Genetic variation within species of the nematode genus Cloacina (Strongyloidea:Cloacininae) parasitic in the stomachs of rock wallabies, Petrogale spp. (Marsupialia:Macropodidae) in Queensland

Abstract

Four morphospecies of Cloacina, parasitic nematodes in the stomachs of rock wallabies (Petrogale spp.) from Queensland, were compared genetically using sequence data of the two internal transcribed spacers of nuclear ribosomal DNA (rDNA). The results suggest that two geographically isolated populations of C. ernabella from P. purpureicollis were genetically distinct. Based on the autapomorphic species concept, these two C. ernabella populations represented different species. For the three other nematode morphospecies, there were genetic differences among individuals of a morphospecies present in different species of host. The results suggest that each may represent a complex of sibling species, with a different species present in each species of rock wallaby examined for that morphospecies. In the C. caenis and C. pearsoni complexes, the lineage present in P. purpureicollis from western Queensland represents a sister taxon to those in the P. pencillata complex from the east coast. In the C. robertsi complex, the taxon parasitic in P. persephone represents the sister taxon to those in the P. pencillata complex and in P. purpureicollis. C. robertsi was found for the first time in P. purpureicollis from Winton in central Queensland, suggesting contact in the recent past between populations of P. purpureicollis and a member of the P. penicillata complex.

Genetic variation within and among species of Cloacina (Strongyloidea: Cloacinine) from the swamp wallaby, Wallabia bicolor (Marsupialia: Macropodidae)

“…rDNA (Chilton et al, 1997b(Chilton et al, , 2009). However, given the extensive diversity of cloacinine nematodes, it is possible that rDNA alone may not always meet the challenges of estimating interrelationships, particularly the cryptic species among various cloacinine nematodes.…”

“…Genotype Length (bp) Polymorphism G + C content Pairwise distance A high sequence variation within individuals of some Cloacina species from W. bicolor was observed (see Tables 2 and 3). A number of previous studies (Chilton et al, 2009Tan et al, 2012) have reported intraspecific variation in DNA sequences of the ITS-1 and/or ITS-2 within several species of the genus Cloacina spp. (ITS-2 2%), Hypodontus macropi (ITS-2 0.1-28%) and Macroponema comani (ITS-1 1.7 and ITS-2 2.3%) from macropodid hosts; however, that found in the present study was higher (except H. macropi) in C. eos (0.3-3.4% for ITS-1; 0.9-4.8% for ITS-2), C. edwardsi (0.8-1.3%; 0.9-2.3%), C. papillatissima (8.5%; no variation) and C. wallabiae (0.3-3.3%; 0.4-3.0%).…”

“…Most are highly-host specific (Beveridge, 1998). Although species of Cloacina from swamp wallabies have not been studied genetically, based on previous investigations (Chilton et al, 2009), it is possible that there may be cryptic species within the various Cloacina morphospecies found in this host. Molecular analyses of several species of Cloacina collected from across the range of host species would allow us to ascertain whether differences in geographical location of the host drive genetic differentiation in its parasites.…”

“…Although studies have been conducted on genetic variation within species of Cloacina (Chilton et al, 1997a(Chilton et al, , 2009), sample sizes have often been small. Given that a number of species of kangaroo and wallaby have extensive, continuous ranges (Beveridge et al, 2010;Van Dyck and Strahan, 2008), an investigation of the genetic variation found within Cloacina species from one particular macropodid host that was distributed across a wide geographical range would be valuable, as it would provide insights into the potential genetic diversification of species within the genus Cloacina across similarly large geographical expanses.…”

Analysis of genetic variation in Globocephaloides populations from macropodid marsupials using a mutation scanning‐based approach

“…There is a clear precedent for cryptic species in strongylid nematodes of macropodid marsupials. A number of previous studies have discovered cryptic species and/or proposed adaptive speciation [13,23,24,[30][31][32][33]. For example, Huby-Chilton et al [31] used a mutation scanning-sequencing approach to detect 5.2% sequence variation in ITS-2 between two forms of Zoniolaimus mawsonae (Nematoda: Strongyloidea) from M. rufus and concluded that they represented sibling species.…”