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

question 22

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

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Definitions:

NPO

An instruction meaning "nil per os" or nothing by mouth, used to restrict oral intake of food and liquids, typically before surgery or certain medical tests.

Expiration Date

The date after which a product like food, medicine, or cosmetics is not recommended to be used.

Divisor

The number used to divide into another number.

Bracket

A support device used in construction and orthodontics, often made of metal, that holds objects together or attaches them to a surface.