Genetic variation within the ticks Ixodes holocyclus and Ixodes cornuatus from South-eastern Australia

Jackson, Janey; Chilton, Neil B.; Beveridge, Ian; Morris, Michelle L.; Andrews, Ross H.

doi:10.1016/s0020-7519(00)00103-x

Cited by 17 publications

(20 citation statements)

References 8 publications

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“…This contradicts the suggestion made by Roberts [1] that these two species may be subspecies of the widespread I. holocyclus . The results of this study are congruent with the results of Song et al [14] and Jackson et al [13]. However neither of these studies included the Western Australian species, I. myrmecobii .…”

Section: Discussionsupporting

confidence: 92%

“…The subgenus comprises nine members, including Ixodes anatis, I. confusus , I. cornuatus , I. cordifer , I. dendrolagi , I. hirsti , I. holocyclus , I. myrmecobii and I. trichosuri [11]. However, the majority of studies have focussed on I. holocyclus and I. cornuatus , a species morphologically similar to I. holocyclus , aiming to determine their distribution [1, 12], morphological and molecular identification [1, 13] and phylogenetic relationships [14]. A number of questions therefore remain to be answered regarding the members of the subgenus Sternalixodes .…”

Section: Introductionmentioning

confidence: 99%

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Phylogenetic analysis of the Australasian paralysis ticks and their relatives (Ixodidae: Ixodes: Sternalixodes)

et al. 2017

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BackgroundThe Australasian paralysis ticks and their relatives, Ixodes Latrielle, subgenus Sternalixodes Schulze, are some of the most important ticks in the region. However, very little is known about their phylogenetic relationships. The aim of this study was to elucidate the evolutionary relationships of members of the subgenus Sternalixodes by undertaking phylogenetic analyses of morphological and molecular datasets.MethodsAdult females (n = 64) of Sternalixodes, including Ixodes anatis Chilton, 1904, Ixodes confusus Roberts, 1960, Ixodes cornuatus Roberts, 1960, Ixodes cordifer Neumann, 1908, Ixodes dendrolagi Wilson, 1967, Ixodes hirsti Hassall, 1931, Ixodes holocyclus Neumann, 1899, Ixodes myrmecobii Roberts, 1962 and Ixodes trichosuri Roberts, 1960, were examined morphologically. Subsequently, these Ixodes spp. were genetically characterised using cytochrome c oxidase subunit 1 (cox1) gene and the internal transcribed spacer 2 (ITS-2) of the rRNA. Both morphological and molecular datasets were analysed using various phylogenetic methods to assess the evolutionary relationship of various members of the subgenus Sternalixodes.ResultsPhylogenetic analyses of the cox1 sequences and morphological characters datasets revealed that the Australian and Papuan Sternalixodes formed a distinct clade with the New Zealand member of the group I. anatis positioned basally, in a separate clade. Ixodes holocyclus, I. cornuatus and I. myrmecobii formed a distinctive clade in both the cox1 and morphological phylogenies. However, based on phylogenetic analysis of the ITS-2 data, I. holocyclus formed a separate clade whereas I. cornuatus and I. myrmecobii grouped in a different clade.ConclusionsThe cox1 and morphological data suggest that the subgenus Sternalixodes is paraphyletic, and I. anatis is not a sternalixodid tick; hence, it should not be included in the subgenus. Based on the phylogenetic analyses of cox1 and ITS-2 sequences, it appears that I. myrmecobii and I. cornuatus are not subspecies of I. holocyclus. Although this study provided better insights into the taxonomic status of the subgenus Sternalixodes, a complete morphological and molecular (using multiple markers) phylogenetic analysis including all members of the subgenus would be required to more accurately elucidate the evolutionary relationships within the subgenus.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Phylogenetic analysis of the Australasian paralysis ticks and their relatives (Ixodidae: Ixodes: Sternalixodes)

et al. 2017

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“…Jackson et al (1998) also found substantial differences between I. holocyclus and I. cornuatus: variation at 52-69% of allozyme loci studied. More recently, Jackson et al (2000) found that up to 80% of allozyme loci studied varied between I. holocyclus and I. cornuatus. Two features of the I. holocyclus ITS2 sequences are striking: the small amount of intraspecific variation and the fact that when there were two nucleotides at some nucleotide positions, one of these nucleotides was always the nucleotide of sequence A.…”

Section: Discussionmentioning

confidence: 99%

“…Jackson et al (1998; studied variation in I. holocyclus and I. cornuatus at 24-27 allozyme loci and found that the two species were genetically distinct. In addition, Jackson et al (2000) found preliminary evidence that I. holocyclus may represent a species complex.…”

Section: Introductionmentioning

confidence: 97%

Low intraspecific variation in the rRNA internal transcribed spacer 2 (ITS2) of the Australian paralysis tick, Ixodes holocyclus

Shaw

Murrell

Barker

2002

Parasitology Research

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Ixodes holocyclus has a narrow, discontinuous distribution along the east coast of Australia. We studied ticks from 17 localities throughout the geographic range of this tick. The ITS2 of I. holocyclus is 793 bp long. We found nucleotide variation at eight of the 588 nucleotide positions (1.4%) that were compared for all ticks. There were eight different nucleotide sequences. Most sequences were not restricted to a particular geographic region. However, sequences F, G and H, which had an adenine at position 197, were found only in the far north of Queensland--all other ticks had a guanine at this position. The low level of intraspecific variation in this tick (0.7%) contrasts with the sequence divergence between I. holocyclus and its close relative, I. cornuatus (13.1%). These data indicate that I. holocyclus does not contain cryptic species despite possible geographic isolation of some populations. We conclude that variation in the ITS2 is likely to be informative about the phylogeny of the group.

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“…A tick's saliva contains a plethora of biologically active molecules that modulate the host's immune response to tick infestation, facilitating the formation of a feeding pool in the host's tissue (Ribeiro, 1995;TABLE 3. The many native hosts of Ixodes holocyclus in Australia (Roberts, 1960;Domrow and Derrick, 1965;Marks and Cribb, 1966;Doube, 1975;Jackson et al, 2000;Campbell et al, 2003) Wikel, 1996Wikel, , 1999Schoeler and Wikel, 2001). To allow successful feeding over several days, ticks need to overcome the host's haemostatic, inflammatory and immune mechanisms (Ribeiro and Francischetti, 2003), and they produce many compounds, including anticoagulants (such as gelatinases), fibrinolytic enzymes and anti-platelet and vasodilator substances (Kemp et al, 1983), to achieve this goal.…”

Section: Production Of IX Holocyclus Toxin In the Tick's Salivary Glmentioning

confidence: 99%

Tick paralysis in Australia caused byIxodes holocyclusNeumann

Hall‐Mendelin

Craig

Hall

et al. 2011

Annals of Tropical Medicine & Parasitology

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Ticks are obligate haematophagous ectoparasites of various animals, including humans, and are abundant in temperate and tropical zones around the world. They are the most important vectors for the pathogens causing disease in livestock and second only to mosquitoes as vectors of pathogens causing human disease. Ticks are formidable arachnids, capable of not only transmitting the pathogens involved in some infectious diseases but also of inducing allergies and causing toxicoses and paralysis, with possible fatal outcomes for the host. This review focuses on tick paralysis, the role of the Australian paralysis tick Ixodes holocyclus, and the role of toxin molecules from this species in causing paralysis in the host.

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Genetic variation within the ticks Ixodes holocyclus and Ixodes cornuatus from South-eastern Australia

Cited by 17 publications

References 8 publications

Phylogenetic analysis of the Australasian paralysis ticks and their relatives (Ixodidae: Ixodes: Sternalixodes)

Phylogenetic analysis of the Australasian paralysis ticks and their relatives (Ixodidae: Ixodes: Sternalixodes)

Low intraspecific variation in the rRNA internal transcribed spacer 2 (ITS2) of the Australian paralysis tick, Ixodes holocyclus

Tick paralysis in Australia caused byIxodes holocyclusNeumann

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