- 著者
- Kakui Keiichi Hiruta Chizue
- 出版者
- NRC Research Press (Canadian Science Publishing)
- 雑誌
- Canadian Journal of Zoology (ISSN:00084301)
- 巻号頁・発行日
- vol.100, no.8, pp.481-487, 2022
- 被引用文献数
- 3
Hermaphroditism has been widely reported in the Crustacea, but protogyny, in which females change to males, is apparently rare and restricted to the peracarid orders Isopoda and Tanaidacea. In the latter, protogyny has been demonstrated in only seven species representing six genera by rearing experiments and indicated for several other genera and species through morphology. Here, we show through rearing experiment and histological observations, protogynous hermaphroditism in the tanaidacean species Nesotanais sp. aff. ryukyuensis Kakui, Kajihara and Mawatari, 2010. Our rearing experiment and size distribution data for wild individuals showed that females can change sex at various sizes (= ages). We found one individual identified externally as a female containing both ovaries and testes, indicating that overt female individuals undergo a short transitional phase as simultaneous hermaphrodites before the sex-change molt. We discuss the relationship among the wide size distribution of sex-changing females, the short life span of males, and the tube-dwelling mode of life.
- 著者
- Yasuda Shumpei P Vogel Peter Tsuchiya Kimiyuki Han Sang-Hoon Lin Liang-Kong Suzuki Hitoshi
- 出版者
- National Research Council Canada
- 雑誌
- Canadian Journal of Zoology (ISSN:00084301)
- 巻号頁・発行日
- vol.83, no.11, pp.1411-1420, 2005-11
- 被引用文献数
- 50
We examined sequence variation in the mitochondrial cytochrome b gene (1140 bp, n = 73) and control region (842–851 bp, n = 74) in the Eurasian harvest mouse (Micromys minutus (Pallas, 1771)), with samples drawn from across its range, from Western Europe to Japan. Phylogeographic analyses revealed region-specific haplotype groupings combined with overall low levels of inter-regional genetic divergence. Despite the enormous intervening distance, European and East Asian samples showed a net nucleotide divergence of only 0.36%. Based on an evolutionary rate for the cytochrome b gene of 2.4%·(site·lineage·million years)–1, the initial divergence time of these populations is estimated at around 80 000 years before present. Our findings are consistent with available fossil evidence that has recorded repeated cycles of extinction and recolonization of Europe by M. minutus through the Quaternary. The molecular data further suggest that recolonization occurred from refugia in the Central to East Asian region. Japanese haplotypes of M. minutus, with the exception of those from Tsushima Is., show limited nucleotide diversity (0.15%) compared with those found on the adjacent Korean Peninsula. This finding suggests recent colonization of the Japanese Archipelago, probably around the last glacial period, followed by rapid population growth.