Takuya Miyake

Mie University, Tu, Mie, Japan

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Publications (9)6.27 Total impact

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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.
    Aquatic Invasions 06/2013; 8(2):219-229. DOI:10.3391/ai.2013.8.2.09 · 1.14 Impact Factor
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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.
    Development Genes and Evolution 04/2012; 222(3):181-7. DOI:10.1007/s00427-012-0395-7 · 2.18 Impact Factor
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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.
    Ichthyological Research 04/2011; 59(2). DOI:10.1007/s10228-011-0260-0 · 0.96 Impact Factor
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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
    Conservation Genetics 04/2010; 12(2):383-400. DOI:10.1007/s10592-010-0146-0 · 1.85 Impact Factor
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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.
    NIPPON SUISAN GAKKAISHI 11/2008; 74(6):1060-1067. DOI:10.2331/suisan.74.1060 · 0.15 Impact Factor
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    Journal of Japan Society on Water Environment 01/2008; 31(7):395-401. DOI:10.2965/jswe.31.395
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    Journal of Japan Society on Water Environment 01/2007; 30(5):277-282. DOI:10.2965/jswe.30.277
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    Journal of Japan Society on Water Environment 01/2006; 29(12):837-842. DOI:10.2965/jswe.29.837
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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.