Eighty Years Ago,a Predatory Crab Was Introduced to a Region

question 94

Multiple Choice

Eighty years ago,a predatory crab was introduced to a region it previously did not inhabit and began preying on a species of marine snail.A scientist was able to locate museum specimens of the snail's shells from prior to the crab's introduction and to compare their thickness-an important factor in how protective the shells are-to the thickness of shells from current snails.Based on the graphs of her results (shown here) ,what form of evolution/natural selection has taken place?

• A) nonadaptive evolution
• B) stabilizing selection
• C) directional selection
• D) diversifying selection
• E) neutral selection

---

Definitions:

High Barriers

Referring to the substantial obstacles that prevent new competitors from easily entering an industry or market.

Economic Profit

The financial gain achieved when revenues exceed the total opportunity costs, including both explicit and implicit costs.

Competitive Price-searcher

This term refers to a market situation where sellers have some control over the pricing of their products due to factors like brand differentiation and lack of perfect information among buyers.

Production Inefficiencies

Situations where resources are not used in the most cost-effective way, leading to waste and decreased output.