracking host movement. Feline immunodeficiency virus (FIV) is a species-specific lentivirus, which has an exceptionally high mutation rate and circulates naturally in wild felids. Using samples derived from 35 lion (Panthera leo) prides, we tested the prediction that FIV in lions (FIV_{P le} ) can be used to track the dispersal of individuals between prides. As FIV_{P le} subtypes are geographically structured throughout Africa, we predicted that this marker could be used to detect phylogeographic structure of lions at smaller spatial scales. Phylogenetic analyses of FIV_{P le} pol-RT sequences showed that core pride members (females and subadults) shared evolutionary close viral lineages which differed from neighbouring core prides, whereas sequences from sexually mature males associated with the same pride were always the most divergent. In six instances, natal pride associations of divergent male lions could be inferred, on the assumption that FIV_{P le} infections are acquired during early life stages. Congruence between the genetic pattern of FIV and pride structure suggests that vertical transmission plays an important role in lion FIV dynamics. At a fine spatial scale, significant viral geographic structuring was also detected between lions occurring north of the Olifants River within the Kruger National Park (KNP) and those occupying the southern and central regions. This pattern was further supported by phylogenetic analyses and the confinement of FIV_{P le} subtype E to the northern region of KNP. The study provides new insights into the use of retroviral sequences to predict host dispersal and fine-scale contemporary geographic structure in a social felid species.

A New Species of Sucking Louse (Phthiraptera: Anoplura: Polyplacidae) From the Gray Mouse Lemur, Microcebus murinus (Primates: Cheirogaleidae), in Madagascar

Lemurpediculus madagascariensis sp. nov. (Phthiraptera: Anoplura: Polyplacidae) is described from the Gray Mouse lemur, Microcebus murinus (J. F. Miller) (Primates: Cheirogaleidae), from Ankarafantsika National Park, Madagascar. Lemurs were trapped using Sherman Live Traps and visually inspected for lice, which were preserved in 90% ethanol. Adults of both sexes and the third-instar nymph of the new species are illustrated and distinguished from the four previously known species of Lemurpediculus: L. verruculosus (Ward); L. petterorum Paulian; L. claytoni Durden, Blanco, and Seabolt; and L. robbinsi Durden, Blanco, and Seabolt. It is not known if the new species of louse is a vector of any pathogens or parasites.

Comparison of Flea (Siphonaptera) Burdens on the Endangered San Joaquin Kit Fox (Vulpes macrotis mutica (Carnivora, Canidae)) Inhabiting Urban and Nonurban Environments in Central Valley, California

The San Joaquin kit fox (Vulpes macrotis mutica Merriam (Carnivora, Canidae)) is an endangered small carnivore endemic to the San Joaquin Valley of California. Commercial and agricultural land expansion has contributed to the species' decline and invasion of more cosmopolitan species, providing means for potential ecological shifts in disease vector and host species. Fleas are common ectoparasites that can serve as important indicators of cross-species interactions and disease risk. We compared flea load and species composition on kit foxes inhabiting urban and nonurban habitats to determine how urbanization affects flea diversity and potential disease spillover from co-occurring species. We identified Echidnophaga gallinacea (Westwood) (Siphonaptera, Pulicidae) and Pulex spp. (L.) in both urban and nonurban populations, and Ctenocephalides felis (Bouche) (Siphonaptera, Pulicidae) only in the urban population. Flea load scores differed significantly across capture sites and with respect to concomitant sarcoptic mange infestation in the urban population, with milder flea infestations more typical of healthy foxes. All observed flea species are known vectors for pathogens that have been detected in mesocarnivores. Further examination of kit fox fleas and their associated pathogens will help to direct conservation and disease preventive measures for both wildlife and humans in the region.

Colonization of Parasites and Vectors

Colonization comprises the physical arrival of a species in a new area, but also its successful establishment within the local community. Oceanic islands, like the Hawaiian and the Galapagos archipelagos, represent excellent systems to study the mechanisms of colonization because of their historical isolation. In this chapter, we first review some of the major mechanisms by which parasites and vectors could arrive to an oceanic island, both naturally or due to human activities, and the factors that may influence their successful establishment in the insular host community. We then explore examples of natural and anthropogenic colonization of the Galapagos Islands by parasites and vectors, focusing on one or more case studies that best represent the diversity of colonization mechanisms that has shaped parasite distribution in the archipelago. Finally, we discuss future directions for research on parasite and vector colonization in Galapagos Islands.

Genetic diversity of Diaphorina citri and its endosymbionts across east and south-east Asia

BACKGROUND

Diaphorina citri is the vector of 'Candidatus Liberibacter asiaticus', the most widespread pathogen associated huanglongbing, the most serious disease of citrus. To enhance our understanding of the distribution and origin of the psyllid, we investigated the genetic diversity and population structures of 24 populations in Asia and one from Florida based on the mtCOI gene. Simultaneously, genetic diversity and population structures of the primary endosymbiont (P-endosymbiont) 'Candidatus Carsonella ruddii' and secondary endosymbiont (S-endosymbiont) 'Candidatus Profftella armatura' of D. citri were determined with the housekeeping genes.

RESULT

AMOVA analysis indicated that populations of D. citri and its endosymbionts in east and south-east Asia were genetically distinct from populations in Pakistan and Florida. Furthermore, P-endosymbiont populations displayed a strong geographical structure across east and south-east Asia, while low genetic diversity indicated the absence of genetic structure among the populations of D. citri and its S-endosymbiont across these regions.

CONCLUSION

The 'Ca. C. ruddii' is more diverse and structured than the D. citri and the 'Ca. P. armatura' across east and south-east Asia. Multiple introductions of the psyllid have occurred in China. Management application for controlling the pest is proposed based on the genetic information of D. citri and its endosymbionts. © 2017 Society of Chemical Industry.

Two New Species of Sucking Lice (Phthiraptera: Anoplura: Polyplacidae) From Endangered, Hibernating Lemurs (Primates: Cheirogaleidae)

Lemurpediculus robbinsi sp. nov. is described from Crossley's dwarf lemur, Cheirogaleus crossleyi A. Grandidier, and Lemurpediculus claytoni sp. nov. is described from Sibree's dwarf lemur, Cheirogaleus sibreei Forsyth Major, from Madagascar. Both sexes of each new louse species are illustrated and distinguished from the two previously known species of Lemurpediculus: L. verruculosus (Ward) and L. petterorum Paulian. With the addition of two new species to the genus, an amended description of Lemurpediculus is provided. The two hosts of the new louse species are morphologically similar, endangered, obligately hibernating lemurs. These two species of lemurs are sometimes sympatric in rainforests in eastern Madagascar. Despite the morphological similarity of the two host species, their lice are morphologically distinct and are easiest to identify based on the shape of the subgenital plate of the female and the shape of the genitalia in the male. Both new species of lice should be considered to be endangered because their hosts are endangered. It is not known if either of the new species of lice are vectors of pathogens or parasites to their hosts.

Strong phylogeographic co-structure between the anther-smut fungus and its white campion host

Although congruence between host and pathogen phylogenies has been extensively investigated, the congruence between host and pathogen genetic structures at the within-species level has received little attention. Using an unprecedented and comprehensive collection of associated plant-pathogen samples, we investigated the degree of congruence between the genetic structures across Europe of two evolutionary and ecological model organisms, the anther-smut pathogen Microbotryum lychnidis-dioicae and its host plant Silene latifolia. We demonstrated a significant and particularly strong level of host-pathogen co-structure, with three main genetic clusters displaying highly similar spatial ranges in Western Europe, Eastern Europe and Italy, respectively. Correcting for the geographical component of genetic variation, significant correlations were still found between the genetic distances of anther-smut and host populations. Inoculation experiments suggested plant local adaptation, at the cluster level, for resistance to pathogens. These findings indicate that the pathogen remained isolated in the same fragmented southern refugia as its host plant during the last glaciation, and that little long-distance dispersal has occurred since the recolonization of Europe for either the plant or the pathogen, despite their known ability to travel across continents. This, together with the inoculation results, suggests that coevolutionary and competitive processes may be drivers of host-pathogen co-structure.

Fleas and Ticks in Carnivores From a Domestic-Wildlife Interface: Implications for Public Health and Wildlife

Fleas and ticks are parasites of wild and domestic mammals, and can be vectors of several pathogens. In rural areas, domestic carnivores such as the domestic dog (Canis lupus familiaris L.), may act as a "bridge" between natural areas and human settlements where ectoparasites can be used as a metric of such link. The aim of this study was to identify fleas, ticks, and Rickettsia spp., collected from domestic and wild carnivores in a natural reserve and surrounding human settlements in Central Chile, using morphological keys and molecular analysis. We surveyed 170 households from which 107 dogs and eight cats were sampled. From the natural reserve, we sampled two chilla foxes (Pseudalopex griseus Gray), two lesser grison (Galictis cuja Molina), three kodkods (Leopardus guigna Molina), and four dogs. From dogs, we collected Ctenocephalides felis Bouché, Ctenocephalides canis Curtis, Pulex irritans L., and Rhipicephalus sanguineus s.l. Latreille; C. felis was the most frequent ectoparasite. Cats were infested only by C. felis and Rh. sanguineus s.l. From wild carnivores, we obtained C. canis and P. irritans, the latter being most frequent. Molecular analysis of P. irritans detected 10 haplotypes and two main clades, which tended to separate fleas from wild and domestic hosts. Molecular analysis of ompA and ompB genes confirmed the presence of Rickettsia felis in fleas collected from owned dogs and cats, which could represent a potential risk factor of R. felis transmission in the area.

Assessing the diversity, host-specificity and infection patterns of apicomplexan parasites in reptiles from Oman, Arabia

Understanding the processes that shape parasite diversification, their distribution and abundance provides valuable information on the dynamics and evolution of disease. In this study, we assessed the diversity, distribution, host-specificity and infection patterns of apicomplexan parasites in amphibians and reptiles from Oman, Arabia. Using a quantitative PCR approach we detected three apicomplexan parasites (haemogregarines, lankesterellids and sarcocystids). A total of 13 haemogregarine haplotypes were identified, which fell into four main clades in a phylogenetic framework. Phylogenetic analysis of six new lankesterellid haplotypes revealed that these parasites were distinct from, but phylogenetically related to, knownLankesterellaspecies and might represent new taxa. The percentage of infected hosts (prevalence) and the number of haemogregarines in the blood (parasitaemia) varied significantly between gecko species. We also found significant differences in parasitaemia between haemogregarine parasite lineages (defined by phylogenetic clustering of haplotypes), suggesting differences in host–parasite compatibility between these lineages. ForPristurus rupestris, we found significant differences in haemogregarine prevalence between geographical areas. Our results suggest that host ecology and host relatedness may influence haemogregarine distributions and, more generally, highlight the importance of screening wild hosts from remote regions to provide new insights into parasite diversity.

Testing parasite 'intimacy': the whipworm Trichuris muris in the European house mouse hybrid zone

Host‐parasite interaction studies across hybrid zones often focus on host genetic variation, treating parasites as homogeneous. ‘Intimately’ associated hosts and parasites might be expected to show similar patterns of genetic structure. In the literature, factors such as no intermediate host and no free‐living stage have been proposed as ‘intimacy’ factors likely constraining parasites to closely follow the evolutionary history of their hosts. To test whether the whipworm, Trichuris muris, is intimately associated with its house mouse host, we studied its population genetics across the European house mouse hybrid zone (HMHZ) which has a strong central barrier to gene flow between mouse taxa. T. muris has a direct life cycle and nonmobile free stage: if these traits constrain the parasite to an intimate association with its host we expect a geographic break in the parasite genetic structure across the HMHZ. We genotyped 205 worms from 56 localities across the HMHZ and additionally T. muris collected from sympatric woodmice (Apodemus spp.) and allopatric murine species, using mt‐COX1, ITS1‐5.8S‐ITS2 rDNA and 10 microsatellites. We show four haplogroups of mt‐COX1 and three clear ITS1‐5.8S‐ITS2 clades in the HMHZ suggesting a complex demographic/phylogeographic history. Microsatellites show strong structure between groups of localities. However, no marker type shows a break across the HMHZ. Whipworms from Apodemus in the HMHZ cluster, and share mitochondrial haplotypes, with those from house mice. We conclude Trichuris should not be regarded as an ‘intimate’ parasite of the house mouse: while its life history might suggest intimacy, passage through alternate hosts is sufficiently common to erase signal of genetic structure associated with any particular host taxon.

Species mtDNA genetic diversity explained by infrapopulation size in a host-symbiont system

Understanding what shapes variation in genetic diversity among species remains a major challenge in evolutionary ecology, and it has been seldom studied in parasites and other host‐symbiont systems. Here, we studied mtDNA variation in a host‐symbiont non‐model system: 418 individual feather mites from 17 feather mite species living on 17 different passerine bird species. We explored how a surrogate of census size, the median infrapopulation size (i.e., the median number of individual parasites per infected host individual), explains mtDNA genetic diversity. Feather mite species genetic diversity was positively correlated with mean infrapopulation size, explaining 34% of the variation. As expected from the biology of feather mites, we found bottleneck signatures for most of the species studied but, in particular, three species presented extremely low mtDNA diversity values given their infrapopulation size. Their star‐like haplotype networks (in contrast with more reticulated networks for the other species) suggested that their low genetic diversity was the consequence of severe bottlenecks or selective sweeps. Our study shows for the first time that mtDNA diversity can be explained by infrapopulation sizes, and suggests that departures from this relationship could be informative of underlying ecological and evolutionary processes.

Past, present and future of host-parasite co-extinctions

Human induced ecosystem alterations and climate change are expected to drive several species to extinction. In this context, the attention of public opinion, and hence conservationists' efforts, are often targeted towards species having emotional, recreational and/or economical value. This tendency may result in a high number of extinctions happening unnoticed. Among these, many could involve parasites. Several studies have highlighted various reasons why we should care about this, that go far beyond the fact that parasites are amazingly diverse. A growing corpus of evidence suggests that parasites contribute much to ecosystems both in terms of biomass and services, and the seemingly paradoxical idea that a healthy ecosystem is one rich in parasites is becoming key to the whole concept of parasite conservation. Although various articles have covered different aspects of host-parasite co-extinctions, I feel that some important conceptual issues still need to be formally addressed. In this review, I will attempt at clarifying some of them, with the aim of providing researchers with a unifying conceptual framework that could help them designing future studies. In doing this, I will try to draw a more clear distinction between the (co-)evolutionary and the ecological dimensions of co-extinction studies, since the ongoing processes that are putting parasites at risk now operate at a scale that is extremely different from the one that has shaped host-parasite networks throughout million years of co-evolution. Moreover, I will emphasize how the complexity of direct and indirect effects of parasites on ecosystems makes it much challenging to identify the mechanisms possibly leading to co-extinction events, and to predict how such events will affect ecosystems in the long run.

Lineage sorting in multihost parasites: Eidmanniella albescens and Fregatiella aurifasciata on seabirds from the Galapagos Islands

Parasites comprise a significant percentage of the biodiversity of the planet and are useful systems to test evolutionary and ecological hypotheses. In this study, we analyze the effect of host species identity and the immediate local species assemblage within mixed species colonies of nesting seabirds on patterns of genetic clustering within two species of multihost ectoparasitic lice. We use three genetic markers (one mitochondrial, COI, and two nuclear, EF1-α and wingless) and maximum likelihood phylogenetic trees to test whether (1) parasites show lineage sorting based on their host species; and (2) switching of lineages to the alternate host species depends on the immediate local species assemblage of individual hosts within a colony. Specifically, we examine the genetic structure of two louse species: Eidmanniella albescens, infecting both Nazca (Sula granti) and blue-footed boobies (Sula nebouxii), and Fregatiella aurifasciata, infecting both great (Fregata minor) and magnificent frigatebirds (Fregata magnificens). We found that host species identity was the only factor explaining the patterns of genetic structure in both parasites. In both cases, there is evident genetic differentiation depending on the host species. Thus, a revision of the taxonomy of these louse species is needed. One possible explanation of this pattern is extremely low louse migration rates between host species, perhaps influenced by fine-scale spatial separation of host species within mixed colonies, and low parasite infrapopulation numbers.

Potential merger of ancient lineages in a passerine bird discovered based on evidence from host-specific ectoparasites

The merger of formerly isolated lineages is hypothesized to occur in vertebrates under certain conditions. However, despite many demonstrated instances of introgression between taxa in secondary contact, examples of lineage mergers are rare. Preliminary mtDNA sequencing of a Malagasy passerine, Xanthomixis zosterops (Passeriformes: Bernieridae), indicated a possible instance of merging lineages. We tested the hypothesis that X. zosterops lineages are merging by comparing mtDNA sequence and microsatellite data, as well as mtDNA sequence data from host-specific feather lice in the genus Myrsidea (Phthiraptera: Menoponidae). Xanthomixis zosterops comprises four deeply divergent, broadly sympatric, cryptic mtDNA clades that likely began diverging approximately 3.6 million years ago. Despite this level of divergence, the microsatellite data indicate that the X. zosterops mtDNA clades are virtually panmictic. Three major phylogroups of Myrsidea were found, supporting previous allopatry of the X. zosterops clades. In combination, the datasets from X. zosterops and its Myrsidea document a potential merger of previously allopatric lineages that likely date to the Pliocene. This represents the first report of sympatric apparent hybridization among more than two terrestrial vertebrate lineages. Further, the mtDNA phylogeographic pattern of X. zosterops, namely the syntopy of more than two deeply divergent cryptic clades, appears to be a novel scenario among vertebrates. We highlight the value of gathering multiple types of data in phylogeographic studies to contribute to the study of vertebrate speciation.

The Chewing Lice (Insecta: Phthiraptera: Ischnocera: Amblycera) of Japanese Pigeons and Doves (Columbiformes), with Descriptions of Three New Species

The chewing louse fauna of pigeons and doves in Japan is reviewed based on published records and new collections. An updated checklist of the chewing lice of Japanese pigeons and doves is provided, and 3 new species are described: Columbicola asukae n. sp. and Coloceras nakamurai n. sp., both from Columba janthina Temminck, 1830 (Japanese wood pigeon), and Columbicola lemoinei n. sp. from Treron formosae permagnus Stejneger, 1887, and Treron formosae medioximus (Bangs, 1901) (whistling green-pigeons). This checklist includes data on the first records of Coloceras chinense (Kellogg and Chapman, 1902), Coloceras piriformis ( Tendeiro, 1969 ), and Columbicola guimaraesi Tendeiro, 1965, in Japan. New host records of Hohorstiella sp. from Columba janthina and Treron formosae permagnus, and Coloceras sp. from Treron sieboldii sieboldii (Temminck, 1835) (white-bellied green-pigeon) are provided.

Shared phylogeographic patterns between the ectocommensal flatworm Temnosewellia albata and its host, the endangered freshwater crayfish Euastacus robertsi

Comparative phylogeography of commensal species may show congruent patterns where the species involved share a common history. Temnosewellia is a genus of flatworms, members of which live in commensal relationships with host freshwater crustaceans. By constructing phylogenetic trees based on mitochondrial COI and 28S nuclear ribosomal gene sequences, this study investigated how evolutionary history has shaped patterns of intraspecific molecular variation in two such freshwater commensals. This study concentrates on the flatworm Temnosewellia albata and its critically endangered crayfish host Euastacus robertsi, which have a narrow climatically-restricted distribution on three mountaintops. The genetic data expands upon previous studies of Euastacus that suggested several vicariance events have led to the population subdivision of Euastacus robertsi. Further, our study compared historical phylogeographic patterning of these species. Our results showed that phylogeographic patterns shared among these commensals were largely congruent, featuring a shared history of limited dispersal between the mountaintops. Several hypotheses were proposed to explain the phylogeographic points of differences between the species. This study contributes significantly to understanding evolutionary relationships of commensal freshwater taxa.

Co-extinct and critically co-endangered species of parasitic lice, and conservation-induced extinction: should lice be reintroduced to their hosts?

The co-extinction of parasitic taxa and their host species is considered a common phenomenon in the current global extinction crisis. However, information about the conservation status of parasitic taxa is scarce. We present a global list of co-extinct and critically co-endangered parasitic lice (Phthiraptera), based on published data on their host-specificity and their hosts’ conservation status according to the IUCN Red List. We list six co-extinct and 40 (possibly 41) critically co-endangered species. Additionally, we recognize 2–4 species that went extinct as a result of conservation efforts to save their hosts. Conservationists should consider preserving host-specific lice as part of their efforts to save species.

Integrating Anisakis spp. parasites data and host genetic structure in the frame of a holistic approach for stock identification of selected Mediterranean Sea fish species

The unique environment of the Mediterranean Sea makes fish stock assessment a major challenge. Stock identification of Mediterranean fisheries has been based mostly from data on biology, morphometrics, artificial tags, otolith shape and fish genetics, with less effort on the use of parasites as biomarkers. Here we use some case studies comparing Mediterranean vs Atlantic fish stocks in a multidisciplinary framework. The generalized Procrustes Rotation (PR) was used to assess the association between host genetics and larval Anisakis spp. datasets on demersal (hake) and pelagic (horse mackerel, swordfish) species. When discordant results emerged, they were due to the different features of the data. While fish population genetics can detect changes over an evolutionary timescale, providing indications on the cohesive action of gene flow, parasites are more suitable biomarkers when considering fish stocks over smaller temporal and spatial scales, hence giving information of fish movements over their lifespan. Future studies on the phylogeographic analysis of parasites suitable as biomarkers, and that of their fish host, performed on the same genes, will represent a further tool to be included in multidisciplinary studies on fish stock structure.

The ethical dimensions of wildlife disease management in an evolutionary context

Best practices in wildlife disease management require robust evolutionary ecological research (EER). This means not only basing management decisions on evolutionarily sound reasoning, but also conducting management in a way that actively contributes to the on-going development of that research. Because good management requires good science, and good science is 'good' science (i.e., effective science is often science conducted ethically), good management therefore also requires practices that accord with sound ethical reasoning. To that end, we propose a two-part framework to assist decision makers to identify ethical pitfalls of wildlife disease management. The first part consists of six values - freedom, fairness, well-being, replacement, reduction, and refinement; these values, developed for the ethical evaluation of EER practices, are also well suited for evaluating the ethics of wildlife disease management. The second part consists of a decision tree to help identify the ethically salient dimensions of wildlife disease management and to guide managers toward ethically responsible practices in complex situations. While ethical reasoning cannot be used to deduce from first principles what practices should be undertaken in every given set of circumstances, it can establish parameters that bound what sorts of practices will be acceptable or unacceptable in certain types of scenarios.

First records of chewing lice (Phthiraptera: Menoponidae) in Pacific migratory shorebirds wintering in Ecuador

Chewing lice were collected from small shorebirds (Charadriformes: Scolopacidae) overwintering in foraging grounds of coastal Ecuador. On 27 occasions at least one louse (3.7%) was collected from six host species. Based on external morphological characters, at least two species of chewing lice could be preliminary identified (family: Menoponidae), including Actornithophilus umbrinus (Burmeister, 1842) and Austromenopon sp. A. umbrinus was found in the Western Sandpiper (Calidris mauri), Least Sandpiper (C. minutilla), Stilt Sandpiper (C. himantopus), Semipalmated Plover (Charadrius semipalmatus) and Wilson's phalarope (Phalaropus tricolor), while Austromenopon sp. is presumably the first record collected from the Surfbird (Aphriza virgata). These findings indicate that the distribution of these chewing lice species covers at least the regions around the equator (latitude 0°) until the Arctic in the north, but probably also includes the entire winter distribution area of the host species. This is the first study of chewing lice from Ecuador's mainland coast and more research is required to understand the host-parasite ecology and ectoparasitic infection in shorebirds stopping over the region.

Evidence of cryptic speciation in mesostigmatid mites from South Africa

Laelaps giganteus and Laelaps muricola (Mesostigmata; Laelapidae) are widespread and locally abundant host generalists on small mammals in southern Africa. The large host range and complex life history of these ectoparasites may allude to possible intraspecific cryptic diversity in these taxa. To assess genetic and morphological diversity in L. giganteus and L. muricola, we sampled 228 rodents at eight localities in South Africa. This sample included nine previously recorded host species and on these, L. muricola was only recorded from Mastomys natalensis and Micaelamys namaquensis while L. giganteus was found on Rhabdomys dilectus and Lemniscomys rosalia. Phylogenetic analyses of partial mtDNA cytochrome oxidase subunit I (COI) and nuclear ITS1 data strongly supported the recognition of L. giganteus and L. muricola, a scenario partly supported by the Tropomyosin intron. Strong support for evolutionary distinct lineages within L. giganteus is found: L. giganteus lineage 1 is confined to R. dilectus and L. giganteus lineage 2 is confined to L. rosalia. These host specific monophyletic lineages were also separated by 9.84% mtDNA sequence divergence and 3.44% nuclear DNA sequence divergence. Since quantitative morphometric analyses were not congruent with these findings, these two lineages more than likely represent cryptic species.

A review of molecular approaches for investigating patterns of coevolution in marine host-parasite relationships

Parasites and their relationships with hosts play a crucial role in the evolutionary pathways of every living organism. One method of investigating host-parasite systems is using a molecular approach. This is particularly important as analyses based solely on morphology or laboratory studies of parasites and their hosts do not take into account historical evolutionary interactions that can shape the distribution, abundance and population structure of parasites and their hosts. However, the predominant host-parasite coevolution literature has focused on terrestrial hosts and their parasites, and there still is a lack of studies in marine environments. Given that marine systems are generally more open than terrestrial ones, they provide fascinating opportunities for large-scale (as well as small-scale) geographic studies. Further, patterns and processes of genetic structuring and systematics are becoming more available across many different taxa (but especially fishes) in many marine systems, providing an excellent basis for examining whether parasites follow host population/species structure. In this chapter, we first highlight the factors and processes that challenge our ability to interpret evolutionary patterns of coevolution of hosts and their parasites in marine systems at different spatial, temporal and taxonomic scales. We then review the use of the most commonly utilized genetic markers in studying marine host-parasite systems. We give an overview and discuss which molecular methodologies resolve evolutionary relationships best and also discuss the applicability of new approaches, such as next-generation sequencing and studies utilizing functional markers to gain insights into more contemporary processes shaping host-parasite relationships.