36套EXE21第10求解

迷途的米兔

One of the questions of interest in the study of the
evolution of spiders is whether the weaving of orb webs
evolved only once or several times. About half the
35,000 known kinds of spiders make webs; a third of the
web weavers make orb webs. Since most orb weavers
belong either to the Araneidae or the Uloboridae
families, the origin of the orb web can be determined
only by ascertaining whether the families are related.
Recent taxonomic analysis of individuals from both
families indicates that the families evolved from different
ancestors, thereby contradicting Wiehle‘s theory. This
theory postulates that the families must be related, based
on the assumption that complex behavior, such as web
building, could evolve only once. According to Kullman,
web structure is the only characteristic that suggests a
relationship between families. The families differ in
appearance, structure of body hair, and arrangement
of eyes. Only Uloborids lack venom glands. Further
identification and study of characteristic features will
undoubtedly answer the question of the evolution of
the orb web.

10. Which of the following statements, if true, most
weakens Wiehle‘s theory that complex behavior
could evolve only once?
(A) Horses, introduced to the New World by the
Spaniards, thrived under diverse climatic
conditions.
(B) Plants of the Palmaceae family, descendants of
a common ancestor, evolved unique seed
forms even though the plants occupy similar
habitats throughout the world.
(C) All mammals are descended from a small,
rodentlike animal whose physical characteris-
tics in some form are found in all its descen-
dants.
(D) Plants in the Cactaceae and Euphorbiaceae
families, although they often look alike and
have developed similar mechanisms to meet
the rigors of the desert, evolved indepen-
dently.
(E) The Cuban anole, which was recently intro-
duced in the Florida wilds, is quickly
replacing the native Florida chameleon
because the anole has no competitors.


答案是D
虽然其他看起来也不对，但是不明白为什么选这个

普渡哥

Wiehle‘s theory 是说the family must be related. D 如果对的话，就可以否认了。

cynchen108

Recent taxonomic analysis of individuals from both
families indicates that the families evolved from different
ancestors, thereby contradicting Wiehle‘s theory.

两种蜘蛛--有相似的特征--但不同源--与Wiehle's theory相矛盾。
即两种**--独立进化--却产生相似结果--的事实 weakens Wiehle's theory。

迷途的米兔

Recent taxonomic analysis of individuals from both
families indicates that the families evolved from different
ancestors, thereby contradicting Wiehle‘s theory.

两种蜘蛛--有相似的特征--但不同源--与Wiehle's theory相矛盾。
即两种**--独立进化--却产生相似结果--的事实 weakens Wiehle's theory。

-- by 会员 cynchen108 (2011/11/18 11:58:47)

谢谢哦！
误会了，老是关注后面那段Thistheory postulates that the families must be related, based
on the assumption that complex behavior, such as web
building, could evolve only once.