In the Course of Observing Cacti from Several Islands, Researchers

question 8

Multiple Choice

In the course of observing cacti from several islands, researchers noted that on islands where cacti had been grazed by cows, they developed more spines per plant. This example shows that

• A) neither cacti nor cows are native to these islands.
• B) cows are not discouraged from eating spiny plants.
• C) herbivory can be a selective force.
• D) cacti on islands without cows are unable to produce spines.

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Definitions:

Microbial Species

A group of microorganisms, such as bacteria, archaea, fungi, and protists, that share similar genetic characteristics and are distinct from other groups.

Horizontal Gene Transfer

The swapping of genetic material in single or multiple-celled organisms through mechanisms that bypass the "vertical" passing down of DNA from ancestor to descendant.

Phylogenetic Species Concept

A concept in biology that defines a species based on the smallest group of individuals that share a common ancestor, representing one branch on the tree of life.

Adaptation

The process by which a species becomes better suited to its environment through the development of physical, behavioral, or physiological changes.