盡管雄招潮蟹知道新生的螯使自己處于不利的地位,，但它們依然選擇戰(zhàn)斗。
（圖片提供:Tanya Detto）
一項(xiàng)新的研究顯示,，當(dāng)發(fā)生領(lǐng)土爭(zhēng)端時(shí)，一些雄招潮蟹通過(guò)假裝的強(qiáng)勢(shì)獲得了勝利。這項(xiàng)研究為較早前的發(fā)現(xiàn)提供了佐證,，即動(dòng)物使用欺騙伎倆的頻率遠(yuǎn)高于人們的想象。
雄招潮蟹揮舞著一支巨大的螯——即便在保衛(wèi)家園的戰(zhàn)斗中折斷了,，這些螯也能在不久后重新長(zhǎng)出來(lái),。盡管新的螯看起來(lái)與最初的一樣,，但它們實(shí)際上要脆弱得多。雄招潮蟹其實(shí)已經(jīng)注意到這只新螯的差別,，因?yàn)樗鼈兏p并且不善于完成捏或拉的動(dòng)作,。然而，當(dāng)面對(duì)另一只挑戰(zhàn)者時(shí),，雄招潮蟹總要裝作什么也沒(méi)有發(fā)生——它們會(huì)做恫嚇狀揮舞自己薄弱但巨大的螯,。根據(jù)澳大利亞生態(tài)學(xué)家小組的研究，這種伎倆通常會(huì)奏效,。研究人員在最近出版的《功能生態(tài)學(xué)》雜志上報(bào)告了這一研究成果,。
研究人員在澳大利亞達(dá)爾文市捕捉了一種名為Uca mjoebergi的招潮蟹，并鑒別出了哪些蟹的螯是原生的,，哪些是新生的,。他們測(cè)量了這些招潮蟹的閉合力以及牽引力——在保衛(wèi)領(lǐng)土的戰(zhàn)斗中，入侵的一方試圖將“原住民”從它們的洞穴中拉出來(lái),。研究人員隨后將一些招潮蟹在它們的洞穴附近釋放,，并觀察其他雄蟹對(duì)前者的挑戰(zhàn)。
為了找到新的洞穴,，那些無(wú)家可歸且具有再生螯的招潮蟹通常會(huì)將那些螯長(zhǎng)得比較小的蟹作為進(jìn)攻的目標(biāo),。大多數(shù)情況下，那些“原住民”會(huì)在毫無(wú)反抗的情況下放棄自己的家,，同時(shí)也就中了入侵者的“奸計(jì)”,。領(lǐng)導(dǎo)這項(xiàng)研究的悉尼市新南威爾士大學(xué)的進(jìn)化生態(tài)學(xué)家Simon Lailvaux表示：“雄性動(dòng)物的體態(tài)特征，例如螯的強(qiáng)度以及牽引力,，是保證它們贏得勝利的關(guān)鍵因素,，以至于當(dāng)它們并不具備這樣的體格時(shí)，有些雄性動(dòng)物竟然會(huì)假裝自己很強(qiáng)壯,。”
然而,，那些生有新螯的招潮蟹在為了保護(hù)家園而不得不與無(wú)家可歸者戰(zhàn)斗時(shí)，它們卻沒(méi)有別的選擇,。當(dāng)戰(zhàn)斗打響時(shí),，前者依然嘗試使用欺騙的伎倆，然而由于螯的質(zhì)量不如后者,，這些招潮蟹往往會(huì)敗下陣來(lái),。
在那些研究動(dòng)物性選擇以及交流系統(tǒng)的科學(xué)家中，信號(hào)中的真實(shí)性正越來(lái)越引起他們的關(guān)注,。并未參與該項(xiàng)研究的美國(guó)查布爾希爾市北卡羅來(lái)納大學(xué)的生物數(shù)學(xué)家Jonathan Rowell表示,，類似的研究——例如針對(duì)小龍蝦、牛蛙和寄居蟹的研究——一直在試圖說(shuō)明動(dòng)物如何依靠欺騙的手段來(lái)保衛(wèi)領(lǐng)土和吸引配偶。Rowell指出：“關(guān)鍵的問(wèn)題是設(shè)法搞清像欺騙這樣的行為模式到底是在物種中遺傳的還是僅僅屬于個(gè)體行為,。”（生物谷Bioon.com）
生物谷推薦原始出處：
Functional Ecology,，doi:10.1111/j.1365-2435.2008.01501.x，Simon P. Lailvaux,，Patricia R. Y. Backwell
Dishonest signalling of fighting ability and multiple performance traits in the fiddler crab Uca mjoebergi
Simon P. Lailvaux 1*, Leeann T. Reaney 2 and Patricia R. Y. Backwell 2
1 Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, Australia; and 2 School of Botany and Zoology, The Australian National University, Canberra, Australia, 0200
ABSTRACT
1. Signals used during male combat are expected to be honest indicators of fighting ability. However, recent studies show that dishonesty in male signalling is more prevalent than previously believed.
2. Here we show that regenerated (leptochelous) claws in male Uca mjoebergi fiddler crabs are not only dishonest signals of two types of whole-organism performance capacities that are likely to be useful during fights (claw closing force and pull-resisting force), but they are also less effective as weapons in situations where males are unable to bluff.
3. Original (brachychelous) male claws are statistically significant predictors (independent of body size) of both closing force and the force required to pull a male out of a tunnel. By contrast, leptochelous claw size does not convey information on those performance capacities following control for body size.
4. Furthermore, claw size affects fighting ability such that leptochelous residents are at a significant competitive disadvantage to brachychelous residents, although claw type does not affect the ability of non-resident males to win fights.
5. This study is among the first to show that male armaments can dishonestly signal performance traits that are likely important for winning fights, and is the first to show evidence for dishonest signalling of multiple components of fighting ability.
