60秒科学:A Little Yolk for Boys

When it comes to lizard¹ sex, size does matter. But not in the way you might think. Because in the June 4th online issue of the journal Current Biology, scientists say that for at least one type of lizard, larger eggs are more likely to make girls while smaller eggs yield boys.

For many animals, the sex of an individual is dictated² solely³ by its chromosomes⁴. But for small alpine⁵ lizards⁶, gender⁷ isn’t so cut-and-dried. The scientists had earlier found that nest temperature can influence the sex of lizard hatchlings. Cooler nests turn out more boys—no matter what their chromosomes say. At the same time, the researchers noticed that larger eggs seemed to make more daughters. But they wanted to put their observation to the test. So they took big eggs and removed some yolk⁸—and, voila, they made males. Adding yolk to a little egg was a recipe for a female.

This size manipulation might allow moms to balance their babies’ sexes when a chilly⁹ nest would otherwise produce mostly sons. Because when it comes to alpine lizards, sex determination all comes down to a practical yolk.

—Karen Hopkin

 

1 lizard   

n.蜥蜴，壁虎

参考例句：

• A chameleon is a kind of lizard.变色龙是一种蜥蜴。
• The lizard darted out its tongue at the insect.蜥蜴伸出舌头去吃小昆虫。

2 dictated   

v.大声讲或读( dictate的过去式和过去分词 )；口授；支配；摆布

参考例句：

• He dictated a letter to his secretary. 他向秘书口授信稿。
• No person of a strong character likes to be dictated to. 没有一个个性强的人愿受人使唤。 来自《简明英汉词典》

3 solely   

adv.仅仅，唯一地

参考例句：

• Success should not be measured solely by educational achievement.成功与否不应只用学业成绩来衡量。
• The town depends almost solely on the tourist trade.这座城市几乎完全靠旅游业维持。

4 chromosomes   

n.染色体( chromosome的名词复数 )

参考例句：

• Chromosomes also determine the sex of animals. 染色体也决定动物的性别。 来自《简明英汉词典》
• Each of four chromosomes divide longitudinally. 四种染色体的每一种都沿着纵向分裂。 来自《现代汉英综合大词典》

5 alpine   

adj.高山的；n.高山植物

参考例句：

• Alpine flowers are abundant there.那里有很多高山地带的花。
• Its main attractions are alpine lakes and waterfalls .它以高山湖泊和瀑布群为主要特色。

6 lizards   

n.蜥蜴( lizard的名词复数 )

参考例句：

• Nothing lives in Pompeii except crickets and beetles and lizards. 在庞培城里除了蟋蟀、甲壳虫和蜥蜴外，没有别的生物。 来自辞典例句
• Can lizards reproduce their tails? 蜥蜴的尾巴断了以后能再生吗？ 来自辞典例句

7 gender   

n.（生理上的）性，（名词、代词等的）性

参考例句：

• French differs from English in having gender for all nouns.法语不同于英语，所有的名词都有性。
• Women are sometimes denied opportunities solely because of their gender.妇女有时仅仅因为性别而无法获得种种机会。

8 yolk   

n.蛋黄，卵黄

参考例句：

• This dish would be more delicious with some yolk powder.加点蛋黄粉，这道菜就会更好吃。
• Egg yolk serves as the emulsifying agent in salad dressing.在色拉调味时，蛋黄能作为乳化剂。

9 chilly   

adj.凉快的，寒冷的

参考例句：

• I feel chilly without a coat.我由于没有穿大衣而感到凉飕飕的。
• I grew chilly when the fire went out.炉火熄灭后，寒气逼人。