A DNA sequence-based study of theSchistosoma indicum(Trematoda: Digenea) group: population phylogeny, taxonomy and historical biogeography

Abstract

Partial (DNA) sequences were collected for 2 mitochondrial loci (Srrna and Lrrna, the rrnS and rrnL rRNA genes respectively) for Schistosoma indicum group species from 4 Southeast Asian countries. The samples included 7 populations, 4 of which were previously unstudied. In 11 cases the combination of locus and population was new. The aim of the study was to provide a phylogeny based on new independent data and multiple populations (earlier studies had mostly used a common set of field samples or laboratory lines) and to examine interrelationships and phylogeography within this species group. Paraphyly of the S. indicum group was confirmed, as was the basal position of Schistosoma incognitum in the Schistosoma phylogeny. Southeast Asian Schistosoma spindale and S. incognitum populations were shown to fall into their respective con-specific cohesive groupings. Estimated divergence times for these taxa were shown to be related to Pleistocene changes in sea level and the radiation of definitive host groups. A revised phylogeographical model is proposed in the light of these findings.

Recent range expansion of an intermediate host for animal schistosome parasites in the Indo-Australian Archipelago: phylogeography of the freshwater gastropod Indoplanorbis exustus in South and Southeast Asia

“…The diversification of the S. indicum group in South and Southeast Asia is not well established yet. However, the emergence of the different species forming the group is thought to have occurred lately during the Late Pleistocene [5], a period coinciding with intra-clade diversification processes in Indoplanorbis . Parasite dispersal and geographical diversification are strongly related to host dispersal ability and degree of connectivity among host populations [88].…”

“…Schistosoma indicum , S. nasale , S. spindale and a new lineage recently discovered, Schistosoma sp. are the four species constituting this group of mammalian parasites endemic to Asia [5, 6]. All four species use the freshwater bulinine planorbid snail Indoplanorbis exustus (Deshayes, 1864) as sole intermediate host during their larval stage.…”

A phylogeny for the pomatiopsidae (Gastropoda: Rissooidea): a resource for taxonomic, parasitological and biodiversity studies

“…Nevertheless, a normal prior (5.0 ± 1.0 Ma) was applied to the TMRCA of the S. sinensium group in the initial paper [60]. The prior was based on a date for the second major Himalayan orogeny; however, this was referring to events isolating Central Asia from the Orient [163], i.e., the acceleration of Tian Shan uplift at 5 Ma [88]. The prior is therefore not directly related to Himalayan events hypothesized in the Tibet or Hunan hypotheses, which mostly concern uplift in Southwest China.…”

Schistosoma comparative genomics: integrating genome structure, parasite biology and anthelmintic discovery

“…Utilising a proven strategy to compare phylogenetically related genomes[11], regions of chromosomal similarity and dissimilarity are identified between basal- ( S. japonicum ) and derived- ( S. mansoni ) schistosome species[12]. Complementing this karyotypic analysis is a review of how improvements in intergenus comparative and functional genomics can be applied to identify schistosome gene products of potential importance to parasite viability, development and host interrelationships.…”