Population genetic structure, diversity and stocking effect of the oriental weatherloach (Misgurnus anguillicaudatus) in an isolated island

Abstract

Genetic endemism of island organisms and the threat to such organisms provided by artificially introduced genes are aspects of major interest in evolutionary and conservation studies of fishes. In this paper the genetic population structure of the oriental weatherloach, Misgurnus anguillicaudatus, in Sado Island of Japan was elucidated by phylogeographic analysis based on partial mitochondrial control region sequences. The specimens were sampled at 62 sites in Sado Island and 14 sites on the mainland close to the island. We found various haplotypes of different origins, most of which had already been reported from the mainland and other places of Japan. This suggests that the loach has been historically introduced to the island from various regions of Japan. Of the 62 sites on the island, cultured/nonnative individuals were confirmed to have been stocked at eight specific sites for feeding of re-introduced Japanese crested ibis (Nipponia nippon). By a Mantel test, geographical and genetic distances were not significantly correlated among the local populations in Sado Island. However a significant correlation was found when the eight stocked local populations were excluded from the analysis. This implied that the genetic distribution pattern of the loach on the island has been disturbed by the stocking. In addition, the nucleotide diversity values of stocked local populations were significantly higher than those of other local populations, also a likely outcome of the stocking. In conclusion, the loach on Environ Biol Fish (2011) 90:211-222 the island likely had their origins in multiple historical introductions and colonizations, where more recent stocking for the ibis has caused further genetic disturbance to their local populations.

Photo images, 3D models and CT scanned data of loaches (Botiidae, Cobitidae and Nemacheilidae) of Japan

“…(Clade A) is a native loach clade of Japan, although the distribution is limited to northern parts such as Hokkaido and eastern Honshu (Morishima et al 2008, Nakajima and Uchiyama 2017). Misgurnus anguillicaudatus (Clade B1) is another clade native to Japan and is widely distributed amongst Hokkaido (likely domestically introduced from Honshu), Honshu, Shikoku, Kyushu and several isolated islands (Morishima et al 2008, Kano et al 2011). Misgurnus anguillicaudatus (Clade B2) is a non-native clade introduced from mainland China and is also widely distributed amongst Honshu, Kyushu and Sado Island (Morishima et al 2008, Kano et al 2011).…”

“…Misgurnus anguillicaudatus (Clade B1) is another clade native to Japan and is widely distributed amongst Hokkaido (likely domestically introduced from Honshu), Honshu, Shikoku, Kyushu and several isolated islands (Morishima et al 2008, Kano et al 2011). Misgurnus anguillicaudatus (Clade B2) is a non-native clade introduced from mainland China and is also widely distributed amongst Honshu, Kyushu and Sado Island (Morishima et al 2008, Kano et al 2011). Misgurnus anguillicaudatus (Jindai), so-called "Jindai-dojyô" in Japanese, meaning "God's vicarious loach" or "loach in God's era", is an unusual local population that is already extinct.…”

“…As well as molecular genetic research (Kitagawa et al 2001a, Kitagawa et al 2001b, Kitagawa et al 2003b, Kitagawa et al 2003a, Kitagawa et al 2005, Suzawa 2006, Morishima et al 2008, Saitoh et al 2010, Kano et al 2011, Shimizu et al 2011, Kano et al 2012, Nakajima 2012, Nakajima 2016, Nakajima and Suzawa 2016, Nakajima and Uchiyama 2017), morphological examinations are needed for further development of loach study. Digital archiving of fish specimens is one of the progressive challenges in ichthyology for open science (Kanagawa Prefectural Museum of Natural History and National Museum of Nature and Science 1998, Berquist et al 2012, Kano et al 2013, Kano et al 2016).…”