Limits...
Comparative Phylogenetic Studies on Schistosoma japonicum and Its Snail Intermediate Host Oncomelania hupensis: Origins, Dispersal and Coevolution.

Attwood SW, Ibaraki M, Saitoh Y, Nihei N, Janies DA - PLoS Negl Trop Dis (2015)

Bottom Line: The results are consistent with a hypothesis of East to West colonisation of China by Oncomelania with a re-invasion of Japan by O. hupensis from China.The results also have implications for the spread of S. japonicum.Additional work is required to assess further the risk of spread of S. japonicum.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Biotherapy, West China Hospital, West China Medical School, Sichuan University, Chengdu, People's Republic of China; Department of Life Sciences, The Natural History Museum, London, United Kingdom.

ABSTRACT

Background: Schistosoma japonicum causes major public health problems in China and the Philippines; this parasite, which is transmitted by freshwater snails of the species Oncomelania hupensis, causes the disease intestinal schistosomiasis in humans and cattle. Researchers working on Schistosoma in Africa have described the relationship between the parasites and their snail intermediate hosts as coevolved or even as an evolutionary arms race. In the present study this hypothesis of coevolution is evaluated for S. japonicum and O. hupensis. The origins and radiation of the snails and the parasite across China, and the taxonomic validity of the sub-species of O. hupensis, are also assessed.

Methodology/principal findings: The findings provide no evidence for coevolution between S. japonicum and O. hupensis, and the phylogeographical analysis suggests a heterochronous radiation of the parasites and snails in response to different palaeogeographical and climatic triggers. The results are consistent with a hypothesis of East to West colonisation of China by Oncomelania with a re-invasion of Japan by O. hupensis from China. The Taiwan population of S. japonicum appears to be recently established in comparison with mainland Chinese populations.

Conclusions/significance: The snail and parasite populations of the western mountain region of China (Yunnan and Sichuan) appear to have been isolated from Southeast Asian populations since the Pleistocene; this has implications for road and rail links being constructed in the region, which will breach biogeographical barriers between China and Southeast Asia. The results also have implications for the spread of S. japonicum. In the absence of coevolution, the parasite may more readily colonise new snail populations to which it is not locally adapted, or even new intermediate host species; this can facilitate its dispersal into new areas. Additional work is required to assess further the risk of spread of S. japonicum.

No MeSH data available.


Related in: MedlinePlus

The locations of the sample sites in China and Japan.The coloured spots indicate areas from which snail and worm populations were sampled (red and green respectively). Most of the red spots lie on top of a green spot, indicating that the snails and the worms were sampled from the same locality. The coloured regions define biogeographical areas, within which there are no significant barriers to snail dispersal (e.g., no high mountains). Philippine samples (worms and snails) were included, but omitted from the map to increase resolution. Abbreviations are listed in Table 1. Plotted using the OpenStreetMap package in R.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4521948&req=5

pntd.0003935.g001: The locations of the sample sites in China and Japan.The coloured spots indicate areas from which snail and worm populations were sampled (red and green respectively). Most of the red spots lie on top of a green spot, indicating that the snails and the worms were sampled from the same locality. The coloured regions define biogeographical areas, within which there are no significant barriers to snail dispersal (e.g., no high mountains). Philippine samples (worms and snails) were included, but omitted from the map to increase resolution. Abbreviations are listed in Table 1. Plotted using the OpenStreetMap package in R.

Mentions: Clearly, S. japonicum continues to pose a serious public health problem and inter-disciplinary research is required to understand the patterns of transmission and persistence of the disease. Phylogeographical studies can shed light on the problem, particularly in determining where the disease comes from, explaining current distributions of the intermediate host and predicting future epidemiology. Comparative phylogenetics can help detect patterns of host-parasite coevolution and indicate any potential for regional adaptation. Despite the potential of such approaches, relatively little work has been done in this area for S. japonicum. The present study was therefore performed in order to apply current phylodynamic techniques to the estimation of sources and tracts of dispersal for this parasite and to test for the signatures of host-parasite coevolution during the evolution of S. japonicum and its intermediate hosts (the latter necessarily having the defining influence on the distribution of the parasite). Strictly, the techniques used here test for phylogenetic congruence rather than directly for coevolution. The absence of phylogenetic congruence would make long-term coevolution unlikely; thus providing an indirect test for the latter. The study aimed to utilise the largest and most geographically extensive data set available (Fig 1).


Comparative Phylogenetic Studies on Schistosoma japonicum and Its Snail Intermediate Host Oncomelania hupensis: Origins, Dispersal and Coevolution.

Attwood SW, Ibaraki M, Saitoh Y, Nihei N, Janies DA - PLoS Negl Trop Dis (2015)

The locations of the sample sites in China and Japan.The coloured spots indicate areas from which snail and worm populations were sampled (red and green respectively). Most of the red spots lie on top of a green spot, indicating that the snails and the worms were sampled from the same locality. The coloured regions define biogeographical areas, within which there are no significant barriers to snail dispersal (e.g., no high mountains). Philippine samples (worms and snails) were included, but omitted from the map to increase resolution. Abbreviations are listed in Table 1. Plotted using the OpenStreetMap package in R.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4521948&req=5

pntd.0003935.g001: The locations of the sample sites in China and Japan.The coloured spots indicate areas from which snail and worm populations were sampled (red and green respectively). Most of the red spots lie on top of a green spot, indicating that the snails and the worms were sampled from the same locality. The coloured regions define biogeographical areas, within which there are no significant barriers to snail dispersal (e.g., no high mountains). Philippine samples (worms and snails) were included, but omitted from the map to increase resolution. Abbreviations are listed in Table 1. Plotted using the OpenStreetMap package in R.
Mentions: Clearly, S. japonicum continues to pose a serious public health problem and inter-disciplinary research is required to understand the patterns of transmission and persistence of the disease. Phylogeographical studies can shed light on the problem, particularly in determining where the disease comes from, explaining current distributions of the intermediate host and predicting future epidemiology. Comparative phylogenetics can help detect patterns of host-parasite coevolution and indicate any potential for regional adaptation. Despite the potential of such approaches, relatively little work has been done in this area for S. japonicum. The present study was therefore performed in order to apply current phylodynamic techniques to the estimation of sources and tracts of dispersal for this parasite and to test for the signatures of host-parasite coevolution during the evolution of S. japonicum and its intermediate hosts (the latter necessarily having the defining influence on the distribution of the parasite). Strictly, the techniques used here test for phylogenetic congruence rather than directly for coevolution. The absence of phylogenetic congruence would make long-term coevolution unlikely; thus providing an indirect test for the latter. The study aimed to utilise the largest and most geographically extensive data set available (Fig 1).

Bottom Line: The results are consistent with a hypothesis of East to West colonisation of China by Oncomelania with a re-invasion of Japan by O. hupensis from China.The results also have implications for the spread of S. japonicum.Additional work is required to assess further the risk of spread of S. japonicum.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Biotherapy, West China Hospital, West China Medical School, Sichuan University, Chengdu, People's Republic of China; Department of Life Sciences, The Natural History Museum, London, United Kingdom.

ABSTRACT

Background: Schistosoma japonicum causes major public health problems in China and the Philippines; this parasite, which is transmitted by freshwater snails of the species Oncomelania hupensis, causes the disease intestinal schistosomiasis in humans and cattle. Researchers working on Schistosoma in Africa have described the relationship between the parasites and their snail intermediate hosts as coevolved or even as an evolutionary arms race. In the present study this hypothesis of coevolution is evaluated for S. japonicum and O. hupensis. The origins and radiation of the snails and the parasite across China, and the taxonomic validity of the sub-species of O. hupensis, are also assessed.

Methodology/principal findings: The findings provide no evidence for coevolution between S. japonicum and O. hupensis, and the phylogeographical analysis suggests a heterochronous radiation of the parasites and snails in response to different palaeogeographical and climatic triggers. The results are consistent with a hypothesis of East to West colonisation of China by Oncomelania with a re-invasion of Japan by O. hupensis from China. The Taiwan population of S. japonicum appears to be recently established in comparison with mainland Chinese populations.

Conclusions/significance: The snail and parasite populations of the western mountain region of China (Yunnan and Sichuan) appear to have been isolated from Southeast Asian populations since the Pleistocene; this has implications for road and rail links being constructed in the region, which will breach biogeographical barriers between China and Southeast Asia. The results also have implications for the spread of S. japonicum. In the absence of coevolution, the parasite may more readily colonise new snail populations to which it is not locally adapted, or even new intermediate host species; this can facilitate its dispersal into new areas. Additional work is required to assess further the risk of spread of S. japonicum.

No MeSH data available.


Related in: MedlinePlus