Geographic pattern of genetic variation in the fox tapeworm Echinococcus multilocularis

Phylogenetic Pattern, Evolutionary Processes and Species Delimitation in the Genus Echinococcus

“…It has often been suggested that the reproductive biology of species of Echinococcus, with a combination of self-fertilisation and extensive asexual reproduction, has a profound effect on evolutionary processes, leading to the genetic uniformity of local populations and rapid genetic differentiation among populations subject to different selection pressures (Smyth and Smyth, 1964;McManus and Smyth, 1986;Bryant and Flockhart, 1986;Haag et al, 2008;Nakao et al, 2009Nakao et al, , 2010aNakao et al, , 2013b. This is thought to occur because the population genetic consequences of obligate self-fertilisation and asexual reproduction are almost complete homozygosity, extensive linkage disequilibrium (non-random association of alleles at different loci) and a distribution of genetic diversity between, rather than within family groups, which will lead to spatial structuring 11 of genetic variation if dispersal is limited.…”

“…As E. felidis and E. granulosus are sister species, then presumably they shared a common ancestor in Asia prior to this time, and divergence of the lineages occurred in geographic isolation. Nakao et al (2009) suggested an origin for E. multilocularis in the region of the land bridge between Asia and North America (Beringia) during the Pleistocene (2.6 M -11,700 years ago), with subsequent spread via foxes across North America, Asia and Europe. The North American, Asian and European clades are hypothesized to have then undergone cycles of isolation in glacial refugia and dispersal from these refugia during inter-glacial periods (Nakao et al 2013b).…”

“…The North American, Asian and European clades are hypothesized to have then undergone cycles of isolation in glacial refugia and dispersal from these refugia during inter-glacial periods (Nakao et al 2013b). In Europe, for example, Nakao et al (2009) proposed an introduction of E. multilocularis in the late Pleistocene, with contraction and subsequent spread from glacial refugia, such as the Iberian, Italian and Balkan peninsulas, presumably initially to the genetically diverse Alpine arch region of Switzerland, southern Germany, eastern France and Austria (Knapp et al, 2009(Knapp et al, , 2015.…”

Genetic survey of alveolar and cystic echinococcoses in Romania: first molecular evidence of Echinococcus multilocularis in humans in the country

“…Five Echinococcus isolates from humans in north-eastern Romania were analyzed by cox1 mitochondrial sequences (789 bp). Given that species analysis of nucleotide composition identifi ed E. multilocularis in all examined isolates, we have compared obtained sequences with those referenced by Nakao et al (2009) in a study on global species geographic pattern and available in GenBank for cox1 from Europe (E1, E3, E5), Asia (A1, A5) and North America (N1, N2). Polymorphic nucleotide sites are shown in Table 2.…”

“…Whereas the sequence pattern of four isolates was completely homologous to the most widespread variant of E. multilocularis identifi ed for Europe in the cox1 gene, one isolate (R5) at the southernmost location (Tutova, Vaslui county) amongst the examined samples exhibited three nucleotide substitutions. Interestingly, one of these mutations (411T/G) corresponded to N1 and N2 haplotypes from North America described by Nakao et al (2009) and to an older human isolate from Austria obtained upon hepatic surgery in 1981 (Gottstein, personal communication; genotyping of the isolate specifi ed in Šnábel et al, 2010). The peculiar genetic composition of E. multilocularis seen in some restricted foci of Europe as Trentino Alto Adige region (Casulli et al, 2005(Casulli et al, , 2009 and in the present isolate from Vaslui county, coupled with the discontinuous distribution of the parasite in recent Europe supports a hypothesis that the European clade has been derived from isolated populations in glacial refugia such as the Italian, Balkan and Iberian peninsulas (Taberlet et al, 1998).…”