Eiji Hosoi

Distribution of two distinct lineages of sika deer (Cervus nippon) on Shikoku Island revealed by mitochondrial DNA analysis

ABSTRACT Nucleotide sequences of sika deer (Cervus nippon) collected from the eastern part of Shikoku Island were investigated & compared with those from other areas. Nucleotide sequence of the whole D-loop region of the mitochondrial DNA was determined by direct sequencing technique for each sample. The phylogenetic tree constructed by the sequences indicates that sika deer from Shikoku Island are divided into two distinct lineages: the northern Japan group and the southern Japan group. Proportion of the northern Japan lineage was higher in the northeastern part of the sampling area. There was no border between the distribution of the two lineages, rather it seemed that their distribution intermingled. Besides, there were locations where both lineages were found within a small area. These results indicate that two lineages might be hybridized in some areas of eastern Shikoku.

Phylogenetic relationship of the southern Japan lineages of the sika deer (Cervus nippon) in Shikoku and Kyushu Islands, Japan

ABSTRACT Samples of the sika deer (Cervus nippon) were collected from Kyushu and Shikoku Islands of Japan and surrounding areas, and their nucleotide sequences were analyzed. Sequences of the whole control region of the mitochondrial DNA were determined and phylogenetic trees were constructed using the neighbor-joining method and the maximum likelihood method. We also investigated gene genealogies for the sequences using the statistical parsimony network approach. Phylogenetic trees showed that only the Yakushima/Tanegashima populations were genetically distant from other populations. The statistical parsimony network, however, indicated a close relationship of the Miyazaki populations to some of the Shikoku populations. It was suggested that Shikoku Island played an important role in the divergence from the southern Japan lineage of C. nippon.

Compensatory response of molar eruption for environment-mediated tooth wear in sika deer

Abstract Teeth move continuously in the occlusal direction after they have approached the occlusal plane, which is considered a compensatory mechanism for loss of tooth crown by wear, although quantitative data have been inadequate. To clarify phenotypic correlation of tooth eruption and wear 10 populations of wild sika deer (Cervus nippon) in Japan were investigated. Mandibles, with ages assigned by cementum annuli of incisor roots, were used to estimate molar wear rate and eruption timing. Molar eruption status was assessed by observation of the buccal side of molars and coded as 3 ordinal levels according to the appearance of a cervical line (a boundary between molar crown and root). Logistic regression of the eruption status revealed that eruption timing of the lower 3rd molar (m3) was significantly different among populations (P < 0.0001) and correlated with m3 wear rate; faster molar wear resulted in faster molar eruption (P < 0.01). Eruption timing of lower 1st (m1) and 2nd (m2) molars did not show significant correlation with wear rate, possibly due to less variation in eruption timing in m1 and m2 than for m3. These findings indicate that the compensatory response of molar eruption occurs for m3 in accordance with wear mediated by environments.

Interspecific comparison of allometry between body weight and chest girth in domestic bovids

The sizes of body parts often co-vary through exponential scaling, known as allometry. The evolution of allometry is central to the generation of morphological diversity. To make inferences regarding the evolved responses in allometry to natural and artificial selection, we compared allometric parameters (slope and intercept) among seven species and breeds of domestic bovids using cross-sectional ontogenetic data and attempted to interpret the differences in these parameters. The allometric slopes were not different among some species, whereas those between breeds within species were, indicating that the slopes were typically invariant but could be changed under strong, specific selection. With the exception of yak, the differences in the intercept independent of the slopes (the alternative intercept) among species might better correspond to their divergence times than the differences in allometric slope, and the remarkably higher alternative intercept found in yaks can be explained by their unique morphological evolution. These findings provide evidence that differences in the alternative intercept can retain traces of the phylogenetic changes derived from differentiation and evolution.

Reproductive Activity of the Small Japanese field mouse (Apodemus argenteus) in Yamaguchi Prefecture, Japan

The small Japanese field mouse (Apodemus argenteus) is endemic to Japan that is distributed on all of the main islands of Japan, including Hokkaido, Honshu, Shikoku and Kyushu, and on smaller islands larger than approximately 150 km 2 (Nakata et al. 2009). It is widely distributed from lowlands to alpine zones, and is semi-arboreal, feeding mainly on seeds, fruits, and arthropods (Abe et al. 2005). The breeding season of this species varies geographically; reproduction peaks in the summer in Hokkaido and in sub-alpine zones of Honshu (Miyao et al. 1963; Fujimaki 1969; Kimura 1977; Tateishi 2006), in the spring and summer in the lowlands and low montane areas of Honshu (Yukawa 1973; Murakami 1974; Nishikata 1979; Torii and Tanaka 1989; Shibata 2000), and in the winter in Kyushu (Yoshida 1972). In Yamaguchi Prefecture, located in the westernmost part of Honshu, characterization of this species is very limited and its life cycle and breeding season remain unknown. Therefore, this study sought to determine the reproductive activity of the small Japanese field mouse in Yamaguchi Prefecture.