Masaya Yago

The University of Tokyo, Tōkyō, Japan

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Publications (9)12.06 Total impact

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    ABSTRACT: Wing morphological variations are described here for the lycaenid butterfly Tongeia fischeri. A landmark-based geometric morphometric approach based on wing venation of 197 male and 187 female butterflies collected in Japan was used to quantify wing size and shape variations between sexes and among populations. Sexual dimorphism in wing size and shape was detected. Females had significantly larger wings than males, while males showed a relatively elongated forewing with a longer apex and narrower wing tornus in comparison to females. Intraspecific variations in wing morphology among populations were revealed for the wing shape, but not wing size. Distinct wing shape differences were found in the vein intersections area around the distal part of the discal cell where median veins originated in the forewing and around the origin of the CU1 vein in the hindwing. In addition, phenotypic relationships inferred from wing shape variations grouped T. fischeri populations into three groups, reflecting the subspecies classification of the species. The spatial variability and phenotypic relationships between conspecific populations of T. fischeri detected here are generally in agreement with the previous molecular study based on mitochondrial and nuclear sequences, suggesting the presence of a phylogenetic signal in the wing shape of T. fischeri, and thus having taxonomic implications.
    Entomological Science 12/2013; · 0.98 Impact Factor
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    ABSTRACT: The widespread lycaenid butterfly Tongeia fischeri is distributed from eastern Europe to northeastern Asia and represented by three geographically isolated populations in Japan. In order to clarify the phylogeographic history of the species, we used sequences of three mitochondrial (COI, Cyt b and ND5) and two nuclear (Rpl5 and Ldh) genes of 207 individuals collected from 55 sites throughout Japan and five sites on the Asian continent. Phylogenetic trees and the median-joining network revealed six evolutionary mitochondrial haplotype clades, which corresponded to the geographic distribution of the species. Common ancestors of Japanese T. fischeri might have come to Japan during the mid-Pleistocene by multiple dispersals of continental populations, probably via a land bridge or narrow channel between western Japan and the Korean Peninsula. The geographical patterns of variation of mitochondrial and nuclear markers are discordant in northeastern Kyushu, possibly as a result of introgressive hybridization during the ancient contact between the Kyushu and Shikoku populations in the last glacial maximum. The phylogeographic pattern of T. fischeri in Japan are probably related to the geological history, Pleistocene climatic oscillations and distribution of the host plant.
    Molecular Phylogenetics and Evolution 10/2012; · 4.07 Impact Factor
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    ABSTRACT: Analysis of female sex pheromone components and subsequent field trap experiments demonstrated that the bombycid moth Trilocha varians uses a mixture of (E,Z)-10,12-hexadecadienal (bombykal) and (E,Z)-10,12-hexadecadienyl acetate (bombykyl acetate) as a sex pheromone. Both of these components are derivatives of (E,Z)-10,12-hexadecadienol (bombykol), the sex pheromone of the domesticated silkmoth Bombyx mori. This finding prompted us to compare the antennal and behavioral responses of T. varians and B. mori to bombykol, bombykal, and bombykyl acetate in detail. The antennae of T. varians males responded to bombykal and bombykyl acetate but not to bombykol, and males were attracted only when lures contained both bombykal and bombykyl acetate. In contrast, the antennae of B. mori males responded to all the three components. Behavioral analysis showed that B. mori males responded to neither bombykal nor bombykyl acetate. Meanwhile, the wing fluttering response of B. mori males to bombykol was strongly inhibited by bombykal and bombykyl acetate, thereby indicating that bombykal and bombykyl acetate act as behavioral antagonists for B. mori males. T. varians would serve as a reference species for B. mori in future investigations into the molecular mechanisms underlying the evolution of sex pheromone communication systems in bombycid moths.
    Naturwissenschaften 03/2012; 99(3):207-15. · 2.14 Impact Factor
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    ABSTRACT: Adults of the Euthalia phemius complex, which is composed of three South‐East Asian nymphalid species, Euthalia phemius, Euthalia ipona, and Euthalia euphemia, were genetically analysed by examining mitochondrial and nuclear genes. The E. phemius complex was also examined morphologically, with particular emphasis on wing markings and male genitalia. No significant differences amongst the three species in the complex were detected with respect to either genetic distance or genital morphology. We therefore conclude that the three currently recognized Euthalia species belong to a single species. Accordingly, E. ipona is synonymized with E. phemius. Euthalia euphemia is treated as a subspecies of E. phemius. Type specimens of all taxa and a synonymic list for the E. phemius complex are also given. In addition, we briefly discuss the evolution and biogeography of the species complex.© 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 164, 304–327.
    Zoological Journal of the Linnean Society 01/2012; 164(2). · 2.66 Impact Factor
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    ABSTRACT: This study describes the molecular phylogeny, laboratory rearing, and karyotype of a bombycid moth, Trilocha varians (F. Walker) (Lepidoptera: Bombycidae), which feeds on leaves of Ficus spp. (Rosales: Moraceae). The larvae of this species were collected in Taipei city, Taiwan, and the Ryukyu Archipelago (Ishigaki and Okinawa Islands, Japan). Molecular phylogenetic analyses revealed that T. varians belongs to the subfamily Bombycinae, thus showing a close relationship to the domesticated silkworm Bombyx mori (L.), a lepidopteran model insect. A laboratory method was developed for rearing T. varians and the time required for development from the embryo to adult was determined. From oviposition to adult emergence, the developmental zero was 10.47 °C and total effective temperature was 531.2 day-degrees, i.e., approximately 30 days for one generation when reared at 28 °C. The haploid of T. varians consisted of n = 26 chromosomes. In highly polyploid somatic nuclei, females showed a large heterochromatin body, indicating that the sex chromosome system in T. varians is WZ/ZZ (female/male). The results of the present study should facilitate the utilization of T. varians as a reference species for B. mori, thereby leading to a greater understanding of the ecology and evolution of bombycid moths.
    Journal of Insect Science 01/2012; 12:49. · 0.88 Impact Factor
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    ABSTRACT: Wolbachia infections were investigated by sequencing the wsp and ftsZ genes in a population of the endangered butterfly Zizina emelina (de l'Orza) (formerly Zizina otis emelina) (Lepidoptera: Lycaenidae), in Toyonaka City, northern Osaka Prefecture, central Japan. Wolbachia was detected in 65, 77, and 86% of field-collected adults in 2004, 2005, and 2007, respectively. Sequencing results revealed the presence of two strains of Wolbachia, wEmeTnl and wEmeTn2, in adults of this population, although no double infection was found. Three (12.5%) of 24 field-collected females infected by wEmeTnl produced offspring with a female-biased sex ratio, whereas all females infected by wEmeTn2 produced almost all-female offspring. In contrast, no uninfected females produced female-biased offspring. Moreover, the mean egg hatchability of broods from wEmeTn2-infected females was almost half that of uninfected females. These results indicate that at least wEmeTn2 is a male-killing strain.
    Annals of the Entomological Society of America 05/2011; · 1.20 Impact Factor
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    ABSTRACT: Eight sexual mosaic offspring of Zizina emelina (Lepidoptera: Lycaenidae) were obtained from females infected with male-killing Wolbachia (wEmeTn2), though they were mostly dead at the stage of pharate adult. Uninfected females or females infected with another strain of Wolbachia (wEmeTn1) pro-duced no mosaics. Therefore, the occurrence of these sexual mosaics was associated with wEmeTn2 infec-tion. In sexual mosaics, the ventral and dorsal parts of genitalia differentiated independently into male-spe-cific and female-specific formations, respectively, i.e., the ventral part of abdominal segment IX may have tendencies to retain male structures, while the dorsal parts of abdominal segments IX and X possess female structures. More than two pairs of ill-developed valvae were observed in several individuals in a deep pouch. The presence of additional valvae would mean that the segment IX or the ventral phallic lobe is at least partly duplicated. INTRODUCTION A sexual mosaic phenotypically combines male and female characters (Laugé, 1985). Although it is known that sexual mosaics of several insect species can be ob -tained from females infected with Wolbachia after antibiotic or heat treatment in the laboratory (Kageyama et al., 2003; Kageyama and Traut, 2004; Narita et al., 2007; Saka moto et al., 2008), the occurrence of sexual mosaics is a rare event. Wol bachia, which are widely distributed among various groups of arthropods (Wer ren et al., 1995; Werren, 1997), often cause a variety of reproductive alterations of hosts, in -cluding cyto plasmic incompatibility (Hoffmann et al., 1990; Turelli and Hoffmann, 1995; Poin sot et al., 2003), parthenogenesis induction (Stouthamer et al., 1990; Weeks and Bre eu wer, 2001), feminization of genetic males (Rigaud et al., 1991; Hiro ki et al., 2002; Negri et al., 2008) and male killing (Hurst et al., 1999; Fialho and Stevens, 2000). The lycaenid butterfly, Zizina emelina (de l'Orza) (previously Zizina otis emelina) (Lepidoptera: Lycaenidae), occurs in Honshu, Shikoku and Kyushu in Japan (Fukuda et al., 1984; Yago et al., 2008), and it is listed in the Red Data List of Japan as one of the most endangered species (Ministry of Environment, Japan, 2006). We obtained offspring of Z. emelina from field-collected females infected with two strains of Wolbachia, wEmeTn1 and wEmeTn2 (Sakamoto et al., in press). The infection of Wol bachia may have some effect on the genetic structure in Z. emelina, but it is unclear whether it is associated with the threat of this butterfly (Sakamoto et al., in press). The wing patterns of offspring from females infected with male-killing Volume 121, Number 5, November and December 2010 443
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    ABSTRACT: Butterflies of the genus Zizina are widely distributed in all zoogeographical regions except the New World (North and South America) and the northern part of Eurasia. We address some of the problems in regard to the taxonomy and bioge-ography of the genus. We inferred phylogenetic relationships for all four species in the current classification of this genus from the ND5 region of mtDNA. From our molecular analyses and morphological evidence, we concluded that this genus contains three species; Z. otis, Z. oxleyi and Z. emelina. The status of the latter species is revised, while Z. labradus and Z. antanossa, which were formerly treated as specifically distinct, are regarded as subspecies of Z. otis. Based on our analyses, we also employ phylogeography to discuss possible speciation events in the genus. Each of the three Zizina species appears to have branched from the common ancestor, with a divergence time estimated to be about 2.5 million years ago. The ancestors of Z. oxleyi and Z. emelina are postulated to have adapted to a temperate climate, diverged in the northern and southern hemispheres, and resulted in the extant species from New Zealand and East Asia, respectively. In contrast, the ancestor of Z. otis adapted mainly to tropical and subtropical zones, and the extant Z. otis dispersed into the Afrotropical, Oriental and Australian regions. Feeding adaptations in the larvae also might have had an effect on specia-tion within Zizina. In addition, our results indicated that there is a possibility that the distribution of the New Zealand Z. oxleyi was reduced in extent by the introduction of Z. otis, which immigrated recently from Australia or its surroundings.
    01/2008;