Proceedings of the National Academy of Sciences, 2019
Recently, the World Health Organization recognized that efforts to interrupt schistosomiasis tran... more Recently, the World Health Organization recognized that efforts to interrupt schistosomiasis transmission through mass drug administration have been ineffective in some regions; one of their new recommended strategies for global schistosomiasis control emphasizes targeting the freshwater snails that transmit schistosome parasites. We sought to identify robust indicators that would enable precision targeting of these snails. At the site of the world’s largest recorded schistosomiasis epidemic—the Lower Senegal River Basin in Senegal—intensive sampling revealed positive relationships between intermediate host snails (abundance, density, and prevalence) and human urogenital schistosomiasis reinfection (prevalence and intensity in schoolchildren after drug administration). However, we also found that snail distributions were so patchy in space and time that obtaining useful data required effort that exceeds what is feasible in standard monitoring and control campaigns. Instead, we ident...
Here, we present the results of a taxonomic survey of the nematodes parasitizing fishes from the ... more Here, we present the results of a taxonomic survey of the nematodes parasitizing fishes from the lagoon flats of Palmyra Atoll, Eastern Indo-Pacific. We performed quantitative parasitological surveys of 653 individual fish from each of the 44 species using the intertidal sand flats that border the atoll’s lagoon. We provide morphological descriptions, prevalence, and mean intensities of the recovered seven species of adult nematode (Pulchrascaris chiloscyllii, Capillariidae gen. sp.,Cucullanus bourdini,Cucullanus oceaniensis,Pseudascarophissp., Spinitectus (Paraspinitectus) palmyraensissp. nov.,Philometra pellucida) and three larval stages (Pulchrascarissp.,Hysterothylaciumsp.,Cucullanussp.). We recorded:Pulchrascaris chiloscylliifromCarcharhinus melanopterus; Capillariidae gen. sp. fromChaetodon lunula,Lutjanus fulvus, andEllochelon vaigiensis;Cucullanus bourdinifromArothron hispidus;Cucullanus oceaniensisfromAbudefduf sordidus;Pseudascarophissp. fromChaetodon auriga,Chaetodon lunu...
Schistosome parasites infect more than 200 million people annually, mostly in sub-Saharan Africa,... more Schistosome parasites infect more than 200 million people annually, mostly in sub-Saharan Africa, where people may be co-infected with more than one species of the parasite. Infection risk for any single species is determined, in part, by the distribution of its obligate intermediate host snail. As the World Health Organization reprioritizes snail control to reduce the global burden of schistosomiasis, there is renewed importance in knowing when and where to target those efforts, which could vary by schistosome species. This study estimates factors associated with schistosomiasis risk in 16 villages located in the Senegal River Basin, a region hyperendemic for Schistosoma haematobium and S. mansoni. We first analyzed the spatial distributions of the two schistosomes’ intermediate host snails (Bulinus spp. and Biomphalaria pfeifferi, respectively) at village water access sites. Then, we separately evaluated the relationships between human S. haematobium and S. mansoni infections and ...
Proceedings of the Royal Society B: Biological Sciences
Dicyemids and orthonectids were traditionally classified in a group called Mesozoa, but their pla... more Dicyemids and orthonectids were traditionally classified in a group called Mesozoa, but their placement in a single clade has been contested and their position(s) within Metazoa is uncertain. Here, we assembled a comprehensive matrix of Lophotrochozoa (Metazoa) and investigated the position of Dicyemida (= Rhombozoa) and Orthonectida, employing multiple phylogenomic approaches. We sequenced seven new transcriptomes and one draft genome from dicyemids ( Dicyema , Dicyemennea ) and two transcriptomes from orthonectids ( Rhopalura ). Using these and published data, we assembled and analysed contamination-filtered datasets with up to 987 genes. Our results recover Mesozoa monophyletic and as a close relative of Platyhelminthes or Gnathifera. Because of the tendency of the long-branch mesozoans to group with other long-branch taxa in our analyses, we explored the impact of approaches purported to help alleviate long-branch attraction (e.g. taxon removal, coalescent inference, gene target...
Crustacea and Arthropod Relationships, Apr 27, 2005
Plate 1.[See Figure 2 in Hrycaj & Popadiü.](A) A diagram depicting mandibular composition (whole ... more Plate 1.[See Figure 2 in Hrycaj & Popadiü.](A) A diagram depicting mandibular composition (whole limb versus limb base only).(B) Dissected adult mandibles of the pillbug, Armadillidium vulgare.(C) Dissected adult mandibles of the firebrat, Thermobia domestica. In B and C, arrowheads point to dissected mandibular appendages.
Proceedings of The Royal Society B: Biological Sciences, Jul 6, 2022
Dicyemids and orthonectids were traditionally classified in a group called Mesozoa, but their pla... more Dicyemids and orthonectids were traditionally classified in a group called Mesozoa, but their placement in a single clade has been contested and their position(s) within Metazoa is uncertain. Here, we assembled a comprehensive matrix of Lophotrochozoa (Metazoa) and investigated the position of Dicyemida (= Rhombozoa) and Orthonectida, employing multiple phylogenomic approaches. We sequenced seven new transcriptomes and one draft genome from dicyemids ( Dicyema , Dicyemennea ) and two transcriptomes from orthonectids ( Rhopalura ). Using these and published data, we assembled and analysed contamination-filtered datasets with up to 987 genes. Our results recover Mesozoa monophyletic and as a close relative of Platyhelminthes or Gnathifera. Because of the tendency of the long-branch mesozoans to group with other long-branch taxa in our analyses, we explored the impact of approaches purported to help alleviate long-branch attraction (e.g. taxon removal, coalescent inference, gene targeting). None of these were able to break the association of Orthonectida with Dicyemida in the maximum-likelihood trees. Contrastingly, the Bayesian analysis and site-specific frequency model in maximum-likelihood did not recover a monophyletic Mesozoa (but only when using a specific 50 gene matrix). The classic hypothesis on monophyletic Mesozoa is possibly reborn and should be further tested.
The parasitic barnacles, Rhizocephala, are a little known group within Australia with only seven ... more The parasitic barnacles, Rhizocephala, are a little known group within Australia with only seven described species from a coastline stretching approximately 59763 km. This study describes a new species of Rhizocephala, Sacculina nectocarcini. The description is based on a unique combination of features pertaining to the structure of the mantle papillae, the retinaculae and the male receptacles. Biological notes, prevalence and intensity of infection are reported for this rhizocephalan, infesting the red rock crab, Nectocarcinus integrifrons, collected from Western Port, Victoria, Australia.
We surveyed copepods parasitic on the fishes at Palmyra, a remote atoll in the Central Indo-Pacif... more We surveyed copepods parasitic on the fishes at Palmyra, a remote atoll in the Central Indo-Pacific faunal region. In total, we collected 849 individual fish, representing 44 species, from the intertidal lagoon flats at Palmyra and recovered 17 parasitic copepod species. The parasitic copepods were:OrbitacolaxwilliamsionMulloidichthysflavolineatus;AnuretesserratusonAcanthurusxanthopterus;CaligusconfususonCarangoidesferdau,Carangoidesorthogrammus,Caranxignobilis,Caranxmelampygus, andCaranxpapuensis;CaliguskapuhilionChaetodonaurigaandChaetodonlunula;CaliguslaticaudusonRhinecanthusaculeatus,Pseudobalistesflavimarginatus,M.flavolineatus,Upeneustaeniopterus,Chrysipteraglauca, andEpinephalusmerra;CaligusmutabilisonLutjanusfulvusandLutjanusmonostigma;CaligusrandallionC.ignobilis;Caligussp. onL.fulvus;CaritusserratusonChanoschanos;LepeophtheiruslewisionA.xanthopterus;LepeophtheirusuluusonC.ignobilis;DissonussimilisonArothronhispidus;Nemesissp. onCarcharhinusmelanopterus;Hatschekialongiabdom...
AimTo improve our understanding of how parasitism interacts with geographical range expansions by... more AimTo improve our understanding of how parasitism interacts with geographical range expansions by quantifying diversity and abundance of parasites in 25 populations of a large marine snail, Kellet's whelk (Kelletia kelletii), throughout its historical and recently expanded range, which are separated by a well‐known biogeographical boundary.LocationCalifornia coast (western North America).MethodsParasitological examinations were conducted on 199 whelks from 25 subtidal reefs throughout its expanded and historical ranges. We calculated infection risk, parasite intensity, and parasite species diversity. Abiotic (temperature, latitude, distance from range limit) and biotic (host density) variables were analysed as potential drivers of differential parasitism between expanded‐ and historical‐range populations.ResultsCompared with historical‐range whelks, expanded‐range whelks were 20% as likely to be infected by parasites, and those that were infected had 6% the number of individual ...
Amphipods are often key species in aquatic food webs due to their functional roles in the ecosyst... more Amphipods are often key species in aquatic food webs due to their functional roles in the ecosystem and as intermediate hosts for trophically transmitted parasites. Amphipods can also host many parasite species, yet few studies address the entire parasite community of a gammarid population, precluding a more dynamic understanding of the food web. We set out to identify and quantify the parasite community of Gammarus lacustris to understand the contributions of the amphipod and its parasites to the Takvatn food web. We identified seven parasite taxa: a direct life cycle gregarine, Rotundula sp., and larval stages of two digenean trematode genera, two cestodes, one nematode, and one acanthocephalan. The larval parasites use either birds or fishes as final hosts. Bird parasites predominated, with trematode Plagiorchis sp. having the highest prevalence (69%) and mean abundance (2.7). Fish parasites were also common, including trematodes Crepidostomum spp., nematode Cystidicola farionis,...
Introduced marine species are a major environmental and economic problem. The rate of these biolo... more Introduced marine species are a major environmental and economic problem. The rate of these biological invasions has substantially increased in recent years due to the globalization of the world's economies. The damage caused by invasive species is often a result of the higher densities and larger sizes they attain compared to where they are native. A prominent hypothesis explaining the success of introduced species is that they are relatively free of the effects of natural enemies. Most notably, they may encounter fewer parasites in their introduced range compared to their native range. Parasites are ubiquitous and pervasive in marine systems, yet their role in marine invasions is relatively unexplored. Although data on parasites of marine organisms exist, the extent to which parasites can mediate marine invasions, or the extent to which invasive parasites and pathogens are responsible for infecting or potentially decimating native marine species have not been examined. In this...
Proceedings of the Royal Society B: Biological Sciences, 2010
In some of the most complex animal societies, individuals exhibit a cooperative division of labou... more In some of the most complex animal societies, individuals exhibit a cooperative division of labour to form castes. The most pronounced types of caste formation involve reproductive and non-reproductive forms that are morphologically distinct. In colonies comprising separate or mobile individuals, this type of caste formation has been recognized only among the arthropods, sea anemones and mole-rats. Here, we document physical and behavioural caste formation in a flatworm. Trematode flatworm parasites undergo repeated clonal reproduction of ‘parthenitae’ within their molluscan hosts forming colonies. We present experimental and observational data demonstrating specialization among trematode parthenitae to form distinct soldier and reproductive castes. Soldiers do not reproduce, have relatively large mouthparts, and are much smaller and thinner than reproductives. Soldiers are also more active, and are disproportionally common in areas of the host where invasions occur. Further, only s...
This experiment, the last we ran under California Sea Grant project number R/CZ-162, was designed... more This experiment, the last we ran under California Sea Grant project number R/CZ-162, was designed to test the settlement preferences of S. carcini under more natural conditions than in our previous experiments, which utilized 0.5 L containers and cyprid densities ranging from 1-75 cyprids ml-1 (see Goddard et al. 2005). Mark Torchin designed the experiment and set up the exposure containers, which were nested in a flow-through system (with filtered outflow); Jeff Goddard and Mark Torchin examined crabs for cyprid settlement; Jeff Goddard dissected and examined crabs for infection by S. carcini.
We apply a Dynamic Energy Budget model to the common liver fluke (Fasciola hepatica), as well as ... more We apply a Dynamic Energy Budget model to the common liver fluke (Fasciola hepatica), as well as its intermediate and final hosts. First, an introduction to the DEB theory is given. We divide the fluke's seven-stage life cycle into three phases and construct an independent model for each. We link DEB variables to measurable quantities like weight, glycogen content, and oxygen consumption, then find model parameters that match predictions to data from existing studies. We compare the present model to existing ...
Proceedings of the National Academy of Sciences, 2019
Recently, the World Health Organization recognized that efforts to interrupt schistosomiasis tran... more Recently, the World Health Organization recognized that efforts to interrupt schistosomiasis transmission through mass drug administration have been ineffective in some regions; one of their new recommended strategies for global schistosomiasis control emphasizes targeting the freshwater snails that transmit schistosome parasites. We sought to identify robust indicators that would enable precision targeting of these snails. At the site of the world’s largest recorded schistosomiasis epidemic—the Lower Senegal River Basin in Senegal—intensive sampling revealed positive relationships between intermediate host snails (abundance, density, and prevalence) and human urogenital schistosomiasis reinfection (prevalence and intensity in schoolchildren after drug administration). However, we also found that snail distributions were so patchy in space and time that obtaining useful data required effort that exceeds what is feasible in standard monitoring and control campaigns. Instead, we ident...
Here, we present the results of a taxonomic survey of the nematodes parasitizing fishes from the ... more Here, we present the results of a taxonomic survey of the nematodes parasitizing fishes from the lagoon flats of Palmyra Atoll, Eastern Indo-Pacific. We performed quantitative parasitological surveys of 653 individual fish from each of the 44 species using the intertidal sand flats that border the atoll’s lagoon. We provide morphological descriptions, prevalence, and mean intensities of the recovered seven species of adult nematode (Pulchrascaris chiloscyllii, Capillariidae gen. sp.,Cucullanus bourdini,Cucullanus oceaniensis,Pseudascarophissp., Spinitectus (Paraspinitectus) palmyraensissp. nov.,Philometra pellucida) and three larval stages (Pulchrascarissp.,Hysterothylaciumsp.,Cucullanussp.). We recorded:Pulchrascaris chiloscylliifromCarcharhinus melanopterus; Capillariidae gen. sp. fromChaetodon lunula,Lutjanus fulvus, andEllochelon vaigiensis;Cucullanus bourdinifromArothron hispidus;Cucullanus oceaniensisfromAbudefduf sordidus;Pseudascarophissp. fromChaetodon auriga,Chaetodon lunu...
Schistosome parasites infect more than 200 million people annually, mostly in sub-Saharan Africa,... more Schistosome parasites infect more than 200 million people annually, mostly in sub-Saharan Africa, where people may be co-infected with more than one species of the parasite. Infection risk for any single species is determined, in part, by the distribution of its obligate intermediate host snail. As the World Health Organization reprioritizes snail control to reduce the global burden of schistosomiasis, there is renewed importance in knowing when and where to target those efforts, which could vary by schistosome species. This study estimates factors associated with schistosomiasis risk in 16 villages located in the Senegal River Basin, a region hyperendemic for Schistosoma haematobium and S. mansoni. We first analyzed the spatial distributions of the two schistosomes’ intermediate host snails (Bulinus spp. and Biomphalaria pfeifferi, respectively) at village water access sites. Then, we separately evaluated the relationships between human S. haematobium and S. mansoni infections and ...
Proceedings of the Royal Society B: Biological Sciences
Dicyemids and orthonectids were traditionally classified in a group called Mesozoa, but their pla... more Dicyemids and orthonectids were traditionally classified in a group called Mesozoa, but their placement in a single clade has been contested and their position(s) within Metazoa is uncertain. Here, we assembled a comprehensive matrix of Lophotrochozoa (Metazoa) and investigated the position of Dicyemida (= Rhombozoa) and Orthonectida, employing multiple phylogenomic approaches. We sequenced seven new transcriptomes and one draft genome from dicyemids ( Dicyema , Dicyemennea ) and two transcriptomes from orthonectids ( Rhopalura ). Using these and published data, we assembled and analysed contamination-filtered datasets with up to 987 genes. Our results recover Mesozoa monophyletic and as a close relative of Platyhelminthes or Gnathifera. Because of the tendency of the long-branch mesozoans to group with other long-branch taxa in our analyses, we explored the impact of approaches purported to help alleviate long-branch attraction (e.g. taxon removal, coalescent inference, gene target...
Crustacea and Arthropod Relationships, Apr 27, 2005
Plate 1.[See Figure 2 in Hrycaj & Popadiü.](A) A diagram depicting mandibular composition (whole ... more Plate 1.[See Figure 2 in Hrycaj & Popadiü.](A) A diagram depicting mandibular composition (whole limb versus limb base only).(B) Dissected adult mandibles of the pillbug, Armadillidium vulgare.(C) Dissected adult mandibles of the firebrat, Thermobia domestica. In B and C, arrowheads point to dissected mandibular appendages.
Proceedings of The Royal Society B: Biological Sciences, Jul 6, 2022
Dicyemids and orthonectids were traditionally classified in a group called Mesozoa, but their pla... more Dicyemids and orthonectids were traditionally classified in a group called Mesozoa, but their placement in a single clade has been contested and their position(s) within Metazoa is uncertain. Here, we assembled a comprehensive matrix of Lophotrochozoa (Metazoa) and investigated the position of Dicyemida (= Rhombozoa) and Orthonectida, employing multiple phylogenomic approaches. We sequenced seven new transcriptomes and one draft genome from dicyemids ( Dicyema , Dicyemennea ) and two transcriptomes from orthonectids ( Rhopalura ). Using these and published data, we assembled and analysed contamination-filtered datasets with up to 987 genes. Our results recover Mesozoa monophyletic and as a close relative of Platyhelminthes or Gnathifera. Because of the tendency of the long-branch mesozoans to group with other long-branch taxa in our analyses, we explored the impact of approaches purported to help alleviate long-branch attraction (e.g. taxon removal, coalescent inference, gene targeting). None of these were able to break the association of Orthonectida with Dicyemida in the maximum-likelihood trees. Contrastingly, the Bayesian analysis and site-specific frequency model in maximum-likelihood did not recover a monophyletic Mesozoa (but only when using a specific 50 gene matrix). The classic hypothesis on monophyletic Mesozoa is possibly reborn and should be further tested.
The parasitic barnacles, Rhizocephala, are a little known group within Australia with only seven ... more The parasitic barnacles, Rhizocephala, are a little known group within Australia with only seven described species from a coastline stretching approximately 59763 km. This study describes a new species of Rhizocephala, Sacculina nectocarcini. The description is based on a unique combination of features pertaining to the structure of the mantle papillae, the retinaculae and the male receptacles. Biological notes, prevalence and intensity of infection are reported for this rhizocephalan, infesting the red rock crab, Nectocarcinus integrifrons, collected from Western Port, Victoria, Australia.
We surveyed copepods parasitic on the fishes at Palmyra, a remote atoll in the Central Indo-Pacif... more We surveyed copepods parasitic on the fishes at Palmyra, a remote atoll in the Central Indo-Pacific faunal region. In total, we collected 849 individual fish, representing 44 species, from the intertidal lagoon flats at Palmyra and recovered 17 parasitic copepod species. The parasitic copepods were:OrbitacolaxwilliamsionMulloidichthysflavolineatus;AnuretesserratusonAcanthurusxanthopterus;CaligusconfususonCarangoidesferdau,Carangoidesorthogrammus,Caranxignobilis,Caranxmelampygus, andCaranxpapuensis;CaliguskapuhilionChaetodonaurigaandChaetodonlunula;CaliguslaticaudusonRhinecanthusaculeatus,Pseudobalistesflavimarginatus,M.flavolineatus,Upeneustaeniopterus,Chrysipteraglauca, andEpinephalusmerra;CaligusmutabilisonLutjanusfulvusandLutjanusmonostigma;CaligusrandallionC.ignobilis;Caligussp. onL.fulvus;CaritusserratusonChanoschanos;LepeophtheiruslewisionA.xanthopterus;LepeophtheirusuluusonC.ignobilis;DissonussimilisonArothronhispidus;Nemesissp. onCarcharhinusmelanopterus;Hatschekialongiabdom...
AimTo improve our understanding of how parasitism interacts with geographical range expansions by... more AimTo improve our understanding of how parasitism interacts with geographical range expansions by quantifying diversity and abundance of parasites in 25 populations of a large marine snail, Kellet's whelk (Kelletia kelletii), throughout its historical and recently expanded range, which are separated by a well‐known biogeographical boundary.LocationCalifornia coast (western North America).MethodsParasitological examinations were conducted on 199 whelks from 25 subtidal reefs throughout its expanded and historical ranges. We calculated infection risk, parasite intensity, and parasite species diversity. Abiotic (temperature, latitude, distance from range limit) and biotic (host density) variables were analysed as potential drivers of differential parasitism between expanded‐ and historical‐range populations.ResultsCompared with historical‐range whelks, expanded‐range whelks were 20% as likely to be infected by parasites, and those that were infected had 6% the number of individual ...
Amphipods are often key species in aquatic food webs due to their functional roles in the ecosyst... more Amphipods are often key species in aquatic food webs due to their functional roles in the ecosystem and as intermediate hosts for trophically transmitted parasites. Amphipods can also host many parasite species, yet few studies address the entire parasite community of a gammarid population, precluding a more dynamic understanding of the food web. We set out to identify and quantify the parasite community of Gammarus lacustris to understand the contributions of the amphipod and its parasites to the Takvatn food web. We identified seven parasite taxa: a direct life cycle gregarine, Rotundula sp., and larval stages of two digenean trematode genera, two cestodes, one nematode, and one acanthocephalan. The larval parasites use either birds or fishes as final hosts. Bird parasites predominated, with trematode Plagiorchis sp. having the highest prevalence (69%) and mean abundance (2.7). Fish parasites were also common, including trematodes Crepidostomum spp., nematode Cystidicola farionis,...
Introduced marine species are a major environmental and economic problem. The rate of these biolo... more Introduced marine species are a major environmental and economic problem. The rate of these biological invasions has substantially increased in recent years due to the globalization of the world's economies. The damage caused by invasive species is often a result of the higher densities and larger sizes they attain compared to where they are native. A prominent hypothesis explaining the success of introduced species is that they are relatively free of the effects of natural enemies. Most notably, they may encounter fewer parasites in their introduced range compared to their native range. Parasites are ubiquitous and pervasive in marine systems, yet their role in marine invasions is relatively unexplored. Although data on parasites of marine organisms exist, the extent to which parasites can mediate marine invasions, or the extent to which invasive parasites and pathogens are responsible for infecting or potentially decimating native marine species have not been examined. In this...
Proceedings of the Royal Society B: Biological Sciences, 2010
In some of the most complex animal societies, individuals exhibit a cooperative division of labou... more In some of the most complex animal societies, individuals exhibit a cooperative division of labour to form castes. The most pronounced types of caste formation involve reproductive and non-reproductive forms that are morphologically distinct. In colonies comprising separate or mobile individuals, this type of caste formation has been recognized only among the arthropods, sea anemones and mole-rats. Here, we document physical and behavioural caste formation in a flatworm. Trematode flatworm parasites undergo repeated clonal reproduction of ‘parthenitae’ within their molluscan hosts forming colonies. We present experimental and observational data demonstrating specialization among trematode parthenitae to form distinct soldier and reproductive castes. Soldiers do not reproduce, have relatively large mouthparts, and are much smaller and thinner than reproductives. Soldiers are also more active, and are disproportionally common in areas of the host where invasions occur. Further, only s...
This experiment, the last we ran under California Sea Grant project number R/CZ-162, was designed... more This experiment, the last we ran under California Sea Grant project number R/CZ-162, was designed to test the settlement preferences of S. carcini under more natural conditions than in our previous experiments, which utilized 0.5 L containers and cyprid densities ranging from 1-75 cyprids ml-1 (see Goddard et al. 2005). Mark Torchin designed the experiment and set up the exposure containers, which were nested in a flow-through system (with filtered outflow); Jeff Goddard and Mark Torchin examined crabs for cyprid settlement; Jeff Goddard dissected and examined crabs for infection by S. carcini.
We apply a Dynamic Energy Budget model to the common liver fluke (Fasciola hepatica), as well as ... more We apply a Dynamic Energy Budget model to the common liver fluke (Fasciola hepatica), as well as its intermediate and final hosts. First, an introduction to the DEB theory is given. We divide the fluke's seven-stage life cycle into three phases and construct an independent model for each. We link DEB variables to measurable quantities like weight, glycogen content, and oxygen consumption, then find model parameters that match predictions to data from existing studies. We compare the present model to existing ...
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Papers by A. Kuris