Seed Dispersal and Habitat Fragmentation | HHMI BioInteractive – Danny Schmidt (2017)

Forests are under intense pressure. In the tropical forests, between 50-90 % of the canopy trees depend on animals for seed dispersal. Even in temperate forests animals such as deer, moose, boar and even bears disperse seeds. Today due to hunting for bush meat many tropical forests are becoming depleted of their seed dispersers.

Here in this HHMI documentary, the researchers Andres Link and Carolina Urbina Malo of Los Andes University in Colombia in Colombia track brown spider monkeys to understand which plant seeds they are dispersing. Plant-animal interactions have been extremely effective in shaping life around us. Animal-mediated seed dispersal can take many diverse forms. One quite unexpected way for instance is to use dung beetles. Researchers in this documentary also use dung beetles to detect the location of the brown spider monkey scats. Understanding the monkeys’ seed dispersal roles in the forest helps to predict which plants will be most affected by human induced forest fragmentation. Once the seeds have been characterized in monkey scats, researchers and their colleagues germinate and replant them to create corridors between isolated patches of forest.

Modern day tropical forests have lost their megafauna through an evolutionary time period know as the Pleistocene extinction. Many tropical trees still carry striking fruit characteristics as an adaptation to the long-dead megafauna These trees produce fruits with protected seeds which can only germinate when the hard shells are broken open by large animals. A prominent tropical biologist Daniel H. Janzen suggested that gomphotheres (extinct elephant-like animals) may have previously been responsible for the dispersal of many such seeds. With their extinction, many tropical trees such as Spondias mombin (Anacardiaceae) became threatened suffering from an extremely limited ability to migrate.