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Sato, Yukuto ; Tsurui-Sato, Kaori ; Katoh, Mitsuho ; Kimura, Ryosuke ; Tatsuta, Haruki ; Tsuji, Kazuki
出版情報: Ecology and Evolution.  2020-12-24.  Wiley
URL: http://hdl.handle.net/20.500.12000/47605
概要: Batesian mimicry is a striking example of Darwinian evolution, in which a mimetic species resembles toxic or unpalatable model species, thereby receiving protection from predators. In some species exhibiting Batesian mimicry, nonmimetic individuals coexist as polymorphism in the same population despite the benefits of mimicry. In a previous study, we proposed that the abundance of mimics is limited by that of the models, leading to polymorphic Batesian mimicry in the swallowtail butterfly, Papilio polytes, on the Ryukyu Islands in Japan. We found that their mimic ratios (MRs), which varied among the Islands, were explained by the model abundance of each habitat, rather than isolation by distance or phylogenetic constraint based on the mitochondrial DNA (mtDNA) analysis. In the present study, this possibility was reexamined based on hundreds of nuclear single nucleotide polymorphisms (SNPs) of 93 P. polytes individuals from five Islands of the Ryukyus. We found that the population genetic and phylogenetic structures of P. polytes largely corresponded to the geographic arrangement of the habitat Islands, and the genetic distances among island populations show significant correlation with the geographic distances, which was not evident by the mtDNA‐based analysis. A partial Mantel test controlling for the present SNP‐based genetic distances revealed that the MRs of P. polytes were strongly correlated with the model abundance of each island, implying that negative frequency‐dependent selection interacting with model species shaped and maintained the mimetic polymorphism. Taken together, our results support the possibility that predation pressure, not isolation by distance or other neutral factors, is a major driving force of evolution of the Batesian mimicry in P. polytes from the Ryukyus.
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2.

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Tsurui, Kaori Sato ; Sato, Yukuto ; Kato, Emi ; Katoh, Mitsuho ; Kimura, Ryosuke ; Tatsuta, Haruki ; Tsuji, Kazuki
出版情報: Ecology and Evolution.  9  pp.5991-6002,  2019-05-29.  Wiley
URL: http://hdl.handle.net/20.500.12000/44865
概要: Batesian mimicry is a well-studied adaptation for predation avoidance, in which a mimetic species resembles an unpalatab le model species. Batesian mimicry can be under positive selection because of the protection gained against predators, due to resemblance to unpalatable model species. However, in some mimetic species, nonmimetic individuals are present in populations, despite the benefits of mimicry. The mechanism for evolution of such mimetic polymorphism remains an open question. Here, we address the hypothesis that the abundance of mimics is limited by that of the models, leading to mimetic polymorphism. In addition, other forces such as the effects of common ancestry and/or isolation by distance may explain this phenomenon. To investigate this question, we focused on the butterfly, Papilio polytes, that exhibits mimetic polymorphism on multiple islands of the Ryukyus, Japan, and performed field surveys and genetic analysis. We found that the mimic ratio of P. polytes was strongly correlated with the model abundance observed on each of the five islands, suggesting negative frequency-dependent selection is driving the evolution of polymorphism in P. polytes populations. Molecular phylogenetic analysis indicated that the southern island populations are the major source of genetic diversity, and the middle and northern island populations arose by relatively recent migration. This view was also supported by mismatch distribution and Tajima's D analyses, suggesting a recent population expansion on the middle and northern islands, and stable population persistence on the southern islands. The frequency of the mimetic forms within P. polytes populations is thus explained by variations in the model abundance rather than by population structure. Thus, we propose that predation pressure, rather than neutral forces, have shaped the Batesian mimicry polymorphism in P. polytes observed in the Ryukyus.
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3.

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Katoh, Mitsuho ; Tatsuta, Haruki ; Tsuji, Kazuki
出版情報: Scientific Reports.  8  2018-09-07.  Springer Nature
URL: http://hdl.handle.net/20.500.12000/44825
概要: Wing polymorphism of butterflies provides a good system in which to study adaptation. The Asian Batesian mimic butterfly Papilio polytes has unmelanized, putative mimetic red spots on its black hind wings. The size of those red spots is non-heritable but it is highly polymorphic, the adaptive significance of which is unknown. We hypothesized that under strong ultraviolet (UV) irradiation, butterflies develop a wider melanized black area to protect the wings from UV damage, and as a result express smaller mimetic red spots. Our field survey on Okinawa Island revealed a negative relationship between the sizes of the red spot and the black area in the wings. The size varied seasonally and was negatively correlated with the intensity of solar UV radiation at the time of capture. Laboratory experiments revealed that the size was reduced by strong UV irradiation not only of the eggs and larvae, but also of their mothers through a putative epigenetic mechanism. The flexible phenotypic expression of the red spots in P. polytes suggests a trade-off between protection against UV damage and predation avoidance, and provides a new insight into the evolution of Batesian mimicry.
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4.

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Ujiiyama, Shumpei ; Tsuji, Kazuki
出版情報: Scientific Reports.  8  pp.1-9,  2018-05-23.  Springer Nature
URL: http://hdl.handle.net/20.500.12000/44808
概要: Invasion by the red imported fire ant, Solenopsis invicta Buren, has destructive effects on native biodiversity, agricul ture and public health. This ant’s aggressive foraging behavior and high reproductive capability have enabled its establishment of wild populations in most regions into which it has been imported. An important aspect of eradication is thorough nest monitoring and destruction during early invasion to prevent range expansion. The question is: How intense must monitoring be on temporal and spatial scales to eradicate the fire ant? Assuming that the ant was introduced into a region and that monitoring was conducted immediately after nest detection in an effort to detect all other potentially established nests, we developed a mathematical model to investigate detection rates. Setting the monitoring limit to three years, the detection rate was maximized when monitoring was conducted shifting bait trap locations and setting them at intervals of 30 m for each monitoring. Monitoring should be conducted in a radius of at least 4 km around the source nest, or wider—depending on how late a nest is found. For ease of application, we also derived equations for finding the minimum bait interval required in an arbitrary ant species for thorough monitoring.
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5.

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Suehiro, Wataru ; Hyodo, Fujio ; Tanaka, Hiroshi O ; Himuro, Chihiro ; Yokoi, Tomoyuki ; Dobata, Shigeto ; Guénard, Benoit ; Dunn, Robert R ; Vargo, Edward L ; Tsuji, Kazuki ; Matsuura, Kenji
出版情報: Scientific Reports.  7  pp.1-10,  2017-11-03.  Springer Nature
URL: http://hdl.handle.net/20.500.12000/44765
概要: Invasions are ecologically destructive and can threaten biodiversity. Trophic flexibility has been proposed as a mechani sm facilitating invasion, with more flexible species better able to invade. The termite hunting needle ant Brachyponera chinensis was introduced from East Asia to the United States where it disrupts native ecosystems. We show that B. chinensis has expanded dietary breadth without shifting trophic position in its introduced range. Transect sampling of ants and termites revealed a negative correlation between the abundance of B. chinensis and the abundance of other ants in introduced populations, but this pattern was not as strong in the native range. Both termite and B. chinensis abundance were higher in the introduced range than in native range. Radiocarbon (14C) analysis revealed that B. chinensis has significantly younger ‘diet age’, the time lag between carbon fixation by photosynthesis and its use by the consumer, in the introduced range than in the native range, while stable isotope analyses showed no change. These results suggest that in the introduced range B. chinensis remains a termite predator but also feeds on other consumer invertebrates with younger diet ages such as herbivorous insects. Radiocarbon analysis allowed us to elucidate cryptic dietary change associated with invasion success.
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6.

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Katoh, Mitsuho ; Tatsuta, Haruki ; Tsuji, Kazuki
出版情報: Scientific Reports.  7  pp.1-7,  2017-07-25.  Springer Nature
URL: http://hdl.handle.net/20.500.12000/44826
概要: Batesian mimicry, a phenomenon in which harmless organisms resemble harmful or unpalatable species, has been extensively studied in evolutionary biology. Model species may differ from population to population of a single mimetic species, so different predation pressures might have driven micro-evolution towards better mimicry among regions. However, there is scant direct evidence of micro-evolutionary change over time in mimicry traits. Papilio polytes shows female-limited Batesian mimicry. On Okinawa, one mimicry model is Pachliopta aristolochiae, which was not present on the island until 1993. In P. polytes, the size of the hind-wing white spot, a mimetic trait, is maternally heritable. Among specimens collected between 1961 and 2016, the average white spot size was unchanged before the model’s arrival but has rapidly increased since then. However, white spot size showed greater variance after the model’s establishment than before. This suggests that before 1993, white spot size in this population was not selectively neutral but was an adaptive trait for mimicking an unpalatable native, Byasa alcinous, which looks like P. aristolochiae apart from the latter’s hind-wing white spot. Thus, some females switched their model to the new one after its arrival.
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7.

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来間, 美紀 ; 河村, 太 ; 辻, 和希 ; Kurima, Miki ; Kawamura, Futoshi ; Tsuji, Kazuki
出版情報: 琉球大学農学部学術報告 — The Science Bulletin of the Faculty of Agriculture. University of the Ryukyus.  pp.49-54,  2009-12.  琉球大学農学部
URL: http://hdl.handle.net/20.500.12000/16869
概要: As a first step for the biological control of pest insects using ants we surveyed the ant fauna and its seasonality on s even farm lands, six of which were greenhouses, in the southern part of Okinawa Island. Cultivated plants were dragon fruits, eggplants, bitter gourds, green peppers and sugarcanes. Ants were collected using pitfall traps every 2 month (with some exception) throughout 2006. Regardless of inside or outside the greenhouses ants were less active and less abundant in the low temperature period from January to March, whereas they were abundant and seemingly active in the high temperature period from May to October. The ant species composition did not differ very much by cultivated plant species. Four species (Tetramorium bicarinatum, Monomorium chinense, Pheidole fervens and P. parva) were most common in those fields, which implies that these four species can have the highest potential as the biological-control agents in the warm season in Okinawa, on one hand. On the other hand, a large portion of those dominant ants consists of exotic tramps species, therefore their risk of biological invasion should be also carefully estimated before using them as control agents.
沖縄におけるアリの生物的害虫防除への利用に向けた第一歩として,沖縄島の7ヶ所の圃場(そのうち6つはハウス)におけるアリ相と個体数の季節変動を約1年間調べた.ピットフォールトラップ法を用いて圃場の中とすぐ外の屋外環境で調査を行った.栽培作物はラン,ドラゴンフルーツ,ナス,ゴーヤ,サトウキビ,ピーマンであった.屋外,ハウスに限らずアリ類は気温が低い1月から3月は採取個体数・種数ともに少なく,気温が高い5月~10月にかけて採取個体数・種数ともに多かった.栽培作物に よるアリ相に大きな違いはみられず,オオシワアリ,クロヒメアリ,ブギオオズアリ,ミナミオオズアリの遍在性が高く個体数も多かっ た.沖縄島の圃場でアリを害虫防除資材として利用する場合,これらの種が高温期に利用できる可能性があると考えられる.その一方で優占種の多くは外来の放浪種であり,利用時にはその侵略性のリスクの検討も必要である.
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8.

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川西, 祐一 ; 大西, 一志 ; 笠原, 啓人 ; 辻, 和希 ; 前川, 秀彰 ; 中島, 裕美子 ; Kawanishi, Yuichi ; Ohnishi, Hitoshi ; Kasahara, Akito ; Tsuji, Kazuki ; Maekawa, Hideaki ; Nakajima, Yumiko
出版情報: 琉球大学21世紀COEプログラム「サンゴ礁島嶼系の生物多様性の総合解析」平成19年度成果発表会.  pp.none-,  2008-03-01.  琉球大学21世紀COEプログラム
URL: http://hdl.handle.net/20.500.12000/4921
概要: 琉球大学21世紀COEプログラム「サンゴ礁島嶼系の生物多様性の総合解析」平成19年度成果発表会(平成20年3月1日開催) 招待講演会会場:理系複号棟102号室,ポスター発表会場:琉球大学50周年記念館1F
研究報告書
9.

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論文(リポジトリ)
大西, 一志 ; 中島, 裕美子 ; 諏訪部, 真友子 ; 菊地, 友則 ; 辻, 和希 ; Ohnishi, Hitoshi ; Nakajima, Yumiko ; Suwabe, Mayuko ; Kikuchi, Tomonori ; Tsuji, Kazuki
出版情報: 琉球大学21世紀プログラム「サンゴ礁島嶼系の生物多様性の総合解析」平成18年度成果発表会.  pp.none-,  2007-03-10.  琉球大学21世紀プログラム
URL: http://hdl.handle.net/20.500.12000/623
概要: 琉球大学21世紀プログラム「サンゴ礁島嶼系の生物多様性の総合解析」平成18年度成果発表会(平成19年3月10日開催) 招待講演会会場:琉球大学50周年記念館1F,ポスター発表会場:琉球大学大学会館3F
研究報告書