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Goodnight SR, Blakeslee AM, McCoy MW. Genetic diversity and population structure of parasite infrapopulations within and across hosts for two trophically transmitted trematode parasites. PeerJ 2025; 13:e19178. [PMID: 40313383 PMCID: PMC12045269 DOI: 10.7717/peerj.19178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2024] [Accepted: 02/25/2025] [Indexed: 05/03/2025] Open
Abstract
Complex parasite life cycles frequently require trophic transfer of parasites from an intermediate host prey to a definitive host predator. This results in aggregated distributions of parasites in predator host populations, which are subsequently expected to host more genetically diverse parasite infrapopulations than lower trophic level hosts. Host dispersal and seasonal population dynamics, particularly in the case of first-intermediate hosts, are also expected to drive population genetic patterns within and across populations. To examine how parasite life history and host ecology influence parasite genetic patterns, we characterized the genetic diversity of within-host infrapopulations, as well as overall population genetic structure, of sympatric tongueworm (Halipegus occidualis) and lungworm (Haematoloechus complexus) freshwater trematode parasite populations. Parasites were collected across three host stages (snail, odonate insect, and frog) and sequenced at the cytochrome oxidase I (COI) mitochondrial region (519 bp for lungworms; 526 bp for tongueworms) to characterize genetic variation within and across hosts. Infection abundance per host and genetic diversity of within-host parasite infrapopulations generally increased with host trophic level, as expected. Additionally, tongueworm assemblages in odonate hosts were essentially equally as genetically diverse (depending on the index used) as those in definitive host frogs; tongueworms have an additional trophic transfer in their life cycle before the odonate stage, which highlights how trophic transmission and multi-host life cycle structure can benefit parasites by increasing genetic diversity of sexually reproducing adult assemblages. We also found that tongueworm populations, which infect a long-lived snail as a first-intermediate host, had higher population genetic diversity than lungworms, which infect a much shorter-lived snail with highly unstable population dynamics. Thus, we expect that first-intermediate host dynamics and dispersal ability played a large role in predicting population-level parasite genetic diversity and genetic structure in this system. This study investigates the effects of small- and large-scale processes on parasite genetic population structure and diversity and provides critical genetic data for future studies on these genera.
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Affiliation(s)
- Sarah R. Goodnight
- Department of Environmental Science and Policy, George Mason University, Woodbridge, VA, United States of America
| | - April M.H. Blakeslee
- Department of Biology, East Carolina University, Greenville, NC, United States of America
| | - Michael W. McCoy
- Department of Biology, Florida Atlantic University (Harbor Branch Campus), Fort Pierce, FL, United States of America
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Cribb TH, Barton DP, Blair D, Bott NJ, Bray RA, Corner RD, Cutmore SC, De Silva MLI, Duong B, Faltýnková A, Gonchar A, Hechinger RF, Herrmann KK, Huston DC, Johnson PTJ, Kremnev G, Kuchta R, Louvard C, Luus-Powell WJ, Martin SB, Miller TL, Pérez-Ponce de León G, Smit NJ, Tkach VV, Truter M, Waki T, Vermaak A, Wee NQX, Yong RQY, Achatz TJ. Challenges in the recognition of trematode species: Consideration of hypotheses in an inexact science. J Helminthol 2025; 99:e54. [PMID: 40260497 DOI: 10.1017/s0022149x25000367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2025]
Abstract
The description and delineation of trematode species is a major ongoing task. Across the field there has been, and currently still is, great variation in the standard of this work and in the sophistication of the proposal of taxonomic hypotheses. Although most species are relatively unambiguously distinct from their congeners, many are either morphologically very similar, including the major and rapidly growing component of cryptic species, or are highly variable morphologically despite little to no molecular variation for standard DNA markers. Here we review challenges in species delineation in the context provided to us by the historical literature, and the use of morphological, geographical, host, and molecular data. We observe that there are potential challenges associated with all these information sources. As a result, we encourage careful proposal of taxonomic hypotheses with consideration for underlying species concepts and frank acknowledgement of weaknesses or conflict in the data. It seems clear that there is no single source of data that provides a wholly reliable answer to our taxonomic challenges but that nuanced consideration of information from multiple sources (the 'integrated approach') provides the best possibility of developing hypotheses that will stand the test of time.
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Affiliation(s)
- T H Cribb
- Queensland Museum, Biodiversity and Geosciences Program, South Brisbane, Queensland4101, Australia
| | - D P Barton
- School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales2658, Australia
| | - D Blair
- College of Science and Engineering, James Cook University, Australia
| | - N J Bott
- School of Science, RMIT University, PO Box 71, BundooraVIC 3083
| | - R A Bray
- Department of Life Sciences, Natural History Museum, Cromwell Road, LondonSW7 5BD, UK
| | - R D Corner
- Department of Primary Industries, Ecosciences Precinct, Dutton Park, Queensland4102, Australia
| | - S C Cutmore
- Queensland Museum, Biodiversity and Geosciences Program, South Brisbane, Queensland4101, Australia
| | - M L I De Silva
- Centre for Sustainable Aquatic Ecosystems, Harry Butler Institute, Murdoch University, Western Australia
| | - B Duong
- School of the Environment, The University of Queensland, 4072Australia
| | - A Faltýnková
- Department of Forest Ecology, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelská 3, Brno, 613 00, Czech Republic
| | - A Gonchar
- Department of Invertebrate Zoology, St Petersburg University, Universitetskaya emb. 7-9, Saint Petersburg199034, Russia
- Laboratory of Parasitic Worms and Protists, Zoological Institute of the Russian Academy of Sciences, Universitetskaya emb. 1, Saint Petersburg199034, Russia
| | - R F Hechinger
- Scripps Insitution of Oceanography, University of California San Diego, La Jolla, California, USA
| | - K K Herrmann
- Tarleton State University, Stephenville, Texas, USA
| | - D C Huston
- Australian National Insect Collection, National Research Collections Australia, CSIRO, PO Box 1700, Canberra, ACT2601, Australia
| | - P T J Johnson
- Ecology and Evolutionary Biology, University of Colorado, Boulder, CO80309, USA
| | - G Kremnev
- Laboratory of Parasitic Worms and Protists, Zoological Institute of the Russian Academy of Sciences, Universitetskaya emb. 1, Saint Petersburg199034, Russia
| | - R Kuchta
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Branišovská 31, 370 05Ceské Budejovice, Czech Republic
| | - C Louvard
- Water Research Group, Unit for Environmental Science and Management, North-West University - Potchefstroom campus, 11 Hoffman St, Potchefstroom 2531, North West, South Africa
| | - W J Luus-Powell
- DSI-NRF SARChI Chair (Ecosystem Health), Department of Biodiversity, University of Limpopo, 0727, South Africa
| | - S B Martin
- Centre for Sustainable Aquatic Ecosystems, Harry Butler Institute, Murdoch University, 90 South Street, Murdoch, 6150, Western Australia, Australia
| | - T L Miller
- Queensland Museum, Biodiversity and Geosciences Program, South Brisbane, Queensland4101, Australia
| | - G Pérez-Ponce de León
- Escuela Nacional de Estudios Superiores Unidad Mérida, Universidad Nacional Autónoma de México, Mérida, Yucatán, C.P. 97357, Mexico
| | - N J Smit
- Water Research Group, Unit for Environmental Science and Management, North-West University - Potchefstroom campus, 11 Hoffman St, Potchefstroom 2531, North West, South Africa
| | - V V Tkach
- Department of Biology, University of North Dakota, Grand Forks, North Dakota, USA
| | - M Truter
- Water Research Group, Unit for Environmental Science and Management, North-West University - Potchefstroom campus, 11 Hoffman St, Potchefstroom 2531, North West, South Africa
| | - T Waki
- Faculty of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba274-8510, Japan
| | - A Vermaak
- Water Research Group, Unit for Environmental Science and Management, North-West University - Potchefstroom campus, 11 Hoffman St, Potchefstroom 2531, North West, South Africa
| | - N Q-X Wee
- Queensland Museum, Biodiversity and Geosciences Program, South Brisbane, Queensland4101, Australia
| | - R Q-Y Yong
- Water Research Group, Unit for Environmental Science and Management, North-West University - Potchefstroom campus, 11 Hoffman St, Potchefstroom 2531, North West, South Africa
| | - T J Achatz
- Department of Natural Sciences, Middle Georgia State University, Macon, Georgia, USA
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Chan AHE, Thaenkham U, Wichaita T, Saralamba S. Validating a web application's use of genetic distance to determine helminth species boundaries and aid in identification. BMC Bioinformatics 2025; 26:85. [PMID: 40102721 PMCID: PMC11917154 DOI: 10.1186/s12859-025-06098-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2024] [Accepted: 02/27/2025] [Indexed: 03/20/2025] Open
Abstract
BACKGROUND Parasitic helminths exhibit significant diversity, complicating both morphological and molecular species identification. Moreover, no helminth-specific tool is currently available to aid in species identification of helminths using molecular data. To address this, we developed and validated a straightforward, user-friendly application named Applying Taxonomic Boundaries for Species Identification of Helminths (ABIapp) using R and the Shiny framework. Serving as a preliminary step in species identification, ABIapp is designed to assist in visualizing taxonomic boundaries for nematodes, trematodes, and cestodes. ABIapp employs a database of genetic distance cut-offs determined by the K-means algorithm to establish taxonomic boundaries for ten genetic markers. Validation of ABIapp was performed both in silico and with actual specimens to determine its classification accuracy. The in silico validation involved 591 genetic distances sourced from 117 publications, while the validation with actual specimens utilized ten specimens. ABIapp's accuracy was also compared with other online platforms to ensure its robustness to assist in helminth identification. RESULTS ABIapp achieved an overall classification accuracy of 76% for in silico validation and 75% for actual specimens. Additionally, compared to other platforms, the classification accuracy of ABIapp was superior, proving its effectiveness to determine helminth taxonomic boundaries. With its user-friendly interface, minimal data input requirements, and precise classification capabilities, ABIapp offers multiple benefits for helminth researchers and can aid in identification. CONCLUSIONS Built on a helminth-specific database, ABIapp serves as a pioneering tool for helminth researchers, offering an invaluable resource for determining species boundaries and aiding in species identification of helminths. The availability of ABIapp to the community of helminth researchers may further enhance research in the field of helminthology. To enhance ABIapp's accuracy and utility, the database will be updated annually.
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Affiliation(s)
- Abigail Hui En Chan
- Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Urusa Thaenkham
- Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Tanaphum Wichaita
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Sompob Saralamba
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
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Bradecina SRB, Miura O. MOLECULAR GENETICS UNVEIL HOST SPECIFICITY OF TREMATODES IN TWO COGENERIC BATILLARIA SNAILS. J Parasitol 2025; 111:102-108. [PMID: 40043746 DOI: 10.1645/23-108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2025] Open
Abstract
Host specificity is essential to understanding the ecology and evolution of parasites, and it is often complicated to estimate because of the presence of morphologically similar but genetically distinct species. Morphological identification of larval trematodes is often challenging because of the lack of diagnostic characteristics that only appear in the sexually mature adult stage. The difficulty in accurate species identification may obscure their compatibility with the host species. We investigate the parasites infecting 2 Asian mud snail species, Batillaria multiformis and Batillaria attramentaria, at 1 site where the 2 host snails co-occur to identify the level of their host specificity. We found that the morphospecies Cercaria batillariae was the most common trematode species in B. attramentaria and B. multiformis. We conducted polymerase chain reaction (PCR) -based restriction fragment-length polymorphism (RFLP) analyses of 77 C. batillariae infections in B. attramentaria and 150 in B. multiformis. We further sequenced the representative RFLP patterns to evaluate their phylogenetic relationship. We observed 6 genetically distinct species infecting 2 host species. Of those, 2 parasite species exclusively infected B. attramentaria, and 1 was found only in B. multiformis. Although 3 parasite species infected both hosts, 2 of them showed highly biased infections to either host species. Our study suggests that trematodes in the Batillaria snails can be host specific and highlighted the usefulness of molecular genetics for assessing host specificity.
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Affiliation(s)
- Sandy Rey B Bradecina
- Graduate School of Kuroshio Science, Kochi University, 200 Monobe, Nankoku, Kochi 783-8502, Japan
| | - Osamu Miura
- Faculty of Agriculture and Marine Science, Kochi University, 200 Monobe, Nankoku, Kochi 783-8502, Japan
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Bray RA, Cutmore SC, Cribb TH. Proposal of a new genus, Doorochen (Digenea: Lepocreadioidea), for reef-inhabiting members of the genus Postlepidapedon Zdzitowiecki, 1993. Parasitol Int 2023; 93:102710. [PMID: 36423873 DOI: 10.1016/j.parint.2022.102710] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 10/30/2022] [Accepted: 11/16/2022] [Indexed: 11/23/2022]
Abstract
A new genus, Doorochen n. gen., is erected for four species of Postlepidapedon Zdzitowiecki, 1993, all of which inhabit members of the labroid genus Choerodon Bleeker, the tuskfishes, and which molecular phylogenies have indicated are not congeneric with the type-species, P. opisthobifurcatum (Zdzitowiecki, 1990) Zdzitowiecki, 1993. Doorochen secundum (Durio & Manter, 1968) n. comb. from Choerodon graphicus (De Vis), the Graphic tuskfish, from the Great Barrier Reef (GBR) and New Caledonia is designated the type-species of the new genus. Other species recognised are Doorochen spissum (Bray, Cribb & Barker, 1997) n. comb. from C. venustus (De Vis), the Venus tuskfish, C. cyanodus (Richardson), the Blue tuskfish, and C. graphicus from the GBR; D. uberis (Bray, Cribb & Barker, 1997) n. comb. from C. schoenleinii (Valenciennes), the Blackspot tuskfish, and C. venustus from the GBR and Moreton Bay; and D. philippinense (Machida, 2004) n. comb. from C. anchorago (Bloch), the Orange-dotted tuskfish, from Philippine waters. In addition to these four species, two new species are described: D. zdzitowieckii n. sp. from C. fasciatus (Günther), the Harlequin tuskfish, and C. graphicus from the GBR; and D. goorchana n. sp. from C. anchorago from the GBR and Palau. The genus Postlepidapedon is now considered to comprise just two species, P. opisthobifurcatum and P. quintum Bray & Cribb, 2001. The relationships of Doorochen, Postlepidapedon, Myzoxenus Manter, 1934 and Intusatrium Durio & Manter, 1968 in the family Lepidapedidae Yamaguti, 1958 are discussed.
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Affiliation(s)
- Rodney A Bray
- Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Scott C Cutmore
- Queensland Museum, Biodiversity and Geosciences Program, South Brisbane, Queensland 4101, Australia
| | - Thomas H Cribb
- School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia.
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Cháves-González LE, Morales-Calvo F, Mora J, Solano-Barquero A, Verocai GG, Rojas A. What lies behind the curtain: Cryptic diversity in helminth parasites of human and veterinary importance. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2022; 2:100094. [PMID: 35800064 PMCID: PMC9253710 DOI: 10.1016/j.crpvbd.2022.100094] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Revised: 05/28/2022] [Accepted: 06/07/2022] [Indexed: 11/17/2022]
Abstract
Parasite cryptic species are morphologically indistinguishable but genetically distinct organisms, leading to taxa with unclear species boundaries. Speciation mechanisms such as cospeciation, host colonization, taxon pulse, and oscillation may lead to the emergence of cryptic species, influencing host-parasite interactions, parasite ecology, distribution, and biodiversity. The study of cryptic species diversity in helminth parasites of human and veterinary importance has gained relevance, since their distribution may affect clinical and epidemiological features such as pathogenicity, virulence, drug resistance and susceptibility, mortality, and morbidity, ultimately affecting patient management, course, and outcome of treatment. At the same time, the need for recognition of cryptic species diversity has implied a transition from morphological to molecular diagnostic methods, which are becoming more available and accessible in parasitology. Here, we discuss the general approaches for cryptic species delineation and summarize some examples found in nematodes, trematodes and cestodes of medical and veterinary importance, along with the clinical implications of their taxonomic status. Lastly, we highlight the need for the correct interpretation of molecular information, and the correct use of definitions when reporting or describing new cryptic species in parasitology, since molecular and morphological data should be integrated whenever possible.
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Affiliation(s)
- Luis Enrique Cháves-González
- Laboratory of Helminthology, Centro de Investigación en Enfermedades Tropicales, University of Costa Rica, San José, Costa Rica
| | - Fernando Morales-Calvo
- Laboratory of Helminthology, Centro de Investigación en Enfermedades Tropicales, University of Costa Rica, San José, Costa Rica
| | - Javier Mora
- Laboratory of Helminthology, Centro de Investigación en Enfermedades Tropicales, University of Costa Rica, San José, Costa Rica
| | - Alberto Solano-Barquero
- Laboratory of Helminthology, Centro de Investigación en Enfermedades Tropicales, University of Costa Rica, San José, Costa Rica
| | - Guilherme G. Verocai
- Department of Veterinary Pathobiology, Texas A&M University, College of Veterinary Medicine and Biomedical Sciences, College Station, TX, USA
| | - Alicia Rojas
- Laboratory of Helminthology, Centro de Investigación en Enfermedades Tropicales, University of Costa Rica, San José, Costa Rica
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López-Jiménez A, Hernández-Mena DI, Solórzano-García B, García-Varela M. Exploring the genetic structure of Parastrigea diovadena Dubois and Macko, 1972 (Digenea: Strigeidae), an endoparasite of the white ibis, Eudocimus albus, from the Neotropical region of Mexico. Parasitol Res 2021; 120:2065-2075. [PMID: 34031714 DOI: 10.1007/s00436-021-07185-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 05/05/2021] [Indexed: 11/28/2022]
Abstract
Parastrigea diovadena Dubois and Macko, 1972, is an allogenic trematode species that infects the intestine of white ibis. This widely distributed Neotropical species has been studied poorly, and nothing is known about its population genetic structure. In the current study, we attempt to fill this gap for the first time and to explore the genetic diversity in P. diovadena populations from three biogeographic provinces (Sierra Madre Oriental, Sierra Madre Occidental, and Sierra Madre del Sur) in the Neotropical region of Mexico. Newly generated sequences of the internal transcribed spacers (ITS) from ribosomal DNA and cytochrome c oxidase subunit 1 (cox 1) from mitochondrial DNA were compared with sequences available from the GenBank data set. Phylogenetic analyses performed with the ITS and cox 1 data sets using maximum likelihood and Bayesian inference unequivocally showed that new sequences of P. diovadena recovered from the white ibis formed a clade with other sequences of specimens previously identified as P. diovadena. The intraspecific genetic divergence among the isolates was very low, ranging from 0 to 0.38% for ITS and from 0 to 1.5% for cox 1, and in combination with the phylogenetic trees confirmed that the isolates belonged to the same species. The cox 1 haplotype network (star-shaped) inferred with 62 sequences revealed 36 haplotypes. The most frequent haplotype (H3, n = 18) corresponded to specimens from all the populations (except Tecolutla, Veracruz). In addition to the common haplotype, we identified four other shared haplotypes (H2, H9, H12, and H14) and 31 unique haplotypes (singlets). In addition, high haplotype diversity (Hd = 0.913), low nucleotide diversity (Pi = 0.0057), and null genetic differentiation or population structure (Fst = 0.0167) were found among the populations from the three biogeographic provinces. The results suggest that the biology of the definitive host has played a key role in the population genetic structure of Parastrigea diovadena in the Neotropical region of Mexico.
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Affiliation(s)
- Alejandra López-Jiménez
- Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México (UNAM), Avenida Universidad 3000, Ciudad Universitaria, CP. 04510, México City, México.,Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Ciudad Universitaria, CP. 04510, México City, México
| | - David Iván Hernández-Mena
- Centro de Investigación Y de Estudios Avanzados, Instituto Politécnico Nacional, Unidad Mérida, Antigua Carretera Progreso Km. 6, Cordemex, 97310, Mérida, Yucatán, México
| | - Brenda Solórzano-García
- Escuela Nacional de Estudios Superiores Unidad Mérida, Universidad Nacional Autónoma de México (ENES-Mérida), Km 4.5 Carretera Mérida-Tetiz, Ucú, Yucatán, México
| | - Martín García-Varela
- Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México (UNAM), Avenida Universidad 3000, Ciudad Universitaria, CP. 04510, México City, México.
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Pinacho-Pinacho CD, Sereno-Uribe AL, Hernández-Orts JS, García-Varela M, Pérez-Ponce de León G. Integrative taxonomy reveals an even greater diversity within the speciose genus Phyllodistomum (Platyhelminthes:Trematoda:Gorgoderidae), parasitic in the urinary bladder of Middle American freshwater fishes, with descriptions of five new species. INVERTEBR SYST 2021. [DOI: 10.1071/is21007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Phyllodistomum is one of the most species-rich genera of parasitic platyhelminths, with 120 species described worldwide; they infect the urinary bladder of marine and freshwater fishes. As the number of new species within the genus has increased, morphological conservatism, and the lack of reliable diagnostic traits make the separation of species a challenging task. The increase of genetic data for Phyllodistomum species has permitted the use of an integrative taxonomy approach as a framework for species discovery and delimitation. DNA sequences (28S rRNA and COI mtDNA) were obtained from individuals of Phyllodistomum sampled in 29 locations across Middle America, and used in combination with morphology, host association and geographic distribution to uncover five new congeneric species. Morphologically, the new species are relatively similar; there are no unique morphological traits to readily distinguish them. We first investigated species boundaries through phylogenetic analyses of the independent and concatenated datasets; analyses recognised five candidate species showing reciprocal monophyly and strong clade support, particularly for COI data. The interspecific 28S rRNA and COI sequence divergence among the new species from 0.4 to 18.4% and from 5.1 to 27% respectively. These results were further validated by a Bayesian species delimitation approach. The five new species are well supported by molecular data used in combination with other sources of information such as host association and geographical distribution and are described herein as Phyllodistomum romualdae sp. nov., P. virmantasi sp. nov., P. isabelae sp. nov., P. scotti sp. nov., and P. simonae sp. nov.
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Zemmer SA, Detwiler JT, Sokol ER, Da Silva Neto JG, Wyderko J, Potts K, Gajewski ZJ, Sarment LV, Benfield EF, Belden LK. Spatial scale and structure of complex life cycle trematode parasite communities in streams. PLoS One 2020; 15:e0241973. [PMID: 33232346 PMCID: PMC7685432 DOI: 10.1371/journal.pone.0241973] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 10/23/2020] [Indexed: 11/19/2022] Open
Abstract
By considering the role of site-level factors and dispersal, metacommunity concepts have advanced our understanding of the processes that structure ecological communities. In dendritic systems, like streams and rivers, these processes may be impacted by network connectivity and unidirectional current. Streams and rivers are central to the dispersal of many pathogens, including parasites with complex, multi-host life cycles. Patterns in parasite distribution and diversity are often driven by host dispersal. We conducted two studies at different spatial scales (within and across stream networks) to investigate the importance of local and regional processes that structure trematode (parasitic flatworms) communities in streams. First, we examined trematode communities in first-intermediate host snails (Elimia proxima) in a survey of Appalachian headwater streams within the Upper New River Basin to assess regional turnover in community structure. We analyzed trematode communities based on both morphotype (visual identification) and haplotype (molecular identification), as cryptic diversity in larval trematodes could mask important community-level variation. Second, we examined communities at multiple sites (headwaters and main stem) within a stream network to assess potential roles of network position and downstream drift. Across stream networks, we found a broad scale spatial pattern in morphotype- and haplotype-defined communities due to regional turnover in the dominant parasite type. This pattern was correlated with elevation, but not with any other environmental factors. Additionally, we found evidence of multiple species within morphotypes, and greater genetic diversity in parasites with hosts limited to in-stream dispersal. Within network parasite prevalence, for at least some parasite taxa, was related to several site-level factors (elevation, snail density and stream depth), and total prevalence decreased from headwaters to main stem. Variation in the distribution and diversity of parasites at the regional scale may reflect differences in the abilities of hosts to disperse across the landscape. Within a stream network, species-environment relationships may counter the effects of downstream dispersal on community structure.
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Affiliation(s)
- Sally A. Zemmer
- Biological Sciences, Virginia Polytechnic and State Institute, Blacksburg, Virginia, United States of America
- * E-mail:
| | | | - Eric R. Sokol
- Biological Sciences, Virginia Polytechnic and State Institute, Blacksburg, Virginia, United States of America
| | - Jeronimo G. Da Silva Neto
- Biological Sciences, Virginia Polytechnic and State Institute, Blacksburg, Virginia, United States of America
| | - Jennie Wyderko
- Biological Sciences, Virginia Polytechnic and State Institute, Blacksburg, Virginia, United States of America
| | - Kevin Potts
- Biological Sciences, Virginia Polytechnic and State Institute, Blacksburg, Virginia, United States of America
| | - Zachary J. Gajewski
- Biological Sciences, Virginia Polytechnic and State Institute, Blacksburg, Virginia, United States of America
| | - Lea V. Sarment
- Biological Sciences, Virginia Polytechnic and State Institute, Blacksburg, Virginia, United States of America
| | - E. F. Benfield
- Biological Sciences, Virginia Polytechnic and State Institute, Blacksburg, Virginia, United States of America
| | - Lisa K. Belden
- Biological Sciences, Virginia Polytechnic and State Institute, Blacksburg, Virginia, United States of America
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Voronova AN, Besprozvannykh VV, Ngo HD, Plekhova NG, Hung NM, Tatonova YV. Paragonimus heterotremus Chen et Hsia, 1964 (Digenea: Paragonimidae): species identification based on the biological and genetic criteria, and pathology of infection. Parasitol Res 2020; 119:4073-4088. [PMID: 33068148 DOI: 10.1007/s00436-020-06929-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 10/11/2020] [Indexed: 10/23/2022]
Abstract
As a result of the experimental infection of rats with metacercariae of Paragonimus heterotremus Chen et Hsia, 1964 from crabs (Potamiscus tannanti) caught in Yen Bai province, Vietnam, it was found that worms migrated into the lungs, to the liver and less frequently to the tissue that lines body cavities of the hosts, where they reached the adult stage, but in the muscles, worms stayed at the larval stage. Studies have shown that for P. heterotremus, rats can simultaneously play the role of the final and paratenic host; herewith, an infection with the trematode of this species can lead to the development of three forms of paragonimiasis: pulmonary, hepatic and muscular. Eggs from the adult worms localised in the liver, unlike eggs from the adult worms localised in the lungs, were not excreted into the external environment, but accumulated inside the organ. Histology and description of changes, which take place on the external surface of organs affected with P. heterotremus, are given in this study. Based on the behavioural characteristics of worms during rat infection and molecular genetic data, we established that worms from Vietnam and India should be assigned to different species of Paragonimus. P. heterotremus distribution is limited to the territory of the Southeast China, Northern Vietnam, Laos and Thailand.
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Affiliation(s)
- Anastasia N Voronova
- Federal Scientific Centre of the East Asia Terrestrial Biodiversity, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia.
| | - Vladimir V Besprozvannykh
- Federal Scientific Centre of the East Asia Terrestrial Biodiversity, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia
| | - Ha Duy Ngo
- Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, Hanoi, Vietnam
| | - Natalia G Plekhova
- Pacific State Medical University, Ministry of Health of the Russian Federation, Vladivostok, Russia
| | - Nguyen Manh Hung
- Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, Hanoi, Vietnam
| | - Yulia V Tatonova
- Federal Scientific Centre of the East Asia Terrestrial Biodiversity, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia
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Voronova AN, Chelomina GN. The SSU rRNA secondary structures of the Plagiorchiida species (Digenea), its applications in systematics and evolutionary inferences. INFECTION GENETICS AND EVOLUTION 2019; 78:104042. [PMID: 31770596 DOI: 10.1016/j.meegid.2019.104042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 08/05/2019] [Accepted: 09/16/2019] [Indexed: 10/25/2022]
Abstract
The small subunit ribosomal RNA (SSU rRNA) is widely used phylogenetic marker in broad groups of organisms and its secondary structure increasingly attracts the attention of researchers as supplementary tool in sequence alignment and advanced phylogenetic studies. Its comparative analysis provides a great contribution to evolutionary biology, allowing find out how the SSU rRNA secondary structure originated, developed and evolved. Herein, we provide the first data on the putative SSU rRNA secondary structures of the Plagiorchiida species. The structures were found to be quite conserved across broad range of species studied, well compatible with those of others eukaryotic SSU rRNA and possessed some peculiarities: cross-shaped structure of the ES6b, additional shortened ES6c2 helix, and elongated ES6a helix and h39 + ES9 region. The secondary structures of variable regions ES3 and ES7 appeared to be tissue-specific while ES6 and ES9 were specific at a family level allowing considering them as promising markers for digenean systematics. Their uniqueness more depends on the length than on the nucleotide diversity of primary sequences which evolutionary rates well differ. The findings have important implications for understanding rRNA evolution, developing molecular taxonomy and systematics of Plagiorchiida as well as for constructing new anthelmintic drugs.
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Affiliation(s)
- A N Voronova
- Federal Scientific Center of the East Asia Terrestrial Biodiversity FEB RAS, 7 Russia, 100-letiya Street, 159, Vladivostok 690022, Russia
| | - G N Chelomina
- Federal Scientific Center of the East Asia Terrestrial Biodiversity FEB RAS, 7 Russia, 100-letiya Street, 159, Vladivostok 690022, Russia.
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12
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Gordy MA, Hanington PC. A fine-scale phylogenetic assessment of digenean trematodes in central Alberta reveals we have yet to uncover their total diversity. Ecol Evol 2019; 9:3153-3238. [PMID: 30962888 PMCID: PMC6434566 DOI: 10.1002/ece3.4939] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 12/17/2018] [Accepted: 12/27/2018] [Indexed: 01/08/2023] Open
Abstract
Despite over 100 years of digenean trematode parasite species descriptions, from a wide diversity of vertebrate and invertebrate host species, our ability to recognize the diversity of trematode species within a single lake remains an incredible challenge. The most challenging aspect is the identification of species from larval stages derived from intermediate hosts, due to the disjointed data of adult worm morphological descriptions, from which species are named, and links to corresponding molecular identifiers in depauperate databases. Cryptic species also play a significant role in the challenge of linking trematode larvae to adults, species identifications, and estimating diversity. Herein, we utilize a large, longitudinal dataset of snail first-intermediate host infection data from lakes in Alberta, Canada, to infer trematode larval diversity using molecular phylogenetics and snail host associations. From our assessments, we uncover a diversity of 79 larval trematode species among just five snail host species. Only 14 species were identified to a previously described species, while the other 65 species are either cryptic or otherwise unrepresented by mitochondrial genes in GenBank. This study currently represents the largest and most diverse singular molecular survey of trematode larval fauna composed of over one thousand mitochondrial sequences. Surprisingly, rarefaction analyses indicate we have yet to capture the complete diversity of trematodes from our sampling area.
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Bray RA, Cribb TH, Cutmore SC. Lepocreadiidae Odhner, 1905 and Aephnidiogenidae Yamaguti, 1934 (Digenea: Lepocreadioidea) of fishes from Moreton Bay, Queensland, Australia, with the erection of a new family and genus. Syst Parasitol 2018; 95:479-498. [PMID: 29855981 PMCID: PMC5993846 DOI: 10.1007/s11230-018-9803-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 05/19/2018] [Indexed: 11/28/2022]
Abstract
Digeneans of the lepocreadioid families Lepocreadiidae Odhner, 1905 and Aephnidiogenidae Yamaguti, 1934 from Moreton Bay, off southern Queensland, Australia, are recorded, along with the erection of a new family, Gibsonivermidae. Molecular data were generated for all representatives of these families collected during this study and a phylogram for members of the superfamily was generated based on the partial 28S rDNA dataset, placing these species in context with those previously sequenced. This phylogenetic analysis demonstrates that the monotypic Gibsonivermis Bray, Cribb & Barker, 1997 is isolated from all other lepocreadioids and supports the erection of Gibsonivermidae n. fam., which is defined morphologically, based particularly on the uniquely elongated male terminal genitalia, the distribution of the uterus in the forebody and the presence of a uroproct. Mobahincia teirae n. g., n. sp. is reported from Platax teira (Forsskål) in Moreton Bay and off Heron Island and New Caledonia. Recognition of this new genus is based on molecular results and the combination of caeca abutting the posterior body wall and the lack of an anterior body scoop or flanges. The following lepocreadioid species are reported from Moreton Bay for the first time: Bianium arabicum Sey, 1996 in Lagocephalus lunaris (Bloch & Schneider), Diploproctodaeum cf. monstrosum Bray, Cribb & Justine, 2010 in Arothron hispidus (Linnaeus), Multitestis magnacetabulum Mamaev, 1970 and Neomultitestis aspidogastriformis Bray & Cribb, 2003 in Platax teira and Opechona austrobacillaris Bray & Cribb, 1998 in Pomatomus saltatrix (Linnaeus). Bianium plicitum (Linton, 1928) is reported from Torquigener squamicauda (Ogilby) for the first time. Sequences of newly collected specimens of Austroholorchis sprenti (Gibson, 1987) indicate that the species forms a clade with other members of the Aephnidiogenidae, agreeing with its morphology. The phylogenetic status of all newly sequenced species is discussed.
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Affiliation(s)
- Rodney A Bray
- Department of Life Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, UK.
| | - Thomas H Cribb
- School of Biological Sciences, The University of Queensland, St Lucia, QLD, 4072, Australia
| | - Scott C Cutmore
- School of Biological Sciences, The University of Queensland, St Lucia, QLD, 4072, Australia
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Voronova A, Chelomina GN. Genetic diversity and phylogenetic relations of salmon trematode Nanophyetus japonensis. Parasitol Int 2018; 67:267-276. [DOI: 10.1016/j.parint.2018.01.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 01/11/2018] [Accepted: 01/14/2018] [Indexed: 02/02/2023]
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Pinacho-Pinacho CD, García-Varela M, Sereno-Uribe AL, Pérez-Ponce de León G. A hyper-diverse genus of acanthocephalans revealed by tree-based and non-tree-based species delimitation methods: Ten cryptic species of Neoechinorhynchus in Middle American freshwater fishes. Mol Phylogenet Evol 2018; 127:30-45. [PMID: 29783021 DOI: 10.1016/j.ympev.2018.05.023] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 04/12/2018] [Accepted: 05/17/2018] [Indexed: 12/20/2022]
Abstract
The genus Neoechinorhynchus represents a hyper-diverse group of acanthocephalans, parasites of fresh and brackish water fish and freshwater turtles, with approximately 116 species described worldwide. Forty-nine species have been recorded in the Americas, nine of them in Middle America. Even though species delimitation methods using DNA sequences have been rarely used for parasitic helminths, the genetic library for species of Neoechinorhynchus has grown in the past few years, enhancing the possibility of using these methods for inferring evolutionary relationships and for establishing more robust species boundaries. In this study, we used non-tree-based and tree-based methods through a coalescent approach to explore the species limits of specimens of Neoechinorhynchus collected in 57 localities across Middle America. We sequenced a large number of individuals to build a comprehensive dataset for three genes: the mitochondrial cytochrome c oxidase subunit I (352 individuals), the internal transcribed spacers (330 individuals), and the D2 + D3 domains of the large subunit (278 individuals). Several species delimitation methods were implemented, i.e., Automatic Barcode Gap Discovery (ABGD), General Mixed Yule-Coalescent Model (GMYC), Bayesian species delimitation (BPP) and species tree (∗BEAST). Additionally, we conducted a detailed morphological study of the diagnostic traits associated with the proboscis of 184 males and 169 females. Overall, our analyses allowed us to validate nine nominal species of Neoechinorhynchus and to identify 10 additional genetic lineages herein regarded as candidate species. This unexpected genetic diversity and the lack of reliable morphological traits show that the genus Neoechinorhynchus includes a group of cryptic species, at least in Middle America.
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Affiliation(s)
- Carlos Daniel Pinacho-Pinacho
- Investigador Cátedra CONACyT, Instituto de Ecología, A.C., Red de Estudios Moleculares Avanzados, Km 2.5 Ant. Carretera a Coatepec, Xalapa, Veracruz 91070, Mexico.
| | - Martín García-Varela
- Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, C.P. 04510, Ap. Postal 70-153, Ciudad Universitaria, Ciudad de México, Mexico.
| | - Ana L Sereno-Uribe
- Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, C.P. 04510, Ap. Postal 70-153, Ciudad Universitaria, Ciudad de México, Mexico.
| | - Gerardo Pérez-Ponce de León
- Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, C.P. 04510, Ap. Postal 70-153, Ciudad Universitaria, Ciudad de México, Mexico.
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Abstract
Paramphistomoids are ubiquitous and widespread digeneans that infect a diverse range of
definitive hosts, being particularly speciose in ruminants. We collected adult worms from
cattle, goats and sheep from slaughterhouses, and cercariae from freshwater snails from
ten localities in Central and West Kenya. We sequenced cox1 (690 bp) and
internal transcribed region 2 (ITS2) (385 bp) genes from a small piece of 79 different
adult worms and stained and mounted the remaining worm bodies for comparisons with
available descriptions. We also sequenced cox1 and ITS2 from 41
cercariae/rediae samples collected from four different genera of planorbid snails.
Combining morphological observations, host use information, genetic distance values and
phylogenetic methods, we delineated 16 distinct clades of paramphistomoids. For four of
the 16 clades, sequences from adult worms and cercariae/rediae matched, providing an
independent assessment for their life cycles. Much work is yet to be done to resolve fully
the relationships among paramphistomoids, but some correspondence between sequence- and
anatomically based classifications were noted. Paramphistomoids of domestic ruminants
provide one of the most abundant sources of parasitic flatworm biomass, and because of the
predilection of several species use Bulinus and
Biomphalaria snail hosts, have interesting linkages with the biology of
animal and human schistosomes to in Africa.
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Abstract
SUMMARYComplex life cycles are common in free-living and parasitic organisms alike. The adaptive decoupling hypothesis postulates that separate life cycle stages have a degree of developmental and genetic autonomy, allowing them to be independently optimized for dissimilar, competing tasks. That is, complex life cycles evolved to facilitate functional specialization. Here, I review the connections between the different stages in parasite life cycles. I first examine evolutionary connections between life stages, such as the genetic coupling of parasite performance in consecutive hosts, the interspecific correlations between traits expressed in different hosts, and the developmental and functional obstacles to stage loss. Then, I evaluate how environmental factors link life stages through carryover effects, where stressful larval conditions impact parasites even after transmission to a new host. There is evidence for both autonomy and integration across stages, so the relevant question becomes how integrated are parasite life cycles and through what mechanisms? By highlighting how genetics, development, selection and the environment can lead to interdependencies among successive life stages, I wish to promote a holistic approach to studying complex life cycle parasites and emphasize that what happens in one stage is potentially highly relevant for later stages.
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Andres MJ, Pulis EE, Overstreet RM. Description of three species of Isorchis (Digenea: Atractotrematidae) from Australia. Acta Parasitol 2016; 61:590-601. [PMID: 27447225 DOI: 10.1515/ap-2016-0079] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 04/11/2016] [Indexed: 01/05/2023]
Abstract
Three species of Isorchis Durio and Manter, 1969 are described from Australian waters. Isorchis megas sp. nov. is described from the spotbanded scat, Selenotoca multifasciata (Richardson), off Western Australia (WA) and Northern Territory (NT); Isorchis currani sp. nov. is described from S. multifasciata off NT; and Isorchis anomalus sp. nov. is described from the milkfish, Chanos chanos Forsskål, off WA. Isorchis megas sp. nov. can be differentiated from the other species of Isorchis by possessing a single, large egg that is greater than 20% of the body length; having a shorter body (the largest specimen is less than 500 μm); and utilizing a scatophagid rather than a chanid host. Isorchis currani sp. nov. can be differentiated from species of Isorchis other than I. megas sp. nov. by utilizing a scatophagid rather than a chanid host; it is differentiated from I. megas sp. nov. in having eggs that are 11-15% of the body length. Isorchis anomalus sp. nov. can be differentiated from all other species of Isorchis in possessing an irregular shaped genital pore rather than one that is circular to oblong. A Bayesian inference analysis of partial 28S rDNA sequences of the three new species of Isorchis and 30 other haploporoids revealed 1) the monophyly of the Atractotrematidae Yamaguti, 1939, 2) the two species of Isorchis infecting S. multifasciata were each other's closest relative, and 3) that Isorchis was most closely related to Pseudomegasolena Machida and Komiya, 1976 rather than Atractotrema Goto and Ozaki, 1929 although sequence data are not yet available for a member of Pseudisorchis Ahmad, 1985.
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Species delimitation in trematodes using DNA sequences: Middle-American Clinostomum as a case study. Parasitology 2016; 143:1773-1789. [PMID: 27571850 DOI: 10.1017/s0031182016001517] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The recent development of genetic methods allows the delineation of species boundaries, especially in organisms where morphological characters are not reliable to differentiate species. However, few empirical studies have used these tools to delineate species among parasitic metazoans. Here we investigate the species boundaries of Clinostomum, a cosmopolitan trematode genus with complex life cycle. We sequenced a mitochondrial [cytochrome c oxidase subunit I (COI)] gene for multiple individuals (adults and metacercariae) from Middle-America. Bayesian phylogenetic analysis of the COI uncovered five reciprocally monophyletic clades. COI sequences were then explored using the Automatic Barcode Gap Discovery to identify putative species; this species delimitation method recognized six species. A subsample was sequenced for a nuclear gene (ITS1, 5·8S, ITS2), and a concatenated phylogenetic analysis was performed through Bayesian inference. The species delimitation of Middle-American Clinostomum was finally validated using a multispecies coalescent analysis (species tree). In total, five putative species are recognized among our samples. Mapping the second intermediate hosts (fish) onto the species tree suggests that metacercariae of these five species exhibit some level of host specificity towards their fish intermediate host (at the family level), irrespective of geographical distribution.
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20
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Blasco-Costa I, Cutmore SC, Miller TL, Nolan MJ. Molecular approaches to trematode systematics: ‘best practice’ and implications for future study. Syst Parasitol 2016; 93:295-306. [DOI: 10.1007/s11230-016-9631-2] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 01/09/2016] [Indexed: 11/29/2022]
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Lagrue C, Joannes A, Poulin R, Blasco-Costa I. Genetic structure and host-parasite co-divergence: evidence for trait-specific local adaptation. Biol J Linn Soc Lond 2015. [DOI: 10.1111/bij.12722] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Clément Lagrue
- Department of Zoology; University of Otago; Dunedin New Zealand
| | - Arnaud Joannes
- Department of Zoology; University of Otago; Dunedin New Zealand
| | - Robert Poulin
- Department of Zoology; University of Otago; Dunedin New Zealand
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Kasl EL, McAllister CT, Robison HW, Connior MB, Font WF, Criscione CD. Evolutionary consequence of a change in life cycle complexity: A link between precocious development and evolution toward female-biased sex allocation in a hermaphroditic parasite. Evolution 2015; 69:3156-70. [PMID: 26508113 DOI: 10.1111/evo.12805] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 10/02/2015] [Accepted: 10/10/2015] [Indexed: 11/29/2022]
Abstract
The evolutionary consequences of changes in the complex life cycles of parasites are not limited to the traits that directly affect transmission. For instance, mating systems that are altered due to precocious sexual maturation in what is typically regarded as an intermediate host may impact opportunities for outcrossing. In turn, reproductive traits may evolve to optimize sex allocation. Here, we test the hypothesis that sex allocation evolved toward a more female-biased function in populations of the hermaphroditic digenean trematode Alloglossidium progeneticum that can precociously reproduce in their second hosts. In these precocious populations, parasites are forced to self-fertilize as they remain encysted in their second hosts. In contrast, parasites in obligate three-host populations have more opportunities to outcross in their third host. We found strong support that in populations with precocious development, allocation to male resources was greatly reduced. We also identified a potential phenotypically plastic response in a body size sex allocation relationship that may be driven by the competition for mates. These results emphasize how changes in life cycle patterns that alter mating systems can impact the evolution of reproductive traits in parasites.
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Affiliation(s)
- Emily L Kasl
- Department of Biology, Texas A&M University, College Station, Texas.
| | - Chris T McAllister
- Science and Mathematics Division, Eastern Oklahoma State College, Idabel, Oklahoma
| | - Henry W Robison
- Department of Biology, Southern Arkansas University, Magnolia, Arkansas
| | - Matthew B Connior
- Life Sciences, Northwest Arkansas Community College, Bentonville, Arkansas
| | - William F Font
- Department of Biological Sciences, Southeastern Louisiana University, Hammond, Louisiana
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