原题
Herpetology: A Tale of Two Lizards
Herpetologists have closely studied the interaction between two species of lizards—the native green anole (Anolis carolinensis) and the invasive brown anole (Anolis sagrei)—in the southeastern United States. Although the two species are similar in size, they occupy different vertical zones: green anoles are found in the tree canopy (treetops), while brown anoles dominate ground-level habitats.
Initially, this vertical separation was interpreted as a natural habitat preference, but further research suggests that it is a defensive response by green anoles to avoid direct competition. Scientists now believe that green anoles were displaced upward due to aggressive territorial behavior by brown anoles. One theory proposes that this forced shift has triggered rapid evolutionary changes in green anoles. Researchers have documented the development of larger toe pads and more lamellae—microscopic scales that enhance grip—allowing green anoles to navigate thinner branches more effectively.
Meanwhile, brown anoles have adapted as well, showing changes in limb length and body coloration in response to new environments and predators. In one Florida study, brown anoles exposed to higher predation developed shorter limbs, which may improve maneuverability in dense vegetation. These findings reveal how competitive pressure can reshape species behavior and morphology within just a few generations, offering a real-time glimpse into evolutionary change.
The passage indicates that studies of the relationship between green anoles and brown anoles are valuable for which of the following reasons?
AThey suggest a way to reduce the harmful effects of invasive species.
BThey allow researchers to witness evolutionary mechanisms at work.
CThey show that adaptations take much longer than previously thought.
DThey provide a glimpse of the complex interplay between predators and prey.
正确答案：B
解题思路
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