VOA慢速英语--研究发现雌性加州秃鹰可以在没有雄性的情况下繁殖

Study Finds Female California Condors² Can Reproduce without a Male

A new study suggests that female California condor¹ birds can reproduce without a male.

Researchers with the San Diego Zoo Wildlife Alliance said genetic³ tests confirmed the findings. The group said that two baby males, called chicks, that hatched in 2001 and 2009 from unfertilized eggs, were related to their mothers. But neither chick was related to a male.

The study was published last week in the Journal of Heredity. It is the first report of asexual reproduction in California condors.

Reproduction from an unfertilized egg can happen in other animals such as sharks and bees.

But in birds, it usually only takes place when females are not around males. In this case, each mother condor had bred with males before. The two mothers involved in the research had produced 34 chicks. Each was with a fertile male condor at the zoo when they produced the eggs without male help.

The researchers said they believe it is the first case of asexual reproduction in any bird species where the female had access to a mate.

Olivia Ryder leads genetics work for the San Diego Zoo Wildlife Alliance. She is also the study's co-writer. She said the findings raise questions about whether this kind of reproduction is happening in other species.

The non-profit Wildlife Alliance runs the San Diego Zoo and Safari⁴ Park. It has been involved in a California condor reproduction program that helped save the huge birds from disappearing.

California condors are the largest flying birds in North America. They used to be found throughout the West Coast. But only 22 remained in the 1980s when the U.S. government captured condors and placed them in zoos to increase their numbers. About 160 were raised at the San Diego Zoo and Safari Park.

There are now more than 500 California condors, including more than 300 that have been released into the wild in California, Arizona, Utah and Mexico.

The asexual reproduction was discovered a number of years ago. Testing of genetic material collected from condors, both living and dead, in reproduction programs and in the wild appeared to confirm the results.

The study tested 467 male California condors to find out if they were related to the two birds in question. None of them were found to have a genetic connection.

California condors can live up to 60 years. But the two male birds that hatched in 2001 and 2009 were not healthy. One was less than 2 years old when he died. The other lived less than eight years.

Words in This Story

hatch –v. to be born by coming out of an egg

asexual –adj. (scientific) of or relating to a kind of reproduction that does not involve the combining of male and female cells

access –n. the ability to get something, enter a place or meet someone

1 condor   

n.秃鹰；秃鹰金币

参考例句：

• The condor soars above the mountain heights.禿鹰翱翔于高山之上。
• A condor prepares to fly in Colombia.一只兀鹰在哥伦比亚准备振翅高飞。

2 condors   

n.神鹰( condor的名词复数 )

参考例句：

• What would our condors feed on if no one was in danger? 你不发生危险，那我们秃鹰吃啥呢？ 来自互联网
• Yo mama so fat she has been declared a natural habitat for Condors. Yomama是如此之肥，她被定为秃鹰的自然栖息地。 来自互联网

3 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

4 safari   

n.远征旅行(探险、考察)；探险队，狩猎队

参考例句：

• When we go on safari we like to cook on an open fire.我们远行狩猎时，喜欢露天生火做饭。
• They went on safari searching for the rare black rhinoceros.他们进行探险旅行，搜寻那稀有的黑犀牛。