Ecologists often build models to depict the relationships between organisms. In such models, an arrow is used to link two organisms in a relationship. The arrowhead is next to the organism that is affected. If the effect is positive, the arrow is labeled with (+), and if negative, then the label is (-). Which of the following models best illustrates the relationship of the Brazil nut tree and the other organisms associated with it?

Question

Quizplus · Accepted Answer

In model B, the arrow from the Brazil nut tree to the orchid is labeled with a (+), indicating a positive relationship. This relationship is known as mutualism because the orchid pollinates the Brazil nut tree and in return receives a place to grow. The arrow from the Brazil nut tree to the agouti is labeled with a (-), indicating a negative relationship. This relationship is known as predation because the agouti eats the Brazil nut tree's seeds. The other models either do not show both positive and negative relationships or label them incorrectly.

Ecologists Often Build Models to Depict the Relationships Between Organisms