话题二十 自然生态
A
[2019·太原市高三阶段性测评]
Where there are humans, there are house sparrows. But despite their suggestive species name, Passer domesticus, they aren't officially domesticated. The bold, tiny and gray-and-brown birds are
found on every continent except Antarctica, hopping around cities, pecking(啄)at leftover food on sidewalks, and sometimes chasing away native bird species. The house sparrows have adapted to living alongside humans, but this friendly behavior to humans is legendary. No one knew what set them apart from the other wild members of the sparrow family.
Looking for a genetic explanation, Mark Ravinet, an evolutionary biologist and his colleagues caught dozens of sparrows at sites across Europe. They set up mist nets that harmlessly trapped the birds as they flew inside — measured and tagged the birds, drew blood samples, and then released them. Back in the lab, they sequenced the birds' DNA. They found that the house sparrow's genes of many regions appeared to have experienced positive selection, helping the birds live alongside humans. The evolutionary process of natural selection may have favored genetic changes that altered their skull shape and allowed them to eat food with starch (淀粉) — similar to domesticated animals like dogs. The most significant sign of positive selection in the birds' DNA was found in a region with two known genes: one is linked to skull development and another helps create the amylase(淀粉酶), which helps break down starch in humans, dogs and other domesticated animals. Changes to both genes might have helped the house sparrows eat human-cultivated foods.
Another evolutionary biologist Samuel Andrew says the work is an exciting new step for bird researchers that could answer many questions about how sparrow species adapted to different conditions. But he and Ravinet agree there may be changes to other genes that were missed in this initial analysis, yet still helped the birds take advantage of humans.
“If you live in a major city, there are more animals around you than you realize，” Ravinet says. “They have a history and a story to tell.”
体裁：说明文 题材：自然 主题：家雀的基因与进化
【文章大意】 本文是一篇说明文。通过积极的基因选择，家雀适应了现在的生存环境。
【难句分析】 No one knew what set them apart from the other wild members of the sparrow family.
分析：本句是一个主从复合句，其中包含一个what引导的宾语从句，作knew的宾语，what在从句中作主语。
译文：没有人知道是什么把它们和麻雀家族的其他野生成员区分开来。
1．What do we know about the house sparrows from Paragraph 1?
A．They are domesticated. B．They are very friendly. C．They are well-adapted.
D．They are a rare species.
答案与解析：C 考查推理判断。根据第一段中的“The bold，tiny... on sidewalks”和“The house sparrows have adapted to living alongside humans”可推知，家雀的适应能力很强。
2．What is the purpose of Ravinet's research?
A．To experience positive selection.
B．To confirm the species name of house sparrows.
C．To compare house sparrows with other domestic animals. D．To genetically explain house sparrows' friendly behavior. 答案与解析：D 考查推理判断。根据第一段中的“but this friendly behavior to humans is legendary.No one knew what set them apart from the other wild members of the sparrow family”及第二段第一句中的“Looking for a genetic explanation”可推知，Ravinet的研究的目的是想从基因上解释家雀具有友好行为的原
因。
3．Why is the amylase important to genetic change? A．Because it helps digest starch. B．Because all animals can create it.
C．Because it promotes skull development. D．Because it can sequence animals' DNA.
答案与解析：A 考查细节理解。根据第二段中的“which helps break down... eat human-cultivated foods”可知，这种淀粉酶对基因改变重要的原因是它有助于消化淀粉。
4．What can we conclude from the text?
A．House sparrows' history is legendary.
B．House sparrows take advantage of humans. C．The skull shape determines animals' evolution.
D．Positive selection in DNA leads to biological evolution. 答案与解析：D 考查推理判断。根据第二段中的“They found that the house sparrow's genes of many regions appeared to have experienced positive selection... similar to domesticated animals like dogs”和倒数第二段中的“the work is an exciting new step for bird researchers that could answer many questions about how sparrow species adapted to different conditions”可推知，积极的基因选择会引起生物的进化。
B
[2019·安徽示范高中高三考试试题]
Have you ever wondered when dogs first became “man's best friend” and the world's favourite pet? If you have, then you're not alone. When and where dogs first began living side by side with humans are questions that have stirred hot debate among scientists. There are a few hard facts that all agree on. These include that dogs were once wolves and they were the first animal to be domesticated(驯养) by humans. They came into human lives some 15,000 years ago, before the dawn of agriculture.
Beyond that, there is little agreement. The earliest bones found
that are unquestionable dogs' and not wolves' date from 14,000 years ago. However, 30,000-year-old skulls have been discovered in
France and Belgium that are not pure wolves' and some scientists think could be dogs'.
With such puzzling evidence, many scientists are now turning to DNA to find out when and where dogs were first domesticated. In one research project, tens of thousands of blood samples have been taken from street dogs around the world. The plan is to compare them with those of wolves. It's even possible to analyse DNA from ancient bones. Tiny pieces of the 30,000-year-old skulls mentioned
earlier are currently being studied, and another DNA study has already shown that ancient dogs preserved in the Alaskan ice fields evolved from Asian wolves, not American ones.
Indeed, the ancient DNA may turn out to be more informative than the DNA of living dogs. Because dogs have accompanied humans around the world for thousands of years, their current distribution may tell us very little of their origins. This is why different groups of scientists believe that dogs variously originated in eastern Asia, Mongolia, Siberia, Europe or Africa.
But why were the animals domesticated in the first place? The most recent theory is that dogs domesticated themselves, initially living in and around our ancient villages to eat any food thrown out. Today, this is a way of life still shared by three quarters of a billion unowned dogs worldwide.
体裁：说明文 题材：人与动物 主题：狗是什么时候成为人类的朋友的
【文章大意】 本文是一篇说明文。研究发现，狗是从狼驯养而来的，早在一万五千年之前狗就进入了我们的生活。科学家通过分析DNA去查证狗最初是在何时何地被驯养的。
【难句分析】 When and where dogs first began living side by side with humans are questions that have stirred hot debate among scientists.
分析：该句为主从复合句。句中“When and where dogs first began living side by side with humans”为when和where引导的主语从句；“that have stirred hot debate among scientists”为that引导的定语从句，修饰先行词“questions”，that在从句中作主语。
译文：狗是何时何地初次开始与人类共同生活的，这个问题在科学家中引起了激烈的讨论。
5．Which is the only statement generally agreed on by scientists studying dogs?
A．Dogs originally were used as farm animals. B．Dogs evolved from wolves found in Europe. C．Dogs helped the development of agriculture. D．Dogs were the first animal to be kept as pets. 答案与解析：D 考查细节理解。根据第一段第一句“Have you ever wondered when dogs first became‘man's best friend’and the world's favourite pet？”，再结合倒数第二句可知，狗是第一种被人类驯养成宠物的动物，故D项正确。
6．Why does the writer first mention the 30,000-year-old
animals' skulls?
A．To show that dogs were much larger in the past. B．To prove that dogs developed from Asian wolves. C．To suggest that dogs may have evolved much earlier. D．To argue that dogs were first kept in France and Belgium. 答案与解析：C 考查推理判断。根据第二段第三句“However,30,000-year-old skulls have been discovered in France
and Belgium that are not pure wolves' and some scientists think could be dogs'”可知，在法国和比利时已经发现了3万年前的头骨，它们不完全是狼的，科学家认为有一些可能是狗的。据此可推知，该处提及三万年前的头骨旨在说明狗的进化历史更早，故C项正确。
7．How did scientists determine the origins of the ancient dogs found in Alaska?
A．By analyzing the age of their bones. B．By examining the animals' DNA. C．By studying the shape of their skulls. D．By comparing them with modern dogs.
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