2011年8月29日 星期一

以COI序列重建鳥穀蛾的分子親緣關係發現一個華南到泰北產新種, M. monacha也被確認為M. monachella的次同物異名

文獻來源: Huang GH, Chen LS, Hirowatari T, Nasu Y, Wang M. 2011. A revision of the Monopis monachella species complex (Lepidoptera: Tineidae) from China. Zoological Journal of the Linnean Society 163(1): 1-14. [link]

Abstract The Monopis monachella species complex from China is revised, and its relationship to other species complexes of the genus Monopis is discussed with reference to morphological, and molecular evidence. Principal component analysis on all available specimens provided supporting evidence for the existence of three species, one of which is described as new: Monopis iunctio Huang & Hirowatari sp. nov. All species are either diagnosed or described, and illustrated, and information is given on their distribution and host range. Additional information is given on the biology and larval stages of Monopis longella. A preliminary phylogenetic study based on mitochondrial cytochrome c oxidase subunit I gene (CO1) sequence data and a key to the species of the M. monachella species complex in China is presented. The types of the new species have been deposited in the Institute of Entomology, Hunan Agricultural University, China and Entomological Laboratory, Osaka Prefecture University, Japan.

2011年8月28日 星期日

全球毒蛾屬之生命條碼建構以及台灣類群之分類修訂與討論

文獻來源:deWaard JR, Mitchell A, Keena MA, Gopurenko D, Boykin LM, et al. (2010) Towards a Global Barcode Library for Lymantria (Lepidoptera: Lymantriinae) Tussock Moths of Biosecurity Concern. PLoS ONE 5(12): e14280. doi:10.1371/journal.pone.0014280 [連結]


簡介

毒蛾屬(Lymantria)為裳蛾科(Erebidae)毒蛾亞科(Lymantriinae)之毒蛾族(Lymantriini)物種數約170種的類群,物種多樣性集中於亞洲地區。由於此屬有不少種類具有幼蟲雜食性、大發生造成森林經濟危害,例如原產歐洲的吉普賽毒蛾(L. dispar)於1868/1869引入北美使其森林之危害以及台灣黑角舞蛾(木毒蛾)(L. xylina)對闊葉林、果樹林甚至木麻黃防風林之危害,故此篇文章針對部份東亞毒蛾屬類群以及不同的地區之吉普賽毒蛾進行分子生命條碼(molecular bacode)之建置與親緣分析。

此篇文章在材料上選取36種518個個體作為樣本,取其粒腺體COI生命條碼序列做親緣分析,獲得高支持度的物種歸群,因此有助於未來森林管理單位從事毒蛾屬大發生或是境外移入之物種快速鑑定作業。

此篇文章亦涵蓋台灣物種的取樣,針對分子親緣重建的結果進行分類處理(於此文章當中之附檔一),以下介紹該處理結果,並綜合近期主要毒蛾屬文獻作討論:

1. Lymantria nebulosa視為獨立於L. sinica之物種,兼論相關類群之誤鑑定

Lymantria nebulosa為Wileman (1910)所發表的台灣新種(模式產地台南關仔嶺),此種在Schintlmeister (2004)當中視為L. sinica之同物異名,Pogue (2007)延續此處理。此篇文章將L. nebulosa視為獨立種,所依據者為中國武夷山產之標本,該單一樣本於分子親緣關係樹中與兩隻台灣產被鑑定為L. sinica之樣本成為一單系群,此枝系再與另一香港產L. sinica成為姊妹群。此分類處理(將L. nebulosa視為獨立於L. sinica之有效種)與分子結果(L. sinica為駢系群)的資訊並不一致,作者認為原因可能有(1) COI生命條碼無法區別此兩物種; (2) 所選取之各地L. sinica樣本有可能有鑑定錯誤或是包含了未描述種之可能; 或是(3) 隨兩物種分歧時伴隨L. sinica之COI多型性之發生。然而此分類處理仍有待釐清者為 (1) L. nebulosa之模式產地為台灣,為何僅選取中國武夷山產個體作此學名的地位恢復(status revived)? (2) 分子親緣重建之樣本少且無樹型支持度,卻仍進行分類處理?(3) 缺乏型態證據的討論。

此外,在Schintlmeister (2004)的文章將影像(Fig. 417)鑑定為L. sinica雄蟲,然而此標本應為當時的未描述種。Pogue (2007)描述一台灣產新種L. pulverea,並指定兩隻花蓮大禹嶺七月採之雄蟲為正模與副模式標本,以及一筆五月採自宜蘭福山植物園之雄蟲作為另一隻副模標本,而大禹嶺產雄蟲之生殖器繪於圖板14-4。Pogue在其圖板3-7收錄了該福山副模而無大禹嶺產之成蟲標本影像,然此福山標本影像應是L紋褐毒蛾 Lymantria grisea kosemponis Strand, 1914雄蟲之誤鑑定。以上描述可知我們並無L. pulverea之大禹嶺標本影像作進一步評斷,直到上個月個人解剖科博館一筆毒蛾屬標本才釐清此物種隻標本鑑定,另此種之雌蟲尚未被描述。

Lymantria pulverea Pogue, 2007 (國立台中科學博物館館藏)

2. 波斑毒蛾 Lymantria mathura subpallida Okano, 1959被處理為獨立於原名種L. mathura外之獨立種,現用組合名為L. subpallida

在Schintlmeister (2004)文章中,其描述台灣產L. mathura之外部顏色斑紋變異甚大,並認為主要出自南部族群的標本偏向原名亞種L. m. mathura,而以北部為主的族群標本偏向日本亞種L. m. aurora,因此將台灣產L. m. subpallida視為aurora之次同物異名。此篇文章似乎忽略Schintlmeister之處理,選取過去認知的L. m. subpallida 3隻樣本(2隻台灣1隻香港產),於COI親緣關係樹上明顯與產於俄羅斯、韓國、日本之L. mathura分群(L. mathura與日本沖繩之L. flavida形成最近姊妹群),此結果初步支持此篇文章的分類處理,然亦如第1項分類處理般缺乏形態資訊。

3. 未來待釐清的L. minomonis/ L. sugii分類問題

台灣產之毒蛾亞屬(subgenus Lymantria)包含有低中高海拔夏季常見的絡毒蛾L. concolor以及另一物種,該物種由Kishida (1986)描述為L. minomonis之台灣特有亞種(模式產地桃源復興巴陵),另一亞種產於沖繩為L. m. okinawaensis Kishida, 1987。Schitlmeister (2004)認為L. minomonis除了由Kishida描述與原名種之雄蟲生殖器之間有些為差異,兩族群之雌蟲生殖器更能夠作為分類依據,他更認為L. minomonis sugii與印度、越南以及中國產之L. similis更接近,綜此將此族群視為獨立種L. sugii。Pogue (2007)將沖繩亞種名直接處理為原名種(minomonis)之次同物異名,並紀錄L. minomonis產於台灣,卻忽略了Kishida的L. sugii處理。此篇文章選取了日本本州山梨縣的一隻L. minomonis樣本,分子親緣與同亞屬的L. monacha (L. 1758)(58隻樣本)支系成為姊妹群,此樣本序列可在未來與台灣產L. sugii/minomonis作比較釐清分類問題。

Lymantria minomonis Matsumura, 1933/sugii Kishida, 1986 (左雄蟲; 右雌蟲)

4. 台灣產毒蛾屬後續研究
台灣目前已記錄毒蛾屬8種,仍有約3~4個新紀錄/新種尚待處理,期待未來能有更具系統性的處理。

Abstract

Background: Detecting and controlling the movements of invasive species, such as insect pests, relies upon rapid and accurate species identification in order to initiate containment procedures by the appropriate authorities. Many species in the tussock moth genus Lymantria are significant forestry pests, including the gypsy moth Lymantria dispar L., and consequently have been a focus for the development of molecular diagnostic tools to assist in identifying species and source populations. In this study we expand the taxonomic and geographic coverage of the DNA barcode reference library, and further test the utility of this diagnostic method, both for species/subspecies assignment and for determination of geographic provenance of populations.

Methodology/Principal Findings: Cytochrome oxidase I (COI) barcodes were obtained from 518 individuals and 36 species of Lymantria, including sequences assembled and generated from previous studies, vouchered material in public collections, and intercepted specimens obtained from surveillance programs in Canada. A maximum likelihood tree was constructed, revealing high bootstrap support for 90% of species clusters. Bayesian species assignment was also tested, and resulted in correct assignment to species and subspecies in all instances. The performance of barcoding was also compared against the commonly employed NB restriction digest system (also based on COI); while the latter is informative for discriminating gypsy moth subspecies, COI barcode sequences provide greater resolution and generality by encompassing a greater number of haplotypes across all Lymantria species, none shared between species.

Conclusions/Significance: This study demonstrates the efficacy of DNA barcodes for diagnosing species of Lymantria and reinforces the view that the approach is an under-utilized resource with substantial potential for biosecurity and surveillance. Biomonitoring agencies currently employing the NB restriction digest system would gather more information by transitioning to the use of DNA barcoding, a change which could be made relatively seamlessly as the same gene region underlies both protocols.

2011年8月16日 星期二

根據現生物種的地理分布資訊, 對寒冷氣候的耐受性及其在分子親緣關係架構中的保守性推測藍灰蝶起源於亞洲大陸並經由白令陸橋播遷至新世界

文獻來源: Vila R, Bell CD, Macniven R, Goldman-Huertas B, Ree RH, Marshall CR, Bálint Z, Johnson K, Benyamini D, Pierce NE. 2011. Phylogeny and palaeoecology of Polyommatus blue butterflies show Beringia was a climate-regulated gateway to the New World. Proceedings of the Royal Society B 278(1719): 2737-2744. [link]

Abstract
Transcontinental dispersals by organisms usually represent improbable events that constitute a major challenge for biogeographers. By integrating molecular phylogeny, historical biogeography and palaeoecology, we test a bold hypothesis proposed by Vladimir Nabokov regarding the origin of Neotropical Polyommatus blue butterflies, and show that Beringia has served as a biological corridor for the dispersal of these insects from Asia into the New World. We present a novel method to estimate ancestral temperature tolerances using distribution range limits of extant organisms, and find that climatic conditions in Beringia acted as a decisive filter in determining which taxa crossed into the New World during five separate invasions over the past 11 Myr. Our results reveal a marked effect of the Miocene–Pleistocene global cooling, and demonstrate that palaeoclimatic conditions left a strong signal on the ecology of present-day taxa in the New World. The phylogenetic conservatism in thermal tolerances that we have identified may permit the reconstruction of the palaeoecology of ancestral organisms, especially mobile taxa that can easily escape from hostile environments rather than adapt to them.

2011年8月14日 星期日

使用四個核基因與兩個粒線體DNA序列重建藍灰蝶節親緣關係時發現大藍灰蝶(Maculinea)的單系性的確因雀斑灰蝶(Phengaris)的插入而不復存在, 而稀有的碇灰蝶(Caeruelea)則為其姐妹群

文獻來源: Ugelvig LV, Vila R, Pierce NE, Nash DR. 2011. A phylogenetic revision of the Glaucopsyche section (Lepidoptera: Lycaenidae), with special focus on the Phengaris–Maculinea clade. Molecular Phylogenetics and Evolution 61(1): 237-243.

Abstract
Despite much research on the socially parasitic large blue butterflies (genus Maculinea) in the past 40 years, their relationship to their closest relatives, Phengaris, is controversial and the relationships among the remaining genera in the Glaucopsyche section are largely unresolved. The evolutionary history of this butterfly section is particularly important to understand the evolution of life history diversity connected to food-plant and host-ant associations in the larval stage. In the present study, we use a combination of four nuclear and two mitochondrial genes to reconstruct the phylogeny of the Glaucopsyche section, and in particular, to study the relationships among and within the Phengaris–Maculinea species.
We find a clear pattern between the clades recovered in the Glaucopsyche section phylogeny and their food-plant associations, with only the Phengaris–Maculinea clade utilising more than one plant family. Maculinea is, for the first time, recovered with strong support as a monophyletic group nested within Phengaris, with the closest relative being the rare genus Caerulea. The genus Glaucopsyche is polyphyletic, including the genera Sinia and Iolana. Interestingly, we find evidence for additional potential cryptic species within the highly endangered Maculinea, which has long been suspected from morphological, ecological and molecular studies.

2011年8月1日 星期一

即始一個分類群的生命條碼庫尚未被完全建置, 若一個樣本的屬級歸屬可以被確認, 那麼使用COI序列仍然可將其放置到正確的高階分類群中

文獻來源: Wilson JJ, Rougerie R, Schonfeld J, Janzen DH, Hallwachs W, Hajibabaei M, Kitching IJ, Haxaire J, Hebert PDN. 2011. When species matches are unavailable are DNA barcodes correctly assigned to higher taxa? An assessment using sphingid moths. BMC Ecology 11: 18 doi:10.1186/1472-6785-11-18.

Background
When a specimen belongs to a species not yet represented in DNA barcode reference libraries there is disagreement over the effectiveness of using sequence comparisons to assign the query accurately to a higher taxon. Library completeness and the assignment criteria used have been proposed as critical factors affecting the accuracy of such assignments but have not been thoroughly investigated. We explored the accuracy of assignments to genus, tribe and subfamily in the Sphingidae, using the almost complete global DNA barcode reference library (1095 species) available for this family. Costa Rican sphingids (118 species), a well-documented, diverse subset of the family, with each of the tribes and subfamilies represented were used as queries. We simulated libraries with different levels of completeness (10-100% of the available species), and recorded assignments (positive or ambiguous) and their accuracy (true or false) under six criteria.

Results A liberal tree-based criterion assigned 83% of queries accurately to genus, 74% to tribe and 90% to subfamily, compared to a strict tree-based criterion, which assigned 75% of queries accurately to genus, 66% to tribe and 84% to subfamily, with a library containing 100% of available species (but excluding the species of the query). The greater number of true positives delivered by more relaxed criteria was negatively balanced by the occurrence of more false positives. This effect was most sharply observed with libraries of the lowest completeness where, for example at the genus level, 32% of assignments were false positives with the liberal criterion versus <1% when using the strict. We observed little difference (<8% using the liberal criterion) however, in the overall accuracy of the assignments between the lowest and highest levels of library completeness at the tribe and subfamily level.

Conclusions
Our results suggest that when using a strict tree-based criterion for higher taxon assignment with DNA barcodes, the likelihood of assigning a query a genus name incorrectly is very low, if a genus name is provided it has a high likelihood of being accurate, and if no genus match is available the query can nevertheless be assigned to a subfamily with high accuracy regardless of library completeness. DNA barcoding often correctly assigned sphingid moths to higher taxa when species matches were unavailable, suggesting that barcode reference libraries can be useful for higher taxon assignments long before they achieve complete species coverage.