野生蛇中首次发现单性生殖-凯发k8官网

 

researchers in the us caught pregnant females from two snake species and ³ analysed the litters.

 

that proved the north american pit ⁴ reproduced without a male, a phenomenon called facultative parthenogenesis（兼单性生殖） that has ⁵ been found only in captive species. 

 

scientists say the findings could change our understanding of animal reproduction and vertebrate evolution.

 

it was thought to be extremely rare for a normally sexual species to reproduce asexually.

 

first identified in domestic chickens, such "virgin births" have been reported in recent years in a few snake, shark, ⁶ and bird species.

 

crucially though, all such virgin births have occurred in ⁷, to females kept away from males.

 

virgin births in vertebrates in general have been viewed as "⁸ novelties", said warren booth, from the university of tulsa, oklahoma, us.

 

professor booth is lead author of a paper published in the royal society's biological letters that challenges this label.

 

he and his collaborators investigated virgin births in wild populations of two ⁹ separated and long-studied species of snake.

 

they captured pregnant copperhead and cottonmouth female pit-vipers from the field, where males were present.

 

the snakes gave birth, allowing the scientists to study the physical and ² characteristics of the litters.

 

of the 22 copperheads（铜斑蛇）, the scientists found one female that must have had a virgin birth. 

 

another single virgin birth occurred within the 37 cottonmouth litters.

 

"i think the frequency is what really shocked us," said prof booth.

 

"that's between 2.5 and 5% of litters produced in these populations may be resulting from parthenogenesis.

 

"that's quite ¹⁰ for something that has been considered an evolutionary novelty," he said.

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