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  3. The opposite of adaptive divergence is an interesting and fairly common expr

The opposite of adaptive divergence is an interesting and fairly common expr

游客2025-05-07  78
问题     The opposite of adaptive divergence is an interesting and fairly common expression of evolution. Whereas related groups of organisms take on widely different characters in becoming adapted to unlike environments in the case of adaptive divergence. We find that Unrelated groups of organisms exhibit adaptive convergence when they spot similar modes of life or become suited for special sorts of environments.  For example, invertebrate marine animals living firmly attached to the sea bottom or to some foreign object tend to develop a sub- cylindrical or conical form. This is illustrated by coral individuals, by many sponges, and even by the diminutive tubes of bryozoans. Adaptive convergence in taking this coral-like form is shown by some brachiopods and pelecypods that grew in fixed position. More readily appreciated is the streamlined fitness of most fishes for moving swiftly through water; they have no neck, the contour of the body is smoothly curved so as to give minimum resistance, and the chief propelling organ is a powerful tail fin. The fact that some fossil reptiles (ichthyosaurs) and modem mammals (whales, dolphins) are wholly fishlike in form is an expression of adaptive convergence, for these air-breathing reptiles and mammals, which are highly efficient swimmers, are not closely related to fishes.  Unrelated or distantly related organisms that develop similarity of form are sometimes designated as homeomorphs (having same form).  [br] Adaptive convergence and adaptive divergence are ______.
选项 A、manifestations of evolution
B、biological phenomena
C、ways in which plants and animals adjust to a common environment
D、demonstrated by brachiopods and pelecypods
答案 A
解析 适应性趋同现象和适应性趋异现象是进化的表现形式。根据第一句话，与适应性趋异现象相反的趋同现象是一种有趣而又相当常见的、与进化有关的表现形式。由此可以推断，趋异现象也是一种进化的表现形式。
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