Unique Island Animals at Greater Risk of Extinction

Unique Island Animals at Greater Risk of Extinction¹

Biologists who study evolution have always been interested in animals that developed on islands.

In some situations, animals on islands changed over time and came to look very different from the same species that lived on the mainland.

The experts point to animals such as the dwarf² elephant that once lived on the Mediterranean³ island of Cyprus. The animal is now extinct. When it lived, however, it was only the size of a small horse. Elephants that live today in Africa and Asia are much larger than that.

In the West Indies, researchers found a giant rodent⁴ that looked like a rat. However, it was about the same size as an American black bear. Rats are, of course, many times smaller than a bear.

Evolutionary⁵ experts came to call this phenomenon "the island effect." They used this term to describe the fact that animals who normally have small bodies "upsize" on an island, while the opposite is true for animals who usually have large bodies.

The "island effect" produces odd-sized animals because large animals require more food than small animals. On an island, there is a limited amount of food. As a result, larger animals become smaller over generations in order to survive with lower food intake⁶.

For small animals, there is not as much risk from predators⁷ on an island, so they often grow larger.

Recently, researchers released their findings about 1,231 existing animals and 350 extinct ones that represent 23 million years of life. They found that animals on islands were more at risk of extinction compared to their relatives on the mainland. The arrival of human settlers increased the extinction risk for these odd animals.

Roberto Rozzi is a paleoecologist at Martin Luther University Halle-Wittenberg in Germany. He was the lead author of the study, published in the journal Science.

Rozzi said he and the other researchers concluded that the "extinction curve ... has become even steeper in recent decades."

The researchers call islands "biodiversity hot spots." Even though they only make up 7 percent of the Earth's land mass, they account for 20 percent of the land species.

Two island countries, the Philippines and Indonesia, in southeast Asia have a large number of unique animals.

The Philippine island of Mindoro has a buffalo⁸ that is only 21 percent of the size of its mainland relatives. The spotted⁹ deer on the islands of Panay and Negros are just 26 percent the size of those on the mainland.

Indonesia's island of Flores is also a laboratory for the "island effect," which is sometimes called Foster's rule. J. Bristol Foster was an animal researcher of the 1960s.

Flores was once home to small elephants, giant rats and a kind of giant stork¹⁰. There was even a very small human species once living on the island called homo floresiensis that was about 106 centimeters tall. That human species was later called "The Hobbit," and it died out about 50,000 years ago.

Katie Lyons co-authored the study. She is a paleoecologist at the University of Nebraska in Lincoln.

She called the island animals "weird¹¹ and wonderful." However, she noted¹² that many of those animals are already extinct, and of the ones that are still alive, about 50 percent are at risk of dying out.

She and the other researchers said the speed of island extinctions started increasing 100,000 years ago.

They said humans played a large part in extinctions. The report noted humans hurt the ecosystem¹³ that supported the unique animals, hunted them, destroyed their living spaces, and brought disease and unwanted invasive species. Even a species that came before humans – homo erectus – hurt the island animals.

Jonathan Chase of the German Centre for Integrative Biodiversity Research also worked on the report. He said the researchers cannot be 100 percent certain all of the extinctions came because of human involvement, because there were other things happening at the same time on the islands.

However, he said, "extinction rates increased dramatically after the arrival of modern humans." He pointed¹⁴ to the elephants on Cyprus as an example and said they were likely overhunted. He said before humans arrived, there may have only been "a few hundred ... and it didn't take long for them to disappear."

Words in This Story

evolution –n. the process by which changes in plants and animals happen over time

unique –adj. used to say that something or someone is unlike anything or anyone else

species –n. a group of animals or plants that are similar and can produce young animals or plants : a group of related animals or plants that is smaller than a genus

extinct –adj. no longer existing

odd –adj. happening in a way that is not planned or regular, different from what is expected

phenomenon –n. something unusual that is difficult to explain

curve –n. a curved line on a graph that shows how something changes or is affected¹⁵ by one or more conditions

steep –adj. rising or falling sharply, a line or a road that goes almost straight up

invasive –adj. tending to spread

dramatically –adv. sudden or extreme

1 extinction   

n.熄灭，消亡，消灭，灭绝，绝种

参考例句：

• The plant is now in danger of extinction.这种植物现在有绝种的危险。
• The island's way of life is doomed to extinction.这个岛上的生活方式注定要消失。

2 dwarf   

n.矮子，侏儒，矮小的动植物；vt.使…矮小

参考例句：

• The dwarf's long arms were not proportional to his height.那侏儒的长臂与他的身高不成比例。
• The dwarf shrugged his shoulders and shook his head. 矮子耸耸肩膀，摇摇头。

3 Mediterranean   

adj.地中海的；地中海沿岸的

参考例句：

• The houses are Mediterranean in character.这些房子都属地中海风格。
• Gibraltar is the key to the Mediterranean.直布罗陀是地中海的要冲。

4 rodent   

n.啮齿动物；adj.啮齿目的

参考例句：

• When there is a full moon,this nocturnal rodent is careful to stay in its burrow.月圆之夜，这种夜间活动的啮齿类动物会小心地呆在地洞里不出来。
• This small rodent can scoop out a long,narrow tunnel in a very short time.这种小啮齿动物能在很短的时间里挖出一条又长又窄的地道来。

5 evolutionary   

adj.进化的；演化的，演变的；[生]进化论的

参考例句：

• Life has its own evolutionary process.生命有其自身的进化过程。
• These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。

6 intake   

n.吸入，纳入；进气口，入口

参考例句：

• Reduce your salt intake.减少盐的摄入量。
• There was a horrified intake of breath from every child.所有的孩子都害怕地倒抽了一口凉气。

7 predators   

n.食肉动物( predator的名词复数 )；奴役他人者（尤指在财务或性关系方面）

参考例句：

• birds and their earthbound predators 鸟和地面上捕食它们的动物
• The eyes of predators are highly sensitive to the slightest movement. 捕食性动物的眼睛能感觉到最细小的动静。 来自《简明英汉词典》

8 buffalo   

n.(北美)野牛；(亚洲)水牛

参考例句：

• Asian buffalo isn't as wild as that of America's. 亚洲水牛比美洲水牛温顺些。
• The boots are made of buffalo hide. 这双靴子是由水牛皮制成的。

9 spotted   

adj.有斑点的，斑纹的，弄污了的

参考例句：

• The milkman selected the spotted cows,from among a herd of two hundred.牛奶商从一群200头牛中选出有斑点的牛。
• Sam's shop stocks short spotted socks.山姆的商店屯积了有斑点的短袜。

10 stork   

n.鹳

参考例句：

• A Fox invited a long-beaked Stork to have dinner with him.狐狸请长嘴鹳同他一起吃饭。
• He is very glad that his wife's going to get a visit from the stork.他为她的妻子将获得参观鹳鸟的机会感到非常高兴。

11 weird   

adj.古怪的，离奇的；怪诞的，神秘而可怕的

参考例句：

• From his weird behaviour,he seems a bit of an oddity.从他不寻常的行为看来，他好像有点怪。
• His weird clothes really gas me.他的怪衣裳简直笑死人。

12 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

13 ecosystem   

n.生态系统

参考例句：

• This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
• We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。

14 pointed   

adj.尖的，直截了当的

参考例句：

• He gave me a very sharp pointed pencil.他给我一支削得非常尖的铅笔。
• She wished to show Mrs.John Dashwood by this pointed invitation to her brother.她想通过对达茨伍德夫人提出直截了当的邀请向她的哥哥表示出来。

15 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。