Species diversity and conservation of Mandarina, an endemic land snail of the Ogasawara Islands

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The endemic land snails, genus Mandarina of the Ogasawara Islands, have diversified into arboreal, semi-arboreal and ground ecotypes. Shell morphologies of Mandarina species have a clear relationship with their respective ecotypes. In addition, marked geographical variations in morphology and genes are found within species. Phylogenetic relationships based on mitochondrial DNA (mtDNA) sequences suggests that Mandarina evolved from Euhadra, a genus distributed on the mainland of Japan. The inferred phylogeny suggests that similar morphologies and ecotypes appeared independently and rapidly in different lineages and islands at different times. This rapid evolution produced some incongruities among phylogenetic relationships, morphology, species taxonomy, and the level of reproductive isolation. Interspecific hybridization occurs between sympatric species due to environmental change, resulting in an admixture of genetic and morphological characteristics. These findings reveal the importance of Mandarina as a model system for evolutionary study. However, a predatory land snail and flatworm have recently been introduced into the Ogasawaras. These predators may rapidly cause the extinction of Mandarina, and thus, a conservation program is needed for Mandarina. In the conservation program for Mandarina, species taxonomy should not be used as a criterion for selection of populations for captive breeding because of incongruence among the phylogeny, morphology, ecology, species taxonomy and reproductive isolation. In addition, the danger of interspecific hybridization should be considered when captive-bred snails are reintroduced into restored or secure habitat. Reprinted from Chiba S (2003) Global Environmental Research 7:29-37, with permission of the Association of International Research Initiatives for Environmental Studies.

Original languageEnglish
Title of host publicationRestoring the Oceanic Island Ecosystem
Subtitle of host publicationImpact and Management of Invasive Alien Species in the Bonin Islands
PublisherSpringer Japan
Number of pages9
ISBN (Electronic)9784431538592
ISBN (Print)9784431538585
Publication statusPublished - 2010


  • adaptive radiation
  • conservation
  • hybridization
  • Mandarina
  • Ogasawara Islands


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