AN ELECTROPHORETIC ANALYSIS OF PATTERNS OF SPECIATION IN CLOACINA-CLARKAE, CLOACINA-COMMUNIS, CLOACINA-PETROGALE AND CLOACINA-SIMILIS (NEMATODA, STRONGYLOIDEA) FROM MACROPODID MARSUPIALS

An electrophoretic study was conducted on Cloacina clarkae, C. communi s, C. petrogale and C. similis based on 19 enzyme loci, C. communis wa s widely distributed in Macropus robustus, showing some genetic variat ion among populations but occasionally switching to other macropodid h osts (M. agilis, M. antilopinus). C. similis occurred in members of th e Petrogale penicillata complex, Macropus dorsalis and Thylogale billa udierii, but showed no evidence of genetic differentiation in spite of its occurrence in different host species and in geographically distin ct regions of Australia. C. clarkae from Macropus eugenii was genetica lly indistinguishable from C. similis and was considered synonymous wi th it, C. petrogale occurred in a similarly diverse range of hosts and geographical regions to C. similis, but was represented electrophoret ically as 4 distinct genetic species, 1 in Petrogale assimilis, a seco nd in P. lateralis purpureicollis, a third in Macropus parryi in Queen sland and a fourth in M. eugenii in South Australia. Although the host and geographical ranges of C. similis and C. petrogale are analogous, the genetic uniformity of the former and diversity of the latter illu strate the incomplete understanding we have of the immediate causes of speciation in nematodes. (C) 1997 Australian Society for Parasitology .