Trees don’t last forever. For a forest to persist, seedlings must grow to replace the oldest plants, but a forest with lots of shade is not a friendly place for a seedling. So trees need help getting their seeds to better locations where they can grow. Zoochory, seed transport by animals, is a popular solution. Trees can wrap their seeds into fleshy fruits and the unit, called a diaspore, can then be plucked by an animal in search of a meal. Hikori Sato examined how important these relationships with animals are, by studying the relationship between Eulemur fulvus, the brown lemur, and two trees, Astrotrichilia asterotricha and Abrahamia deflexa.

A montage of a four images. A brown lemur in the twilight, looking annoyed that it's been spotted. Some light green spherical fruits and some brown slightly squashed spherical fruits. At the right are some saplings that look like very small green plants that a herbivore might like to eat.
Study subjects. (a) The common brown lemur (Eulemur fulvus) feeding in a fruiting canopy of Astrotrichilia asterotricha. (b) Fruits covered with a hard shell and small seeds of Astrotrichilia asterotricha. (c) Seedling of Astrotrichilia asterotricha with phanerocotylar epigeal foliaceous cotyledons. (d) Fruits of Abrahamia deflexa. (e) Cryptocotylar hypogeal seedling of Abrahamia deflexa with reserve-storage cotyledons. Image Sato 2022.

Sato carried out a survey in Ankarafantsika National Park in northwestern Madagascar. Here he staked out Astrotrichilia asterotricha, a tree that fruits in the dry season, and Abrahamia deflexa, which fruits in the wet season. Before fruiting began, he carefully chose the trees whose crowns had the best visibility for fruit and then set up watch.