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[品種資訊→] 加拉巴哥陸龜的求偶生活

加拉巴哥陸龜的求偶生活

20160208 Animal Sex: How Galapagos Tortoises Do It
http://www.livescience.com/53632 ... agos-tortoises.html



The giant tortoises of the Galápagos Islands are infamous for being one of the animals that inspired Charles Darwin to formulate his theory of natural selection. But it may come as a surprise that despite their fame, the Galápagos tortoises have long been a bit of a mystery to scientists — at least when it comes to their sexual and social behaviors.

"One of the great misconceptions of iconic organisms is that we know much about them," said James Gibbs, a conservation biologist at the SUNY College of Environmental Science and Forestry in Syracuse, New York, who studies giant tortoises. "But tortoise social behavior is barely known, and we're just starting to figure all this out."

As Darwin noticed, there are two distinct types of Galápagos tortoises: saddleback tortoises (including the famed Lonesome George) and dome-shaped tortoises, so-named for the structure of their shells. But aside from having different shells, these reptiles also have very different behaviors. [See Images of Lonesome George, a Giant Galapagos Tortoise]

Saddleback tortoises live in dry environments where there's little to eat for 9 months of the year, Gibbs told Live Science. As their name implies, saddleback tortoises' shells rise in the front like saddles — this adaptation allows them to extend their long necks up to feed on cactus trees.

Male saddlebacks vie for control over cactus trees, but will allow as many females into their shaded domains as possible.

Domed tortoises, on the other hand, live in moist regions where food is plentiful and close to the ground, and the shape of their shells prevents them from extending their short necks up.

Because of the abundance of food, these tortoises don't control territories and instead roam around to find mates, probably using their noses as their guides, Gibbs said. "Having said that, we suspect — and it's probably true — that they may also use ultrasonic communication."

Galápagos tortoises mate throughout the year, but sexual activity typically heats up during the hot months in the beginning of the year.

When two male saddlebacks come across one another, they battle for access to cactus trees — and therefore mates. These fights, however, amount to little more than neck-stretching competitions, with the longer-necked tortoises ultimately coming out victorious (though biting is also sometimes involved).

Male dome-shape tortoises, by comparison, engage much less in competition. "There's a lot more food, but they do sometimes act like bumper cars and just bump into each other with a loud noise," Gibbs said.

Male Galápagos tortoises aren't in the business of wooing their potential mates; rather, they show their interest by harassing the much smaller females. That is to say, a male will spend up to three or four days following a female, trying to mount her, and pushing her around a bit.

"They interfere with daily activities and feeding, but we don't know if it's part of the male's strategy to wear [the female] down," Gibbs said.

Galápagos tortoises, like other reptiles, have cloaca (a single orifice for waste and reproduction) at the base of their tails. The lining of the male's cloaca folds out to form a "penis," which he needs to insert into the female's cloaca for insemination — an act that requires the female's cooperation, as she needs to extend her tail out and lift it so that the male has access.

"Tortoise mating is quite an affair to watch," Gibbs said, adding that males will thrust for 10 to 20 minutes while making loud groaning noises that can carry for miles.

After mating, the female Galápagos tortoise may store the sperm of her mate in her body for at least 7 years for later use.


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拜託一下,看哪位大大有空
幫忙翻成中文,造福其他龜友
想幫忙的自己在樓上留言
這樣就不會重覆翻譯了
養龜之道,當徐徐圖之,並非朝夕可成之功也。
治爬治得好小菜一碟,養爬養得好方成境界。
Saving the world,one tortoise/turtle at a time。

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我來翻吧,今晚交稿。

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以下是我嘗試做出的翻譯。由於本身並非研究陸龜的專家,因此有些用詞或許不夠專業,請多指教並敬請包含。

因著身為啟發查理斯•達爾文構思出物競天擇理論的其中一種動物,加拉巴哥群島上的象龜因此聞名。但令人驚訝的是,儘管牠們如此有名,長期以來自然科學家對加拉巴哥象龜的了解,至少在牠們的性行為與社會行為上,仍是存在著一些未解之謎。

紐約西拉鳩斯市州立大學環境科學與林業學系的保育生物學家,詹姆斯•吉布斯所研究的便是象龜。他這樣說:「我們對於那些具代表性的物種,其中一項大誤解便是,我們以為自己對牠們所知甚多。然而,陸龜的社會行事實上罕為人知,而我們其實才剛開始嘗試要去了解而已」。

正如達爾文所觀察到的,加拉巴哥象龜有兩種不同的品種:鞍背象龜(包括著名的寂寞喬治)與圓背象龜,牠們之所以被如此命名是因著牠們背甲形狀的不同。然而,除了背甲形狀不同外,牠們的行為也很不一樣(見圖片堛漫t獨喬治,一隻巨大的加拉巴哥象龜)。

吉伯斯對美國生活科學雜誌表示,鞍背象龜生活在乾燥的環境,這些環境一年當中有九個月缺乏食物。正如牠們的名字所表達的,鞍背象龜的背甲在前方翹起,如同馬鞍一般,這項適應環境的演化使得牠們能夠將長長的脖子向上伸出,以至於可以取得仙人掌樹上的食物。

雄性的鞍背象龜之間會為了控制仙人掌樹的地盤而競爭,但牠們卻願意盡可能容許最多數量的雌龜進入牠們所掌控之地盤的蔭下。

反之,圓背象龜生活在潮濕的地區,食物來源豐富且靠近地面,而牠們背甲的形狀也使牠們無法將牠們短短的脖子往上伸。

吉伯斯說,因著食物不虞匱乏,圓背象龜沒有控制地盤的習性。相反的,牠們到處遊走去尋找配偶,這大概是透過嗅覺來做為引導。「不過,我們懷疑--這也可能是真的--牠們也透過超聲波作為溝通。」

加拉巴哥象龜一年到頭都有交配行為,但一般來說,交配的行為在一年開頭幾個最熱的月份急速增加。

當兩隻雄性的鞍背象龜相遇時,牠們會為了爭取仙人掌樹的地盤而戰,勝出的便能得到交配權。這些打鬥,大多僅止於一些伸長頸部的競爭,而頸項較長的個體最終贏得勝利(雖然有時牠們的打鬥也會包括啃咬)。

相較之下,雄性的圓背象龜之間的競爭更少。吉伯斯說道:「牠們那堛滬鼓咱R裕多了。不過,有時候牠們確實也會像碰碰車一樣,互相碰撞並發出巨大的聲響」。

雄性的加拉巴哥象龜並不會花心思去求偶。相反的,牠們的表達方式乃是對體型比牠們小得多的雌龜進行騷擾。也就是說,一隻雄龜會花三到四天的時間一直跟著雌龜,不斷嘗試騎上牠的背進行交配,並且舉止有些粗暴。

吉布斯說:「雄龜會阻止雌龜的日常活動與進食,但這是否是牠們用來耗損雌龜意志的策略之一,我們並不曉得。」

加拉巴哥象龜與其他的爬蟲類動物一樣,牠們的泄殖腔在尾巴的底部(排泄與生殖共用一個出口)。雄龜透過將泄殖腔的襯裡外翻,使陰莖露出,並且將之插入雌龜的泄殖腔以達成授精的目的。這個行動需要雌龜的配合才能完成,因為雌龜需要將尾巴伸出並往上舉,雄龜的陰莖才有辦法進入雌龜的泄殖腔。

吉伯斯說:「陸龜的交配行為值得一看」,他補充說,雄龜將會花10至20分鐘的時間進行交配行為,在此同時也會發出巨大的呻吟聲,這聲音甚至可以傳到幾英里之外。

在交配之後,雌龜可將精液保存在體內至少七年之久,以便未來使用。
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