Ecology: Herbivory and Its Types

Herbivory Definition and Types

• Herbivory is the consumption of plant material, a common antagonistic interaction in ecological systems.
• Herbivores can be divided into two broad categories: specialists and generalists.
• Specialist herbivores feed on one or a few plant species, while generalist herbivores have a broader diet.
• Examples of herbivores include Daphnia pulex, wildebeest, marine iguana, leaf-mining insect, and many others.

Herbivore Feeding Guilds

• Herbivores feed on different plant parts, including leaves, flowers, fruits, and seeds.
• Folivores, florivores, frugivores, and granivores are examples of herbivore feeding guilds.

Herbivory Impact on Plants and Ecosystems

• Herbivores form an important link in terrestrial and aquatic food webs, removing around 10% of net primary production.
• Herbivory can have a major impact on plants, but it often does not kill the plant.
• Herbivore exclusion experiments are used to investigate the effects of herbivores on plant individuals, populations, and communities.

Effects of Herbivory on Plant Fitness and Population

• Herbivory can affect plant fitness, reducing acorn production in oak trees, for example.
• Herbivory can also affect plant population growth rates through increased mortality or reproductive output.
• Herbivores can influence plant diversity by adding or removing species, or altering competitive interactions between plant species.

Herbivory and Ecosystem Structure

• Herbivores can have effects on the structure and diversity of plant communities, redistributing nutrients over large spatial scales.
• Herbivores can also impact the global climate by changing vegetation structure.

Plant Defense Strategies

• Plants adopt two strategies to cope with herbivory: resistance and tolerance.
• Resistance is the ability to prevent herbivore damage, while tolerance is the ability to mitigate the negative effects of herbivory.
• Anti-herbivore defenses can be structural, chemical, or biotic.

Anti-Herbivore Defenses

• Structural defenses include surface features that deter herbivores, such as hairy leaves or spines.
• Chemical defenses include a diverse range of compounds that prevent herbivores from feeding or affect them after ingestion.
• Biotic defenses involve mutualisms with other organisms, such as ants that protect acacia trees.
• Plants invest in defenses only when necessary, and may change their defense strategy over time or in response to herbivore attack.