11月15日,，據(jù)國(guó)外媒體報(bào)道，對(duì)于我們?nèi)祟?，男朋友送女朋友禮物是司空見慣的事,，實(shí)際上,，在自然界也有這一聰明的舉動(dòng)，研究發(fā)現(xiàn),，雄蜘蛛為了完成交配,，也會(huì)把一個(gè)包裝好的禮物送給“女朋友”， 雌性蜘蛛甚至還很“勢(shì)利”,，對(duì)那些沒有價(jià)值的禮物不屑一顧,。
雄盜蛛（nursery web spiders）一般會(huì)準(zhǔn)備一個(gè)用絲包住的禮物獻(xiàn)給“女朋友”，討她的歡心,。大多數(shù)禮物都是包裝精美的昆蟲,，但有些禮物是不能食用的植物種子或已經(jīng)被吃掉的昆蟲的空殼，雌盜蛛看不上,，會(huì)很不高興地走開,，這時(shí)雄盜蛛會(huì)“裝死”，然后嘗試尋找新的“女朋友”,。此項(xiàng)研究報(bào)告發(fā)表在最新一期的《BMC進(jìn)化生物學(xué)》（BMC Evolutionary Biology）雜志上,。
雄盜蛛向“意中人”獻(xiàn)上的禮物通常是可以食用的蒼蠅；有的雄盜蛛比較吝嗇,，送一個(gè)毫無價(jià)值的禮物,，如棉花羊毛球、干枯的花朵,、吃剩的昆蟲殘留物,；有的不解風(fēng)情，不送禮物,。所有禮物都會(huì)被包裝,，雌蛛不拆開包裝就不知道里面的禮物是什么。研究表明,，送禮物的雄蛛比不送禮物的雄蛛完成交配的成功率更高,。然而，對(duì)于那些送毫無價(jià)值禮物的雄蛛,，雌蛛讓它們輸送精子的時(shí)間比那些送可食用禮物的雄蜘蛛的時(shí)間要短,。
看來，雄盜蛛和雌盜蛛顯然能夠評(píng)估禮物的價(jià)值,，并相應(yīng)地調(diào)整對(duì)待伴侶的方式,。雌盜蛛對(duì)沒有送好禮物的“男朋友”不喜歡，匆匆結(jié)束交配,；而雄蜘蛛看到“女朋友”對(duì)禮物不滿意或試圖盡快結(jié)束交配,，就會(huì)裝死。研究人員有時(shí)會(huì)看到雄盜蛛和雌盜蛛會(huì)為一個(gè)可以食用的禮物而打架,，但從來不會(huì)為一個(gè)毫無價(jià)值的禮物打架,。
領(lǐng)導(dǎo)這項(xiàng)研究的瑪麗亞·阿爾博（Maria Albo ）解釋說,，“雄盜蛛用包裝好的禮物欺騙雌盜蛛的感情，這涉及復(fù)雜的成本和收益方程,。雄盜蛛花時(shí)間找禮物和包裝禮物,，禮物越有價(jià)值，獲得的交配時(shí)間越長(zhǎng),，射精管得以輸送更多的精子到受精囊,，并有可能產(chǎn)生更多的后代，但雌盜蛛也很精明,，會(huì)識(shí)別欺騙行為,，當(dāng)它們發(fā)現(xiàn)收到的禮物毫無價(jià)值時(shí)會(huì)盡早終止交配。”
她繼續(xù)說,，“交配后雌蛛產(chǎn)一個(gè)卵袋,，內(nèi)裝受精卵。最后的研究結(jié)果表明,，雌蛛很“勢(shì)利”,，如果沒有收到禮物，受精卵的數(shù)量明顯減少,，但收到可食用或不能食用的禮物的雌蛛之間的差別不大,。所以送禮物很重要，雄蜘蛛往往能作弊成功,，包一個(gè)沒有用的禮物蒙混過關(guān),，這或許可以解釋為什么蜘蛛數(shù)量一直如此龐大。”（生物谷 Bioon.com）
doi:10.1186/1471-2148-11-329
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Worthless donations: male deception and female counter play in a nuptial gift-giving spider
Maria J Albo , Gudrun Winther , Cristina Tuni , Soren Toft and Trine Bilde
Background
In nuptial gift-giving species, benefits of acquiring a mate may select for male deception by donation of worthless gifts. We investigated the effect of worthless gifts on mating success in the spider Pisaura mirabilis. Males usually offer an insect prey wrapped in silk; however, worthless gifts containing inedible items are reported. We tested male mating success in the following experimental groups: protein enriched fly gift (PG), regular fly gift (FG), worthless gift (WG), or no gift (NG).
Results
Males that offered worthless gifts acquired similar mating success as males offering nutritional gifts, while males with no gift experienced reduced mating success. The results suggest that strong selection on the nuptial gift-giving trait facilitates male deception by donation of worthless gifts. Females terminated matings faster when males offered worthless donations; this demonstrate a cost of deception for the males as shorter matings lead to reduced sperm transfer and thus give the deceiving males a disadvantage in sperm competition.
Conclusion
We propose that the gift wrapping trait allows males to exploit female foraging preference by disguising the gift content thus deceiving females into mating without acquiring direct benefits. Female preference for a genuine prey gift combined with control over mating duration, however, counteracts the male deception.
