Abstract
The green plants of terrestrial ecosystems produce the largest part of the planet’s biomass and thereby form the
base for animal consumers.The interactions between terrestrial
plants, pollinators, herbivores, and animals from
higher trophic levels are so complex that only a fraction
of these interdependent networks has been elucidated to
date.Chemical cues guidemost of these interactions where
they serve numerous functions.This chapter highlights the
ecology of only a few plant-animal systems and the compounds
that are crucial for these interactions.
In plant interactions with other organisms, secondary
metabolites often serve as attractants, deterrents, nutrients,
toxins, or pigments. The extraordinarily high
numbers of secondary metabolites produced by plants
provides them with a large vocabulary to interact with
organisms on multiple trophic levels. Without a doubt,
there are many more compounds and functional roles still
to be discovered. Two general strategies for metabolite
production of plants can be observed in the examples
shown above. First, the constitutive production of defense
compounds or signals in specific tissues or developmental
stages affects interacting organisms like herbivores or pollinators.
Second, plant metabolites produced in response
to outside cues either defend the plant directly or serve as
signals to attract organisms of other trophic levels. Often,
one compound can interact with several levels of a multitrophic
system, which results in a high complexity. In its
natural environment, the plant is embedded in a multitude
of interactions on two and more trophic levels that
can be organ-specific for leaves, roots, stems, flowers, and
fruits.
Although our understanding of plant–animal interactions
has already much improved in the past decades, it is
still a major challenge to unravel these complex, interdependent
networks and to elucidate their ecological impact
on plants and their interacting organisms.
