How well animals help plants by dispersing seeds can depend on the animal’s personality

Rafał Zwolak and Andrew Sih

Personalities are not exclusively a human trait. Animals, from insects to primates, also show consistent behavioral tendencies. Even within the same species, some individuals are bolder and others more cautious; some are more and others less social; some are very active and others rather idle. These differences are likely to influence a multitude of important ecological processes. We argue that seed dispersal is one of them.

Hypothetical trade-offs involved in seed dispersal by (A) bolder and (B) more cautious individuals, illustrated with an example of a seed caching squirrel. Red boxes denote animal decisions that are likely unfavorable to plants; green boxes denote favorable ones. Size of the boxes reflects relative probability of a given decision for bold vs. shy animals. Illustration credit: Emily Underwood.
Hypothetical trade-offs involved in seed dispersal by (A) bolder and (B) more cautious individuals, illustrated with an example of a seed caching squirrel. Red boxes denote animal decisions that are likely unfavorable to plants; green boxes denote favorable ones. Size of the boxes reflects relative probability of a given decision for bold vs. shy animals. Illustration credit: Emily Underwood.

Plants are rooted in place and can travel only as seeds. Still, even seeds cannot roam on their own. Animals, on the other hand, are notoriously mobile: they run, fly, swim, slither, and move in many other ways. So, many plant species use animals as carriers of their seeds, paying for transportation by producing nutritious fruits or seeds that can be stored for times of scarcity (think of acorns). As a consequence, how animal seed dispersers move, where they put seeds and in what condition determines the abundance and distribution of future plant generations. Personalities affect all these processes. Importantly, seed transportation by animals with different behavioral tendencies creates distinctive trade-offs. For instance, shy animals might be more likely to carry fruits away for consumption in safe spots, which can lead to longer travel distances. However, safe places are often in dense cover, so plants growing from these seeds will face scarcity of light and many competitors. Bold animals, while less likely to move seeds away, can place them in more open sites, where new plants have higher chances of survival and growth. Moreover, different behavioral tendencies are often linked together into so-called “behavioral syndromes”. As an example, bold animals tend to be more active than shy ones. These linkages can create unexpected connections between different decisions that are involved in seed dispersal, such as how far to travel, which fruit to choose, and where to eat them.

Taking into account animal personalities can improve our understanding of seed dispersal, but there is very little research combining these topics. To encourage more studies, we review existing evidence, propose mechanisms linking animal personalities and seed dispersal, and outline theoretical expectations for future studies to test.

Read the paper in full here.

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