Allozymic Variation in the Japanese Clawed Salamander,Onychodactylus japonicus(Amphibia: Caudata: Hynobiidae), with Special Reference to the Presence of Two Sympatric Genetic Types

Abstract

We conducted an electrophoretic survey to examine geographic genetic variation in samples from 17 localities of the Japanese clawed salamander, Onychodactylus japonicus. This species was divided into six genetic groups (N-Tohoku, S-Tohoku, Tsukuba, SW-Honshu, Kinki, and Shikoku) that were largely concordant with clades or subclades recognized in our previous mtDNA study. Although the relationships among these six groups were not clarified, genetic distances between them were not small (mean Nel's D=0. 146-0.471). Among these groups, the geographically isolated Tsukuba group was genetically distinct, possibly as a result of population isolation. In a locality of western Honshu, two groups, SW-Honshu and Shikoku, were found to occur sympatrically. Although several presumable hybrid individuals were found, hybridization between these two groups seemed to occur very rarely. These results indicate that the Shikoku group is specifically distinct from the SW-Honshu group, whose range includes the type locality of O. japonicus.

Hybridizing salamanders experience accelerated diversification

“…This latter definition is less conservative than the former. We excluded cases where one or two individuals exhibited cyto-nuclear discordance between markers such as allozymes and mtDNA (as observed for members of Sirenidae 56 , and several Hynobiids [57][58][59][60] ), as we did not perceive these cases to meet the criteria of substantial and replicated genealogical discordance. Although inference of hybridization via the detection of genealogical discordance warrants caution, our narrow definition of hybridization does not recognize these species as hybridizable.…”

Two new Salamanders of the genus Onychodactylus from Eastern Honshu, Japan (Amphibia, Caudata, Hynobiidae)

“…This genus was traditionally considered to contain only two species, O. japonicus (Houttuyn) from Japan and O. fischeri (Boulenger) from Russian Far East, northeast China, and Korean Peninsula (Sato 1943;Nakamura & Uéno 1963;Kuzmin 1995). However, recent genetic studies (Yoshikawa et al 2008(Yoshikawa et al , 2010a(Yoshikawa et al , 2010b(Yoshikawa et al , 2012 The S-Tohoku group was recognized in the previous genetic studies based on mtDNA and allozymes (Yoshikawa et al 2008(Yoshikawa et al , 2010a(Yoshikawa et al , 2012, and was reported to be a sister taxon of O. tsukubaensis from central Kanto District of eastern Honshu. The S-Tohoku group is distributed in southern part of Tohoku District and adjacent northern parts of Ibaraki Prefecture of Kanto District and Niigata Prefecture of Hokuriku District in eastern Honshu, and is parapatric with O. japonicus sensu stricto and O. nipponoborealis (SW-Honshu and N-Tohoku groups in previous studies, respectively) without distinct geographic barriers, and their distributional ranges slightly overlap in some localities near species boundaries.…”

“…and subsequent taxonomic revisions (Poyarkov et al 2012; Yoshikawa & Matsui 2013; Yoshikawa et al 2013) added six species to this genus, by separating three species from O. fischeri sensu lato (O. koreanus Min, Poyarkov & Vieites, O. zhangyapingi Che, Poyarkov, Li & Yan, and O. zhaoermii Che, Poyarkov & Yan), and three species from O. japonicus sensu lato (O. nipponoborealis Kuro-o, Poyarkov & Vieites, O. tsukubaensis Yoshikawa & Matsui, O. kinneburiYoshikawa, Matsui, Tanabe & Okayama). However, of the six cryptic species recognized byYoshikawa et al ( , 2010a, two (southern Tohoku [S-Tohoku] and Kinki groups) remained undescribed.…”

Allozymic Variation and Phylogeography of Two Genetic Types ofOnychodactylus japonicus(Amphibia: Caudata: Hynobiidae) Sympatric in the Kinki District, Japan

“…Of these, sympatric distributions are seen between Subclades III-B and IV-A in the Kinki to Hokuriku Districts of western Honshu, and between III-C and IV-B at several localities in the Chugoku Mountains (west-ernmost Honshu). Yoshikawa et al (2010) conducted an electrophoretic survey to elucidate genetic variation in O. japonicus based on biparental allozyme markers and demonstrated that this species is divided into six genetic groups that correspond to clades or subclades recognized in mtDNA analyses. Of these, the SW-Honshu group (corresponding to Clade III), Kinki group (Subclade IV-A), and Shikoku group (Subclade IV-B) are found in southwestern Japan, and reproductive isolation between the SW-Honshu and Shikoku groups in a sympatric locality has been clarified.…”

“…Of these, the SW-Honshu group (corresponding to Clade III), Kinki group (Subclade IV-A), and Shikoku group (Subclade IV-B) are found in southwestern Japan, and reproductive isolation between the SW-Honshu and Shikoku groups in a sympatric locality has been clarified. However, reproductive isolation between the SW-Honshu and Kinki groups, which seemed likely from unique genetic features in the Kinki group, was not clear because sympatric localities were not included in the previous study (Yoshikawa et al, 2010). It was therefore necessary to clarify their genetic relationships for subsequent taxonomic reassessment of O. japonicus.…”