2011年12月5日 星期一

尺蛾科分子親緣關係研究進展


文獻來源:Sihvonen, P., M. Mutanen, L. Kaila, G. Brehm, A. Hausmann, H. S. Staude. 2011. Comprehensive Molecular Sampling Yields a Robust Phylogeny for Geometrid Moths (Lepidoptera: Geometridae). PLoS ONE 6(6): e20356. doi:10.1371/journal.pone.0020356 [全文]


簡介
尺蛾為鱗翅目當中擁有第二高物種多樣性的科級,全世界約有23,000已被描述的物種。除了近期的幾篇形態與分子為主的研究,此類群在高階親緣關係上仍待探討。

此篇文章選取全球具代表性尺蛾分類群,藉由八段基因來重建親緣關係。結果顯示 (1) 尺蛾科確為單系群,其姊妹枝系為偽燕蛾科 (Sematuridae)+鳳蛾顆 (Epicopeiidae),然而此結果與Mutanen (2010)以及Reiger et. al (2009)有出入;(2) 尺蛾科內部的分子親緣關係與2007年Yamamoto與Sota的研究中主要亞科的關係所得結果相同,姬尺蛾亞科與波(花)尺蛾亞科枝系為其他亞科之姊妹群,然而幾個物種數少的亞科關係則尚待釐清;(3) 星尺蛾與細尺蛾兩亞科在此篇文章形成一多系群;(4) 枝尺蛾亞科雖為單系群然而樹型支持度低,且納入了過去被視為獨立亞科之“空點尺蛾亞科 (Orthostixinae)”與Alsophilinae亞科之取樣物種;(4) 過去所劃定的族級族多非單系群。

雖然此篇文章以相較前人研究增加了倍數的分類群,然而仍有關鍵類群尚未納入,例如“空點尺蛾亞科 (Orthostixinae)”之模式屬Orthostixis、主要產於澳洲的狹義星尺蛾亞科類群,以及非洲產Diptychini族(被認為可能是尾尺蛾族Ourapterygini之姊妹群)等,則留待未來進行研究。

Abstract
Background: The moth family Geometridae (inchworms or loopers), with approximately 23 000 described species, is the second most diverse family of the Lepidoptera. Apart from a few recent attempts based on morphology and molecular studies, the phylogeny of these moths has remained largely uninvestigated.

Methodology/Principal Findings: We performed a rigorous and extensive molecular analysis of eight genes to examine the geometrid affinities in a global context, including a search for its potential sister-taxa. Our maximum likelihood analyses included 164 taxa distributed worldwide, of which 150 belong to the Geometridae. The selected taxa represent all previously recognized subfamilies and nearly 90% of recognized tribes, and originate from all over world. We found the Geometridae to be monophyletic with the Sematuridae+Epicopeiidae clade potentially being its sister-taxon. We found all previously recognized subfamilies to be monophyletic, with a few taxa misplaced, except the Oenochrominae+Desmobathrinae complex that is a polyphyletic assemblage of taxa and the Orthostixinae, which was positioned within the Ennominae. The Sterrhinae and Larentiinae were found to be sister to the remaining taxa, followed by Archiearinae, the polyphyletic assemblage of Oenochrominae+Desmobathrinae moths, Geometrinae and Ennominae.

Conclusions/Significance: Our study provides the first comprehensive phylogeny of the Geometridae in a global context. Our results generally agree with the other, more restricted studies, suggesting that the general phylogenetic patterns of the Geometridae are now well-established. Generally the subfamilies, many tribes, and assemblages of tribes were well supported but their interrelationships were often weakly supported by our data. The Eumeleini were particularly difficult to place in the current system, and several tribes were found to be para- or polyphyletic.

2011年12月4日 星期日

由形態特徵重建新熱帶美洲蛺蝶Hamadryas屬之親緣關係並著重發聲結構的失去與其他替代性別辨識機制產生的討論

文獻來源:Garzo-Orduna, I. J. 2011. Phylogenetic evidence for loss of sound production and a shift in sexual recognition signals in Hamadryas butterflies (Nymphalidae: Biblidinae). Systematic Entomology. DOI: 10.1111/j.1365-3113.2011.00599.x

簡介

分布於新熱帶美洲的Hamadryas屬為蛺蝶科Biblidinae亞科類群,共計有20個物種,當中約有近半數具有前翅發聲結構、少數具有雌雄翅紋二型性與雄蟲具發香鱗片的種類。由過去的生物學顯示此屬辨識特徵尚有翅背面如花部狀紋路、吸食腐敗果實、停棲時頭下尾上以及飛行路徑飄忽不定。

過去30年間雖然有此屬的屬內歸群處理,然而尚未有以支序學所建立的親緣關係研究,本文章即首次以形態特徵重建親緣,並討論以下議題:(1) Hamadryas是否為一單系枝系,具有哪些衍徵來支持?(2) 此屬姊妹群為何? (3) 評估過去所建立亞屬之單系性;(4) 演化上如發聲、二型性與發香鱗等特徵出現與先後的判定與討論。

結果討論顯示

(1) Hamadryas屬為單系群;

(2) 此屬姊妹群為Ectima屬;

(3) 除了H. laodamia枝系外其餘過去之屬內亞屬歸群皆非單系群;

(4) 在發聲、二型性與發香鱗等特徵的演化上,發聲結構在特徵分析中被拆解為獨立的四個前翅翅脈特徵,然而能夠發聲的行為僅產生過一次(單一起源),該枝系當中的H. laodamia與其近緣種則再次失去此發聲結構。雖然H. laodamia枝系失去發聲能力,此支系卻擁有雄蟲發香鱗與翅型/翅紋雌雄二型性的特徵。作者因此認為若發聲行為是作為物種辨識用,則失去發聲行為的枝系則以發香鱗與二型性等特徵替代辨識。目前尚不清楚此三特徵組的出現順序,待後續研究。

(5) 藉由親緣關係樹所得之雌雄二型性特徵分佈,作者也比對此結果是否符合過去三個雌雄二型性起源假說(註)之一。由於雌雄二型性枝系H. laodamia的雌蟲翅紋為祖徵,而雄蟲翅紋為衍徵,因此雖然沒有直接的證據支持,此結果仍較符合達爾文所提出的雌蟲偏好特定雄蟲特徵的假說;

(6) 由於所重建之親緣關係樹整體樹型支持度不高,後續仍有待幼蟲形態資訊以及分子證據的加入,此外對於雌雄蟲辨識所利用特徵的方式,則需要更詳盡的野外觀察與網室試驗來解釋。

註:過去三個主要之雌雄二型性起源假說

(1) 達爾文 (1971) - 性擇假說,由雌性偏好與特定雄性產生後代的選汰方式達成;

(2) 華萊士 (1889) - 天擇假說:雌性儘可能產生隱蔽自身的形狀、斑紋等(相對於祖先型者)來增加適存值;

(3) Silberglied (1984)- 雄性間互動假說:雄性藉由視覺來辨識其他雄性個體的物種異同,並用以對同種雌性進行展示。

Abstract

The neotropical butterfly genus Hamadryas Hubner comprises 20 species that exhibit an intriguing variation in their natural history traits. Although revised in 1983, no phylogenetic hypothesis was presented: the first phylogenetic hypothesis is estimated here based on 93 characters and including species from the three other genera in the tribe Ageroniini. The phylogeny is used to test the monophyly of the genus, establish the sister group of Hamadryas and identify its apomorphies. The tree allows the inference of patterns of character change in sound production and sexual dimorphism. Implied weights show that Hamadryas is monophyletic and corroborate Ectima Doubleday as a sister genus. Previously suggested subgenera for Hamadryas were non-monophyletic, with the exception of the laodamia clade, supported by the presence of a complete sterigma. Sound production is inferred to be a derived condition in Hamadryas that has been lost in the laodamia clade. This, plus the presence of androconial organs and sexual dimorphism in the laodamia clade, suggests a shift in sexual recognition signalling. Furthermore, the phylogeny indicates that the colour pattern of males in the laodamia clade is novel, supporting a Darwinian origin of sexual dimorphism.