The functional guilds of dung beetles mediate secondary seed dispersal in a tropical savanna

Abstract

Seed dispersal is an ecosystem service of great importance and can be carried out in two ways: primary or secondary dispersal. Secondary seed dispersal occurs after seeds present in the dung of primary dispersers, mostly herbivorous vertebrates, have been displaced. Dung beetles are directly related to secondary seed dispersal and are almost entirely responsible for this type of dispersal. They can be classified in functional guilds according to the way they manipulate the resource, namely, as: endocoprids (nest and feed directly on the resource), paracoprids (dig tunnels and bury parts of the feces below or close to the resource), and telecoprids (remove a portion of the resource and bury it in tunnels). Here, we investigate how secondary seed dispersal above and below ground was affected by functional guild and dung beetle size in an important tropical savanna, the Brazilian Cerrado. Our main findings reveal that paracoprids perform horizontal dispersal of seeds above ground, and telecoprids are important for horizontal dispersal both above and below ground. Paracoprids and telecoprids act in a complementary way in seed dispersal. These two guilds are crucial for the maintenance of the ecosystem service of seed dispersal and can potentially contribute to the success and survival of seeds. Furthermore, dung beetles can favor the maintenance and conservation of essential plant species for the Cerrado through secondary seed dispersal. That could potentially increase the success of projects to restore areas with degraded soil in the biome.