• 書名     Mimicry, Crypsis, Masquerade and Other Adaptive Resemblances 
• 作者     Donald L. J. Quicke 
• 出版者 Wiley Blackwell 
• ISBN    111893153X, 9781118931530 
• 頁數     576 頁

內容目錄

相關書籍

圖片來自本文

原文標題：Identification of doublesex alleles associated with the female-limited Batesian mimicry polymorphism in Papilio memnon (open access)


摘要

The female-limited Batesian mimicry polymorphism in Papilio butterflies is an intriguing system for investigating the mechanism of maintenance of genetic polymorphisms. In Papilio polytes, an autosomal region encompassing the sex-determinant gene doublesex controls female-limited mimicry polymorphism. In the closely related species P. memnon, which also exhibits female-limited Batesian mimicry polymorphism, we identified two allelic sequences of the doublesex gene that corresponded exactly with the mimetic and non-mimetic female phenotypes. Thus, the genetic basis of the mimicry polymorphism in P. memnon is similar to that in P. polytes. However, the mimetic and non-mimetic alleles of the two species were not identical, and the divergence of alleles occurred independently in P. memnon and P. polytes. Different mutation-selection processes may have resulted in the convergent patterns of mimicry polymorphism in these Papilio butterflies.

自從控制非洲的白鳳蝶 (Papilio dardanus) 的雌性限性擬態/多態性翅紋的基因座發現後，來到2014年，控制玉帶鳳蝶雌性限性擬態/多態性的超基因 doublesex 的序列與機制也被發掘出來 (可參考這篇文章與這個新聞) 。那麼有著類似斑紋變化，同樣是經典的擬態案例的大鳳蝶呢？

同樣是京都大學的曾田貞滋教授團隊與師大生科系的林仲平教授合作的研究，在這篇文章中，他們發現控制大鳳蝶的超基因與玉帶鳳蝶相似，都位於doublesex這個基因座上，也有表現擬態的顯性 (H) 與隱性 (h)。然而，雖然大鳳蝶與玉帶鳳蝶是同一個亞屬，但兩種目的基因的序列並不相同，而且系統發生學的分析顯示兩者間的基因來源是獨立演化而來。

系統發生學分析顯示玉帶鳳蝶與大鳳蝶的親緣關係

以系統發生學的方式分析doublesex基因序列的關係，顯示大鳳蝶與玉帶鳳蝶間的基因來源是獨立演化而來

控制表型的基因在種間是獨立演化而來其實是滿普遍的現象，但為何這個研究要特地分析兩種的序列以證明其獨立演化來源呢？因為以毒蝶來說，控制斑紋的超基因是會藉由雜交而在不同族群間交換，如果把以系統發生學的方式分析毒蝶的超基因，會發現每個支系混雜不同的族群，而在這篇文章中可以發現兩者的分化顯著，顯示其推動基因演化的機制與毒蝶有所差異。

圖片來源：https://reefbuilders.com/2014/11/14/survival-reef-part-1-masquerading-false-colours/#

標題：Temporal dynamics of the mimetic allele frequency at the doublesex locus, which controls polymorphic Batesian mimicry in Papilio memnon butterflies (open access)

摘要

Tracking allele frequencies is essential for understanding how polymorphisms of adaptive traits are maintained. In Papilio memnon butterflies, which exhibit a female-limited Batesian mimicry polymorphism (wing-pattern polymorphism), two alleles at the doublesex (dsx) locus correspond to mimetic and non-mimetic forms in females; males carry both dsx alleles but display only the non-mimetic form. This polymorphism is thought to be maintained by a negative frequency-dependent selection. By tracking dsx allele frequencies in both sexes at a Taiwanese site over four years, we found that the mimetic allele persists at intermediate frequencies even when the unpalatable model papilionid butterflies (Pachliopta and Atrophaneura species) were very rare or absent. The rates of male mate choice did not differ between the two female forms; neither did insemination number nor age composition, suggesting equivalent reproductive performance of the two forms over time. Our results characterised the temporal dynamics of the mimetic allele frequency in the field for the first time and give insights into underlying processes involved in the persistence of the female-limited Batesian mimicry polymorphism.

大鳳蝶是貝氏擬態的教科書經典案例，在亞洲對這個自家後院就看到的物種自不用說，而西方透過自華萊士時代的紀錄與研究，幾乎全世界都對這個例子的多態性、雌雄二態性與擬態間的關係與來源十分感興趣。這篇文章是京都大學的曾田貞滋教授 (Teiji Sota)及他的學生，與師大生科的林仲平教授合作，以台灣的大鳳蝶為材料，進行長達四年 (2013-2016) 的野外觀察與基因體研究的一部份成果。

這個研究的關鍵在於：首先，貝氏擬態的前提是以負向頻率(negative frequency-dependent selection)為選汰機制，意思也就是在已知的環境中，擬態者的數量不能過多，否則天敵遇到大部份的個體都能吃的話，這個擬態斑紋就可能失效。然而像斑紋高度多態性又牽涉雌雄二態的大鳳蝶，控制擬態的超基因 (supergene) 的族群基因頻率在環境中，如何在擬態與非擬態型中取得平衡就是個很有趣的問題了。



這個團隊執行了幾個部份的調查與實驗。(1) 他們在台灣花蓮以穿越線調查蝴蝶的狀況，並且分析其年齡、身體尺寸、天敵攻擊的咬痕，與交配的次數；(2) 分析大鳳蝶與其擬態模型紅紋鳳蝶 (Pachliopta aristolochiae)、大紅紋鳳蝶 (Atrophaneura polyeuctes) 與台灣麝香鳳蝶 (Atrophaneura febanus) 在這四年中的族群數量 (2) 設計行為的實驗測試大鳳蝶雄性對不同表型的雌性是否具有交配偏好；(3) 野外採集的個體帶回至實驗室進行分生的分析，將其基因型統計是否符合哈溫定律。主要的結果支持兩性的基因頻度的調查皆符合哈溫定律，而雄性無論對擬態或非擬態型的雌性都沒有特殊的擇偶偏好。在四年的觀察與採集中，doublesex的基因頻度維持在中等程度，並未因擬態模型的數量變動偵測到顯著變化，也未發現明顯的負向頻度選汰。也就是說，擬態模型在環境中的頻度與雄性無明顯擇偶偏好，都對doublesex的基因頻度沒有顯著的影響, 而這可能是大鳳蝶能夠維持斑紋多態性的原因。

===
以下是對這個研究的一些觀點：

1. 這個研究的個體僅從花蓮取得，不知是否足以推及解釋台灣其他區域的族群。
2.  一般來說，大鳳蝶的擬態對象認為是紅紋鳳蝶 (Pachliopta aristolochiae)，而這個研究則認為不曾被紀錄是擬態對象的大紅紋鳳蝶 (Atrophaneura polyeuctes) 與台灣麝香鳳蝶 (Atrophaneura febanus) 也同時是其擬態模型。然而，紅紋鳳蝶與另兩種蝴蝶的棲地類型有所差異，根據這個研究的資料，在花蓮的研究地點紀錄的紅紋鳳蝶個體僅有1隻，遠低於大紅紋的21隻，有可能其觀測與採集地點並非天擇作用於擬態斑紋的主要活躍區域，因此擬態者的擬態模型與補食者的動物相的差異，可能影響基因頻率的觀察結果，而非單純的「維持在中等程度進而維持族群中翅紋的多態性」。若是未來能加入更廣泛區域的資料，能讓相關研究更加完整。
3. 雖然大鳳蝶的擬態關係常被用來解釋擬態現象，但畢竟是以人類的視覺角度來觀察，而且大鳳蝶翅紋多態性的變化程度遠比想象中的高，如果一點點差異就會造成擬態效果的變化，那麼所謂「擬態型」的個體與其基因頻度或許要再評估。

用來進行實驗的葵瓜子 photo: P. Allen Smith

標題：Protection by association: Evidence for aposematic commensalism

photo: Olympic Naturual History Photos

標題：A comparative analysis of the evolution of imperfect mimicry

摘要

Although exceptional examples of adaptation are frequently celebrated, some outcomes of natural selection seem far from perfect. For example, many hoverflies (Diptera: Syrphidae) are harmless (Batesian) mimics of stinging Hymenoptera. However, although some hoverfly species are considered excellent mimics, other species bear only a superficial resemblance to their models and it is unclear why this is so. To evaluate hypotheses that have been put forward to explain interspecific variation in the mimetic fidelity of Palearctic Syrphidae we use a comparative approach. We show that the most plausible explanation is that predators impose less selection for mimetic fidelity on smaller hoverfly species because they are less profitable prey items. In particular, our findings, in combination with previous results, allow us to reject several key hypotheses for imperfect mimicry: first, human ratings of mimetic fidelity are positively correlated with both morphometric measures and avian rankings, indicating that variation in mimetic fidelity is not simply an illusion based on human perception; second, no species of syrphid maps out in multidimensional space as being intermediate in appearance between several different hymenopteran model species, as the multimodel hypothesis requires; and third, we find no evidence for a negative relationship between mimetic fidelity and abundance, which calls into question the kin-selection hypothesis. By contrast, a strong positive relationship between mimetic fidelity and body size supports the relaxed-selection hypothesis, suggesting that reduced predation pressure on less profitable prey species limits the selection for mimetic perfection.

不完美擬態 (imperfect mimicry) 指的是一個擬態物種（以人類觀點）猛一看很像A物種，但仔細端詳後又發現其實不太像，有時又會覺得很像B物種，但又覺得有差異，對人類來說就覺得「擬態的不完美」。這個看似對立於「完美擬態」的現象看似成立，其實存在著很多爭議，像是為什麼要有點不像？不像的部分對擬態也有貢獻？其實擬態兩個以上的物種？關於這些問題的研究產生很多對立的結果，到目前為止並未有一致的結論。

Fig. 1  食蚜蠅的斑紋分析，圓圈代表model，三角形代表mimics，白色代表蜜蜂型，灰色代表胡蜂型。 結果顯示兩型間的相似方向並不重疊。

Fig. 4 斑紋相似度與身體尺寸有強烈的正相關（詳細統計結果見原文）

這篇文章藉由比較性的方法來討論不完美擬態的演化來源。太細節的部分就姑且不談，作者群透過比較食蚜蠅 (hoverfly) 的型態（尺寸、斑紋與不同的接受者）與系統發生學的方式，發現以下幾個有趣的證據：

1. 透過型態的測量與鳥類的觀點來看，以人類的角度來判斷物種是否不完美擬態太過簡化這個現象；

2. 經過分析後發現，本來認為可能是擬態兩個擬態模型的食蚜蠅，其實沒有任何一個物種的斑紋實際上同時涉入兩種以上的擬態環，顯示「擬態多物種假說」值得存疑；

3. 沒有任何證據顯示擬態的精確度與物種豐度有負相關（物種數量越少，擬態的越精確），這可能與親屬選汰 (kin selection) 有關；

4. 擬態的精確度與身體尺寸有強烈的正相關，支持緩和選汰假說 (relaxed-selection hypothesis)，顯示獲益較少的物種受到較少的捕食壓力，影響擬態精確度的選汰。

這個研究以食蚜蠅為例子是因為那實在是不完美擬態的典範，然而這篇文章並非完全解答這個現象，至少就食蚜蠅的總物種數來說，文中討論的物種數比例上不算多，有可能陷入見樹不見林的風險。不完美擬態也廣泛的發生在各種其他類群的昆蟲上，這個研究的論點是基於「不完美擬態是到目前為止的終點」，但更多觀察到的現象讓我們覺得「不完美擬態可能只是完美擬態的過程」，代表不同的類群不同的演化故事，帶來的結論可能大相逕庭。

photo from Papilio dardanus (wiki)

標題：Characterising the phenotypic diversity of Papilio dardanus wing patterns using an extensive museum collection.

摘要

The history of 20th Century evolutionary biology can be followed through the study of mimetic butterflies. From the initial findings of discontinuous polymorphism through the debates regarding the evolution of mimicry and the step-size of evolutionary change, to the studies on supergene evolution and molecular characterisation of butterfly genomes, mimetic butterflies have been at the heart of evolutionary thought for over 100 years. During this time, few species have received as much attention and in-depth study as Papilio dardanus. To assist all aspects of mimicry research, we present a complete data-derived overview of the extent of polymorphism within this species. Using historical samples permanently held by the NHM London, we document the extent of phenotypic variation and characterise the diversity present in each of the subspecies and how it varies across Africa. We also demonstrate an association between ‘‘imperfect’’ mimetic forms and the transitional race formed in the area where Eastern and Western African populations meet around Lake Victoria. We present a novel portal for access to this collection, www.mimeticbutterflies.org, allowing remote access to this unique repository. It is hoped that this online resource can act as a nucleus for the sharing and dissemination of other collections databases and imagery connected with mimetic butterflies.

非洲白鳳蝶的多態型，左上方框內是雄性，線的上方是各種斑蝶與細蝶，線的下方是各型雌性白鳳蝶 photo from mimeticbutterflies.org

非洲的白鳳蝶(Papilio dardanus)是知名的貝氏擬態的鳳蝶，其豐富的多態型各自擬態非洲各地的細蝶、斑蝶等不好吃的種類。白鳳蝶的擬態實際上只有雌性參與其中，而雄性只有一種型態，在多態型的雌性中，除了擬態各種不同的蝴蝶外，神奇的也存在雄性型的雌性。

1960年代，透過孟德爾式的遺傳學雜交試驗瞭解不同族群間的斑紋變化，而且結果顯示白鳳蝶的斑紋變化是來自一個超基因；到了2008年，基於現代的分生技術，終於找到超基因的位置。即使如此，雌性的型態實在太多了，除了上面這些看起來精準擬態的斑紋外，也有更多看起來是中間型的種類，因此雖然已經研究到基因體層級的情況下，基礎的斑紋與地理分佈還沒有整體性的調查過。

雌性各種不同的型與名稱 photo from Fig. 1

這篇透過英國倫敦自然史博物館(the Natural History Museum, London)的極大量鱗翅目館藏，蒐集標籤上的採集資訊，將採集的地點轉換成現代的地點並查出座標，把各個不同的斑紋分類後，再轉換為二維座標系統輸入地理資訊系統 (GIS)，把各個不同的斑紋分類後，就能每個型態的分佈呈現在現代的地圖上，並且透過採集點的連線，推估分佈範圍。

取樣密度與地點 photo from Fig. 3 各型的分佈範圍 photo from Fig. 6

結果就如上圖，把大部分的斑紋的分佈範圍推估出來，而那些看起來不完美擬態的斑紋分佈於維多利亞湖附近，支持這是西部與東部族群相遇的雜交區。

中間型的分佈區域 photo from Fig. 7

這分析的概念很簡單，但卻是瞭解一個擬態群的多樣性最快的方式，而且最重要的，這仰賴保存完整與大量的標本館藏。這樣的研究說明透過良好的想法與完整的分析，即使基礎的研究也能從中得到大量的資訊，也更凸顯標本蒐藏的重要性。

photo from Morpho menelaus (wiki)

標題：Both Palatable and Unpalatable Butterflies Use Bright Colors to Signal Difficulty of Capture to Predators
Birds are able to recognize and learn to avoid attacking unpalatable, chemically defended butterflies after unpleasant experiences with them. It has also been suggested that birds learn to avoid prey that are efficient at escaping. This, however, remains poorly documented. Here, we argue that butterflies may utilize a variety of escape tactics against insectivorous birds and review evidence that birds avoid attacking butterflies that are hard to catch. We suggest that signaling difficulty of capture to predators is a widespread phenomenon in butterflies, and this ability may not be limited to palatable butterflies. The possibility that both palatable and unpalatable species signal difficulty of capture has not been fully explored, but helps explain the existence of aposematic coloration and escape mimicry in butterflies lacking defensive chemicals. This possibility may also change the role that putative Müllerian and Batesian mimics play in a variety of classical mimicry rings, thus opening new perspectives in the evolution of mimicry in butterflies.

作者討論的蝴蝶之一，摩爾福蝶。背面與腹面差異很大，其飛行行為讓人覺得很難追。 photo from Morpho menelaus (wiki)

文章中的範例之一，Parides anchises nephalion photo from Aluisio Ribeiro

photo from wongchunxing.com Myrmarachne Merotai （非本實驗中用種類）

標題：Locomotory mimicry in ant-like spiders

摘要

The jumping spider genus Myrmarachne (Salticidae) consists of over 200 species of morphologically accurate ant mimics, enabling Myrmarachne to evade ant-averse predators that confuse the spiders with ants (Batesian mimicry). A conspicuous but untested trait of Myrmarachne, which is frequently mentioned in the literature, is locomotory mimicry. For these spiders, locomotion that is more ant like than salticid like may be an integral part of the suite of mimetic signals. We quantified the locomotory pattern of several species of non-ant-like salticids, Myrmarachne, and ants from Australia. We found that the locomotion of the mimics generally resembles that of ants, but not of other salticids. To tease out the effects of locomotion from those based on morphology, ant-eating salticids as visual predators were presented with 3D animations of ant-like salticids walking either in ant or in salticid fashion. Ant-eating salticids spent significantly longer looking at the stimulus with ant-like movement and were significantly more likely to visually track and stalk the stimulus with ant-like movement. Overall, our results suggest that there is selection pressure on Myrmarachne for increased resemblance to a model by locomotor mimicry, despite the associated costs when faced with ant-eating predators.

蟻蛛屬 (Myrmarachne，跳蛛科)全世界超過200種，令人驚訝的是精確的擬態各種螞蟻的型態與行為，可能帶給這群跳蛛躲避其他天敵的好處，被認為是一種貝氏擬態。但令人疑惑的是，跳蛛科有另外一群種類是專吃螞蟻的，蟻蛛也可能被其他專吃螞蟻的跳蛛攻擊，這樣擬態螞蟻反而可能承受更大的風險，使得科學家一直想弄清楚這群蟻蛛到底是想怎樣？

雖然以人類的角度來看，蟻蛛看起來像螞蟻，走起來像螞蟻，可是有科學上的證據嗎？意外的不多，大部分是觀察式的證據，因此這篇文章的作者們想透過分析澳洲的蟻蛛與螞蟻的行為比較，還有為了弄清楚行為與型態對擬態的貢獻，也把蟻蛛的3D影像播放給吃螞蟻蜘蛛看，同時藉由科學上的行為分析與捕食者的觀點來分析，蟻蛛到底像不像螞蟻。

實驗中觀察的種類之一，Myrmarachne smaragdina，Darwin， Female photo from Dr. Greg Anderson

行為的紀錄分為三個類型：非螞蟻型跳蛛（其他跳蛛）、蟻蛛與螞蟻的行為模式，分析蟻蛛的行為究竟比較偏向普通的跳蛛，還是比較類似於螞蟻。行為的實驗則透過3D動畫建模，做出蟻蛛的型態，但行為分別是螞蟻與普通跳蛛的動畫，然後播放給吃螞蟻的跳蛛看（給蜘蛛看卡通的意思），分析蟻蛛究竟是透過行為或是型態來欺騙捕食者。

結果顯示蟻蛛的行為的確比較接近螞蟻而非像其他的跳蛛。吃螞蟻的跳蛛花了比較長的時間在螞蟻行為的蟻蛛影像上，顯示即使對捕食者來說，蟻蛛的行為也非常像螞蟻。因此總和來說，雖然偶爾可能面對來自吃螞蟻的蜘蛛的風險，蟻蛛的確受到某些未知的天擇壓力，迫使這樣精確擬態螞蟻的型態與行為留存。

大杜鵑 (Cuculus canorus) photo from ouse washes

標題：Hawk models, hawk mimics, and antipredator behavior of prey.

摘要

Prey typically respond to potential predators by taking flight. This results in an optimal flight initiation distance (FID) at which the risk of remaining and the cost of flight are equal. Thus, FID is strongly negatively correlated with susceptibility to predation by the sparrowhawk Accipiter nisus across species of small European birds. However, not everything that looks like a hawk is in fact a hawk. Aggressive mimicry arises from the resemblance between a dangerous model such as a predatory hawk and an innocuous mimic such as a cuckoo that makes errors made by individuals that encounter models and mimics potentially dangerous and life threatening. A prime example of such aggressive mimicry is the hawk-like appearance of common cuckoos Cuculus canorus and other cuckoos. If mimicry is efficient, we should expect that species of small birds that are prey of hawks and hosts of cuckoos react just as strongly to a cuckoo as to the presence of a dangerous model like a sparrowhawk. We used FID of small birds as a measure of the reaction of prey to models and mimics, predicting that FID would be negatively related to susceptibility to predation and positively to risk of cuckoo parasitism. Both susceptibility to sparrowhawk predation and rate of brood parasitism by the common cuckoo independently explained variation in FID, consistent with the expectation that both hawks and cuckoos have imposed significant selection pressures on FID and that species of small birds perceive cuckoos as true mimics of hawks.

獵物遇到天敵要逃跑的時候，通常會評估「到底要不要跑？」

覺得奇怪嗎？遇到天敵，先跑，就對了啊，難道還等天敵到面前了才傻傻的要跑嗎？

對於野外一天到晚被人盯著瞧，隨時可能被吃掉的物種來說，隨時隨地都可能遇到天敵，但不是隨時隨地都有力氣可以跑，如果太早跑反而提早被發現，因此這些物種會評估到底捕食者離我多近才要跑，這稱為flight initiation distance (FID)，也可以叫做初始逃跑距離，就是捕食者離我到多近的食後才開始逃跑。那麼為什麼會有這個距離呢？因為有些獵物身上有些隱蔽色或有些警戒色之類用來躲避天敵的機制，如果捕食者雖然靠的很近但其實沒發現，那麼就不用浪費力氣逃跑，可是相對的會遭遇非常高的風險：萬一被發現就跑不掉了。

雀鷹 (Accipiter nisus) photo from Eurasian sparrow hawk (wiki)

那麼有意思的事情就發生了。大杜鵑 (Cuculus canorus)眾所皆知，有把蛋下在別人的巢裡，讓別的鳥幫牠孵蛋的行為。有人覺得大杜鵑長的像雀鷹 (Accipiter nisus)，早期的科學家認為這是一種貝氏擬態，但後來發現有另一種可能：這些大杜鵑長的像雀鷹，把那些要幫牠孵蛋的鳥嚇走，大杜鵑就能順利的去這些鳥的巢裡下蛋了？

作者藉由測量那些幫忙孵蛋的小型鳥的FID來測試這件事。之前有研究顯示，歐洲的小型鳥的FID與感知捕食的壓力的平衡點是負相關（體型越小靠的越近），因此如果小型鳥感應到的是捕食壓力，那麼應該是負相關，如果感知到的是普通的杜鵑偷生蛋行為，則是正相關。大杜鵑看起來就像雀鷹的話，那麼小型鳥的FID應該會與看到雀鷹的FID結果相似。作者觀察了63種鳥類行為的結果顯示，雖然某些小型鳥對大杜鵑的反應就像對雀鷹一樣，但相較於捕食的壓力，對於認知「杜鵑來下蛋」這件事還是比較強烈，因此大杜鵑擬態雀鷹可能有侵略型擬態的作用，但作者還是認為這還是種貝氏擬態，功用可能在於寄生到比較兇的寄主時，不會被這些寄主反過來攻擊甚至喪命。綜合以上顯示兩種行為都帶給這些小型鳥不同的壓力，這使FID的測量與結果可能來自於更為複合的行為觀察才能解釋。

photo from BugGuide

標題：The evolution of Batesian mimicry within the North American Asidini (Coleoptera: Tenebrionidae).

摘要

The asidine darkling beetles (Coleoptera: Tenebrionidae: Asidini) are a diverse tribe of flightless tenebrionids found in many arid and sub-arid habitats around the world. The 263 currently described North American species are contained in ten genera, all of which are restricted to the western half of the continent. The Asidini, like all members of the subfamily Pimeliinae, lack defensive glands. Instead, several phenotypic traits occur within the tribe that may help limit predation. These include the contrasting defensive strategies of crypsis, through either background matching or pattern disruption, and Batesian mimicry of the chemically defended genus Eleodes. Dorsal elytral morphology was assessed between 53 North American asidine species and 13 common Eleodes model species using multiple methodologies to assess similarities between species in the two groups that might indicate mimetic relationships. A phylogeny of the North American asidines is used to map the occurrence of differing defensive strategies within the tribe. Crypsis is reconstructed as the ancestral state, with two origins for Batesian mimicry and multiple reversals. The combination of strongly to weakly cryptic species and varying levels of mimetic fidelity to Eleodes model species make the asidines a promising lineage upon which to further explore the evolution of defensive phenotypes.

八種顯示隱蔽色的Pelecyphorus spp photo from Fig. 1

這個研究所說的是北美的一個擬步行蟲科(Tenebrionidae)其下的一個族 Asidini (漠甲亞科，Pimeliinae)的貝氏擬態斑紋的演化，若要瞭解這個文章，要先配合另一篇文章，Phylogenetic revision of the North American Asidini (Coleoptera: Tenebrionidae)來看。這個族共包含263種，所有的種類都缺乏防禦腺體（可能是不會臭），整個族都棲息在乾燥的環境（可能是沙漠或周遭），大部分的種類都看起來像沙子的顏色，但有幾個種看起來像另一類的擬步行蟲 Eleodes spp.，因此作者對於這些看起來擬態的斑紋的演化趨勢有興趣。整體的架構是這樣，作者先發表了整個族的系統發生學，然後才有這篇討論斑紋演化的文章。

photo from Fig. 2 中間、正下方、左下為擬態者Stenomorpha spp. 其餘為擬態模型Eleodes spp.

研究中使用了11個背方的特徵，這些特徵看起來跟Eleodes spp.的擬態是有關聯的，如果是這樣的話，那把這兩類的物種同時放在一個分析矩陣下跑樹的話，兩者應該會跑在一起，而且有可能可以找出哪些特徵讓兩者看起來這麼像。另一方面作者使用這個族的樹，把擬態的特徵映象至樹上，追溯這些斑紋在樹上的變化，就能瞭解演化趨勢。

結果發現支持這兩類看起來想似的主要特徵是「背面不反光」與「顏色斑紋單一」，而整體的演化趨勢來看的話，如同大部分其他的例子，隱蔽色是祖徵，可能與Eleodes spp.的擬態特徵是複數起源。

雖然說擬態起來的相似度還是要從整體的行為斑紋來看，但分別把特徵拆開追溯其演化趨勢，有助於讓我們了解究竟相似度從何而來，也可以為未來更細膩的研究打下基礎。

photo from K. Kunte

標題：A genetic mechanism for female-limited Batesian mimicry in Papilio butterfly.

摘要

In Batesian mimicry, animals avoid predation by resembling distasteful models. In the swallowtail butterfly Papilio polytes, only mimetic-form females resemble the unpalatable butterfly Pachliopta aristolochiae. A recent report showed that a single gene, doublesex (dsx), controls this mimicry; however, the detailed molecular mechanisms remain unclear. Here we determined two whole-genome sequences of P. polytes and a related species, Papilio xuthus, identifying a single ~130-kb autosomal inversion, including dsx, between mimetic (H-type) and non-mimetic (h-type) chromosomes in P. polytes. This inversion is associated with the mimicry-related locus H, as identified by linkage mapping. Knockdown experiments demonstrated that female-specific dsx isoforms expressed from the inverted H allele (dsx(H)) induce mimetic coloration patterns and simultaneously repress non-mimetic patterns. In contrast, dsx(h) does not alter mimetic patterns. We propose that dsx(H) switches the coloration of predetermined wing patterns and that female-limited polymorphism is tightly maintained by chromosomal inversion.

photo from Fig 3

基因knockdown後，不同處理的斑紋表現 photo from Fig. 5

左圖為有毒的珊瑚蛇，右圖為無毒擬態者猩紅王蛇

作者使用的黏土模型，由上而下為共域型/雜交型/異域型 photo from Fig. 3

北美火焰蠑螈 (Plethodon cinereus) photo from Salamander Chronicles

由下而上為火焰蠑螈(model)，紅背蠑螈紅化型(mimic)，紅背蠑螈黑色型(non-mimetic) photo from Andy Kraemer

標題：Model toxin level does not directly influence the evolution of mimicry in the salamander Plethodon cinereus.

摘要

The resemblance between palatable mimics and unpalatable models in Batesian mimicry systems is tempered by many factors, including the toxicity of the model species. Model toxicity is thought to influence both the occurrence of mimicry and the evolution of mimetic phenotypes, such that mimicry is most likely to persist when models are particularly toxic. Additionally, model toxicity may influence the evolution of mimetic phenotype by allowing inaccurate mimicry to evolve through a mechanism termed ‘relaxed selection’. We tested these hypotheses in a salamander mimicry system between the model Notophthalmus viridescens and the mimic Plethodon cinereus, in which N. viridescens toxicity takes the form of tetrodotoxin. Surprisingly, though we discovered geographic variation in model toxin level, we found no support for the hypotheses that model toxicity directly influences either the occurrence of mimicry or the evolution of mimic phenotype. Instead, a link between N. viridescens size and toxicity may indirectly lead to relaxed selection in this mimicry system. Additionally, limitations of predator perception or variation in the rate of phenotypic evolution of models and mimics may account for the evolution of imperfect mimicry in this salamander species. Finally, variation in predator communities among localities or modern changes in environmental conditions may contribute to the patchy occurrence of mimicry in P. cinereus.

photo from Virginia Herpetological Society 紅背蠑螈的不同型態變化

1. 捕食者的受覺與北美蠑螈間體色的貝氏擬態與警醒程度的關係
2. 北美的貝氏擬態的蠑螈顯示擬態者也能影響擬態系統的演化方向

文中的擬態者 勞旦橫口鳚 (Plagiotremus laudandus) photo from Dianne J. Bray, 2011, Bicolor Fangblenny, Plagiotremus laudandus, in Fishes of Australia

文章中的被擬態者，金鰭稀棘䲁 (Meiacanthus atrodorsalis) photo: Dianne J. Bray, 2011, Eyelash Fangblenny, Meiacanthus atrodorsalis, in Fishes of Australia, accessed 31 Mar 2016

標題：Multiple selective pressures apply to a coral reef fish mimic: a case of Batesian-aggressive mimicry.

摘要

Mimics closely resemble unrelated species to avoid predation, capture prey or gain access to hosts or reproductive opportunities. However, the classification of mimicry systems into three established evolutionary mechanisms (protection, reproduction and foraging) can be contentious because multiple benefits may be gained by mimics, causing the evolution of such systems to be driven by more than one selective agent. However, data on such systems are generally speculative or anecdotal. This study provides empirical evidence that dual benefits apply to a coral reef fish mimic in terms of increased access to food (aggressive mimicry) and reduced predation risk (Batesian mimicry). Bicolour fangblennies Plagiotremus laudandus gained access to more reef fish victims, which they attack to feed on fins and scales, when they spent more time associated with their model Meiacanthus atrodorsalis. Furthermore, exact replicas of P. laudandus incurred fewer approaches from potential predators compared with control replicas that varied in resemblance to P. laudandus. Predators with trichromatic visual systems (three distinct spectral sensitivities) could potentially distinguish between replicas based on colour based on theoretical vision models. Therefore, this mimicry system could be best described as Batesian–aggressive mimicry in which mimicry evolution is driven by multiple simultaneous selective pressures.

photo from Fig. 1 a) i. 金鰭稀棘鳚 (Meiacanthus atrodorsalis) ii. 勞旦橫口鳚 (Plagiotremus laudandus) b) 三種手工實驗用假魚與控制組物種粗吻橫口鳚 (P. rhinorhynchos)

通常科學家會把牽涉擬態的物種歸類，譬如說這是貝氏擬態，那是穆氏擬態，也有可能是介於兩者間的負貝氏擬態，那麼會不會有一個物種同時牽涉兩種擬態的系統呢？

photo from Fig. 2 此圖說明model/mimic比例的高低與攻擊成功率無關（黑圈圈），但花在model旁邊時間越多，成功率較高（白鑽石）

photo from Fig. 3 左邊是捕食性魚類，右邊是非捕食性魚類 從上而下分別是三組：沒model/有mimic (Lizard island)，有model/有mimic (Lizard island)，有model/有mimic (Pulau Hoga)

photo from doublesex is a mimicry supergene

標題：The status of supergenes in the 21st century: recombination suppression in Batesian mimicry and sex chromosomes and other complex adaptations.


摘要

I review theoretical models for the evolution of supergenes in the cases of Bate- sian mimicry in butterflies, distylous plants and sex chromosomes. For each of these systems, I outline the genetic evidence that led to the proposal that they involve multiple genes that interact during ‘complex adaptations’, and at which the mutations involved are not unconditionally advantageous, but show advanta- ges that trade-off against some disadvantages. I describe recent molecular genetic studies of these systems and questions they raise about the evolution of sup- pressed recombination. Nonrecombining regions of sex chromosomes have long been known, but it is not yet fully understood why recombination suppression repeatedly evolved in systems in distantly related taxa, but does not always evolve. Recent studies of distylous plants are tending to support the existence of recom- bination-suppressed genome regions, which may include modest numbers of genes and resemble recently evolved sex-linked regions. For Batesian mimicry, however, molecular genetic work in two butterfly species suggests a new super- gene scenario, with a single gene mutating to produce initial adaptive pheno-types, perhaps followed by modifiers specifically refining and perfecting the new phenotype.

先說，這篇很難，完全在說分子生物學層級的機制。

作者整理有關貝氏擬態、性別決定與植物的二型花柱(distyly)討論基因重組與超基因的分子演化機制。這邊稍微整理貝氏擬態的部分，主要是談到有關這60年來藉由大鳳蝶 (Papilio memnon)、玉帶鳳蝶(P. polytes)與非洲白鳳蝶 (P. dardanus)的遺傳學與基因體學的研究，討論超基因如何出現的分子機制，如何透過基因重組的方式讓控制不同區域斑紋的基因逐漸在染色體上靠攏，作者整理兩個假說，說明兩個以上的擬態斑紋基因是如何出現在基因體內的兩種機制，分別是同染色體的調控與異染色體的調控（內文圖一）。這個整理對於擬態生物學關於分子層級的調控機制的研究提供一個統整性的框架。

未來將不再只是毒蝶內的穆氏擬態，貝氏擬態的背後神秘的作用機制也會越來越明朗。

photo from Cleridae (wiki)

標題：Aposematism and mimicry in soft-bodied beetles of the superfamily Cleroidea (Insecta)

摘要

The evolution of animal life strategies is among the main themes of current evolutionary biology. Checkered beetles, soft-winged flower beetles and their allies (superfamily Cleroidea), exhibit well-known aposematic colour patterns, particularly in the family Cleridae, which participate in mimicry complexes mostly with unpalatable beetles, ants and velvet ants representing a Mullerian–Batesian continuum. Many cleroids also exhibit attenuated hardening of cuticular layers resulting in a soft-bodied appearance. Here, a molecular phylogenetic analysis of the entire Cleroidea was performed using sequences of two nuclear and two mitochondrial loci of ~4 kb total length. Inferred phylogenies were used to reconstruct ancestral colour patterns and involvement in mimicry complexes. The hypothesis of a soft-bodied ancestor of Cleridae and allies was tested. The phylogenetic analyses corroborated the expanded Cleroidea concept including Byturidae and Biphyllidae formerly classified as Cucujoidea. Character state optimization showed cryptic col- oration was the ancestral state in Cleroidea, from which aposematic coloration originated several times in distant cleroid lineages. Within Cleridae, mimicry also arose from an ancestor that was cryptic, and multiple lineages that mimicked unpalatable beetles (Chrysomelidae, Meloidae, Lycidae) and stinging Hymenoptera evolved. Aposematic coloration was acquired in all major clerid lineages including Thanerocleridae, which are either the sister group of Chaetosomatidae or Cleridae. These findings suggest that mimetic traits in the clerid clade evolved at various times, possibly soon after the origin of soft-bodiedness. The adaptive value of aposematism in cleroids is likely to be enhanced in soft-bodied species, as this trait provides limited means of protection against predators, and therefore may promote the acquisition of aposematic and mimetic col- oration in various ecological situations.

郭公蟲 (Cleroids)是鞘翅目下的一個總科，全球約有3000種，從訪花到食腐肉的食性都有，有的郭公蟲還是飼料害蟲（如赤足郭公蟲）。這類群的外觀有的看起來像菊虎，有的看起來像葉蚤，有的看起來像螞蟻，說白了就是一個到處複製其物種斑紋的類群，可是這樣的斑紋演化是怎麼來的，其祖先是隱蔽色還是原本就有這些警戒色呢？郭公蟲的身體有硬有軟，這些硬的類群跟軟的類群各自獨立演化，或者這是一個各種不同的衍徵呢？

photo from content

作者用了兩個核基因（18S 與 28S的D2區域）與兩個粒線體基因（16S與cox1），大約4kb的長度來重建郭公蟲總科的親緣關係。細部的分類就不談了，特徵追溯的結果顯示郭公蟲總科的體色的祖徵應該是隱蔽色（82％），擬態螞蟻或其他甲蟲的特徵都是各自演化出來的。而軟/硬身體的類群則顯示郭公蟲總科的祖徵的身體是硬的而且有的是隱蔽色（97％）。這個演化關係似乎暗示軟身體的那群與演化出警戒色/擬態的關係比較緊密（軟身體群比較多與警戒色/擬態的類群），或許是因為身體柔軟受到捕食者（也就是天擇）的影響比較大，因此演化的方向朝著留下具有警戒色/擬態的類群。

photo from content

現在推測特徵演化大部分用MCMC的參數模型，這個研究也是，對於這個模型的使用沒什麼太大的意見，甚至可以說這種變動式的模型更適合計算演化特徵的改變，只是說這種方法算出來後，各個節上所呈現的是機率，這該如何解釋呢？該說那個共祖有x%的機會是A特徵，(1-x%)的機會是B特徵嗎？可是學生態的人很難理解這點，因為野外看到的特徵就是100%是某樣子（我這裡所說的不是野外族群的比例，那是另一個計算法了），不會因為時空背景有差異（有誰可以說說5%的機率看到某支蟲是紅色實際上應該是怎樣？一直在亂數閃爍嗎？）

我想，這就是薛丁格的貓吧。