貓科動物的保護色

山東 趙 娜

物競天擇，適者生存。 在漫長的進化過程中，貓科動物也進化出了不同的保護色和自我保護模式。

難詞探意

1. camouflage /'k?m?flɑ??/ n. （動物的）保護色；保護形狀

2. diffusion /d?'fju??n/ n. 擴散；傳播

Many animals use camouflage to make them harder to see. Hunters do this so that the animals they want to eat don't see them and run away. And prey animals, such as deer and zebra, use camouflage to avoid being eaten. But why do large cats have such different patterns? Lions don't have any spots at all, but cheetahs （獵豹） have small black spots. While tigers have large black stripes and orange fur,leopards and jaguars （美洲豹） have much more complicated patterns of spots.

Will Allen at the University of Bristol is interested in this question. For his PhD in vision science, he decided to study large cats to try to find out the reasons for these different patterns. Will says that, to find the answer, he also needed to talk to scientists from many different fields, such as psychology, biology, engineering and computer science. Experts from each of these areas of science helped him with his work.

Earlier studies had shown that camouflage was more common among cats that lived in forests. But Will says that these studies didn't explain why a leopard's spots are different from a cheetah's spots,for example. He decided to use a mathematical technique called “reaction-diffusion”. This allowed him to play with different patterns on a computer screen and produce exact matches for different animals. In this way, he could compare camouflage patterns with the animals' behaviour and habitat much more accurately.

His results help to explain the differences. Will says that there is a clear connection between patterns and environment. Cats in forests with lots of trees and plants have more complicated patterns than cats which live in areas without lots of trees. And cats that spend more time in trees have more irregular patterns than cats that hunt at night. Will explains that a cat's camouflage depends on where it lives and how it hunts. Evolution has created the most suitable pattern for each particular hunter.Will's studies mean we can look at a big cat's fur and predict its habitat and lifestyle.

Decide if each statement is true （T） or false （F）.

（ ）1. Prey animals use camouflage to avoid being found by their enemies.

（ ）2. Will Allen referred to some experts in other fields besides vision science.

（ ）3. Early studies explained why leopards'spots are different from cheetahs'spots.

（ ）4. Will believes in the relationship between camouflage patterns and environment.

（ ）5. A big cat's fur might give away its living environment and how it lives.

Choose one word from the table using its proper form to complete each sentence.

1. Both hunters and ____________animals use camouflage because they don't want to be seen.

2. Will Allen wanted to understand why different large cats had different ____________on their fur.

3. He needed help from ____________in different fields such as biology and engineering.

4. Using “reaction-diffusion” allowed him to ____________animals' lifestyles and the patterns on their fur.

5. His research suggests that if there are lots of ____________in a cat's habitat, its camouflage patterns are more complicated.