Takuya Miyake

Mie University, Tu, Mie, Japan

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Publications (10)8.19 Total impact

  • T. Miyake · K. Isowa · T. Ishikawa · A. Komaru · K. Kawamura
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    ABSTRACT: Genetic characteristics of four wild (Mie, Fukui, Shimane and Nagasaki) and five cultured populations (selectively bred for 12 years with an origin of Ehime population) of the Japanese pearl oyster, Pinctada fucata martensii, were evaluated by using AFLP markers. Six primer pairs generated 1019 loci in total, among which 45.2–55.1 % was polymorphic among populations. Although there was no significant difference in gene diversity between wild (0.170–0.174) and cultured (0.158–0.173) populations, genetic relatedness in cultured populations (0.316–0.450) was about three times higher than that in wild populations (0.110–0.165). In addition, genetic differentiation was about twenty times larger in cultured populations (Nei’s distance: 0.0111) than in wild populations (Nei’s distance: 0.0005). These results mean that selective breeding can cause marked inbreeding as well as large genetic differentiation among cultured populations in a short period. On the other hand, it was suggested that genetic homogenization in the wild, probably due to a large-scale transport of cultured oysters, had progressed in the sea around Japan. In conclusion, it is necessary to prevent inbreeding by the reconsideration of the style of selective breeding in cultured populations, while the escape of gametes or spats of cultured strains in the wild should be avoided for the preservation of genetic characteristics in native populations of P. f. martensii.
    No preview · Article · Aug 2015 · Aquaculture International
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    ABSTRACT: Hybridization between native and non-native fishes is a serious global problem. Thus, there is a need to develop monitoring methods for predicting potential hybridization to evaluate the risk of genetic introgression and to identify important areas for conservation of pure native populations. Here, we developed a prediction model for intersubspecific hybridization, based on distribution and genetic data. We selected Rhodeus ocellatus kurumeus and R. ocellatus ocellatus as the native and non-native subspecies, respectively. First, we developed generalized linear models (GLMs) for the species habitat requirements by using presence/absence data and environmental variables. The best-fit models showed river length gave conflicting effects for the two subspecies. Next, we developed a GLM using the ratio of non-native haplotypes in mitochondrial DNA as an objective variable, with the predicted probabilities of the occurrence of each fish and spatial information as explanatory variables. The best-fit model selected the distance from the center of native distribution and the non-native habitat requirement as key factors. Our findings indicate that hybridization occurs highly and/or initially near the margin of native distribution where non-native habitat requirements are available. Our model could identify sites in native habitats with very low potential risk for genetic invasion as important areas for conservation of pure native populations.
    No preview · Article · Jun 2013 · Aquatic Invasions
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    ABSTRACT: The clam Corbicula leana exists in two forms, hermaphrodites and males. Our previous study on mitochondrial DNA suggested that the male nuclear DNA might have derived from hermaphrodite C. leana relatively recently. To clarify the origin of males in the clam, sequences of the nuclear 28S rDNA divergent domain (which is 441-444 bp long) in androgenetic hermaphrodites and males and dioecious (bisexual) species were analyzed. Unexpectedly, the nuclear 28S rDNA haplotypes of males and hermaphrodites were distinct. Haplotype network analysis indicated that males and hermaphrodites are reproductively isolated from each other without sharing the same nuclear haplotype. These results support a hypothesis that the egg nuclear genome of androgenetic hermaphrodites is replaced by the male sperm genome, and only males develop after fertilization by a male spermatozoon.
    Full-text · Article · Apr 2012 · Development Genes and Evolution
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    ABSTRACT: The distributions of seven bitterling species and subspecies—Tanakia lanceolata, T. limbata, Acheilognathus tabira nakamurae, A. rhombeus, Rhodeus ocellatus kurumeus, R. ocellatus ocellatus, and R. atremius atremius—in northern Kyushu were predicted using generalized linear models (GLMs) in order to provide information helpful for conserving native bitterlings and preventing the expansion of alien bitterling species. Predictions were made according to the following procedure: (1) a set of GLMs for each species was formulated using environmental data from 710 sites that were derived using digital maps and GIS software, from which the best fit model for each species was selected using the Akaike information criterion for predicting the fish occurrence, (2) model performance was evaluated based on the receiver-operating characteristics (ROC) analysis using occurrence and environmental data from 362 sites, and (3) potential distributions of the bitterling were analyzed using the best fit models and environmental data for 1,272 sites, of which 200 data points without occurrence data were prepared. The best fit models revealed that 4–6 environmental factors were important in predicting seven bitterling distributions, which was supported by the area under the ROC curve (AUC) values of these fishes ranging from 0.753 to 0.927. The AUC values in model evaluation were significantly greater than 0.5 for six fishes, suggesting the moderate accuracies of these best fit models for predicting the fish distributions. These predictive models can be used for evaluating potential native bitterling richness and the potential distribution expansion of an alien subspecies.
    Full-text · Article · Apr 2011 · Ichthyological Research
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    ABSTRACT: Rhodeus atremius is an endemic bitterling fish from Japan comprising two endangered subspecies, R. a. atremius and R. a. suigensis. The latter subspecies, which had dramatically declined in last decades, was reported to contain two distinct mtDNA lineages. In order to estimate the optimized units for conservation management, the genetic structure of R. atremius was inferred by analyzing mtDNA and microsatellite markers (MS). Allelic richness and heterozygosity of MS in R. a. suigensis was less than half that in R. a. atremius. In R. a. suigensis, not only within-population genetic diversity but also among-population genetic divergence was low, with the exception of population Ah1, while the diversity was high and the divergence showed isolation by distance in R. a. atremius. In mtDNA and MS, R. a. suigensis concordantly formed a single lineage, while R. a. atremius encompassed four mtDNA lineages, two of which were completely admixed into one group on the basis of MS. In population Ah1 a striking introgression between the two subspecies was suggested by a Bayesian-based assignment test, with the presence of mtDNA haplotype of R. a. atremius. Contrary to the prevailing theory, R. a. suigensis corresponds to a single conservation unit, while three units seem appropriate for R. a. atremius. In addition, low genetic diversity of R. a. suigensis might have arisen mainly as a result of recent bottlenecks before population fragmentation, followed by current anthropogenic effects. Genetic introgression in population Ah1 was probably the result of human transplantation of R. a. atremius. KeywordsBottleneck–Evolutionary Conservation Unit–Genetic diversity–Introgression–Metapopulation– Rhodeus atremius
    Full-text · Article · Apr 2010 · Conservation Genetics
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    ABSTRACT: Japanese rosy bitterling Rhodeus ocellatus kurumeus is an endangered cyprinid species in Japan, due to hybridization with its subspecies R. o. ocellatus introduced from mainland China. In order to collect information for conservation, the present distribution of R. o. kurumeus in Kyushu was studied using genetic and morphological markers. Of the 46 populations examined, mitochondrial DNA (mtDNA) of R. o. kurumeus was observed in 41 populations, among which that of R. o. ocellatus was also recognized in 13 populations. Although R. o. kurumeus was widely distributed in the northern-middle part of Kyushu, it is suggested that introgression by R. o. ocellatus has been allopatrically progressing in many habitats of R. o. kurumeus. The averaged number of pored lateral line scales positively regressed with the frequency of R. o. ocellatus mtDNA. It is evident that the number of pored lateral line scales is a more efficient morphological marker than the presence of a guanine layer along the anterior margin of the pelvic fins in the identification of R. o. kurumeus.
    Full-text · Article · Nov 2008 · NIPPON SUISAN GAKKAISHI
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    ABSTRACT: The present distributions of exotic fishes were investigated in creeks flowing into farmlands around northern Ariake and Yatsushiro Bay, Kyushu Island, Japan. Six exotic species introduced from foreign countries and six exotic species introduced from other internal regions in Japan were captured from several creeks in this area. In particular, Carassius cuvieri, Gambusia affinis, Opsariichthys uncirostris uncirostris, and Lepomis macrochirus were found in 83, 29, 29 and 20 sites, respectively. As other exotic species, Oreochromis niloticus, Ischikauia steenackeri, and Squalidus chankaensis tsuchigae were first recorded from this area. The tendencies on sympatric or allopatric appearances were investigated on the basis of the distributions of each of the exotic and native species. A few exotics such as C. cuvieri, G. affinis, and L. macrochirus, and a few natives such as Pseudorasbora parva and Abbottina rivularis indicated their sympatric appearances. In contrast, the allopatric appearances were indicated between these exotics and several natives. The allopatric tendency was estimated to be attributed to differences in habitat that each species preferred. Although Oryzias latipes preferred the dead water regions similarly to these exotics, this species showed its allopatric appearances with G. affinis and L. macrochirus. The distribution of this species was estimated to be limited by the distributions of these exotics.
    Full-text · Article · Jan 2008 · Journal of Japan Society on Water Environment
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    ABSTRACT: The presence and populations of freshwater fishes and the revetment conditions in creeks were investigated at 48 sampling sites around the Sea of Ariake in northwestern Kyushu, Japan. Each creek studied in this survey was classified into one of the three following types in terms of revetment conditions: Type-1, the creeks have earthen revetments except when crossing roads; Type-2, although there are concrete revetments in the creeks, these revetments are short, and agricultural water flows over the revetments and reaches bank vegetations or earthen banks except during the agricultural off-season; Type-3, there are high concrete revetments around the creeks, and agricultural water does not flow over the revetments during any season. The amount of Hemigrammocypris rasborella present was affected by the revetment conditions, and the amount present in Type-3 was significantly lower than those in Type-1 and Type-2. The populations of H. rasborella, Rhodeus ocellatus kurumeus, and Pseudorasbora parva were affected by the revetment conditions. For H. rasborella and R. ocellatus kurumeus, the populations in Type-3 were significantly lower than those in Type-1 and Type-2. For P. parva, the population in Type-3 was significantly lower than that in Type-1.
    Full-text · Article · Jan 2007 · Journal of Japan Society on Water Environment
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    ABSTRACT: The populations of Japanese bitterlings and unionid mussels and the land use of the watershed were investigated in 36 sampling sites in the Tatara river system in northern Kyushu, Japan. Five bitterling species were found in 11 sites in the system. Although Rhodeus ocellatus kurumeus was found to be distributed in 23 sites in 1983, this species was found in three sites in this study. The population of the bitterlings decreased in the sites with a high urbanization rate, although the populations of several other fish species showed no dependence on the urbanization rate. The population of the mussels showed a negative correlation with urbanization rate. In addition, the mussels populations showed positive relationship with the bitterling populations. These three relationships indicate that the decrease in the bitterling population due to the urbanization of the watershed was responsible for the decrease in the mussel population.
    Full-text · Article · Jan 2006 · Journal of Japan Society on Water Environment
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    ABSTRACT: The appearances and populations of freshwater fish species and the revetment conditions in the creeks were investigated at 48 sampling sites around Sea of Ariake in northwestern Kyushu Island, Japan. Each creek in this survey was classified into three following types by revetment conditions; Type-1: Creeks have earthen revetments except for the crossing to the roads; Type-2: Although there are the concrete revetments in creeks, these revetments are short in height, and the agricultural water crosses over the revetments and reaches bank vegetations or earthen banks except for agricultural off-season; Type-3: There are high concrete revetments in creeks, and the agricultural water do not cross over the revetments in all season. The appearance rates of Hemigrammocypris rasborella was affected by the revetment conditions, and the rates in Type-3 was significantly lower than those in Type-2 and Type-3. The populations of H. rasborella, Rhodeus ocellatus kurumeus, and Pseudorasbora parva was affected by the revetment conditions. In case of H. rasborella and R. ocellatus kurumeus, the populations in Type-3 were significantly lower than those in Type-2 and Type-3. In case of P. parva, the population in Type-3 was significantly lower than in Type-1. These results indicate that the changes of the revetment conditions in the creeks by the farm land consolidation have much impact on the appearances and populations of several freshwater fish species however, the concrete revetments such as Type-2 have low impacts on these species.
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