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

Abstract

Three species of Globocephaloides, parasitic nematodes occurring in macropodid marsupials in different areas of Australia, were characterized by the sequences of the first and second internal transcribed spacers (ITS-1 and ITS-2) of nuclear ribosomal DNA. Samples were subjected to PCR-coupled SSCP analysis and targeted sequencing, in order to assess genetic variation within and among individuals from different host species. Both SSCP and sequence data supported the current classification of morphospecies. Contrary to a previous hypothesis that cryptic species exist within the Globocephaloides trifidospicularis "complex", no or minor (0.2%) variation was detected among individuals from different hosts or geographical origins. Within G. macropodis populations, there was a consistent difference in both the ITS-1 (5.2%) and ITS-2 (7.1%) sequences between individuals derived from Macropus agilis and those from Macropus dorsalis. Although the results suggested that G. macropodis from each host species represented sibling species, future morphological study of individuals representing each G. macropodis genotype is warranted to provide further support for this hypothesis. (Nucleotide sequence data have been deposited in the GenBank database under accession nos. GQ131400-GQ131409.).

The population genetics of parasitic nematodes of wild animals

“…In some cases, these studies also show whether, and if so, how, populations within these cryptic species are geographically structured. For example, geographical structuring of genetic diversity was not seen in populations of Globocephaloides trifidospicularis [ 26 ], nor in several species within the Hypodontus macropi complex [ 27 ], nor in Rugopharynx australis from Macropus robustus and M. rufus [ 28 ], nor in several Capillaria species [ 29 ], but was observed in populations of H. macropi from subspecies of Macropus robustus , H. macropi from subspecies of Macropus rufogriseus [ 27 ] and Labiosimplex australis from M. rufogriseus [ 30 ]. In some cases, studies have failed to detect any genetic variation within parasitic nematode species at all, such as in H. macropi from Petrogale persephone [ 27 ], Globocephaloides affinis from Macropus dorsalis [ 26 ], and several other Cloacina species [ 31 ], but this may be due to the very low numbers of hosts and parasites studied (Table 2 ).…”

“…One taxon in P. persephone , the other in all other host species. [ 31 ] Globocephaloides macropodis 4 Macropus dorsalis ; 1 M. agilis ITS1 and ITS2 G. macropodis from each host species had fixed differences at 5.2% and 7.1% of nucleotides in ITS1 and ITS2, respectively [ 26 ] …”

Resurrection and redescription of Globocephaloides wallabiae Johnston et Mawson, 1939 (Nematoda, Trichostrongyloidea) from macropodid marsupials in north-eastern Australia

“…In a recent molecular study, Fazenda et al (2009) analyzed the genetic variation in populations of Globocephaloides using single-stranded conformation polymorphism followed by targeted sequencing, and determined that there was consistent and significant difference in the sequences of the internal transcribed spacers of the nuclear ribosomal DNA (5% and 7% for ITS-1 and ITS-2, respectively) between G. macropodis derived from M. dorsalis and M. agilis (compared with no variation among individual worms from each host species). In the present study, the posterior and anterior ends of male and female specimens (AHC 45367) from G. macropodis used for molecular study (Fazenda et al 2009) were examined in detail by light microscopy.…”

“…In the present study, the posterior and anterior ends of male and female specimens (AHC 45367) from G. macropodis used for molecular study (Fazenda et al 2009) were examined in detail by light microscopy.…”

“…Recently, Fazenda et al (2009) assessed genetic variation in populations of Globocephaloides using a mutation scanning-based approach and demonstrated that there was a consistent difference in the sequences of the internal transcribed spacers (ITS) of nuclear ribosomal DNA between individuals of G. macropodis derived from M. agilis and those obtained Fazenda et al 140 from M. dorsalis. These molecular data raised the hypothesis that two sibling species occur in Queensland, G. macropodis in M. agilis and a second species in M. dorsalis.…”