Final answer:
A compound leaf gives a plant a selective advantage in avoiding herbivory through the production of toxic compounds, therefore deterring animals from consumption, and the ability to sacrifice part of the leaf while preserving the rest.
Step-by-step explanation:
The claim that a compound leaf gives a plant a selective advantage to avoid herbivory can be justified by understanding the different defense mechanisms plants use against herbivores. While some mechanisms involve mechanical defenses like thorns, or the release of strong odors to discourage herbivores, plants can also produce toxic compounds as a chemical defense. These toxic substances, which include tannins and polyacetylenes, deter animals from consuming them. In particular, compound leaves can contribute to this defense strategy by allowing the plant to sacrifice part of the leaf while preserving the rest, and in some cases, they may be associated with more complex chemical defenses.
For example, the foxglove produces digitalis, a compound that is highly toxic when ingested by animals. By evolving to produce such compounds, compound leaves enhance their defense capability, making them less appealing to herbivores. This allows the plant not only to survive but also to potentially recover from damage caused by herbivory or other environmental phenomena. The division of leaves into leaflets, as seen in compound leaves, means that herbivores might only consume small portions, reducing the overall impact on the plant and providing a significant survival advantage.