日本科學(xué)家的研究發(fā)現(xiàn),，黑猩猩睪丸能產(chǎn)生的精子數(shù)量比大猩猩多200倍,，比猩猩多14倍。猩猩中傾向濫交的種類一般具有較大的睪丸,，而此次的研究最終證實它們也確實能產(chǎn)生更多的精子,。這一份研究已經(jīng)發(fā)表在《美國靈長類學(xué)雜志》(American Journal of Primatology)上。
研究人員原先認(rèn)為黑猩猩之所以擁有較大的睪丸,，可能是因為數(shù)只雄性黑猩猩之間需要互相競爭,，以便贏得雌性黑猩猩的芳心。因此它們必須產(chǎn)生更多的精子,，以便贏得競爭,。
此次，研究人員對生活在日本和印度尼西亞的黑猩猩、大猩猩和猩猩進(jìn)行了研究,。他們設(shè)法獲取了不同種類猩猩的睪丸組織切片,，并在顯微鏡下進(jìn)行分析，結(jié)果發(fā)現(xiàn)不同種類之間存在顯著差異,。
他們注意到產(chǎn)生精子的睪丸組織,，大猩猩的要比猩猩的和黑猩猩的薄很多。黑猩猩睪丸產(chǎn)生的精子數(shù)量超過猩猩的14倍,，而比大猩猩,，這種世界上現(xiàn)存最大的靈長類動物，則要多出更多,。 “我們的數(shù)據(jù)顯示,，黑猩猩一般可以產(chǎn)生比大猩猩多200倍的精子，”研究人員花本秀子解釋說,。對于這三種猩猩種類,，研究人員目前已經(jīng)確認(rèn)，其睪丸的大小和其產(chǎn)生精子的數(shù)量成正比,。
研究人員同時還宣稱此次的發(fā)現(xiàn)支持這樣一種理論,，即認(rèn)為產(chǎn)精能力直接關(guān)系到求偶競爭以及交配競爭中的地位和成敗。
之前的研究中提出這樣一種觀點,，認(rèn)為實行一夫多妻制的猩猩種類,，如大猩猩，睪丸較小,，因為它們一只雄性猩猩統(tǒng)治整個族群,，首領(lǐng)獨享與所有母猩猩的交配權(quán)。而在相對濫交的種類,，如黑猩猩中,，雄性個體之間將存在較為激烈的競爭，數(shù)只雄性黑猩猩將為博取一只雌性的交配權(quán)而相互競爭,。這種爭競機制被認(rèn)為正是驅(qū)動產(chǎn)精能力加強和睪丸變得更大的動因,，也因此能產(chǎn)生更多的精子。
然而在實際操作中,，猩猩的產(chǎn)精能力是很難進(jìn)行精確測量的,。 “通常，你要想獲取合適的樣本非常困難,，即使它們生活在動物園中也是一樣,。” 花本秀子女士說。“因此,，只能用睪丸重量或者睪丸/身體重量比來作為產(chǎn)精能力的指標(biāo),。”
在此之前，目視觀察已經(jīng)證實，相對自身體積,，黑猩猩擁有比其他種類猩猩更大的睪丸,，但不清楚這是否意味著它們能因此產(chǎn)生更多的精子。而這次的研究為這一說法提供了堅實的依據(jù),。（生物谷Bioon.com）
生物谷推薦原文出處：
American Journal of Primatology DOI: 10.1002/ajp.20930
A comparative study on testicular microstructure and relative sperm production in gorillas, chimpanzees, and orangutans
Hideko Fujii-Hanamoto1,*, Kiyoaki Matsubayashi2, Mayumi Nakano1, Hiroshi Kusunoki3, Tomoo Enomoto1
Keywords:Pongo pygmaeus;Gorilla gorilla;Pan troglodytes;testicular histology;relative sperm production
Abstract
We performed histological analyses for comparing testicular microstructure between the gorilla, chimpanzee, and orangutan. Testicular samples were obtained by autopsy or biopsy from 10 gorillas, 11 chimpanzees, and 7 orangutans from several zoos and institutes. The seminiferous epithelia were thick in the chimpanzee and orangutan but thin in the gorilla. Leydig cells in the interstitial tissue were abundant in the gorilla. The acrosomic system was extremely well developed in the orangutans. Our study reveals that the cycle of seminiferous epithelium in orangutan testis can be divided into ten stages, whereas that in human, chimpanzee, and gorilla testes can be divided into only six stages. Phylogenetic analyses of the number of divisions may indicate that the seminiferous epithelium of our common ancestor has changed since the orangutan diverged from it. Furthermore, we performed comparative analyses of testicular microstructure to estimate relative sperm production among these three animals, and proposed a new indicator (namely the spermatogenic index, SI) closely related to sperm production. The SI indicated that a chimpanzee usually produces about 223 times more sperm than a gorilla and about 14 times more than an orangutan. Our data demonstrate the significance of the SI for estimating sperm production, thus aiding our understanding of the reproductive strategy as well as testis weight and relative testis size in investigated primates.
