Hiroshi Takahashi

Fallen leaves and unpalatable plants as alternative foods for sika deer under food limitation

Feeding behavior and rumen contents of sika deer (Cervus nippon Temminck) under food limitation were studied on Nakanoshima Island, Hokkaido. During the phase of population growth, the deer subsisted on tree bark and twigs, deciduous leaves and dwarf bamboos (Sasa spp.) in the winter. After a crash in population, the deer began feeding on the fallen leaves of deciduous trees and continued to do so throughout the year. They also ate unpalatable plants Cephalotaxus harringtonia var. nana Rehd., Senecio cannabifolius Less. and Cynanchum caudatum Maxim. as winter foods, which used to remain untouched by deer, and had accordingly expanded their distributions, following a decrease in the amount of dwarf bamboos available. These facts suggest that sika deer drastically shift their foods and exploit alternative foods under conditions of food limitation.

Detection of Rickettsia helvetica DNA from peripheral blood of Sika deer (Cervus nippon yesoensis) in Japan.

Partial nucleotide sequences of the citrate synthase and 17-kDa genes of Rickettsia helvetica were detected from peripheral blood samples of Sika deer (Cervus nippon yesoensis) in Hokkaido, Japan. Results suggest the presence of a rickettsiemia associated with R. helvetica. This is the first evidence of R. helvetica infection in Sika deer and indicates that this species may represent a potential reservoir host of R. helvetica in Japan.

Phylogeography of lateral plate dimorphism in the freshwater type of ninespine sticklebacks, genus Pungitius

Abstract The freshwater type of ninespine sticklebacks, genus Pungitius, is widely distributed in northern Japan and reproductively isolated from other genetically divergent types endemic to small regions in Japan. This type expresses dimorphism in its lateral plate morphology: complete and partial row morphs. The two morphs show a parapatric distribution in Japan. To clarify the process involving the distribution of these two morphs, we examined their phylogeography based on restriction fragment length polymorphism of an entire mitochondrial DNA (mtDNA). The survey was carried out with seven restriction enzymes on the populations of the freshwater type collected from 41 localities across the distribution range in Japan, and 6 further Pungitius populations from the Okhotsk Sea coast of Russia were appended. An unweighted pair-group method with arithmetic averages (UPGMA) tree among 54 mtDNA haplotypes resolved eight clustering groups that differed in sequence divergence by approximately 1.3%–2.1%. Two of the eight groups were found only in Russia. mtDNA phylogenies constructed by neighbor-joining and Wagner parsimony methods suggested that the haplotypes of each plate morph were polyphyletic. The geographic distribution pattern of these groups suggests that they should be classified into two broad categories, one with extensive distribution and the other with localized distribution of the constituent haplotypes within a group. The former groups were found mainly in the populations with the completely plated morph and the latter groups with the partially plated morph. It is supposed that twice dispersals of dimorphic or complete plated ancestors and genetic differentiation during the interglacial played an important role in the formation of the present distribution of the two morphs in Japan.

GEDIMAP: a database of genetic diversity for Japanese freshwater fishes

Genetic diversity is a key component of biodiversity, and thus represents important information for evolutionary and conservation biology. DNA sequence data are primary sources of information on genetic diversity and are now accumulated and managed in international databases, such as the DNA Data Bank of Japan (DDBJ), the European Molecular Biology Laboratory (EMBL) Nucleotide Sequence Database, and GenBank of the US National Center for Biotechnology Information (NCBI). Such databases provide basic information that is used in most areas of contemporary bioscience (Brunak et al. 2002). MitoFish (Nishida 2009), a DNA database devoted to the mitochondrial DNA (mtDNA) genomes of fish, supports research into fish biology, and contains links to other international DNA databases and general fish databases (e.g., FishBase; Froese and Pauly 2009). Genetic diversity and divergence within and among local populations within a species are primary elements of biodiversity at the genetic level and are of essential conceptual and practical importance (Avise 2004). Genetic data from population genetic and phylogeographic studies based on various genetic markers, especially mtDNA sequences, are increasingly being reported. However, the DNA databases mentioned above do not provide effective functions for accumulating and searching for population genetic data, which are based on allele frequencies in each population with geographical data. Thus, when researchers want to browse or reuse data from previous studies, they typically need to reconstruct such a dataset by combining information described in original papers with that deposited in the DNA databases. Further, probably because of the lack of a platform for accumulating such information, a significant proportion of the papers do not provide fundamental information for reconstructing the population genetic data analyzed in those papers. Thus, it is difficult for anyone to use these valuable data secondarily. This situation impedes evolutionary and biogeographic research and applications in biodiversity conservation based on comprehensive population genetic data, and it leads to a waste of human, monetary, and wildlife resources. To improve this situation, we have constructed a comprehensive database for genetic diversity in Japanese freshwater fish. Freshwater fish are good targets for studying evolution and biogeography because of their restricted dispersal ability and conspicuous intraspecific divergence (Avise 2000; Watanabe et al. 2006). Research in this area will benefit from accumulated population genetic data. Here, we outline and describe the application of the database. ‘‘GEDIMAP’’ (genetic diversity and distribution map) is a public database primarily for mtDNA genetic diversity data within populations of freshwater fish in and around Japan (URL: http://gedimap.zool.kyoto-u.ac.jp/). The beta version was released in January 2008, and the current K. Watanabe (&) R. Kakioka K. Tominaga Department of Zoology, Division of Biological Science, Graduate School of Science, Kyoto University, KitashirakawaOiwakecho, Sakyo-ku, Kyoto 606-8502, Japan e-mail: watanak@terra.zool.kyoto-u.ac.jp

Distinct spawning migration patterns in sympatric Japan Sea and Pacific Ocean forms of threespine stickleback Gasterosteus aculeatus

Spawning migration patterns were compared between sympatric populations of the anadromous Japan Sea (JS) form and Pacific Ocean (PO) form of the threespine stickleback Gasterosteus aculeatus in the Lake Akkeshi–Bekanbeushi River system, eastern Hokkaido, Japan. In Akkeshi Bay and Lake Akkeshi, the JS form had longer collecting peak periods and more collection peaks than the PO form. Furthermore, although the PO form migrated upstream in freshwater habitats, the greater part of the JS form stayed in brackish waters before breeding. These findings suggest that the 2 forms have distinctly different spawning migration patterns and breeding grounds.

Hybrid Male Sterility between the Fresh- and Brackish-water Types of Ninespine Stickleback Pungitius pungitius (Pisces, Gasterosteidae)

Abstract Two ecologically distinct forms, fresh- and brackish-water types, of ninespine stickleback coexist in several freshwater systems on the coast of eastern Hokkaido. Recent genetic analyses of 13 allozyme loci revealed genetic separation between the two types even though their spawning grounds were in close proximity. On the other hand, there is only a small difference in mitochondrial DNA (mtDNA) sequence between the two types suggesting that they diverged quite recently or that mtDNA introgression occurred between them. To test for postzygotic reproductive isolating mechanisms and hybrid mediated gene flow, we examined the viability and reproductive performance of reciprocal F1 hybrids. The hybrids grew to the adult size normally and both sexes expressed secondary sexual characters in the reciprocal crosses. The female hybrids were reciprocally fertile, while the male hybrids were reciprocally sterile. Histological and flow-cytometric analyses of the hybrid testis revealed that the sterility pattern was classified as ‘gametic sterility,’ with gonads of normal size but abnormal spermatogenesis. To our knowledge, the present finding is a novel example of one sex hybrid sterility in the stickleback family (Gasterosteidae).

Immobilization of Sika Deer with Medetomidine and Ketamine, and Antagonism by Atipamezole

Forty wild sika deer (Cervus nippon) were immobilized with medetomidine and ketamine and reversed by atipamezole in summer and fall captures from September 1994 to October 1995. For large yearling and older deer, mean ± SD doses of 57.0 ± 15.6 μg/kg medetomidine and 1.64 ± 0.49 mg/kg (male) or 4.02 ± 1.16 mg/kg (female) of ketamine were administered by intramuscular injection. For calves and small yearlings, 69.3 ± 7.0 μg/kg medetomidine and 2.69 ± 0.44 mg/kg ketamine were administered. While immobilized, deer were easy to handle, and muscles were well relaxed. After intramuscular administration of atipamezole (about 5 times the dose of medetomidine), deer recovered rapidly and smoothly.

Fecal nitrogen as an index of dietary nitrogen in two sika deer Cervus nippon populations

We tested the reliability of fecal nitrogen (FN) to predict dietary nitrogen (DN) in two sika deerCervus nippon Heude, 1884 populations with greatly differing habitats. One was near the village of Nishiokoppe (area A) and the other was on Nakanoshima Island (area B) in Hokkaido, Japan. To estimate FN, we washed feces through a sieve, and diet was identified based on rumen-content analysis. The diet in area A was mostly composed of grass and legumes of agricultural origin, with browse being only a minor component. In contrast, browse such as deciduous foliage was the main component of the diet in area B. Dietary nitrogen was significantly regressed by FN within specific areas. On the other hand, the DN-FN-relationship had a similar slope but significantly different intercepts between areas. DN-FN-relationships differed between diets with and without an agricultural component, irrespective of browse. Thus, the difference in the DN-FN-relationship between areas was explained by differences in dietary composition. We therefore conclude that FN may be useful in predicting DN in diverse dietary situations regardless of the ratio of browse in the diet of free-ranging ungulates, but that dependence on agricultural pastures may hinder the utility of FN as an index of DN.

In-situ characterization technique of compound semiconductor heterostructure growth and device processing steps based on UHV contactless capacitance-voltage measurement

Abstract In this paper, the applicability of an ultra-high vacuum (UHV) contactless capacitance-voltage ( C-V ) measurement method is evaluated for use in non-destructive characterization of crystal growth and device processing steps for the compound semiconductor heterostructure microelectronics. The UHV gap length between the sample surface and the field plate was made by an optical measurement using the Goos–Haenchen effect, and its accuracy was discussed by a theoretical calculation. Then, zero-bias position of the surface Fermi level, conduction type and doping were successfully determined on free surfaces of GaAs and InP by basic C-V measurements. Finally, the technique was applied to characterize each step of the UHV-based surface passivation process for InP utilizing the Si interface control layer (Si ICL). Change of the surface state distribution after each step was successfully detected without breaking UHV, demonstrating the powerful capability of the method.

Variation in the herd composition counts of sika deer

Herd composition counts (HCC) are commonly used to assess population status in deer. We evaluated the reliability of HCC of sika deer (Cervus nippon Temminck) using repeated counts and by comparing estimated sex ratios and calf-to-female ratios of marked deer on Nakanoshima Island, Hokkaido, Japan between April 1999 and October 2000. Although both total counts and sex and age ratios fluctuated greatly by month, seasonal changes showed a relatively small variance. This suggested that seasonal changes in behavior within sex and age classes contributed to biased ratio estimates obtained from HCC. Route counts should be used as a relative population abundance index with estimates of detection probability, especially for females. Adult sex ratios and age ratios from HCC were unbiased during the rutting season (October–November), and age ratios in spring could be used if yearlings are counted as adults.